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diff --git a/graphics/lodepng.cpp b/graphics/lodepng.cpp
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+++ b/graphics/lodepng.cpp
@@ -0,0 +1,6410 @@
+/*
+LodePNG version 20200306
+
+Copyright (c) 2005-2020 Lode Vandevenne
+
+This software is provided 'as-is', without any express or implied
+warranty. In no event will the authors be held liable for any damages
+arising from the use of this software.
+
+Permission is granted to anyone to use this software for any purpose,
+including commercial applications, and to alter it and redistribute it
+freely, subject to the following restrictions:
+
+    1. The origin of this software must not be misrepresented; you must not
+    claim that you wrote the original software. If you use this software
+    in a product, an acknowledgment in the product documentation would be
+    appreciated but is not required.
+
+    2. Altered source versions must be plainly marked as such, and must not be
+    misrepresented as being the original software.
+
+    3. This notice may not be removed or altered from any source
+    distribution.
+*/
+
+/*
+The manual and changelog are in the header file "lodepng.h"
+Rename this file to lodepng.cpp to use it for C++, or to lodepng.c to use it for C.
+*/
+
+#include "lodepng.h"
+
+#ifdef LODEPNG_COMPILE_DISK
+#include <limits.h> /* LONG_MAX */
+#include <stdio.h> /* file handling */
+#endif /* LODEPNG_COMPILE_DISK */
+
+#ifdef LODEPNG_COMPILE_ALLOCATORS
+#include <stdlib.h> /* allocations */
+#endif /* LODEPNG_COMPILE_ALLOCATORS */
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1310) /*Visual Studio: A few warning types are not desired here.*/
+#pragma warning( disable : 4244 ) /*implicit conversions: not warned by gcc -Wall -Wextra and requires too much casts*/
+#pragma warning( disable : 4996 ) /*VS does not like fopen, but fopen_s is not standard C so unusable here*/
+#endif /*_MSC_VER */
+
+const char* LODEPNG_VERSION_STRING = "20200306";
+
+/*
+This source file is built up in the following large parts. The code sections
+with the "LODEPNG_COMPILE_" #defines divide this up further in an intermixed way.
+-Tools for C and common code for PNG and Zlib
+-C Code for Zlib (huffman, deflate, ...)
+-C Code for PNG (file format chunks, adam7, PNG filters, color conversions, ...)
+-The C++ wrapper around all of the above
+*/
+
+/* ////////////////////////////////////////////////////////////////////////// */
+/* ////////////////////////////////////////////////////////////////////////// */
+/* // Tools for C, and common code for PNG and Zlib.                       // */
+/* ////////////////////////////////////////////////////////////////////////// */
+/* ////////////////////////////////////////////////////////////////////////// */
+
+/*The malloc, realloc and free functions defined here with "lodepng_" in front
+of the name, so that you can easily change them to others related to your
+platform if needed. Everything else in the code calls these. Pass
+-DLODEPNG_NO_COMPILE_ALLOCATORS to the compiler, or comment out
+#define LODEPNG_COMPILE_ALLOCATORS in the header, to disable the ones here and
+define them in your own project's source files without needing to change
+lodepng source code. Don't forget to remove "static" if you copypaste them
+from here.*/
+
+#ifdef LODEPNG_COMPILE_ALLOCATORS
+static void* lodepng_malloc(size_t size) {
+#ifdef LODEPNG_MAX_ALLOC
+  if(size > LODEPNG_MAX_ALLOC) return 0;
+#endif
+  return malloc(size);
+}
+
+/* NOTE: when realloc returns NULL, it leaves the original memory untouched */
+static void* lodepng_realloc(void* ptr, size_t new_size) {
+#ifdef LODEPNG_MAX_ALLOC
+  if(new_size > LODEPNG_MAX_ALLOC) return 0;
+#endif
+  return realloc(ptr, new_size);
+}
+
+static void lodepng_free(void* ptr) {
+  free(ptr);
+}
+#else /*LODEPNG_COMPILE_ALLOCATORS*/
+/* TODO: support giving additional void* payload to the custom allocators */
+void* lodepng_malloc(size_t size);
+void* lodepng_realloc(void* ptr, size_t new_size);
+void lodepng_free(void* ptr);
+#endif /*LODEPNG_COMPILE_ALLOCATORS*/
+
+/* convince the compiler to inline a function, for use when this measurably improves performance */
+/* inline is not available in C90, but use it when supported by the compiler */
+#if (defined(__STDC_VERSION__) && (__STDC_VERSION__ >= 199901L)) || (defined(__cplusplus) && (__cplusplus >= 199711L))
+#define LODEPNG_INLINE inline
+#else
+#define LODEPNG_INLINE /* not available */
+#endif
+
+/* restrict is not available in C90, but use it when supported by the compiler */
+#if (defined(__GNUC__) && (__GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 1))) ||\
+    (defined(_MSC_VER) && (_MSC_VER >= 1400)) || \
+    (defined(__WATCOMC__) && (__WATCOMC__ >= 1250) && !defined(__cplusplus))
+#define LODEPNG_RESTRICT __restrict
+#else
+#define LODEPNG_RESTRICT /* not available */
+#endif
+
+/* Replacements for C library functions such as memcpy and strlen, to support platforms
+where a full C library is not available. The compiler can recognize them and compile
+to something as fast. */
+
+static void lodepng_memcpy(void* LODEPNG_RESTRICT dst,
+                           const void* LODEPNG_RESTRICT src, size_t size) {
+  size_t i;
+  for(i = 0; i < size; i++) ((char*)dst)[i] = ((const char*)src)[i];
+}
+
+static void lodepng_memset(void* LODEPNG_RESTRICT dst,
+                           int value, size_t num) {
+  size_t i;
+  for(i = 0; i < num; i++) ((char*)dst)[i] = (char)value;
+}
+
+/* does not check memory out of bounds, do not use on untrusted data */
+static size_t lodepng_strlen(const char* a) {
+  const char* orig = a;
+  /* avoid warning about unused function in case of disabled COMPILE... macros */
+  (void)(&lodepng_strlen);
+  while(*a) a++;
+  return (size_t)(a - orig);
+}
+
+#define LODEPNG_MAX(a, b) (((a) > (b)) ? (a) : (b))
+#define LODEPNG_MIN(a, b) (((a) < (b)) ? (a) : (b))
+#define LODEPNG_ABS(x) ((x) < 0 ? -(x) : (x))
+
+#if defined(LODEPNG_COMPILE_PNG) || defined(LODEPNG_COMPILE_DECODER)
+/* Safely check if adding two integers will overflow (no undefined
+behavior, compiler removing the code, etc...) and output result. */
+static int lodepng_addofl(size_t a, size_t b, size_t* result) {
+  *result = a + b; /* Unsigned addition is well defined and safe in C90 */
+  return *result < a;
+}
+#endif /*defined(LODEPNG_COMPILE_PNG) || defined(LODEPNG_COMPILE_DECODER)*/
+
+#ifdef LODEPNG_COMPILE_DECODER
+/* Safely check if multiplying two integers will overflow (no undefined
+behavior, compiler removing the code, etc...) and output result. */
+static int lodepng_mulofl(size_t a, size_t b, size_t* result) {
+  *result = a * b; /* Unsigned multiplication is well defined and safe in C90 */
+  return (a != 0 && *result / a != b);
+}
+
+#ifdef LODEPNG_COMPILE_ZLIB
+/* Safely check if a + b > c, even if overflow could happen. */
+static int lodepng_gtofl(size_t a, size_t b, size_t c) {
+  size_t d;
+  if(lodepng_addofl(a, b, &d)) return 1;
+  return d > c;
+}
+#endif /*LODEPNG_COMPILE_ZLIB*/
+#endif /*LODEPNG_COMPILE_DECODER*/
+
+
+/*
+Often in case of an error a value is assigned to a variable and then it breaks
+out of a loop (to go to the cleanup phase of a function). This macro does that.
+It makes the error handling code shorter and more readable.
+
+Example: if(!uivector_resize(&lz77_encoded, datasize)) ERROR_BREAK(83);
+*/
+#define CERROR_BREAK(errorvar, code){\
+  errorvar = code;\
+  break;\
+}
+
+/*version of CERROR_BREAK that assumes the common case where the error variable is named "error"*/
+#define ERROR_BREAK(code) CERROR_BREAK(error, code)
+
+/*Set error var to the error code, and return it.*/
+#define CERROR_RETURN_ERROR(errorvar, code){\
+  errorvar = code;\
+  return code;\
+}
+
+/*Try the code, if it returns error, also return the error.*/
+#define CERROR_TRY_RETURN(call){\
+  unsigned error = call;\
+  if(error) return error;\
+}
+
+/*Set error var to the error code, and return from the void function.*/
+#define CERROR_RETURN(errorvar, code){\
+  errorvar = code;\
+  return;\
+}
+
+/*
+About uivector, ucvector and string:
+-All of them wrap dynamic arrays or text strings in a similar way.
+-LodePNG was originally written in C++. The vectors replace the std::vectors that were used in the C++ version.
+-The string tools are made to avoid problems with compilers that declare things like strncat as deprecated.
+-They're not used in the interface, only internally in this file as static functions.
+-As with many other structs in this file, the init and cleanup functions serve as ctor and dtor.
+*/
+
+#ifdef LODEPNG_COMPILE_ZLIB
+#ifdef LODEPNG_COMPILE_ENCODER
+/*dynamic vector of unsigned ints*/
+typedef struct uivector {
+  unsigned* data;
+  size_t size; /*size in number of unsigned longs*/
+  size_t allocsize; /*allocated size in bytes*/
+} uivector;
+
+static void uivector_cleanup(void* p) {
+  ((uivector*)p)->size = ((uivector*)p)->allocsize = 0;
+  lodepng_free(((uivector*)p)->data);
+  ((uivector*)p)->data = NULL;
+}
+
+/*returns 1 if success, 0 if failure ==> nothing done*/
+static unsigned uivector_resize(uivector* p, size_t size) {
+  size_t allocsize = size * sizeof(unsigned);
+  if(allocsize > p->allocsize) {
+    size_t newsize = allocsize + (p->allocsize >> 1u);
+    void* data = lodepng_realloc(p->data, newsize);
+    if(data) {
+      p->allocsize = newsize;
+      p->data = (unsigned*)data;
+    }
+    else return 0; /*error: not enough memory*/
+  }
+  p->size = size;
+  return 1; /*success*/
+}
+
+static void uivector_init(uivector* p) {
+  p->data = NULL;
+  p->size = p->allocsize = 0;
+}
+
+/*returns 1 if success, 0 if failure ==> nothing done*/
+static unsigned uivector_push_back(uivector* p, unsigned c) {
+  if(!uivector_resize(p, p->size + 1)) return 0;
+  p->data[p->size - 1] = c;
+  return 1;
+}
+#endif /*LODEPNG_COMPILE_ENCODER*/
+#endif /*LODEPNG_COMPILE_ZLIB*/
+
+/* /////////////////////////////////////////////////////////////////////////// */
+
+/*dynamic vector of unsigned chars*/
+typedef struct ucvector {
+  unsigned char* data;
+  size_t size; /*used size*/
+  size_t allocsize; /*allocated size*/
+} ucvector;
+
+/*returns 1 if success, 0 if failure ==> nothing done*/
+static unsigned ucvector_resize(ucvector* p, size_t size) {
+  if(size > p->allocsize) {
+    size_t newsize = size + (p->allocsize >> 1u);
+    void* data = lodepng_realloc(p->data, newsize);
+    if(data) {
+      p->allocsize = newsize;
+      p->data = (unsigned char*)data;
+    }
+    else return 0; /*error: not enough memory*/
+  }
+  p->size = size;
+  return 1; /*success*/
+}
+
+static ucvector ucvector_init(unsigned char* buffer, size_t size) {
+  ucvector v;
+  v.data = buffer;
+  v.allocsize = v.size = size;
+  return v;
+}
+
+/* ////////////////////////////////////////////////////////////////////////// */
+
+#ifdef LODEPNG_COMPILE_PNG
+#ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
+
+/*free string pointer and set it to NULL*/
+static void string_cleanup(char** out) {
+  lodepng_free(*out);
+  *out = NULL;
+}
+
+static char* alloc_string_sized(const char* in, size_t insize) {
+  char* out = (char*)lodepng_malloc(insize + 1);
+  if(out) {
+    lodepng_memcpy(out, in, insize);
+    out[insize] = 0;
+  }
+  return out;
+}
+
+/* dynamically allocates a new string with a copy of the null terminated input text */
+static char* alloc_string(const char* in) {
+  return alloc_string_sized(in, lodepng_strlen(in));
+}
+#endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
+#endif /*LODEPNG_COMPILE_PNG*/
+
+/* ////////////////////////////////////////////////////////////////////////// */
+
+#if defined(LODEPNG_COMPILE_DECODER) || defined(LODEPNG_COMPILE_PNG)
+static unsigned lodepng_read32bitInt(const unsigned char* buffer) {
+  return (((unsigned)buffer[0] << 24u) | ((unsigned)buffer[1] << 16u) |
+         ((unsigned)buffer[2] << 8u) | (unsigned)buffer[3]);
+}
+#endif /*defined(LODEPNG_COMPILE_DECODER) || defined(LODEPNG_COMPILE_PNG)*/
+
+#if defined(LODEPNG_COMPILE_PNG) || defined(LODEPNG_COMPILE_ENCODER)
+/*buffer must have at least 4 allocated bytes available*/
+static void lodepng_set32bitInt(unsigned char* buffer, unsigned value) {
+  buffer[0] = (unsigned char)((value >> 24) & 0xff);
+  buffer[1] = (unsigned char)((value >> 16) & 0xff);
+  buffer[2] = (unsigned char)((value >>  8) & 0xff);
+  buffer[3] = (unsigned char)((value      ) & 0xff);
+}
+#endif /*defined(LODEPNG_COMPILE_PNG) || defined(LODEPNG_COMPILE_ENCODER)*/
+
+/* ////////////////////////////////////////////////////////////////////////// */
+/* / File IO                                                                / */
+/* ////////////////////////////////////////////////////////////////////////// */
+
+#ifdef LODEPNG_COMPILE_DISK
+
+/* returns negative value on error. This should be pure C compatible, so no fstat. */
+static long lodepng_filesize(const char* filename) {
+  FILE* file;
+  long size;
+  file = fopen(filename, "rb");
+  if(!file) return -1;
+
+  if(fseek(file, 0, SEEK_END) != 0) {
+    fclose(file);
+    return -1;
+  }
+
+  size = ftell(file);
+  /* It may give LONG_MAX as directory size, this is invalid for us. */
+  if(size == LONG_MAX) size = -1;
+
+  fclose(file);
+  return size;
+}
+
+/* load file into buffer that already has the correct allocated size. Returns error code.*/
+static unsigned lodepng_buffer_file(unsigned char* out, size_t size, const char* filename) {
+  FILE* file;
+  size_t readsize;
+  file = fopen(filename, "rb");
+  if(!file) return 78;
+
+  readsize = fread(out, 1, size, file);
+  fclose(file);
+
+  if(readsize != size) return 78;
+  return 0;
+}
+
+unsigned lodepng_load_file(unsigned char** out, size_t* outsize, const char* filename) {
+  long size = lodepng_filesize(filename);
+  if(size < 0) return 78;
+  *outsize = (size_t)size;
+
+  *out = (unsigned char*)lodepng_malloc((size_t)size);
+  if(!(*out) && size > 0) return 83; /*the above malloc failed*/
+
+  return lodepng_buffer_file(*out, (size_t)size, filename);
+}
+
+/*write given buffer to the file, overwriting the file, it doesn't append to it.*/
+unsigned lodepng_save_file(const unsigned char* buffer, size_t buffersize, const char* filename) {
+  FILE* file;
+  file = fopen(filename, "wb" );
+  if(!file) return 79;
+  fwrite(buffer, 1, buffersize, file);
+  fclose(file);
+  return 0;
+}
+
+#endif /*LODEPNG_COMPILE_DISK*/
+
+/* ////////////////////////////////////////////////////////////////////////// */
+/* ////////////////////////////////////////////////////////////////////////// */
+/* // End of common code and tools. Begin of Zlib related code.            // */
+/* ////////////////////////////////////////////////////////////////////////// */
+/* ////////////////////////////////////////////////////////////////////////// */
+
+#ifdef LODEPNG_COMPILE_ZLIB
+#ifdef LODEPNG_COMPILE_ENCODER
+
+typedef struct {
+  ucvector* data;
+  unsigned char bp; /*ok to overflow, indicates bit pos inside byte*/
+} LodePNGBitWriter;
+
+static void LodePNGBitWriter_init(LodePNGBitWriter* writer, ucvector* data) {
+  writer->data = data;
+  writer->bp = 0;
+}
+
+/*TODO: this ignores potential out of memory errors*/
+#define WRITEBIT(writer, bit){\
+  /* append new byte */\
+  if(((writer->bp) & 7u) == 0) {\
+    if(!ucvector_resize(writer->data, writer->data->size + 1)) return;\
+    writer->data->data[writer->data->size - 1] = 0;\
+  }\
+  (writer->data->data[writer->data->size - 1]) |= (bit << ((writer->bp) & 7u));\
+  ++writer->bp;\
+}
+
+/* LSB of value is written first, and LSB of bytes is used first */
+static void writeBits(LodePNGBitWriter* writer, unsigned value, size_t nbits) {
+  if(nbits == 1) { /* compiler should statically compile this case if nbits == 1 */
+    WRITEBIT(writer, value);
+  } else {
+    /* TODO: increase output size only once here rather than in each WRITEBIT */
+    size_t i;
+    for(i = 0; i != nbits; ++i) {
+      WRITEBIT(writer, (unsigned char)((value >> i) & 1));
+    }
+  }
+}
+
+/* This one is to use for adding huffman symbol, the value bits are written MSB first */
+static void writeBitsReversed(LodePNGBitWriter* writer, unsigned value, size_t nbits) {
+  size_t i;
+  for(i = 0; i != nbits; ++i) {
+    /* TODO: increase output size only once here rather than in each WRITEBIT */
+    WRITEBIT(writer, (unsigned char)((value >> (nbits - 1u - i)) & 1u));
+  }
+}
+#endif /*LODEPNG_COMPILE_ENCODER*/
+
+#ifdef LODEPNG_COMPILE_DECODER
+
+typedef struct {
+  const unsigned char* data;
+  size_t size; /*size of data in bytes*/
+  size_t bitsize; /*size of data in bits, end of valid bp values, should be 8*size*/
+  size_t bp;
+  unsigned buffer; /*buffer for reading bits. NOTE: 'unsigned' must support at least 32 bits*/
+} LodePNGBitReader;
+
+/* data size argument is in bytes. Returns error if size too large causing overflow */
+static unsigned LodePNGBitReader_init(LodePNGBitReader* reader, const unsigned char* data, size_t size) {
+  size_t temp;
+  reader->data = data;
+  reader->size = size;
+  /* size in bits, return error if overflow (if size_t is 32 bit this supports up to 500MB)  */
+  if(lodepng_mulofl(size, 8u, &reader->bitsize)) return 105;
+  /*ensure incremented bp can be compared to bitsize without overflow even when it would be incremented 32 too much and
+  trying to ensure 32 more bits*/
+  if(lodepng_addofl(reader->bitsize, 64u, &temp)) return 105;
+  reader->bp = 0;
+  reader->buffer = 0;
+  return 0; /*ok*/
+}
+
+/*
+ensureBits functions:
+Ensures the reader can at least read nbits bits in one or more readBits calls,
+safely even if not enough bits are available.
+Returns 1 if there are enough bits available, 0 if not.
+*/
+
+/*See ensureBits documentation above. This one ensures exactly 1 bit */
+/*static unsigned ensureBits1(LodePNGBitReader* reader) {
+  if(reader->bp >= reader->bitsize) return 0;
+  reader->buffer = (unsigned)reader->data[reader->bp >> 3u] >> (reader->bp & 7u);
+  return 1;
+}*/
+
+/*See ensureBits documentation above. This one ensures up to 9 bits */
+static unsigned ensureBits9(LodePNGBitReader* reader, size_t nbits) {
+  size_t start = reader->bp >> 3u;
+  size_t size = reader->size;
+  if(start + 1u < size) {
+    reader->buffer = (unsigned)reader->data[start + 0] | ((unsigned)reader->data[start + 1] << 8u);
+    reader->buffer >>= (reader->bp & 7u);
+    return 1;
+  } else {
+    reader->buffer = 0;
+    if(start + 0u < size) reader->buffer |= reader->data[start + 0];
+    reader->buffer >>= (reader->bp & 7u);
+    return reader->bp + nbits <= reader->bitsize;
+  }
+}
+
+/*See ensureBits documentation above. This one ensures up to 17 bits */
+static unsigned ensureBits17(LodePNGBitReader* reader, size_t nbits) {
+  size_t start = reader->bp >> 3u;
+  size_t size = reader->size;
+  if(start + 2u < size) {
+    reader->buffer = (unsigned)reader->data[start + 0] | ((unsigned)reader->data[start + 1] << 8u) |
+                     ((unsigned)reader->data[start + 2] << 16u);
+    reader->buffer >>= (reader->bp & 7u);
+    return 1;
+  } else {
+    reader->buffer = 0;
+    if(start + 0u < size) reader->buffer |= reader->data[start + 0];
+    if(start + 1u < size) reader->buffer |= ((unsigned)reader->data[start + 1] << 8u);
+    reader->buffer >>= (reader->bp & 7u);
+    return reader->bp + nbits <= reader->bitsize;
+  }
+}
+
+/*See ensureBits documentation above. This one ensures up to 25 bits */
+static LODEPNG_INLINE unsigned ensureBits25(LodePNGBitReader* reader, size_t nbits) {
+  size_t start = reader->bp >> 3u;
+  size_t size = reader->size;
+  if(start + 3u < size) {
+    reader->buffer = (unsigned)reader->data[start + 0] | ((unsigned)reader->data[start + 1] << 8u) |
+                     ((unsigned)reader->data[start + 2] << 16u) | ((unsigned)reader->data[start + 3] << 24u);
+    reader->buffer >>= (reader->bp & 7u);
+    return 1;
+  } else {
+    reader->buffer = 0;
+    if(start + 0u < size) reader->buffer |= reader->data[start + 0];
+    if(start + 1u < size) reader->buffer |= ((unsigned)reader->data[start + 1] << 8u);
+    if(start + 2u < size) reader->buffer |= ((unsigned)reader->data[start + 2] << 16u);
+    reader->buffer >>= (reader->bp & 7u);
+    return reader->bp + nbits <= reader->bitsize;
+  }
+}
+
+/*See ensureBits documentation above. This one ensures up to 32 bits */
+static LODEPNG_INLINE unsigned ensureBits32(LodePNGBitReader* reader, size_t nbits) {
+  size_t start = reader->bp >> 3u;
+  size_t size = reader->size;
+  if(start + 4u < size) {
+    reader->buffer = (unsigned)reader->data[start + 0] | ((unsigned)reader->data[start + 1] << 8u) |
+                     ((unsigned)reader->data[start + 2] << 16u) | ((unsigned)reader->data[start + 3] << 24u);
+    reader->buffer >>= (reader->bp & 7u);
+    reader->buffer |= (((unsigned)reader->data[start + 4] << 24u) << (8u - (reader->bp & 7u)));
+    return 1;
+  } else {
+    reader->buffer = 0;
+    if(start + 0u < size) reader->buffer |= reader->data[start + 0];
+    if(start + 1u < size) reader->buffer |= ((unsigned)reader->data[start + 1] << 8u);
+    if(start + 2u < size) reader->buffer |= ((unsigned)reader->data[start + 2] << 16u);
+    if(start + 3u < size) reader->buffer |= ((unsigned)reader->data[start + 3] << 24u);
+    reader->buffer >>= (reader->bp & 7u);
+    return reader->bp + nbits <= reader->bitsize;
+  }
+}
+
+/* Get bits without advancing the bit pointer. Must have enough bits available with ensureBits. Max nbits is 31. */
+static unsigned peekBits(LodePNGBitReader* reader, size_t nbits) {
+  /* The shift allows nbits to be only up to 31. */
+  return reader->buffer & ((1u << nbits) - 1u);
+}
+
+/* Must have enough bits available with ensureBits */
+static void advanceBits(LodePNGBitReader* reader, size_t nbits) {
+  reader->buffer >>= nbits;
+  reader->bp += nbits;
+}
+
+/* Must have enough bits available with ensureBits */
+static unsigned readBits(LodePNGBitReader* reader, size_t nbits) {
+  unsigned result = peekBits(reader, nbits);
+  advanceBits(reader, nbits);
+  return result;
+}
+
+/* Public for testing only. steps and result must have numsteps values. */
+unsigned lode_png_test_bitreader(const unsigned char* data, size_t size,
+                                 size_t numsteps, const size_t* steps, unsigned* result) {
+  size_t i;
+  LodePNGBitReader reader;
+  unsigned error = LodePNGBitReader_init(&reader, data, size);
+  if(error) return 0;
+  for(i = 0; i < numsteps; i++) {
+    size_t step = steps[i];
+    unsigned ok;
+    if(step > 25) ok = ensureBits32(&reader, step);
+    else if(step > 17) ok = ensureBits25(&reader, step);
+    else if(step > 9) ok = ensureBits17(&reader, step);
+    else ok = ensureBits9(&reader, step);
+    if(!ok) return 0;
+    result[i] = readBits(&reader, step);
+  }
+  return 1;
+}
+#endif /*LODEPNG_COMPILE_DECODER*/
+
+static unsigned reverseBits(unsigned bits, unsigned num) {
+  /*TODO: implement faster lookup table based version when needed*/
+  unsigned i, result = 0;
+  for(i = 0; i < num; i++) result |= ((bits >> (num - i - 1u)) & 1u) << i;
+  return result;
+}
+
+/* ////////////////////////////////////////////////////////////////////////// */
+/* / Deflate - Huffman                                                      / */
+/* ////////////////////////////////////////////////////////////////////////// */
+
+#define FIRST_LENGTH_CODE_INDEX 257
+#define LAST_LENGTH_CODE_INDEX 285
+/*256 literals, the end code, some length codes, and 2 unused codes*/
+#define NUM_DEFLATE_CODE_SYMBOLS 288
+/*the distance codes have their own symbols, 30 used, 2 unused*/
+#define NUM_DISTANCE_SYMBOLS 32
+/*the code length codes. 0-15: code lengths, 16: copy previous 3-6 times, 17: 3-10 zeros, 18: 11-138 zeros*/
+#define NUM_CODE_LENGTH_CODES 19
+
+/*the base lengths represented by codes 257-285*/
+static const unsigned LENGTHBASE[29]
+  = {3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 17, 19, 23, 27, 31, 35, 43, 51, 59,
+     67, 83, 99, 115, 131, 163, 195, 227, 258};
+
+/*the extra bits used by codes 257-285 (added to base length)*/
+static const unsigned LENGTHEXTRA[29]
+  = {0, 0, 0, 0, 0, 0, 0,  0,  1,  1,  1,  1,  2,  2,  2,  2,  3,  3,  3,  3,
+      4,  4,  4,   4,   5,   5,   5,   5,   0};
+
+/*the base backwards distances (the bits of distance codes appear after length codes and use their own huffman tree)*/
+static const unsigned DISTANCEBASE[30]
+  = {1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49, 65, 97, 129, 193, 257, 385, 513,
+     769, 1025, 1537, 2049, 3073, 4097, 6145, 8193, 12289, 16385, 24577};
+
+/*the extra bits of backwards distances (added to base)*/
+static const unsigned DISTANCEEXTRA[30]
+  = {0, 0, 0, 0, 1, 1, 2,  2,  3,  3,  4,  4,  5,  5,   6,   6,   7,   7,   8,
+       8,    9,    9,   10,   10,   11,   11,   12,    12,    13,    13};
+
+/*the order in which "code length alphabet code lengths" are stored as specified by deflate, out of this the huffman
+tree of the dynamic huffman tree lengths is generated*/
+static const unsigned CLCL_ORDER[NUM_CODE_LENGTH_CODES]
+  = {16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15};
+
+/* ////////////////////////////////////////////////////////////////////////// */
+
+/*
+Huffman tree struct, containing multiple representations of the tree
+*/
+typedef struct HuffmanTree {
+  unsigned* codes; /*the huffman codes (bit patterns representing the symbols)*/
+  unsigned* lengths; /*the lengths of the huffman codes*/
+  unsigned maxbitlen; /*maximum number of bits a single code can get*/
+  unsigned numcodes; /*number of symbols in the alphabet = number of codes*/
+  /* for reading only */
+  unsigned char* table_len; /*length of symbol from lookup table, or max length if secondary lookup needed*/
+  unsigned short* table_value; /*value of symbol from lookup table, or pointer to secondary table if needed*/
+} HuffmanTree;
+
+static void HuffmanTree_init(HuffmanTree* tree) {
+  tree->codes = 0;
+  tree->lengths = 0;
+  tree->table_len = 0;
+  tree->table_value = 0;
+}
+
+static void HuffmanTree_cleanup(HuffmanTree* tree) {
+  lodepng_free(tree->codes);
+  lodepng_free(tree->lengths);
+  lodepng_free(tree->table_len);
+  lodepng_free(tree->table_value);
+}
+
+/* amount of bits for first huffman table lookup (aka root bits), see HuffmanTree_makeTable and huffmanDecodeSymbol.*/
+/* values 8u and 9u work the fastest */
+#define FIRSTBITS 9u
+
+/* a symbol value too big to represent any valid symbol, to indicate reading disallowed huffman bits combination,
+which is possible in case of only 0 or 1 present symbols. */
+#define INVALIDSYMBOL 65535u
+
+/* make table for huffman decoding */
+static unsigned HuffmanTree_makeTable(HuffmanTree* tree) {
+  static const unsigned headsize = 1u << FIRSTBITS; /*size of the first table*/
+  static const unsigned mask = (1u << FIRSTBITS) /*headsize*/ - 1u;
+  size_t i, numpresent, pointer, size; /*total table size*/
+  unsigned* maxlens = (unsigned*)lodepng_malloc(headsize * sizeof(unsigned));
+  if(!maxlens) return 83; /*alloc fail*/
+
+  /* compute maxlens: max total bit length of symbols sharing prefix in the first table*/
+  lodepng_memset(maxlens, 0, headsize * sizeof(*maxlens));
+  for(i = 0; i < tree->numcodes; i++) {
+    unsigned symbol = tree->codes[i];
+    unsigned l = tree->lengths[i];
+    unsigned index;
+    if(l <= FIRSTBITS) continue; /*symbols that fit in first table don't increase secondary table size*/
+    /*get the FIRSTBITS MSBs, the MSBs of the symbol are encoded first. See later comment about the reversing*/
+    index = reverseBits(symbol >> (l - FIRSTBITS), FIRSTBITS);
+    maxlens[index] = LODEPNG_MAX(maxlens[index], l);
+  }
+  /* compute total table size: size of first table plus all secondary tables for symbols longer than FIRSTBITS */
+  size = headsize;
+  for(i = 0; i < headsize; ++i) {
+    unsigned l = maxlens[i];
+    if(l > FIRSTBITS) size += (1u << (l - FIRSTBITS));
+  }
+  tree->table_len = (unsigned char*)lodepng_malloc(size * sizeof(*tree->table_len));
+  tree->table_value = (unsigned short*)lodepng_malloc(size * sizeof(*tree->table_value));
+  if(!tree->table_len || !tree->table_value) {
+    lodepng_free(maxlens);
+    /* freeing tree->table values is done at a higher scope */
+    return 83; /*alloc fail*/
+  }
+  /*initialize with an invalid length to indicate unused entries*/
+  for(i = 0; i < size; ++i) tree->table_len[i] = 16;
+
+  /*fill in the first table for long symbols: max prefix size and pointer to secondary tables*/
+  pointer = headsize;
+  for(i = 0; i < headsize; ++i) {
+    unsigned l = maxlens[i];
+    if(l <= FIRSTBITS) continue;
+    tree->table_len[i] = l;
+    tree->table_value[i] = pointer;
+    pointer += (1u << (l - FIRSTBITS));
+  }
+  lodepng_free(maxlens);
+
+  /*fill in the first table for short symbols, or secondary table for long symbols*/
+  numpresent = 0;
+  for(i = 0; i < tree->numcodes; ++i) {
+    unsigned l = tree->lengths[i];
+    unsigned symbol = tree->codes[i]; /*the huffman bit pattern. i itself is the value.*/
+    /*reverse bits, because the huffman bits are given in MSB first order but the bit reader reads LSB first*/
+    unsigned reverse = reverseBits(symbol, l);
+    if(l == 0) continue;
+    numpresent++;
+
+    if(l <= FIRSTBITS) {
+      /*short symbol, fully in first table, replicated num times if l < FIRSTBITS*/
+      unsigned num = 1u << (FIRSTBITS - l);
+      unsigned j;
+      for(j = 0; j < num; ++j) {
+        /*bit reader will read the l bits of symbol first, the remaining FIRSTBITS - l bits go to the MSB's*/
+        unsigned index = reverse | (j << l);
+        if(tree->table_len[index] != 16) return 55; /*invalid tree: long symbol shares prefix with short symbol*/
+        tree->table_len[index] = l;
+        tree->table_value[index] = i;
+      }
+    } else {
+      /*long symbol, shares prefix with other long symbols in first lookup table, needs second lookup*/
+      /*the FIRSTBITS MSBs of the symbol are the first table index*/
+      unsigned index = reverse & mask;
+      unsigned maxlen = tree->table_len[index];
+      /*log2 of secondary table length, should be >= l - FIRSTBITS*/
+      unsigned tablelen = maxlen - FIRSTBITS;
+      unsigned start = tree->table_value[index]; /*starting index in secondary table*/
+      unsigned num = 1u << (tablelen - (l - FIRSTBITS)); /*amount of entries of this symbol in secondary table*/
+      unsigned j;
+      if(maxlen < l) return 55; /*invalid tree: long symbol shares prefix with short symbol*/
+      for(j = 0; j < num; ++j) {
+        unsigned reverse2 = reverse >> FIRSTBITS; /* l - FIRSTBITS bits */
+        unsigned index2 = start + (reverse2 | (j << (l - FIRSTBITS)));
+        tree->table_len[index2] = l;
+        tree->table_value[index2] = i;
+      }
+    }
+  }
+
+  if(numpresent < 2) {
+    /* In case of exactly 1 symbol, in theory the huffman symbol needs 0 bits,
+    but deflate uses 1 bit instead. In case of 0 symbols, no symbols can
+    appear at all, but such huffman tree could still exist (e.g. if distance
+    codes are never used). In both cases, not all symbols of the table will be
+    filled in. Fill them in with an invalid symbol value so returning them from
+    huffmanDecodeSymbol will cause error. */
+    for(i = 0; i < size; ++i) {
+      if(tree->table_len[i] == 16) {
+        /* As length, use a value smaller than FIRSTBITS for the head table,
+        and a value larger than FIRSTBITS for the secondary table, to ensure
+        valid behavior for advanceBits when reading this symbol. */
+        tree->table_len[i] = (i < headsize) ? 1 : (FIRSTBITS + 1);
+        tree->table_value[i] = INVALIDSYMBOL;
+      }
+    }
+  } else {
+    /* A good huffman tree has N * 2 - 1 nodes, of which N - 1 are internal nodes.
+    If that is not the case (due to too long length codes), the table will not
+    have been fully used, and this is an error (not all bit combinations can be
+    decoded): an oversubscribed huffman tree, indicated by error 55. */
+    for(i = 0; i < size; ++i) {
+      if(tree->table_len[i] == 16) return 55;
+    }
+  }
+
+  return 0;
+}
+
+/*
+Second step for the ...makeFromLengths and ...makeFromFrequencies functions.
+numcodes, lengths and maxbitlen must already be filled in correctly. return
+value is error.
+*/
+static unsigned HuffmanTree_makeFromLengths2(HuffmanTree* tree) {
+  unsigned* blcount;
+  unsigned* nextcode;
+  unsigned error = 0;
+  unsigned bits, n;
+
+  tree->codes = (unsigned*)lodepng_malloc(tree->numcodes * sizeof(unsigned));
+  blcount = (unsigned*)lodepng_malloc((tree->maxbitlen + 1) * sizeof(unsigned));
+  nextcode = (unsigned*)lodepng_malloc((tree->maxbitlen + 1) * sizeof(unsigned));
+  if(!tree->codes || !blcount || !nextcode) error = 83; /*alloc fail*/
+
+  if(!error) {
+    for(n = 0; n != tree->maxbitlen + 1; n++) blcount[n] = nextcode[n] = 0;
+    /*step 1: count number of instances of each code length*/
+    for(bits = 0; bits != tree->numcodes; ++bits) ++blcount[tree->lengths[bits]];
+    /*step 2: generate the nextcode values*/
+    for(bits = 1; bits <= tree->maxbitlen; ++bits) {
+      nextcode[bits] = (nextcode[bits - 1] + blcount[bits - 1]) << 1u;
+    }
+    /*step 3: generate all the codes*/
+    for(n = 0; n != tree->numcodes; ++n) {
+      if(tree->lengths[n] != 0) {
+        tree->codes[n] = nextcode[tree->lengths[n]]++;
+        /*remove superfluous bits from the code*/
+        tree->codes[n] &= ((1u << tree->lengths[n]) - 1u);
+      }
+    }
+  }
+
+  lodepng_free(blcount);
+  lodepng_free(nextcode);
+
+  if(!error) error = HuffmanTree_makeTable(tree);
+  return error;
+}
+
+/*
+given the code lengths (as stored in the PNG file), generate the tree as defined
+by Deflate. maxbitlen is the maximum bits that a code in the tree can have.
+return value is error.
+*/
+static unsigned HuffmanTree_makeFromLengths(HuffmanTree* tree, const unsigned* bitlen,
+                                            size_t numcodes, unsigned maxbitlen) {
+  unsigned i;
+  tree->lengths = (unsigned*)lodepng_malloc(numcodes * sizeof(unsigned));
+  if(!tree->lengths) return 83; /*alloc fail*/
+  for(i = 0; i != numcodes; ++i) tree->lengths[i] = bitlen[i];
+  tree->numcodes = (unsigned)numcodes; /*number of symbols*/
+  tree->maxbitlen = maxbitlen;
+  return HuffmanTree_makeFromLengths2(tree);
+}
+
+#ifdef LODEPNG_COMPILE_ENCODER
+
+/*BPM: Boundary Package Merge, see "A Fast and Space-Economical Algorithm for Length-Limited Coding",
+Jyrki Katajainen, Alistair Moffat, Andrew Turpin, 1995.*/
+
+/*chain node for boundary package merge*/
+typedef struct BPMNode {
+  int weight; /*the sum of all weights in this chain*/
+  unsigned index; /*index of this leaf node (called "count" in the paper)*/
+  struct BPMNode* tail; /*the next nodes in this chain (null if last)*/
+  int in_use;
+} BPMNode;
+
+/*lists of chains*/
+typedef struct BPMLists {
+  /*memory pool*/
+  unsigned memsize;
+  BPMNode* memory;
+  unsigned numfree;
+  unsigned nextfree;
+  BPMNode** freelist;
+  /*two heads of lookahead chains per list*/
+  unsigned listsize;
+  BPMNode** chains0;
+  BPMNode** chains1;
+} BPMLists;
+
+/*creates a new chain node with the given parameters, from the memory in the lists */
+static BPMNode* bpmnode_create(BPMLists* lists, int weight, unsigned index, BPMNode* tail) {
+  unsigned i;
+  BPMNode* result;
+
+  /*memory full, so garbage collect*/
+  if(lists->nextfree >= lists->numfree) {
+    /*mark only those that are in use*/
+    for(i = 0; i != lists->memsize; ++i) lists->memory[i].in_use = 0;
+    for(i = 0; i != lists->listsize; ++i) {
+      BPMNode* node;
+      for(node = lists->chains0[i]; node != 0; node = node->tail) node->in_use = 1;
+      for(node = lists->chains1[i]; node != 0; node = node->tail) node->in_use = 1;
+    }
+    /*collect those that are free*/
+    lists->numfree = 0;
+    for(i = 0; i != lists->memsize; ++i) {
+      if(!lists->memory[i].in_use) lists->freelist[lists->numfree++] = &lists->memory[i];
+    }
+    lists->nextfree = 0;
+  }
+
+  result = lists->freelist[lists->nextfree++];
+  result->weight = weight;
+  result->index = index;
+  result->tail = tail;
+  return result;
+}
+
+/*sort the leaves with stable mergesort*/
+static void bpmnode_sort(BPMNode* leaves, size_t num) {
+  BPMNode* mem = (BPMNode*)lodepng_malloc(sizeof(*leaves) * num);
+  size_t width, counter = 0;
+  for(width = 1; width < num; width *= 2) {
+    BPMNode* a = (counter & 1) ? mem : leaves;
+    BPMNode* b = (counter & 1) ? leaves : mem;
+    size_t p;
+    for(p = 0; p < num; p += 2 * width) {
+      size_t q = (p + width > num) ? num : (p + width);
+      size_t r = (p + 2 * width > num) ? num : (p + 2 * width);
+      size_t i = p, j = q, k;
+      for(k = p; k < r; k++) {
+        if(i < q && (j >= r || a[i].weight <= a[j].weight)) b[k] = a[i++];
+        else b[k] = a[j++];
+      }
+    }
+    counter++;
+  }
+  if(counter & 1) lodepng_memcpy(leaves, mem, sizeof(*leaves) * num);
+  lodepng_free(mem);
+}
+
+/*Boundary Package Merge step, numpresent is the amount of leaves, and c is the current chain.*/
+static void boundaryPM(BPMLists* lists, BPMNode* leaves, size_t numpresent, int c, int num) {
+  unsigned lastindex = lists->chains1[c]->index;
+
+  if(c == 0) {
+    if(lastindex >= numpresent) return;
+    lists->chains0[c] = lists->chains1[c];
+    lists->chains1[c] = bpmnode_create(lists, leaves[lastindex].weight, lastindex + 1, 0);
+  } else {
+    /*sum of the weights of the head nodes of the previous lookahead chains.*/
+    int sum = lists->chains0[c - 1]->weight + lists->chains1[c - 1]->weight;
+    lists->chains0[c] = lists->chains1[c];
+    if(lastindex < numpresent && sum > leaves[lastindex].weight) {
+      lists->chains1[c] = bpmnode_create(lists, leaves[lastindex].weight, lastindex + 1, lists->chains1[c]->tail);
+      return;
+    }
+    lists->chains1[c] = bpmnode_create(lists, sum, lastindex, lists->chains1[c - 1]);
+    /*in the end we are only interested in the chain of the last list, so no
+    need to recurse if we're at the last one (this gives measurable speedup)*/
+    if(num + 1 < (int)(2 * numpresent - 2)) {
+      boundaryPM(lists, leaves, numpresent, c - 1, num);
+      boundaryPM(lists, leaves, numpresent, c - 1, num);
+    }
+  }
+}
+
+unsigned lodepng_huffman_code_lengths(unsigned* lengths, const unsigned* frequencies,
+                                      size_t numcodes, unsigned maxbitlen) {
+  unsigned error = 0;
+  unsigned i;
+  size_t numpresent = 0; /*number of symbols with non-zero frequency*/
+  BPMNode* leaves; /*the symbols, only those with > 0 frequency*/
+
+  if(numcodes == 0) return 80; /*error: a tree of 0 symbols is not supposed to be made*/
+  if((1u << maxbitlen) < (unsigned)numcodes) return 80; /*error: represent all symbols*/
+
+  leaves = (BPMNode*)lodepng_malloc(numcodes * sizeof(*leaves));
+  if(!leaves) return 83; /*alloc fail*/
+
+  for(i = 0; i != numcodes; ++i) {
+    if(frequencies[i] > 0) {
+      leaves[numpresent].weight = (int)frequencies[i];
+      leaves[numpresent].index = i;
+      ++numpresent;
+    }
+  }
+
+  lodepng_memset(lengths, 0, numcodes * sizeof(*lengths));
+
+  /*ensure at least two present symbols. There should be at least one symbol
+  according to RFC 1951 section 3.2.7. Some decoders incorrectly require two. To
+  make these work as well ensure there are at least two symbols. The
+  Package-Merge code below also doesn't work correctly if there's only one
+  symbol, it'd give it the theoretical 0 bits but in practice zlib wants 1 bit*/
+  if(numpresent == 0) {
+    lengths[0] = lengths[1] = 1; /*note that for RFC 1951 section 3.2.7, only lengths[0] = 1 is needed*/
+  } else if(numpresent == 1) {
+    lengths[leaves[0].index] = 1;
+    lengths[leaves[0].index == 0 ? 1 : 0] = 1;
+  } else {
+    BPMLists lists;
+    BPMNode* node;
+
+    bpmnode_sort(leaves, numpresent);
+
+    lists.listsize = maxbitlen;
+    lists.memsize = 2 * maxbitlen * (maxbitlen + 1);
+    lists.nextfree = 0;
+    lists.numfree = lists.memsize;
+    lists.memory = (BPMNode*)lodepng_malloc(lists.memsize * sizeof(*lists.memory));
+    lists.freelist = (BPMNode**)lodepng_malloc(lists.memsize * sizeof(BPMNode*));
+    lists.chains0 = (BPMNode**)lodepng_malloc(lists.listsize * sizeof(BPMNode*));
+    lists.chains1 = (BPMNode**)lodepng_malloc(lists.listsize * sizeof(BPMNode*));
+    if(!lists.memory || !lists.freelist || !lists.chains0 || !lists.chains1) error = 83; /*alloc fail*/
+
+    if(!error) {
+      for(i = 0; i != lists.memsize; ++i) lists.freelist[i] = &lists.memory[i];
+
+      bpmnode_create(&lists, leaves[0].weight, 1, 0);
+      bpmnode_create(&lists, leaves[1].weight, 2, 0);
+
+      for(i = 0; i != lists.listsize; ++i) {
+        lists.chains0[i] = &lists.memory[0];
+        lists.chains1[i] = &lists.memory[1];
+      }
+
+      /*each boundaryPM call adds one chain to the last list, and we need 2 * numpresent - 2 chains.*/
+      for(i = 2; i != 2 * numpresent - 2; ++i) boundaryPM(&lists, leaves, numpresent, (int)maxbitlen - 1, (int)i);
+
+      for(node = lists.chains1[maxbitlen - 1]; node; node = node->tail) {
+        for(i = 0; i != node->index; ++i) ++lengths[leaves[i].index];
+      }
+    }
+
+    lodepng_free(lists.memory);
+    lodepng_free(lists.freelist);
+    lodepng_free(lists.chains0);
+    lodepng_free(lists.chains1);
+  }
+
+  lodepng_free(leaves);
+  return error;
+}
+
+/*Create the Huffman tree given the symbol frequencies*/
+static unsigned HuffmanTree_makeFromFrequencies(HuffmanTree* tree, const unsigned* frequencies,
+                                                size_t mincodes, size_t numcodes, unsigned maxbitlen) {
+  unsigned error = 0;
+  while(!frequencies[numcodes - 1] && numcodes > mincodes) --numcodes; /*trim zeroes*/
+  tree->lengths = (unsigned*)lodepng_malloc(numcodes * sizeof(unsigned));
+  if(!tree->lengths) return 83; /*alloc fail*/
+  tree->maxbitlen = maxbitlen;
+  tree->numcodes = (unsigned)numcodes; /*number of symbols*/
+
+  error = lodepng_huffman_code_lengths(tree->lengths, frequencies, numcodes, maxbitlen);
+  if(!error) error = HuffmanTree_makeFromLengths2(tree);
+  return error;
+}
+#endif /*LODEPNG_COMPILE_ENCODER*/
+
+/*get the literal and length code tree of a deflated block with fixed tree, as per the deflate specification*/
+static unsigned generateFixedLitLenTree(HuffmanTree* tree) {
+  unsigned i, error = 0;
+  unsigned* bitlen = (unsigned*)lodepng_malloc(NUM_DEFLATE_CODE_SYMBOLS * sizeof(unsigned));
+  if(!bitlen) return 83; /*alloc fail*/
+
+  /*288 possible codes: 0-255=literals, 256=endcode, 257-285=lengthcodes, 286-287=unused*/
+  for(i =   0; i <= 143; ++i) bitlen[i] = 8;
+  for(i = 144; i <= 255; ++i) bitlen[i] = 9;
+  for(i = 256; i <= 279; ++i) bitlen[i] = 7;
+  for(i = 280; i <= 287; ++i) bitlen[i] = 8;
+
+  error = HuffmanTree_makeFromLengths(tree, bitlen, NUM_DEFLATE_CODE_SYMBOLS, 15);
+
+  lodepng_free(bitlen);
+  return error;
+}
+
+/*get the distance code tree of a deflated block with fixed tree, as specified in the deflate specification*/
+static unsigned generateFixedDistanceTree(HuffmanTree* tree) {
+  unsigned i, error = 0;
+  unsigned* bitlen = (unsigned*)lodepng_malloc(NUM_DISTANCE_SYMBOLS * sizeof(unsigned));
+  if(!bitlen) return 83; /*alloc fail*/
+
+  /*there are 32 distance codes, but 30-31 are unused*/
+  for(i = 0; i != NUM_DISTANCE_SYMBOLS; ++i) bitlen[i] = 5;
+  error = HuffmanTree_makeFromLengths(tree, bitlen, NUM_DISTANCE_SYMBOLS, 15);
+
+  lodepng_free(bitlen);
+  return error;
+}
+
+#ifdef LODEPNG_COMPILE_DECODER
+
+/*
+returns the code. The bit reader must already have been ensured at least 15 bits
+*/
+static unsigned huffmanDecodeSymbol(LodePNGBitReader* reader, const HuffmanTree* codetree) {
+  unsigned short code = peekBits(reader, FIRSTBITS);
+  unsigned short l = codetree->table_len[code];
+  unsigned short value = codetree->table_value[code];
+  if(l <= FIRSTBITS) {
+    advanceBits(reader, l);
+    return value;
+  } else {
+    unsigned index2;
+    advanceBits(reader, FIRSTBITS);
+    index2 = value + peekBits(reader, l - FIRSTBITS);
+    advanceBits(reader, codetree->table_len[index2] - FIRSTBITS);
+    return codetree->table_value[index2];
+  }
+}
+#endif /*LODEPNG_COMPILE_DECODER*/
+
+#ifdef LODEPNG_COMPILE_DECODER
+
+/* ////////////////////////////////////////////////////////////////////////// */
+/* / Inflator (Decompressor)                                                / */
+/* ////////////////////////////////////////////////////////////////////////// */
+
+/*get the tree of a deflated block with fixed tree, as specified in the deflate specification
+Returns error code.*/
+static unsigned getTreeInflateFixed(HuffmanTree* tree_ll, HuffmanTree* tree_d) {
+  unsigned error = generateFixedLitLenTree(tree_ll);
+  if(error) return error;
+  return generateFixedDistanceTree(tree_d);
+}
+
+/*get the tree of a deflated block with dynamic tree, the tree itself is also Huffman compressed with a known tree*/
+static unsigned getTreeInflateDynamic(HuffmanTree* tree_ll, HuffmanTree* tree_d,
+                                      LodePNGBitReader* reader) {
+  /*make sure that length values that aren't filled in will be 0, or a wrong tree will be generated*/
+  unsigned error = 0;
+  unsigned n, HLIT, HDIST, HCLEN, i;
+
+  /*see comments in deflateDynamic for explanation of the context and these variables, it is analogous*/
+  unsigned* bitlen_ll = 0; /*lit,len code lengths*/
+  unsigned* bitlen_d = 0; /*dist code lengths*/
+  /*code length code lengths ("clcl"), the bit lengths of the huffman tree used to compress bitlen_ll and bitlen_d*/
+  unsigned* bitlen_cl = 0;
+  HuffmanTree tree_cl; /*the code tree for code length codes (the huffman tree for compressed huffman trees)*/
+
+  if(!ensureBits17(reader, 14)) return 49; /*error: the bit pointer is or will go past the memory*/
+
+  /*number of literal/length codes + 257. Unlike the spec, the value 257 is added to it here already*/
+  HLIT =  readBits(reader, 5) + 257;
+  /*number of distance codes. Unlike the spec, the value 1 is added to it here already*/
+  HDIST = readBits(reader, 5) + 1;
+  /*number of code length codes. Unlike the spec, the value 4 is added to it here already*/
+  HCLEN = readBits(reader, 4) + 4;
+
+  bitlen_cl = (unsigned*)lodepng_malloc(NUM_CODE_LENGTH_CODES * sizeof(unsigned));
+  if(!bitlen_cl) return 83 /*alloc fail*/;
+
+  HuffmanTree_init(&tree_cl);
+
+  while(!error) {
+    /*read the code length codes out of 3 * (amount of code length codes) bits*/
+    if(lodepng_gtofl(reader->bp, HCLEN * 3, reader->bitsize)) {
+      ERROR_BREAK(50); /*error: the bit pointer is or will go past the memory*/
+    }
+    for(i = 0; i != HCLEN; ++i) {
+      ensureBits9(reader, 3); /*out of bounds already checked above */
+      bitlen_cl[CLCL_ORDER[i]] = readBits(reader, 3);
+    }
+    for(i = HCLEN; i != NUM_CODE_LENGTH_CODES; ++i) {
+      bitlen_cl[CLCL_ORDER[i]] = 0;
+    }
+
+    error = HuffmanTree_makeFromLengths(&tree_cl, bitlen_cl, NUM_CODE_LENGTH_CODES, 7);
+    if(error) break;
+
+    /*now we can use this tree to read the lengths for the tree that this function will return*/
+    bitlen_ll = (unsigned*)lodepng_malloc(NUM_DEFLATE_CODE_SYMBOLS * sizeof(unsigned));
+    bitlen_d = (unsigned*)lodepng_malloc(NUM_DISTANCE_SYMBOLS * sizeof(unsigned));
+    if(!bitlen_ll || !bitlen_d) ERROR_BREAK(83 /*alloc fail*/);
+    lodepng_memset(bitlen_ll, 0, NUM_DEFLATE_CODE_SYMBOLS * sizeof(*bitlen_ll));
+    lodepng_memset(bitlen_d, 0, NUM_DISTANCE_SYMBOLS * sizeof(*bitlen_d));
+
+    /*i is the current symbol we're reading in the part that contains the code lengths of lit/len and dist codes*/
+    i = 0;
+    while(i < HLIT + HDIST) {
+      unsigned code;
+      ensureBits25(reader, 22); /* up to 15 bits for huffman code, up to 7 extra bits below*/
+      code = huffmanDecodeSymbol(reader, &tree_cl);
+      if(code <= 15) /*a length code*/ {
+        if(i < HLIT) bitlen_ll[i] = code;
+        else bitlen_d[i - HLIT] = code;
+        ++i;
+      } else if(code == 16) /*repeat previous*/ {
+        unsigned replength = 3; /*read in the 2 bits that indicate repeat length (3-6)*/
+        unsigned value; /*set value to the previous code*/
+
+        if(i == 0) ERROR_BREAK(54); /*can't repeat previous if i is 0*/
+
+        replength += readBits(reader, 2);
+
+        if(i < HLIT + 1) value = bitlen_ll[i - 1];
+        else value = bitlen_d[i - HLIT - 1];
+        /*repeat this value in the next lengths*/
+        for(n = 0; n < replength; ++n) {
+          if(i >= HLIT + HDIST) ERROR_BREAK(13); /*error: i is larger than the amount of codes*/
+          if(i < HLIT) bitlen_ll[i] = value;
+          else bitlen_d[i - HLIT] = value;
+          ++i;
+        }
+      } else if(code == 17) /*repeat "0" 3-10 times*/ {
+        unsigned replength = 3; /*read in the bits that indicate repeat length*/
+        replength += readBits(reader, 3);
+
+        /*repeat this value in the next lengths*/
+        for(n = 0; n < replength; ++n) {
+          if(i >= HLIT + HDIST) ERROR_BREAK(14); /*error: i is larger than the amount of codes*/
+
+          if(i < HLIT) bitlen_ll[i] = 0;
+          else bitlen_d[i - HLIT] = 0;
+          ++i;
+        }
+      } else if(code == 18) /*repeat "0" 11-138 times*/ {
+        unsigned replength = 11; /*read in the bits that indicate repeat length*/
+        replength += readBits(reader, 7);
+
+        /*repeat this value in the next lengths*/
+        for(n = 0; n < replength; ++n) {
+          if(i >= HLIT + HDIST) ERROR_BREAK(15); /*error: i is larger than the amount of codes*/
+
+          if(i < HLIT) bitlen_ll[i] = 0;
+          else bitlen_d[i - HLIT] = 0;
+          ++i;
+        }
+      } else /*if(code == INVALIDSYMBOL)*/ {
+        ERROR_BREAK(16); /*error: tried to read disallowed huffman symbol*/
+      }
+      /*check if any of the ensureBits above went out of bounds*/
+      if(reader->bp > reader->bitsize) {
+        /*return error code 10 or 11 depending on the situation that happened in huffmanDecodeSymbol
+        (10=no endcode, 11=wrong jump outside of tree)*/
+        /* TODO: revise error codes 10,11,50: the above comment is no longer valid */
+        ERROR_BREAK(50); /*error, bit pointer jumps past memory*/
+      }
+    }
+    if(error) break;
+
+    if(bitlen_ll[256] == 0) ERROR_BREAK(64); /*the length of the end code 256 must be larger than 0*/
+
+    /*now we've finally got HLIT and HDIST, so generate the code trees, and the function is done*/
+    error = HuffmanTree_makeFromLengths(tree_ll, bitlen_ll, NUM_DEFLATE_CODE_SYMBOLS, 15);
+    if(error) break;
+    error = HuffmanTree_makeFromLengths(tree_d, bitlen_d, NUM_DISTANCE_SYMBOLS, 15);
+
+    break; /*end of error-while*/
+  }
+
+  lodepng_free(bitlen_cl);
+  lodepng_free(bitlen_ll);
+  lodepng_free(bitlen_d);
+  HuffmanTree_cleanup(&tree_cl);
+
+  return error;
+}
+
+/*inflate a block with dynamic of fixed Huffman tree. btype must be 1 or 2.*/
+static unsigned inflateHuffmanBlock(ucvector* out, LodePNGBitReader* reader,
+                                    unsigned btype) {
+  unsigned error = 0;
+  HuffmanTree tree_ll; /*the huffman tree for literal and length codes*/
+  HuffmanTree tree_d; /*the huffman tree for distance codes*/
+
+  HuffmanTree_init(&tree_ll);
+  HuffmanTree_init(&tree_d);
+
+  if(btype == 1) error = getTreeInflateFixed(&tree_ll, &tree_d);
+  else /*if(btype == 2)*/ error = getTreeInflateDynamic(&tree_ll, &tree_d, reader);
+
+  while(!error) /*decode all symbols until end reached, breaks at end code*/ {
+    /*code_ll is literal, length or end code*/
+    unsigned code_ll;
+    ensureBits25(reader, 20); /* up to 15 for the huffman symbol, up to 5 for the length extra bits */
+    code_ll = huffmanDecodeSymbol(reader, &tree_ll);
+    if(code_ll <= 255) /*literal symbol*/ {
+      if(!ucvector_resize(out, out->size + 1)) ERROR_BREAK(83 /*alloc fail*/);
+      out->data[out->size - 1] = (unsigned char)code_ll;
+    } else if(code_ll >= FIRST_LENGTH_CODE_INDEX && code_ll <= LAST_LENGTH_CODE_INDEX) /*length code*/ {
+      unsigned code_d, distance;
+      unsigned numextrabits_l, numextrabits_d; /*extra bits for length and distance*/
+      size_t start, backward, length;
+
+      /*part 1: get length base*/
+      length = LENGTHBASE[code_ll - FIRST_LENGTH_CODE_INDEX];
+
+      /*part 2: get extra bits and add the value of that to length*/
+      numextrabits_l = LENGTHEXTRA[code_ll - FIRST_LENGTH_CODE_INDEX];
+      if(numextrabits_l != 0) {
+        /* bits already ensured above */
+        length += readBits(reader, numextrabits_l);
+      }
+
+      /*part 3: get distance code*/
+      ensureBits32(reader, 28); /* up to 15 for the huffman symbol, up to 13 for the extra bits */
+      code_d = huffmanDecodeSymbol(reader, &tree_d);
+      if(code_d > 29) {
+        if(code_d <= 31) {
+          ERROR_BREAK(18); /*error: invalid distance code (30-31 are never used)*/
+        } else /* if(code_d == INVALIDSYMBOL) */{
+          ERROR_BREAK(16); /*error: tried to read disallowed huffman symbol*/
+        }
+      }
+      distance = DISTANCEBASE[code_d];
+
+      /*part 4: get extra bits from distance*/
+      numextrabits_d = DISTANCEEXTRA[code_d];
+      if(numextrabits_d != 0) {
+        /* bits already ensured above */
+        distance += readBits(reader, numextrabits_d);
+      }
+
+      /*part 5: fill in all the out[n] values based on the length and dist*/
+      start = out->size;
+      if(distance > start) ERROR_BREAK(52); /*too long backward distance*/
+      backward = start - distance;
+
+      if(!ucvector_resize(out, out->size + length)) ERROR_BREAK(83 /*alloc fail*/);
+      if(distance < length) {
+        size_t forward;
+        lodepng_memcpy(out->data + start, out->data + backward, distance);
+        start += distance;
+        for(forward = distance; forward < length; ++forward) {
+          out->data[start++] = out->data[backward++];
+        }
+      } else {
+        lodepng_memcpy(out->data + start, out->data + backward, length);
+      }
+    } else if(code_ll == 256) {
+      break; /*end code, break the loop*/
+    } else /*if(code_ll == INVALIDSYMBOL)*/ {
+      ERROR_BREAK(16); /*error: tried to read disallowed huffman symbol*/
+    }
+    /*check if any of the ensureBits above went out of bounds*/
+    if(reader->bp > reader->bitsize) {
+      /*return error code 10 or 11 depending on the situation that happened in huffmanDecodeSymbol
+      (10=no endcode, 11=wrong jump outside of tree)*/
+      /* TODO: revise error codes 10,11,50: the above comment is no longer valid */
+      ERROR_BREAK(51); /*error, bit pointer jumps past memory*/
+    }
+  }
+
+  HuffmanTree_cleanup(&tree_ll);
+  HuffmanTree_cleanup(&tree_d);
+
+  return error;
+}
+
+static unsigned inflateNoCompression(ucvector* out, LodePNGBitReader* reader,
+                                     const LodePNGDecompressSettings* settings) {
+  size_t bytepos;
+  size_t size = reader->size;
+  unsigned LEN, NLEN, error = 0;
+
+  /*go to first boundary of byte*/
+  bytepos = (reader->bp + 7u) >> 3u;
+
+  /*read LEN (2 bytes) and NLEN (2 bytes)*/
+  if(bytepos + 4 >= size) return 52; /*error, bit pointer will jump past memory*/
+  LEN = (unsigned)reader->data[bytepos] + ((unsigned)reader->data[bytepos + 1] << 8u); bytepos += 2;
+  NLEN = (unsigned)reader->data[bytepos] + ((unsigned)reader->data[bytepos + 1] << 8u); bytepos += 2;
+
+  /*check if 16-bit NLEN is really the one's complement of LEN*/
+  if(!settings->ignore_nlen && LEN + NLEN != 65535) {
+    return 21; /*error: NLEN is not one's complement of LEN*/
+  }
+
+  if(!ucvector_resize(out, out->size + LEN)) return 83; /*alloc fail*/
+
+  /*read the literal data: LEN bytes are now stored in the out buffer*/
+  if(bytepos + LEN > size) return 23; /*error: reading outside of in buffer*/
+
+  lodepng_memcpy(out->data + out->size - LEN, reader->data + bytepos, LEN);
+  bytepos += LEN;
+
+  reader->bp = bytepos << 3u;
+
+  return error;
+}
+
+static unsigned lodepng_inflatev(ucvector* out,
+                                 const unsigned char* in, size_t insize,
+                                 const LodePNGDecompressSettings* settings) {
+  unsigned BFINAL = 0;
+  LodePNGBitReader reader;
+  unsigned error = LodePNGBitReader_init(&reader, in, insize);
+
+  if(error) return error;
+
+  while(!BFINAL) {
+    unsigned BTYPE;
+    if(!ensureBits9(&reader, 3)) return 52; /*error, bit pointer will jump past memory*/
+    BFINAL = readBits(&reader, 1);
+    BTYPE = readBits(&reader, 2);
+
+    if(BTYPE == 3) return 20; /*error: invalid BTYPE*/
+    else if(BTYPE == 0) error = inflateNoCompression(out, &reader, settings); /*no compression*/
+    else error = inflateHuffmanBlock(out, &reader, BTYPE); /*compression, BTYPE 01 or 10*/
+
+    if(error) return error;
+  }
+
+  return error;
+}
+
+unsigned lodepng_inflate(unsigned char** out, size_t* outsize,
+                         const unsigned char* in, size_t insize,
+                         const LodePNGDecompressSettings* settings) {
+  ucvector v = ucvector_init(*out, *outsize);
+  unsigned error = lodepng_inflatev(&v, in, insize, settings);
+  *out = v.data;
+  *outsize = v.size;
+  return error;
+}
+
+static unsigned inflatev(ucvector* out, const unsigned char* in, size_t insize,
+                        const LodePNGDecompressSettings* settings) {
+  if(settings->custom_inflate) {
+    unsigned error = settings->custom_inflate(&out->data, &out->size, in, insize, settings);
+    out->allocsize = out->size;
+    return error;
+  } else {
+    return lodepng_inflatev(out, in, insize, settings);
+  }
+}
+
+#endif /*LODEPNG_COMPILE_DECODER*/
+
+#ifdef LODEPNG_COMPILE_ENCODER
+
+/* ////////////////////////////////////////////////////////////////////////// */
+/* / Deflator (Compressor)                                                  / */
+/* ////////////////////////////////////////////////////////////////////////// */
+
+static const size_t MAX_SUPPORTED_DEFLATE_LENGTH = 258;
+
+/*search the index in the array, that has the largest value smaller than or equal to the given value,
+given array must be sorted (if no value is smaller, it returns the size of the given array)*/
+static size_t searchCodeIndex(const unsigned* array, size_t array_size, size_t value) {
+  /*binary search (only small gain over linear). TODO: use CPU log2 instruction for getting symbols instead*/
+  size_t left = 1;
+  size_t right = array_size - 1;
+
+  while(left <= right) {
+    size_t mid = (left + right) >> 1;
+    if(array[mid] >= value) right = mid - 1;
+    else left = mid + 1;
+  }
+  if(left >= array_size || array[left] > value) left--;
+  return left;
+}
+
+static void addLengthDistance(uivector* values, size_t length, size_t distance) {
+  /*values in encoded vector are those used by deflate:
+  0-255: literal bytes
+  256: end
+  257-285: length/distance pair (length code, followed by extra length bits, distance code, extra distance bits)
+  286-287: invalid*/
+
+  unsigned length_code = (unsigned)searchCodeIndex(LENGTHBASE, 29, length);
+  unsigned extra_length = (unsigned)(length - LENGTHBASE[length_code]);
+  unsigned dist_code = (unsigned)searchCodeIndex(DISTANCEBASE, 30, distance);
+  unsigned extra_distance = (unsigned)(distance - DISTANCEBASE[dist_code]);
+
+  size_t pos = values->size;
+  /*TODO: return error when this fails (out of memory)*/
+  unsigned ok = uivector_resize(values, values->size + 4);
+  if(ok) {
+    values->data[pos + 0] = length_code + FIRST_LENGTH_CODE_INDEX;
+    values->data[pos + 1] = extra_length;
+    values->data[pos + 2] = dist_code;
+    values->data[pos + 3] = extra_distance;
+  }
+}
+
+/*3 bytes of data get encoded into two bytes. The hash cannot use more than 3
+bytes as input because 3 is the minimum match length for deflate*/
+static const unsigned HASH_NUM_VALUES = 65536;
+static const unsigned HASH_BIT_MASK = 65535; /*HASH_NUM_VALUES - 1, but C90 does not like that as initializer*/
+
+typedef struct Hash {
+  int* head; /*hash value to head circular pos - can be outdated if went around window*/
+  /*circular pos to prev circular pos*/
+  unsigned short* chain;
+  int* val; /*circular pos to hash value*/
+
+  /*TODO: do this not only for zeros but for any repeated byte. However for PNG
+  it's always going to be the zeros that dominate, so not important for PNG*/
+  int* headz; /*similar to head, but for chainz*/
+  unsigned short* chainz; /*those with same amount of zeros*/
+  unsigned short* zeros; /*length of zeros streak, used as a second hash chain*/
+} Hash;
+
+static unsigned hash_init(Hash* hash, unsigned windowsize) {
+  unsigned i;
+  hash->head = (int*)lodepng_malloc(sizeof(int) * HASH_NUM_VALUES);
+  hash->val = (int*)lodepng_malloc(sizeof(int) * windowsize);
+  hash->chain = (unsigned short*)lodepng_malloc(sizeof(unsigned short) * windowsize);
+
+  hash->zeros = (unsigned short*)lodepng_malloc(sizeof(unsigned short) * windowsize);
+  hash->headz = (int*)lodepng_malloc(sizeof(int) * (MAX_SUPPORTED_DEFLATE_LENGTH + 1));
+  hash->chainz = (unsigned short*)lodepng_malloc(sizeof(unsigned short) * windowsize);
+
+  if(!hash->head || !hash->chain || !hash->val  || !hash->headz|| !hash->chainz || !hash->zeros) {
+    return 83; /*alloc fail*/
+  }
+
+  /*initialize hash table*/
+  for(i = 0; i != HASH_NUM_VALUES; ++i) hash->head[i] = -1;
+  for(i = 0; i != windowsize; ++i) hash->val[i] = -1;
+  for(i = 0; i != windowsize; ++i) hash->chain[i] = i; /*same value as index indicates uninitialized*/
+
+  for(i = 0; i <= MAX_SUPPORTED_DEFLATE_LENGTH; ++i) hash->headz[i] = -1;
+  for(i = 0; i != windowsize; ++i) hash->chainz[i] = i; /*same value as index indicates uninitialized*/
+
+  return 0;
+}
+
+static void hash_cleanup(Hash* hash) {
+  lodepng_free(hash->head);
+  lodepng_free(hash->val);
+  lodepng_free(hash->chain);
+
+  lodepng_free(hash->zeros);
+  lodepng_free(hash->headz);
+  lodepng_free(hash->chainz);
+}
+
+
+
+static unsigned getHash(const unsigned char* data, size_t size, size_t pos) {
+  unsigned result = 0;
+  if(pos + 2 < size) {
+    /*A simple shift and xor hash is used. Since the data of PNGs is dominated
+    by zeroes due to the filters, a better hash does not have a significant
+    effect on speed in traversing the chain, and causes more time spend on
+    calculating the hash.*/
+    result ^= ((unsigned)data[pos + 0] << 0u);
+    result ^= ((unsigned)data[pos + 1] << 4u);
+    result ^= ((unsigned)data[pos + 2] << 8u);
+  } else {
+    size_t amount, i;
+    if(pos >= size) return 0;
+    amount = size - pos;
+    for(i = 0; i != amount; ++i) result ^= ((unsigned)data[pos + i] << (i * 8u));
+  }
+  return result & HASH_BIT_MASK;
+}
+
+static unsigned countZeros(const unsigned char* data, size_t size, size_t pos) {
+  const unsigned char* start = data + pos;
+  const unsigned char* end = start + MAX_SUPPORTED_DEFLATE_LENGTH;
+  if(end > data + size) end = data + size;
+  data = start;
+  while(data != end && *data == 0) ++data;
+  /*subtracting two addresses returned as 32-bit number (max value is MAX_SUPPORTED_DEFLATE_LENGTH)*/
+  return (unsigned)(data - start);
+}
+
+/*wpos = pos & (windowsize - 1)*/
+static void updateHashChain(Hash* hash, size_t wpos, unsigned hashval, unsigned short numzeros) {
+  hash->val[wpos] = (int)hashval;
+  if(hash->head[hashval] != -1) hash->chain[wpos] = hash->head[hashval];
+  hash->head[hashval] = (int)wpos;
+
+  hash->zeros[wpos] = numzeros;
+  if(hash->headz[numzeros] != -1) hash->chainz[wpos] = hash->headz[numzeros];
+  hash->headz[numzeros] = (int)wpos;
+}
+
+/*
+LZ77-encode the data. Return value is error code. The input are raw bytes, the output
+is in the form of unsigned integers with codes representing for example literal bytes, or
+length/distance pairs.
+It uses a hash table technique to let it encode faster. When doing LZ77 encoding, a
+sliding window (of windowsize) is used, and all past bytes in that window can be used as
+the "dictionary". A brute force search through all possible distances would be slow, and
+this hash technique is one out of several ways to speed this up.
+*/
+static unsigned encodeLZ77(uivector* out, Hash* hash,
+                           const unsigned char* in, size_t inpos, size_t insize, unsigned windowsize,
+                           unsigned minmatch, unsigned nicematch, unsigned lazymatching) {
+  size_t pos;
+  unsigned i, error = 0;
+  /*for large window lengths, assume the user wants no compression loss. Otherwise, max hash chain length speedup.*/
+  unsigned maxchainlength = windowsize >= 8192 ? windowsize : windowsize / 8u;
+  unsigned maxlazymatch = windowsize >= 8192 ? MAX_SUPPORTED_DEFLATE_LENGTH : 64;
+
+  unsigned usezeros = 1; /*not sure if setting it to false for windowsize < 8192 is better or worse*/
+  unsigned numzeros = 0;
+
+  unsigned offset; /*the offset represents the distance in LZ77 terminology*/
+  unsigned length;
+  unsigned lazy = 0;
+  unsigned lazylength = 0, lazyoffset = 0;
+  unsigned hashval;
+  unsigned current_offset, current_length;
+  unsigned prev_offset;
+  const unsigned char *lastptr, *foreptr, *backptr;
+  unsigned hashpos;
+
+  if(windowsize == 0 || windowsize > 32768) return 60; /*error: windowsize smaller/larger than allowed*/
+  if((windowsize & (windowsize - 1)) != 0) return 90; /*error: must be power of two*/
+
+  if(nicematch > MAX_SUPPORTED_DEFLATE_LENGTH) nicematch = MAX_SUPPORTED_DEFLATE_LENGTH;
+
+  for(pos = inpos; pos < insize; ++pos) {
+    size_t wpos = pos & (windowsize - 1); /*position for in 'circular' hash buffers*/
+    unsigned chainlength = 0;
+
+    hashval = getHash(in, insize, pos);
+
+    if(usezeros && hashval == 0) {
+      if(numzeros == 0) numzeros = countZeros(in, insize, pos);
+      else if(pos + numzeros > insize || in[pos + numzeros - 1] != 0) --numzeros;
+    } else {
+      numzeros = 0;
+    }
+
+    updateHashChain(hash, wpos, hashval, numzeros);
+
+    /*the length and offset found for the current position*/
+    length = 0;
+    offset = 0;
+
+    hashpos = hash->chain[wpos];
+
+    lastptr = &in[insize < pos + MAX_SUPPORTED_DEFLATE_LENGTH ? insize : pos + MAX_SUPPORTED_DEFLATE_LENGTH];
+
+    /*search for the longest string*/
+    prev_offset = 0;
+    for(;;) {
+      if(chainlength++ >= maxchainlength) break;
+      current_offset = (unsigned)(hashpos <= wpos ? wpos - hashpos : wpos - hashpos + windowsize);
+
+      if(current_offset < prev_offset) break; /*stop when went completely around the circular buffer*/
+      prev_offset = current_offset;
+      if(current_offset > 0) {
+        /*test the next characters*/
+        foreptr = &in[pos];
+        backptr = &in[pos - current_offset];
+
+        /*common case in PNGs is lots of zeros. Quickly skip over them as a speedup*/
+        if(numzeros >= 3) {
+          unsigned skip = hash->zeros[hashpos];
+          if(skip > numzeros) skip = numzeros;
+          backptr += skip;
+          foreptr += skip;
+        }
+
+        while(foreptr != lastptr && *backptr == *foreptr) /*maximum supported length by deflate is max length*/ {
+          ++backptr;
+          ++foreptr;
+        }
+        current_length = (unsigned)(foreptr - &in[pos]);
+
+        if(current_length > length) {
+          length = current_length; /*the longest length*/
+          offset = current_offset; /*the offset that is related to this longest length*/
+          /*jump out once a length of max length is found (speed gain). This also jumps
+          out if length is MAX_SUPPORTED_DEFLATE_LENGTH*/
+          if(current_length >= nicematch) break;
+        }
+      }
+
+      if(hashpos == hash->chain[hashpos]) break;
+
+      if(numzeros >= 3 && length > numzeros) {
+        hashpos = hash->chainz[hashpos];
+        if(hash->zeros[hashpos] != numzeros) break;
+      } else {
+        hashpos = hash->chain[hashpos];
+        /*outdated hash value, happens if particular value was not encountered in whole last window*/
+        if(hash->val[hashpos] != (int)hashval) break;
+      }
+    }
+
+    if(lazymatching) {
+      if(!lazy && length >= 3 && length <= maxlazymatch && length < MAX_SUPPORTED_DEFLATE_LENGTH) {
+        lazy = 1;
+        lazylength = length;
+        lazyoffset = offset;
+        continue; /*try the next byte*/
+      }
+      if(lazy) {
+        lazy = 0;
+        if(pos == 0) ERROR_BREAK(81);
+        if(length > lazylength + 1) {
+          /*push the previous character as literal*/
+          if(!uivector_push_back(out, in[pos - 1])) ERROR_BREAK(83 /*alloc fail*/);
+        } else {
+          length = lazylength;
+          offset = lazyoffset;
+          hash->head[hashval] = -1; /*the same hashchain update will be done, this ensures no wrong alteration*/
+          hash->headz[numzeros] = -1; /*idem*/
+          --pos;
+        }
+      }
+    }
+    if(length >= 3 && offset > windowsize) ERROR_BREAK(86 /*too big (or overflown negative) offset*/);
+
+    /*encode it as length/distance pair or literal value*/
+    if(length < 3) /*only lengths of 3 or higher are supported as length/distance pair*/ {
+      if(!uivector_push_back(out, in[pos])) ERROR_BREAK(83 /*alloc fail*/);
+    } else if(length < minmatch || (length == 3 && offset > 4096)) {
+      /*compensate for the fact that longer offsets have more extra bits, a
+      length of only 3 may be not worth it then*/
+      if(!uivector_push_back(out, in[pos])) ERROR_BREAK(83 /*alloc fail*/);
+    } else {
+      addLengthDistance(out, length, offset);
+      for(i = 1; i < length; ++i) {
+        ++pos;
+        wpos = pos & (windowsize - 1);
+        hashval = getHash(in, insize, pos);
+        if(usezeros && hashval == 0) {
+          if(numzeros == 0) numzeros = countZeros(in, insize, pos);
+          else if(pos + numzeros > insize || in[pos + numzeros - 1] != 0) --numzeros;
+        } else {
+          numzeros = 0;
+        }
+        updateHashChain(hash, wpos, hashval, numzeros);
+      }
+    }
+  } /*end of the loop through each character of input*/
+
+  return error;
+}
+
+/* /////////////////////////////////////////////////////////////////////////// */
+
+static unsigned deflateNoCompression(ucvector* out, const unsigned char* data, size_t datasize) {
+  /*non compressed deflate block data: 1 bit BFINAL,2 bits BTYPE,(5 bits): it jumps to start of next byte,
+  2 bytes LEN, 2 bytes NLEN, LEN bytes literal DATA*/
+
+  size_t i, numdeflateblocks = (datasize + 65534u) / 65535u;
+  unsigned datapos = 0;
+  for(i = 0; i != numdeflateblocks; ++i) {
+    unsigned BFINAL, BTYPE, LEN, NLEN;
+    unsigned char firstbyte;
+    size_t pos = out->size;
+
+    BFINAL = (i == numdeflateblocks - 1);
+    BTYPE = 0;
+
+    LEN = 65535;
+    if(datasize - datapos < 65535u) LEN = (unsigned)datasize - datapos;
+    NLEN = 65535 - LEN;
+
+    if(!ucvector_resize(out, out->size + LEN + 5)) return 83; /*alloc fail*/
+
+    firstbyte = (unsigned char)(BFINAL + ((BTYPE & 1u) << 1u) + ((BTYPE & 2u) << 1u));
+    out->data[pos + 0] = firstbyte;
+    out->data[pos + 1] = (unsigned char)(LEN & 255);
+    out->data[pos + 2] = (unsigned char)(LEN >> 8u);
+    out->data[pos + 3] = (unsigned char)(NLEN & 255);
+    out->data[pos + 4] = (unsigned char)(NLEN >> 8u);
+    lodepng_memcpy(out->data + pos + 5, data + datapos, LEN);
+    datapos += LEN;
+  }
+
+  return 0;
+}
+
+/*
+write the lz77-encoded data, which has lit, len and dist codes, to compressed stream using huffman trees.
+tree_ll: the tree for lit and len codes.
+tree_d: the tree for distance codes.
+*/
+static void writeLZ77data(LodePNGBitWriter* writer, const uivector* lz77_encoded,
+                          const HuffmanTree* tree_ll, const HuffmanTree* tree_d) {
+  size_t i = 0;
+  for(i = 0; i != lz77_encoded->size; ++i) {
+    unsigned val = lz77_encoded->data[i];
+    writeBitsReversed(writer, tree_ll->codes[val], tree_ll->lengths[val]);
+    if(val > 256) /*for a length code, 3 more things have to be added*/ {
+      unsigned length_index = val - FIRST_LENGTH_CODE_INDEX;
+      unsigned n_length_extra_bits = LENGTHEXTRA[length_index];
+      unsigned length_extra_bits = lz77_encoded->data[++i];
+
+      unsigned distance_code = lz77_encoded->data[++i];
+
+      unsigned distance_index = distance_code;
+      unsigned n_distance_extra_bits = DISTANCEEXTRA[distance_index];
+      unsigned distance_extra_bits = lz77_encoded->data[++i];
+
+      writeBits(writer, length_extra_bits, n_length_extra_bits);
+      writeBitsReversed(writer, tree_d->codes[distance_code], tree_d->lengths[distance_code]);
+      writeBits(writer, distance_extra_bits, n_distance_extra_bits);
+    }
+  }
+}
+
+/*Deflate for a block of type "dynamic", that is, with freely, optimally, created huffman trees*/
+static unsigned deflateDynamic(LodePNGBitWriter* writer, Hash* hash,
+                               const unsigned char* data, size_t datapos, size_t dataend,
+                               const LodePNGCompressSettings* settings, unsigned final) {
+  unsigned error = 0;
+
+  /*
+  A block is compressed as follows: The PNG data is lz77 encoded, resulting in
+  literal bytes and length/distance pairs. This is then huffman compressed with
+  two huffman trees. One huffman tree is used for the lit and len values ("ll"),
+  another huffman tree is used for the dist values ("d"). These two trees are
+  stored using their code lengths, and to compress even more these code lengths
+  are also run-length encoded and huffman compressed. This gives a huffman tree
+  of code lengths "cl". The code lengths used to describe this third tree are
+  the code length code lengths ("clcl").
+  */
+
+  /*The lz77 encoded data, represented with integers since there will also be length and distance codes in it*/
+  uivector lz77_encoded;
+  HuffmanTree tree_ll; /*tree for lit,len values*/
+  HuffmanTree tree_d; /*tree for distance codes*/
+  HuffmanTree tree_cl; /*tree for encoding the code lengths representing tree_ll and tree_d*/
+  unsigned* frequencies_ll = 0; /*frequency of lit,len codes*/
+  unsigned* frequencies_d = 0; /*frequency of dist codes*/
+  unsigned* frequencies_cl = 0; /*frequency of code length codes*/
+  unsigned* bitlen_lld = 0; /*lit,len,dist code lengths (int bits), literally (without repeat codes).*/
+  unsigned* bitlen_lld_e = 0; /*bitlen_lld encoded with repeat codes (this is a rudimentary run length compression)*/
+  size_t datasize = dataend - datapos;
+
+  /*
+  If we could call "bitlen_cl" the the code length code lengths ("clcl"), that is the bit lengths of codes to represent
+  tree_cl in CLCL_ORDER, then due to the huffman compression of huffman tree representations ("two levels"), there are
+  some analogies:
+  bitlen_lld is to tree_cl what data is to tree_ll and tree_d.
+  bitlen_lld_e is to bitlen_lld what lz77_encoded is to data.
+  bitlen_cl is to bitlen_lld_e what bitlen_lld is to lz77_encoded.
+  */
+
+  unsigned BFINAL = final;
+  size_t i;
+  size_t numcodes_ll, numcodes_d, numcodes_lld, numcodes_lld_e, numcodes_cl;
+  unsigned HLIT, HDIST, HCLEN;
+
+  uivector_init(&lz77_encoded);
+  HuffmanTree_init(&tree_ll);
+  HuffmanTree_init(&tree_d);
+  HuffmanTree_init(&tree_cl);
+  /* could fit on stack, but >1KB is on the larger side so allocate instead */
+  frequencies_ll = (unsigned*)lodepng_malloc(286 * sizeof(*frequencies_ll));
+  frequencies_d = (unsigned*)lodepng_malloc(30 * sizeof(*frequencies_d));
+  frequencies_cl = (unsigned*)lodepng_malloc(NUM_CODE_LENGTH_CODES * sizeof(*frequencies_cl));
+
+  if(!frequencies_ll || !frequencies_d || !frequencies_cl) error = 83; /*alloc fail*/
+
+  /*This while loop never loops due to a break at the end, it is here to
+  allow breaking out of it to the cleanup phase on error conditions.*/
+  while(!error) {
+    lodepng_memset(frequencies_ll, 0, 286 * sizeof(*frequencies_ll));
+    lodepng_memset(frequencies_d, 0, 30 * sizeof(*frequencies_d));
+    lodepng_memset(frequencies_cl, 0, NUM_CODE_LENGTH_CODES * sizeof(*frequencies_cl));
+
+    if(settings->use_lz77) {
+      error = encodeLZ77(&lz77_encoded, hash, data, datapos, dataend, settings->windowsize,
+                         settings->minmatch, settings->nicematch, settings->lazymatching);
+      if(error) break;
+    } else {
+      if(!uivector_resize(&lz77_encoded, datasize)) ERROR_BREAK(83 /*alloc fail*/);
+      for(i = datapos; i < dataend; ++i) lz77_encoded.data[i - datapos] = data[i]; /*no LZ77, but still will be Huffman compressed*/
+    }
+
+    /*Count the frequencies of lit, len and dist codes*/
+    for(i = 0; i != lz77_encoded.size; ++i) {
+      unsigned symbol = lz77_encoded.data[i];
+      ++frequencies_ll[symbol];
+      if(symbol > 256) {
+        unsigned dist = lz77_encoded.data[i + 2];
+        ++frequencies_d[dist];
+        i += 3;
+      }
+    }
+    frequencies_ll[256] = 1; /*there will be exactly 1 end code, at the end of the block*/
+
+    /*Make both huffman trees, one for the lit and len codes, one for the dist codes*/
+    error = HuffmanTree_makeFromFrequencies(&tree_ll, frequencies_ll, 257, 286, 15);
+    if(error) break;
+    /*2, not 1, is chosen for mincodes: some buggy PNG decoders require at least 2 symbols in the dist tree*/
+    error = HuffmanTree_makeFromFrequencies(&tree_d, frequencies_d, 2, 30, 15);
+    if(error) break;
+
+    numcodes_ll = LODEPNG_MIN(tree_ll.numcodes, 286);
+    numcodes_d = LODEPNG_MIN(tree_d.numcodes, 30);
+    /*store the code lengths of both generated trees in bitlen_lld*/
+    numcodes_lld = numcodes_ll + numcodes_d;
+    bitlen_lld = (unsigned*)lodepng_malloc(numcodes_lld * sizeof(*bitlen_lld));
+    /*numcodes_lld_e never needs more size than bitlen_lld*/
+    bitlen_lld_e = (unsigned*)lodepng_malloc(numcodes_lld * sizeof(*bitlen_lld_e));
+    if(!bitlen_lld || !bitlen_lld_e) ERROR_BREAK(83); /*alloc fail*/
+    numcodes_lld_e = 0;
+
+    for(i = 0; i != numcodes_ll; ++i) bitlen_lld[i] = tree_ll.lengths[i];
+    for(i = 0; i != numcodes_d; ++i) bitlen_lld[numcodes_ll + i] = tree_d.lengths[i];
+
+    /*run-length compress bitlen_ldd into bitlen_lld_e by using repeat codes 16 (copy length 3-6 times),
+    17 (3-10 zeroes), 18 (11-138 zeroes)*/
+    for(i = 0; i != numcodes_lld; ++i) {
+      unsigned j = 0; /*amount of repetitions*/
+      while(i + j + 1 < numcodes_lld && bitlen_lld[i + j + 1] == bitlen_lld[i]) ++j;
+
+      if(bitlen_lld[i] == 0 && j >= 2) /*repeat code for zeroes*/ {
+        ++j; /*include the first zero*/
+        if(j <= 10) /*repeat code 17 supports max 10 zeroes*/ {
+          bitlen_lld_e[numcodes_lld_e++] = 17;
+          bitlen_lld_e[numcodes_lld_e++] = j - 3;
+        } else /*repeat code 18 supports max 138 zeroes*/ {
+          if(j > 138) j = 138;
+          bitlen_lld_e[numcodes_lld_e++] = 18;
+          bitlen_lld_e[numcodes_lld_e++] = j - 11;
+        }
+        i += (j - 1);
+      } else if(j >= 3) /*repeat code for value other than zero*/ {
+        size_t k;
+        unsigned num = j / 6u, rest = j % 6u;
+        bitlen_lld_e[numcodes_lld_e++] = bitlen_lld[i];
+        for(k = 0; k < num; ++k) {
+          bitlen_lld_e[numcodes_lld_e++] = 16;
+          bitlen_lld_e[numcodes_lld_e++] = 6 - 3;
+        }
+        if(rest >= 3) {
+          bitlen_lld_e[numcodes_lld_e++] = 16;
+          bitlen_lld_e[numcodes_lld_e++] = rest - 3;
+        }
+        else j -= rest;
+        i += j;
+      } else /*too short to benefit from repeat code*/ {
+        bitlen_lld_e[numcodes_lld_e++] = bitlen_lld[i];
+      }
+    }
+
+    /*generate tree_cl, the huffmantree of huffmantrees*/
+    for(i = 0; i != numcodes_lld_e; ++i) {
+      ++frequencies_cl[bitlen_lld_e[i]];
+      /*after a repeat code come the bits that specify the number of repetitions,
+      those don't need to be in the frequencies_cl calculation*/
+      if(bitlen_lld_e[i] >= 16) ++i;
+    }
+
+    error = HuffmanTree_makeFromFrequencies(&tree_cl, frequencies_cl,
+                                            NUM_CODE_LENGTH_CODES, NUM_CODE_LENGTH_CODES, 7);
+    if(error) break;
+
+    /*compute amount of code-length-code-lengths to output*/
+    numcodes_cl = NUM_CODE_LENGTH_CODES;
+    /*trim zeros at the end (using CLCL_ORDER), but minimum size must be 4 (see HCLEN below)*/
+    while(numcodes_cl > 4u && tree_cl.lengths[CLCL_ORDER[numcodes_cl - 1u]] == 0) {
+      numcodes_cl--;
+    }
+
+    /*
+    Write everything into the output
+
+    After the BFINAL and BTYPE, the dynamic block consists out of the following:
+    - 5 bits HLIT, 5 bits HDIST, 4 bits HCLEN
+    - (HCLEN+4)*3 bits code lengths of code length alphabet
+    - HLIT + 257 code lengths of lit/length alphabet (encoded using the code length
+      alphabet, + possible repetition codes 16, 17, 18)
+    - HDIST + 1 code lengths of distance alphabet (encoded using the code length
+      alphabet, + possible repetition codes 16, 17, 18)
+    - compressed data
+    - 256 (end code)
+    */
+
+    /*Write block type*/
+    writeBits(writer, BFINAL, 1);
+    writeBits(writer, 0, 1); /*first bit of BTYPE "dynamic"*/
+    writeBits(writer, 1, 1); /*second bit of BTYPE "dynamic"*/
+
+    /*write the HLIT, HDIST and HCLEN values*/
+    /*all three sizes take trimmed ending zeroes into account, done either by HuffmanTree_makeFromFrequencies
+    or in the loop for numcodes_cl above, which saves space. */
+    HLIT = (unsigned)(numcodes_ll - 257);
+    HDIST = (unsigned)(numcodes_d - 1);
+    HCLEN = (unsigned)(numcodes_cl - 4);
+    writeBits(writer, HLIT, 5);
+    writeBits(writer, HDIST, 5);
+    writeBits(writer, HCLEN, 4);
+
+    /*write the code lengths of the code length alphabet ("bitlen_cl")*/
+    for(i = 0; i != numcodes_cl; ++i) writeBits(writer, tree_cl.lengths[CLCL_ORDER[i]], 3);
+
+    /*write the lengths of the lit/len AND the dist alphabet*/
+    for(i = 0; i != numcodes_lld_e; ++i) {
+      writeBitsReversed(writer, tree_cl.codes[bitlen_lld_e[i]], tree_cl.lengths[bitlen_lld_e[i]]);
+      /*extra bits of repeat codes*/
+      if(bitlen_lld_e[i] == 16) writeBits(writer, bitlen_lld_e[++i], 2);
+      else if(bitlen_lld_e[i] == 17) writeBits(writer, bitlen_lld_e[++i], 3);
+      else if(bitlen_lld_e[i] == 18) writeBits(writer, bitlen_lld_e[++i], 7);
+    }
+
+    /*write the compressed data symbols*/
+    writeLZ77data(writer, &lz77_encoded, &tree_ll, &tree_d);
+    /*error: the length of the end code 256 must be larger than 0*/
+    if(tree_ll.lengths[256] == 0) ERROR_BREAK(64);
+
+    /*write the end code*/
+    writeBitsReversed(writer, tree_ll.codes[256], tree_ll.lengths[256]);
+
+    break; /*end of error-while*/
+  }
+
+  /*cleanup*/
+  uivector_cleanup(&lz77_encoded);
+  HuffmanTree_cleanup(&tree_ll);
+  HuffmanTree_cleanup(&tree_d);
+  HuffmanTree_cleanup(&tree_cl);
+  lodepng_free(frequencies_ll);
+  lodepng_free(frequencies_d);
+  lodepng_free(frequencies_cl);
+  lodepng_free(bitlen_lld);
+  lodepng_free(bitlen_lld_e);
+
+  return error;
+}
+
+static unsigned deflateFixed(LodePNGBitWriter* writer, Hash* hash,
+                             const unsigned char* data,
+                             size_t datapos, size_t dataend,
+                             const LodePNGCompressSettings* settings, unsigned final) {
+  HuffmanTree tree_ll; /*tree for literal values and length codes*/
+  HuffmanTree tree_d; /*tree for distance codes*/
+
+  unsigned BFINAL = final;
+  unsigned error = 0;
+  size_t i;
+
+  HuffmanTree_init(&tree_ll);
+  HuffmanTree_init(&tree_d);
+
+  error = generateFixedLitLenTree(&tree_ll);
+  if(!error) error = generateFixedDistanceTree(&tree_d);
+
+  if(!error) {
+    writeBits(writer, BFINAL, 1);
+    writeBits(writer, 1, 1); /*first bit of BTYPE*/
+    writeBits(writer, 0, 1); /*second bit of BTYPE*/
+
+    if(settings->use_lz77) /*LZ77 encoded*/ {
+      uivector lz77_encoded;
+      uivector_init(&lz77_encoded);
+      error = encodeLZ77(&lz77_encoded, hash, data, datapos, dataend, settings->windowsize,
+                         settings->minmatch, settings->nicematch, settings->lazymatching);
+      if(!error) writeLZ77data(writer, &lz77_encoded, &tree_ll, &tree_d);
+      uivector_cleanup(&lz77_encoded);
+    } else /*no LZ77, but still will be Huffman compressed*/ {
+      for(i = datapos; i < dataend; ++i) {
+        writeBitsReversed(writer, tree_ll.codes[data[i]], tree_ll.lengths[data[i]]);
+      }
+    }
+    /*add END code*/
+    if(!error) writeBitsReversed(writer,tree_ll.codes[256], tree_ll.lengths[256]);
+  }
+
+  /*cleanup*/
+  HuffmanTree_cleanup(&tree_ll);
+  HuffmanTree_cleanup(&tree_d);
+
+  return error;
+}
+
+static unsigned lodepng_deflatev(ucvector* out, const unsigned char* in, size_t insize,
+                                 const LodePNGCompressSettings* settings) {
+  unsigned error = 0;
+  size_t i, blocksize, numdeflateblocks;
+  Hash hash;
+  LodePNGBitWriter writer;
+
+  LodePNGBitWriter_init(&writer, out);
+
+  if(settings->btype > 2) return 61;
+  else if(settings->btype == 0) return deflateNoCompression(out, in, insize);
+  else if(settings->btype == 1) blocksize = insize;
+  else /*if(settings->btype == 2)*/ {
+    /*on PNGs, deflate blocks of 65-262k seem to give most dense encoding*/
+    blocksize = insize / 8u + 8;
+    if(blocksize < 65536) blocksize = 65536;
+    if(blocksize > 262144) blocksize = 262144;
+  }
+
+  numdeflateblocks = (insize + blocksize - 1) / blocksize;
+  if(numdeflateblocks == 0) numdeflateblocks = 1;
+
+  error = hash_init(&hash, settings->windowsize);
+
+  if(!error) {
+    for(i = 0; i != numdeflateblocks && !error; ++i) {
+      unsigned final = (i == numdeflateblocks - 1);
+      size_t start = i * blocksize;
+      size_t end = start + blocksize;
+      if(end > insize) end = insize;
+
+      if(settings->btype == 1) error = deflateFixed(&writer, &hash, in, start, end, settings, final);
+      else if(settings->btype == 2) error = deflateDynamic(&writer, &hash, in, start, end, settings, final);
+    }
+  }
+
+  hash_cleanup(&hash);
+
+  return error;
+}
+
+unsigned lodepng_deflate(unsigned char** out, size_t* outsize,
+                         const unsigned char* in, size_t insize,
+                         const LodePNGCompressSettings* settings) {
+  ucvector v = ucvector_init(*out, *outsize);
+  unsigned error = lodepng_deflatev(&v, in, insize, settings);
+  *out = v.data;
+  *outsize = v.size;
+  return error;
+}
+
+static unsigned deflate(unsigned char** out, size_t* outsize,
+                        const unsigned char* in, size_t insize,
+                        const LodePNGCompressSettings* settings) {
+  if(settings->custom_deflate) {
+    return settings->custom_deflate(out, outsize, in, insize, settings);
+  } else {
+    return lodepng_deflate(out, outsize, in, insize, settings);
+  }
+}
+
+#endif /*LODEPNG_COMPILE_DECODER*/
+
+/* ////////////////////////////////////////////////////////////////////////// */
+/* / Adler32                                                                / */
+/* ////////////////////////////////////////////////////////////////////////// */
+
+static unsigned update_adler32(unsigned adler, const unsigned char* data, unsigned len) {
+  unsigned s1 = adler & 0xffffu;
+  unsigned s2 = (adler >> 16u) & 0xffffu;
+
+  while(len != 0u) {
+    unsigned i;
+    /*at least 5552 sums can be done before the sums overflow, saving a lot of module divisions*/
+    unsigned amount = len > 5552u ? 5552u : len;
+    len -= amount;
+    for(i = 0; i != amount; ++i) {
+      s1 += (*data++);
+      s2 += s1;
+    }
+    s1 %= 65521u;
+    s2 %= 65521u;
+  }
+
+  return (s2 << 16u) | s1;
+}
+
+/*Return the adler32 of the bytes data[0..len-1]*/
+static unsigned adler32(const unsigned char* data, unsigned len) {
+  return update_adler32(1u, data, len);
+}
+
+/* ////////////////////////////////////////////////////////////////////////// */
+/* / Zlib                                                                   / */
+/* ////////////////////////////////////////////////////////////////////////// */
+
+#ifdef LODEPNG_COMPILE_DECODER
+
+static unsigned lodepng_zlib_decompressv(ucvector* out,
+                                         const unsigned char* in, size_t insize,
+                                         const LodePNGDecompressSettings* settings) {
+  unsigned error = 0;
+  unsigned CM, CINFO, FDICT;
+
+  if(insize < 2) return 53; /*error, size of zlib data too small*/
+  /*read information from zlib header*/
+  if((in[0] * 256 + in[1]) % 31 != 0) {
+    /*error: 256 * in[0] + in[1] must be a multiple of 31, the FCHECK value is supposed to be made that way*/
+    return 24;
+  }
+
+  CM = in[0] & 15;
+  CINFO = (in[0] >> 4) & 15;
+  /*FCHECK = in[1] & 31;*/ /*FCHECK is already tested above*/
+  FDICT = (in[1] >> 5) & 1;
+  /*FLEVEL = (in[1] >> 6) & 3;*/ /*FLEVEL is not used here*/
+
+  if(CM != 8 || CINFO > 7) {
+    /*error: only compression method 8: inflate with sliding window of 32k is supported by the PNG spec*/
+    return 25;
+  }
+  if(FDICT != 0) {
+    /*error: the specification of PNG says about the zlib stream:
+      "The additional flags shall not specify a preset dictionary."*/
+    return 26;
+  }
+
+  error = inflatev(out, in + 2, insize - 2, settings);
+  if(error) return error;
+
+  if(!settings->ignore_adler32) {
+    unsigned ADLER32 = lodepng_read32bitInt(&in[insize - 4]);
+    unsigned checksum = adler32(out->data, (unsigned)(out->size));
+    if(checksum != ADLER32) return 58; /*error, adler checksum not correct, data must be corrupted*/
+  }
+
+  return 0; /*no error*/
+}
+
+
+unsigned lodepng_zlib_decompress(unsigned char** out, size_t* outsize, const unsigned char* in,
+                                 size_t insize, const LodePNGDecompressSettings* settings) {
+  ucvector v = ucvector_init(*out, *outsize);
+  unsigned error = lodepng_zlib_decompressv(&v, in, insize, settings);
+  *out = v.data;
+  *outsize = v.size;
+  return error;
+}
+
+/*expected_size is expected output size, to avoid intermediate allocations. Set to 0 if not known. */
+static unsigned zlib_decompress(unsigned char** out, size_t* outsize, size_t expected_size,
+                                const unsigned char* in, size_t insize, const LodePNGDecompressSettings* settings) {
+  if(settings->custom_zlib) {
+    return settings->custom_zlib(out, outsize, in, insize, settings);
+  } else {
+    unsigned error;
+    ucvector v = ucvector_init(*out, *outsize);
+    if(expected_size) {
+      /*reserve the memory to avoid intermediate reallocations*/
+      ucvector_resize(&v, *outsize + expected_size);
+      v.size = *outsize;
+    }
+    error = lodepng_zlib_decompressv(&v, in, insize, settings);
+    *out = v.data;
+    *outsize = v.size;
+    return error;
+  }
+}
+
+#endif /*LODEPNG_COMPILE_DECODER*/
+
+#ifdef LODEPNG_COMPILE_ENCODER
+
+unsigned lodepng_zlib_compress(unsigned char** out, size_t* outsize, const unsigned char* in,
+                               size_t insize, const LodePNGCompressSettings* settings) {
+  size_t i;
+  unsigned error;
+  unsigned char* deflatedata = 0;
+  size_t deflatesize = 0;
+
+  error = deflate(&deflatedata, &deflatesize, in, insize, settings);
+
+  *out = NULL;
+  *outsize = 0;
+  if(!error) {
+    *outsize = deflatesize + 6;
+    *out = (unsigned char*)lodepng_malloc(*outsize);
+    if(!*out) error = 83; /*alloc fail*/
+  }
+
+  if(!error) {
+    unsigned ADLER32 = adler32(in, (unsigned)insize);
+    /*zlib data: 1 byte CMF (CM+CINFO), 1 byte FLG, deflate data, 4 byte ADLER32 checksum of the Decompressed data*/
+    unsigned CMF = 120; /*0b01111000: CM 8, CINFO 7. With CINFO 7, any window size up to 32768 can be used.*/
+    unsigned FLEVEL = 0;
+    unsigned FDICT = 0;
+    unsigned CMFFLG = 256 * CMF + FDICT * 32 + FLEVEL * 64;
+    unsigned FCHECK = 31 - CMFFLG % 31;
+    CMFFLG += FCHECK;
+
+    (*out)[0] = (unsigned char)(CMFFLG >> 8);
+    (*out)[1] = (unsigned char)(CMFFLG & 255);
+    for(i = 0; i != deflatesize; ++i) (*out)[i + 2] = deflatedata[i];
+    lodepng_set32bitInt(&(*out)[*outsize - 4], ADLER32);
+  }
+
+  lodepng_free(deflatedata);
+  return error;
+}
+
+/* compress using the default or custom zlib function */
+static unsigned zlib_compress(unsigned char** out, size_t* outsize, const unsigned char* in,
+                              size_t insize, const LodePNGCompressSettings* settings) {
+  if(settings->custom_zlib) {
+    return settings->custom_zlib(out, outsize, in, insize, settings);
+  } else {
+    return lodepng_zlib_compress(out, outsize, in, insize, settings);
+  }
+}
+
+#endif /*LODEPNG_COMPILE_ENCODER*/
+
+#else /*no LODEPNG_COMPILE_ZLIB*/
+
+#ifdef LODEPNG_COMPILE_DECODER
+static unsigned zlib_decompress(unsigned char** out, size_t* outsize, size_t expected_size,
+                                const unsigned char* in, size_t insize, const LodePNGDecompressSettings* settings) {
+  if(!settings->custom_zlib) return 87; /*no custom zlib function provided */
+  (void)expected_size;
+  return settings->custom_zlib(out, outsize, in, insize, settings);
+}
+#endif /*LODEPNG_COMPILE_DECODER*/
+#ifdef LODEPNG_COMPILE_ENCODER
+static unsigned zlib_compress(unsigned char** out, size_t* outsize, const unsigned char* in,
+                              size_t insize, const LodePNGCompressSettings* settings) {
+  if(!settings->custom_zlib) return 87; /*no custom zlib function provided */
+  return settings->custom_zlib(out, outsize, in, insize, settings);
+}
+#endif /*LODEPNG_COMPILE_ENCODER*/
+
+#endif /*LODEPNG_COMPILE_ZLIB*/
+
+/* ////////////////////////////////////////////////////////////////////////// */
+
+#ifdef LODEPNG_COMPILE_ENCODER
+
+/*this is a good tradeoff between speed and compression ratio*/
+#define DEFAULT_WINDOWSIZE 2048
+
+void lodepng_compress_settings_init(LodePNGCompressSettings* settings) {
+  /*compress with dynamic huffman tree (not in the mathematical sense, just not the predefined one)*/
+  settings->btype = 2;
+  settings->use_lz77 = 1;
+  settings->windowsize = DEFAULT_WINDOWSIZE;
+  settings->minmatch = 3;
+  settings->nicematch = 128;
+  settings->lazymatching = 1;
+
+  settings->custom_zlib = 0;
+  settings->custom_deflate = 0;
+  settings->custom_context = 0;
+}
+
+const LodePNGCompressSettings lodepng_default_compress_settings = {2, 1, DEFAULT_WINDOWSIZE, 3, 128, 1, 0, 0, 0};
+
+
+#endif /*LODEPNG_COMPILE_ENCODER*/
+
+#ifdef LODEPNG_COMPILE_DECODER
+
+void lodepng_decompress_settings_init(LodePNGDecompressSettings* settings) {
+  settings->ignore_adler32 = 0;
+  settings->ignore_nlen = 0;
+
+  settings->custom_zlib = 0;
+  settings->custom_inflate = 0;
+  settings->custom_context = 0;
+}
+
+const LodePNGDecompressSettings lodepng_default_decompress_settings = {0, 0, 0, 0, 0};
+
+#endif /*LODEPNG_COMPILE_DECODER*/
+
+/* ////////////////////////////////////////////////////////////////////////// */
+/* ////////////////////////////////////////////////////////////////////////// */
+/* // End of Zlib related code. Begin of PNG related code.                 // */
+/* ////////////////////////////////////////////////////////////////////////// */
+/* ////////////////////////////////////////////////////////////////////////// */
+
+#ifdef LODEPNG_COMPILE_PNG
+
+/* ////////////////////////////////////////////////////////////////////////// */
+/* / CRC32                                                                  / */
+/* ////////////////////////////////////////////////////////////////////////// */
+
+
+#ifndef LODEPNG_NO_COMPILE_CRC
+/* CRC polynomial: 0xedb88320 */
+static unsigned lodepng_crc32_table[256] = {
+           0u, 1996959894u, 3993919788u, 2567524794u,  124634137u, 1886057615u, 3915621685u, 2657392035u,
+   249268274u, 2044508324u, 3772115230u, 2547177864u,  162941995u, 2125561021u, 3887607047u, 2428444049u,
+   498536548u, 1789927666u, 4089016648u, 2227061214u,  450548861u, 1843258603u, 4107580753u, 2211677639u,
+   325883990u, 1684777152u, 4251122042u, 2321926636u,  335633487u, 1661365465u, 4195302755u, 2366115317u,
+   997073096u, 1281953886u, 3579855332u, 2724688242u, 1006888145u, 1258607687u, 3524101629u, 2768942443u,
+   901097722u, 1119000684u, 3686517206u, 2898065728u,  853044451u, 1172266101u, 3705015759u, 2882616665u,
+   651767980u, 1373503546u, 3369554304u, 3218104598u,  565507253u, 1454621731u, 3485111705u, 3099436303u,
+   671266974u, 1594198024u, 3322730930u, 2970347812u,  795835527u, 1483230225u, 3244367275u, 3060149565u,
+  1994146192u,   31158534u, 2563907772u, 4023717930u, 1907459465u,  112637215u, 2680153253u, 3904427059u,
+  2013776290u,  251722036u, 2517215374u, 3775830040u, 2137656763u,  141376813u, 2439277719u, 3865271297u,
+  1802195444u,  476864866u, 2238001368u, 4066508878u, 1812370925u,  453092731u, 2181625025u, 4111451223u,
+  1706088902u,  314042704u, 2344532202u, 4240017532u, 1658658271u,  366619977u, 2362670323u, 4224994405u,
+  1303535960u,  984961486u, 2747007092u, 3569037538u, 1256170817u, 1037604311u, 2765210733u, 3554079995u,
+  1131014506u,  879679996u, 2909243462u, 3663771856u, 1141124467u,  855842277u, 2852801631u, 3708648649u,
+  1342533948u,  654459306u, 3188396048u, 3373015174u, 1466479909u,  544179635u, 3110523913u, 3462522015u,
+  1591671054u,  702138776u, 2966460450u, 3352799412u, 1504918807u,  783551873u, 3082640443u, 3233442989u,
+  3988292384u, 2596254646u,   62317068u, 1957810842u, 3939845945u, 2647816111u,   81470997u, 1943803523u,
+  3814918930u, 2489596804u,  225274430u, 2053790376u, 3826175755u, 2466906013u,  167816743u, 2097651377u,
+  4027552580u, 2265490386u,  503444072u, 1762050814u, 4150417245u, 2154129355u,  426522225u, 1852507879u,
+  4275313526u, 2312317920u,  282753626u, 1742555852u, 4189708143u, 2394877945u,  397917763u, 1622183637u,
+  3604390888u, 2714866558u,  953729732u, 1340076626u, 3518719985u, 2797360999u, 1068828381u, 1219638859u,
+  3624741850u, 2936675148u,  906185462u, 1090812512u, 3747672003u, 2825379669u,  829329135u, 1181335161u,
+  3412177804u, 3160834842u,  628085408u, 1382605366u, 3423369109u, 3138078467u,  570562233u, 1426400815u,
+  3317316542u, 2998733608u,  733239954u, 1555261956u, 3268935591u, 3050360625u,  752459403u, 1541320221u,
+  2607071920u, 3965973030u, 1969922972u,   40735498u, 2617837225u, 3943577151u, 1913087877u,   83908371u,
+  2512341634u, 3803740692u, 2075208622u,  213261112u, 2463272603u, 3855990285u, 2094854071u,  198958881u,
+  2262029012u, 4057260610u, 1759359992u,  534414190u, 2176718541u, 4139329115u, 1873836001u,  414664567u,
+  2282248934u, 4279200368u, 1711684554u,  285281116u, 2405801727u, 4167216745u, 1634467795u,  376229701u,
+  2685067896u, 3608007406u, 1308918612u,  956543938u, 2808555105u, 3495958263u, 1231636301u, 1047427035u,
+  2932959818u, 3654703836u, 1088359270u,  936918000u, 2847714899u, 3736837829u, 1202900863u,  817233897u,
+  3183342108u, 3401237130u, 1404277552u,  615818150u, 3134207493u, 3453421203u, 1423857449u,  601450431u,
+  3009837614u, 3294710456u, 1567103746u,  711928724u, 3020668471u, 3272380065u, 1510334235u,  755167117u
+};
+
+/*Return the CRC of the bytes buf[0..len-1].*/
+unsigned lodepng_crc32(const unsigned char* data, size_t length) {
+  unsigned r = 0xffffffffu;
+  size_t i;
+  for(i = 0; i < length; ++i) {
+    r = lodepng_crc32_table[(r ^ data[i]) & 0xffu] ^ (r >> 8u);
+  }
+  return r ^ 0xffffffffu;
+}
+#else /* !LODEPNG_NO_COMPILE_CRC */
+unsigned lodepng_crc32(const unsigned char* data, size_t length);
+#endif /* !LODEPNG_NO_COMPILE_CRC */
+
+/* ////////////////////////////////////////////////////////////////////////// */
+/* / Reading and writing PNG color channel bits                             / */
+/* ////////////////////////////////////////////////////////////////////////// */
+
+/* The color channel bits of less-than-8-bit pixels are read with the MSB of bytes first,
+so LodePNGBitWriter and LodePNGBitReader can't be used for those. */
+
+static unsigned char readBitFromReversedStream(size_t* bitpointer, const unsigned char* bitstream) {
+  unsigned char result = (unsigned char)((bitstream[(*bitpointer) >> 3] >> (7 - ((*bitpointer) & 0x7))) & 1);
+  ++(*bitpointer);
+  return result;
+}
+
+/* TODO: make this faster */
+static unsigned readBitsFromReversedStream(size_t* bitpointer, const unsigned char* bitstream, size_t nbits) {
+  unsigned result = 0;
+  size_t i;
+  for(i = 0 ; i < nbits; ++i) {
+    result <<= 1u;
+    result |= (unsigned)readBitFromReversedStream(bitpointer, bitstream);
+  }
+  return result;
+}
+
+static void setBitOfReversedStream(size_t* bitpointer, unsigned char* bitstream, unsigned char bit) {
+  /*the current bit in bitstream may be 0 or 1 for this to work*/
+  if(bit == 0) bitstream[(*bitpointer) >> 3u] &=  (unsigned char)(~(1u << (7u - ((*bitpointer) & 7u))));
+  else         bitstream[(*bitpointer) >> 3u] |=  (1u << (7u - ((*bitpointer) & 7u)));
+  ++(*bitpointer);
+}
+
+/* ////////////////////////////////////////////////////////////////////////// */
+/* / PNG chunks                                                             / */
+/* ////////////////////////////////////////////////////////////////////////// */
+
+unsigned lodepng_chunk_length(const unsigned char* chunk) {
+  return lodepng_read32bitInt(&chunk[0]);
+}
+
+void lodepng_chunk_type(char type[5], const unsigned char* chunk) {
+  unsigned i;
+  for(i = 0; i != 4; ++i) type[i] = (char)chunk[4 + i];
+  type[4] = 0; /*null termination char*/
+}
+
+unsigned char lodepng_chunk_type_equals(const unsigned char* chunk, const char* type) {
+  if(lodepng_strlen(type) != 4) return 0;
+  return (chunk[4] == type[0] && chunk[5] == type[1] && chunk[6] == type[2] && chunk[7] == type[3]);
+}
+
+unsigned char lodepng_chunk_ancillary(const unsigned char* chunk) {
+  return((chunk[4] & 32) != 0);
+}
+
+unsigned char lodepng_chunk_private(const unsigned char* chunk) {
+  return((chunk[6] & 32) != 0);
+}
+
+unsigned char lodepng_chunk_safetocopy(const unsigned char* chunk) {
+  return((chunk[7] & 32) != 0);
+}
+
+unsigned char* lodepng_chunk_data(unsigned char* chunk) {
+  return &chunk[8];
+}
+
+const unsigned char* lodepng_chunk_data_const(const unsigned char* chunk) {
+  return &chunk[8];
+}
+
+unsigned lodepng_chunk_check_crc(const unsigned char* chunk) {
+  unsigned length = lodepng_chunk_length(chunk);
+  unsigned CRC = lodepng_read32bitInt(&chunk[length + 8]);
+  /*the CRC is taken of the data and the 4 chunk type letters, not the length*/
+  unsigned checksum = lodepng_crc32(&chunk[4], length + 4);
+  if(CRC != checksum) return 1;
+  else return 0;
+}
+
+void lodepng_chunk_generate_crc(unsigned char* chunk) {
+  unsigned length = lodepng_chunk_length(chunk);
+  unsigned CRC = lodepng_crc32(&chunk[4], length + 4);
+  lodepng_set32bitInt(chunk + 8 + length, CRC);
+}
+
+unsigned char* lodepng_chunk_next(unsigned char* chunk, unsigned char* end) {
+  if(chunk >= end || end - chunk < 12) return end; /*too small to contain a chunk*/
+  if(chunk[0] == 0x89 && chunk[1] == 0x50 && chunk[2] == 0x4e && chunk[3] == 0x47
+    && chunk[4] == 0x0d && chunk[5] == 0x0a && chunk[6] == 0x1a && chunk[7] == 0x0a) {
+    /* Is PNG magic header at start of PNG file. Jump to first actual chunk. */
+    return chunk + 8;
+  } else {
+    size_t total_chunk_length;
+    unsigned char* result;
+    if(lodepng_addofl(lodepng_chunk_length(chunk), 12, &total_chunk_length)) return end;
+    result = chunk + total_chunk_length;
+    if(result < chunk) return end; /*pointer overflow*/
+    return result;
+  }
+}
+
+const unsigned char* lodepng_chunk_next_const(const unsigned char* chunk, const unsigned char* end) {
+  if(chunk >= end || end - chunk < 12) return end; /*too small to contain a chunk*/
+  if(chunk[0] == 0x89 && chunk[1] == 0x50 && chunk[2] == 0x4e && chunk[3] == 0x47
+    && chunk[4] == 0x0d && chunk[5] == 0x0a && chunk[6] == 0x1a && chunk[7] == 0x0a) {
+    /* Is PNG magic header at start of PNG file. Jump to first actual chunk. */
+    return chunk + 8;
+  } else {
+    size_t total_chunk_length;
+    const unsigned char* result;
+    if(lodepng_addofl(lodepng_chunk_length(chunk), 12, &total_chunk_length)) return end;
+    result = chunk + total_chunk_length;
+    if(result < chunk) return end; /*pointer overflow*/
+    return result;
+  }
+}
+
+unsigned char* lodepng_chunk_find(unsigned char* chunk, unsigned char* end, const char type[5]) {
+  for(;;) {
+    if(chunk >= end || end - chunk < 12) return 0; /* past file end: chunk + 12 > end */
+    if(lodepng_chunk_type_equals(chunk, type)) return chunk;
+    chunk = lodepng_chunk_next(chunk, end);
+  }
+}
+
+const unsigned char* lodepng_chunk_find_const(const unsigned char* chunk, const unsigned char* end, const char type[5]) {
+  for(;;) {
+    if(chunk >= end || end - chunk < 12) return 0; /* past file end: chunk + 12 > end */
+    if(lodepng_chunk_type_equals(chunk, type)) return chunk;
+    chunk = lodepng_chunk_next_const(chunk, end);
+  }
+}
+
+unsigned lodepng_chunk_append(unsigned char** out, size_t* outsize, const unsigned char* chunk) {
+  unsigned i;
+  size_t total_chunk_length, new_length;
+  unsigned char *chunk_start, *new_buffer;
+
+  if(lodepng_addofl(lodepng_chunk_length(chunk), 12, &total_chunk_length)) return 77;
+  if(lodepng_addofl(*outsize, total_chunk_length, &new_length)) return 77;
+
+  new_buffer = (unsigned char*)lodepng_realloc(*out, new_length);
+  if(!new_buffer) return 83; /*alloc fail*/
+  (*out) = new_buffer;
+  (*outsize) = new_length;
+  chunk_start = &(*out)[new_length - total_chunk_length];
+
+  for(i = 0; i != total_chunk_length; ++i) chunk_start[i] = chunk[i];
+
+  return 0;
+}
+
+/*Sets length and name and allocates the space for data and crc but does not
+set data or crc yet. Returns the start of the chunk in chunk. The start of
+the data is at chunk + 8. To finalize chunk, add the data, then use
+lodepng_chunk_generate_crc */
+static unsigned lodepng_chunk_init(unsigned char** chunk,
+                                   ucvector* out,
+                                   unsigned length, const char* type) {
+  size_t new_length = out->size;
+  if(lodepng_addofl(new_length, length, &new_length)) return 77;
+  if(lodepng_addofl(new_length, 12, &new_length)) return 77;
+  if(!ucvector_resize(out, new_length)) return 83; /*alloc fail*/
+  *chunk = out->data + new_length - length - 12u;
+
+  /*1: length*/
+  lodepng_set32bitInt(*chunk, length);
+
+  /*2: chunk name (4 letters)*/
+  lodepng_memcpy(*chunk + 4, type, 4);
+
+  return 0;
+}
+
+/* like lodepng_chunk_create but with custom allocsize */
+static unsigned lodepng_chunk_createv(ucvector* out,
+                                      unsigned length, const char* type, const unsigned char* data) {
+  unsigned char* chunk;
+  CERROR_TRY_RETURN(lodepng_chunk_init(&chunk, out, length, type));
+
+  /*3: the data*/
+  lodepng_memcpy(chunk + 8, data, length);
+
+  /*4: CRC (of the chunkname characters and the data)*/
+  lodepng_chunk_generate_crc(chunk);
+
+  return 0;
+}
+
+unsigned lodepng_chunk_create(unsigned char** out, size_t* outsize,
+                              unsigned length, const char* type, const unsigned char* data) {
+  ucvector v = ucvector_init(*out, *outsize);
+  unsigned error = lodepng_chunk_createv(&v, length, type, data);
+  *out = v.data;
+  *outsize = v.size;
+  return error;
+}
+
+/* ////////////////////////////////////////////////////////////////////////// */
+/* / Color types, channels, bits                                            / */
+/* ////////////////////////////////////////////////////////////////////////// */
+
+/*checks if the colortype is valid and the bitdepth bd is allowed for this colortype.
+Return value is a LodePNG error code.*/
+static unsigned checkColorValidity(LodePNGColorType colortype, unsigned bd) {
+  switch(colortype) {
+    case LCT_GREY:       if(!(bd == 1 || bd == 2 || bd == 4 || bd == 8 || bd == 16)) return 37; break;
+    case LCT_RGB:        if(!(                                 bd == 8 || bd == 16)) return 37; break;
+    case LCT_PALETTE:    if(!(bd == 1 || bd == 2 || bd == 4 || bd == 8            )) return 37; break;
+    case LCT_GREY_ALPHA: if(!(                                 bd == 8 || bd == 16)) return 37; break;
+    case LCT_RGBA:       if(!(                                 bd == 8 || bd == 16)) return 37; break;
+    case LCT_MAX_OCTET_VALUE: return 31; /* invalid color type */
+    default: return 31; /* invalid color type */
+  }
+  return 0; /*allowed color type / bits combination*/
+}
+
+static unsigned getNumColorChannels(LodePNGColorType colortype) {
+  switch(colortype) {
+    case LCT_GREY: return 1;
+    case LCT_RGB: return 3;
+    case LCT_PALETTE: return 1;
+    case LCT_GREY_ALPHA: return 2;
+    case LCT_RGBA: return 4;
+    case LCT_MAX_OCTET_VALUE: return 0; /* invalid color type */
+    default: return 0; /*invalid color type*/
+  }
+}
+
+static unsigned lodepng_get_bpp_lct(LodePNGColorType colortype, unsigned bitdepth) {
+  /*bits per pixel is amount of channels * bits per channel*/
+  return getNumColorChannels(colortype) * bitdepth;
+}
+
+/* ////////////////////////////////////////////////////////////////////////// */
+
+void lodepng_color_mode_init(LodePNGColorMode* info) {
+  info->key_defined = 0;
+  info->key_r = info->key_g = info->key_b = 0;
+  info->colortype = LCT_RGBA;
+  info->bitdepth = 8;
+  info->palette = 0;
+  info->palettesize = 0;
+}
+
+/*allocates palette memory if needed, and initializes all colors to black*/
+static void lodepng_color_mode_alloc_palette(LodePNGColorMode* info) {
+  size_t i;
+  /*if the palette is already allocated, it will have size 1024 so no reallocation needed in that case*/
+  /*the palette must have room for up to 256 colors with 4 bytes each.*/
+  if(!info->palette) info->palette = (unsigned char*)lodepng_malloc(1024);
+  if(!info->palette) return; /*alloc fail*/
+  for(i = 0; i != 256; ++i) {
+    /*Initialize all unused colors with black, the value used for invalid palette indices.
+    This is an error according to the PNG spec, but common PNG decoders make it black instead.
+    That makes color conversion slightly faster due to no error handling needed.*/
+    info->palette[i * 4 + 0] = 0;
+    info->palette[i * 4 + 1] = 0;
+    info->palette[i * 4 + 2] = 0;
+    info->palette[i * 4 + 3] = 255;
+  }
+}
+
+void lodepng_color_mode_cleanup(LodePNGColorMode* info) {
+  lodepng_palette_clear(info);
+}
+
+unsigned lodepng_color_mode_copy(LodePNGColorMode* dest, const LodePNGColorMode* source) {
+  lodepng_color_mode_cleanup(dest);
+  lodepng_memcpy(dest, source, sizeof(LodePNGColorMode));
+  if(source->palette) {
+    dest->palette = (unsigned char*)lodepng_malloc(1024);
+    if(!dest->palette && source->palettesize) return 83; /*alloc fail*/
+    lodepng_memcpy(dest->palette, source->palette, source->palettesize * 4);
+  }
+  return 0;
+}
+
+LodePNGColorMode lodepng_color_mode_make(LodePNGColorType colortype, unsigned bitdepth) {
+  LodePNGColorMode result;
+  lodepng_color_mode_init(&result);
+  result.colortype = colortype;
+  result.bitdepth = bitdepth;
+  return result;
+}
+
+static int lodepng_color_mode_equal(const LodePNGColorMode* a, const LodePNGColorMode* b) {
+  size_t i;
+  if(a->colortype != b->colortype) return 0;
+  if(a->bitdepth != b->bitdepth) return 0;
+  if(a->key_defined != b->key_defined) return 0;
+  if(a->key_defined) {
+    if(a->key_r != b->key_r) return 0;
+    if(a->key_g != b->key_g) return 0;
+    if(a->key_b != b->key_b) return 0;
+  }
+  if(a->palettesize != b->palettesize) return 0;
+  for(i = 0; i != a->palettesize * 4; ++i) {
+    if(a->palette[i] != b->palette[i]) return 0;
+  }
+  return 1;
+}
+
+void lodepng_palette_clear(LodePNGColorMode* info) {
+  if(info->palette) lodepng_free(info->palette);
+  info->palette = 0;
+  info->palettesize = 0;
+}
+
+unsigned lodepng_palette_add(LodePNGColorMode* info,
+                             unsigned char r, unsigned char g, unsigned char b, unsigned char a) {
+  if(!info->palette) /*allocate palette if empty*/ {
+    lodepng_color_mode_alloc_palette(info);
+    if(!info->palette) return 83; /*alloc fail*/
+  }
+  if(info->palettesize >= 256) {
+    return 108; /*too many palette values*/
+  }
+  info->palette[4 * info->palettesize + 0] = r;
+  info->palette[4 * info->palettesize + 1] = g;
+  info->palette[4 * info->palettesize + 2] = b;
+  info->palette[4 * info->palettesize + 3] = a;
+  ++info->palettesize;
+  return 0;
+}
+
+/*calculate bits per pixel out of colortype and bitdepth*/
+unsigned lodepng_get_bpp(const LodePNGColorMode* info) {
+  return lodepng_get_bpp_lct(info->colortype, info->bitdepth);
+}
+
+unsigned lodepng_get_channels(const LodePNGColorMode* info) {
+  return getNumColorChannels(info->colortype);
+}
+
+unsigned lodepng_is_greyscale_type(const LodePNGColorMode* info) {
+  return info->colortype == LCT_GREY || info->colortype == LCT_GREY_ALPHA;
+}
+
+unsigned lodepng_is_alpha_type(const LodePNGColorMode* info) {
+  return (info->colortype & 4) != 0; /*4 or 6*/
+}
+
+unsigned lodepng_is_palette_type(const LodePNGColorMode* info) {
+  return info->colortype == LCT_PALETTE;
+}
+
+unsigned lodepng_has_palette_alpha(const LodePNGColorMode* info) {
+  size_t i;
+  for(i = 0; i != info->palettesize; ++i) {
+    if(info->palette[i * 4 + 3] < 255) return 1;
+  }
+  return 0;
+}
+
+unsigned lodepng_can_have_alpha(const LodePNGColorMode* info) {
+  return info->key_defined
+      || lodepng_is_alpha_type(info)
+      || lodepng_has_palette_alpha(info);
+}
+
+static size_t lodepng_get_raw_size_lct(unsigned w, unsigned h, LodePNGColorType colortype, unsigned bitdepth) {
+  size_t bpp = lodepng_get_bpp_lct(colortype, bitdepth);
+  size_t n = (size_t)w * (size_t)h;
+  return ((n / 8u) * bpp) + ((n & 7u) * bpp + 7u) / 8u;
+}
+
+size_t lodepng_get_raw_size(unsigned w, unsigned h, const LodePNGColorMode* color) {
+  return lodepng_get_raw_size_lct(w, h, color->colortype, color->bitdepth);
+}
+
+
+#ifdef LODEPNG_COMPILE_PNG
+
+/*in an idat chunk, each scanline is a multiple of 8 bits, unlike the lodepng output buffer,
+and in addition has one extra byte per line: the filter byte. So this gives a larger
+result than lodepng_get_raw_size. Set h to 1 to get the size of 1 row including filter byte. */
+static size_t lodepng_get_raw_size_idat(unsigned w, unsigned h, unsigned bpp) {
+  /* + 1 for the filter byte, and possibly plus padding bits per line. */
+  /* Ignoring casts, the expression is equal to (w * bpp + 7) / 8 + 1, but avoids overflow of w * bpp */
+  size_t line = ((size_t)(w / 8u) * bpp) + 1u + ((w & 7u) * bpp + 7u) / 8u;
+  return (size_t)h * line;
+}
+
+#ifdef LODEPNG_COMPILE_DECODER
+/*Safely checks whether size_t overflow can be caused due to amount of pixels.
+This check is overcautious rather than precise. If this check indicates no overflow,
+you can safely compute in a size_t (but not an unsigned):
+-(size_t)w * (size_t)h * 8
+-amount of bytes in IDAT (including filter, padding and Adam7 bytes)
+-amount of bytes in raw color model
+Returns 1 if overflow possible, 0 if not.
+*/
+static int lodepng_pixel_overflow(unsigned w, unsigned h,
+                                  const LodePNGColorMode* pngcolor, const LodePNGColorMode* rawcolor) {
+  size_t bpp = LODEPNG_MAX(lodepng_get_bpp(pngcolor), lodepng_get_bpp(rawcolor));
+  size_t numpixels, total;
+  size_t line; /* bytes per line in worst case */
+
+  if(lodepng_mulofl((size_t)w, (size_t)h, &numpixels)) return 1;
+  if(lodepng_mulofl(numpixels, 8, &total)) return 1; /* bit pointer with 8-bit color, or 8 bytes per channel color */
+
+  /* Bytes per scanline with the expression "(w / 8u) * bpp) + ((w & 7u) * bpp + 7u) / 8u" */
+  if(lodepng_mulofl((size_t)(w / 8u), bpp, &line)) return 1;
+  if(lodepng_addofl(line, ((w & 7u) * bpp + 7u) / 8u, &line)) return 1;
+
+  if(lodepng_addofl(line, 5, &line)) return 1; /* 5 bytes overhead per line: 1 filterbyte, 4 for Adam7 worst case */
+  if(lodepng_mulofl(line, h, &total)) return 1; /* Total bytes in worst case */
+
+  return 0; /* no overflow */
+}
+#endif /*LODEPNG_COMPILE_DECODER*/
+#endif /*LODEPNG_COMPILE_PNG*/
+
+#ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
+
+static void LodePNGUnknownChunks_init(LodePNGInfo* info) {
+  unsigned i;
+  for(i = 0; i != 3; ++i) info->unknown_chunks_data[i] = 0;
+  for(i = 0; i != 3; ++i) info->unknown_chunks_size[i] = 0;
+}
+
+static void LodePNGUnknownChunks_cleanup(LodePNGInfo* info) {
+  unsigned i;
+  for(i = 0; i != 3; ++i) lodepng_free(info->unknown_chunks_data[i]);
+}
+
+static unsigned LodePNGUnknownChunks_copy(LodePNGInfo* dest, const LodePNGInfo* src) {
+  unsigned i;
+
+  LodePNGUnknownChunks_cleanup(dest);
+
+  for(i = 0; i != 3; ++i) {
+    size_t j;
+    dest->unknown_chunks_size[i] = src->unknown_chunks_size[i];
+    dest->unknown_chunks_data[i] = (unsigned char*)lodepng_malloc(src->unknown_chunks_size[i]);
+    if(!dest->unknown_chunks_data[i] && dest->unknown_chunks_size[i]) return 83; /*alloc fail*/
+    for(j = 0; j < src->unknown_chunks_size[i]; ++j) {
+      dest->unknown_chunks_data[i][j] = src->unknown_chunks_data[i][j];
+    }
+  }
+
+  return 0;
+}
+
+/******************************************************************************/
+
+static void LodePNGText_init(LodePNGInfo* info) {
+  info->text_num = 0;
+  info->text_keys = NULL;
+  info->text_strings = NULL;
+}
+
+static void LodePNGText_cleanup(LodePNGInfo* info) {
+  size_t i;
+  for(i = 0; i != info->text_num; ++i) {
+    string_cleanup(&info->text_keys[i]);
+    string_cleanup(&info->text_strings[i]);
+  }
+  lodepng_free(info->text_keys);
+  lodepng_free(info->text_strings);
+}
+
+static unsigned LodePNGText_copy(LodePNGInfo* dest, const LodePNGInfo* source) {
+  size_t i = 0;
+  dest->text_keys = 0;
+  dest->text_strings = 0;
+  dest->text_num = 0;
+  for(i = 0; i != source->text_num; ++i) {
+    CERROR_TRY_RETURN(lodepng_add_text(dest, source->text_keys[i], source->text_strings[i]));
+  }
+  return 0;
+}
+
+static unsigned lodepng_add_text_sized(LodePNGInfo* info, const char* key, const char* str, size_t size) {
+  char** new_keys = (char**)(lodepng_realloc(info->text_keys, sizeof(char*) * (info->text_num + 1)));
+  char** new_strings = (char**)(lodepng_realloc(info->text_strings, sizeof(char*) * (info->text_num + 1)));
+
+  if(new_keys) info->text_keys = new_keys;
+  if(new_strings) info->text_strings = new_strings;
+
+  if(!new_keys || !new_strings) return 83; /*alloc fail*/
+
+  ++info->text_num;
+  info->text_keys[info->text_num - 1] = alloc_string(key);
+  info->text_strings[info->text_num - 1] = alloc_string_sized(str, size);
+  if(!info->text_keys[info->text_num - 1] || !info->text_strings[info->text_num - 1]) return 83; /*alloc fail*/
+
+  return 0;
+}
+
+unsigned lodepng_add_text(LodePNGInfo* info, const char* key, const char* str) {
+  return lodepng_add_text_sized(info, key, str, lodepng_strlen(str));
+}
+
+void lodepng_clear_text(LodePNGInfo* info) {
+  LodePNGText_cleanup(info);
+}
+
+/******************************************************************************/
+
+static void LodePNGIText_init(LodePNGInfo* info) {
+  info->itext_num = 0;
+  info->itext_keys = NULL;
+  info->itext_langtags = NULL;
+  info->itext_transkeys = NULL;
+  info->itext_strings = NULL;
+}
+
+static void LodePNGIText_cleanup(LodePNGInfo* info) {
+  size_t i;
+  for(i = 0; i != info->itext_num; ++i) {
+    string_cleanup(&info->itext_keys[i]);
+    string_cleanup(&info->itext_langtags[i]);
+    string_cleanup(&info->itext_transkeys[i]);
+    string_cleanup(&info->itext_strings[i]);
+  }
+  lodepng_free(info->itext_keys);
+  lodepng_free(info->itext_langtags);
+  lodepng_free(info->itext_transkeys);
+  lodepng_free(info->itext_strings);
+}
+
+static unsigned LodePNGIText_copy(LodePNGInfo* dest, const LodePNGInfo* source) {
+  size_t i = 0;
+  dest->itext_keys = 0;
+  dest->itext_langtags = 0;
+  dest->itext_transkeys = 0;
+  dest->itext_strings = 0;
+  dest->itext_num = 0;
+  for(i = 0; i != source->itext_num; ++i) {
+    CERROR_TRY_RETURN(lodepng_add_itext(dest, source->itext_keys[i], source->itext_langtags[i],
+                                        source->itext_transkeys[i], source->itext_strings[i]));
+  }
+  return 0;
+}
+
+void lodepng_clear_itext(LodePNGInfo* info) {
+  LodePNGIText_cleanup(info);
+}
+
+static unsigned lodepng_add_itext_sized(LodePNGInfo* info, const char* key, const char* langtag,
+                                        const char* transkey, const char* str, size_t size) {
+  char** new_keys = (char**)(lodepng_realloc(info->itext_keys, sizeof(char*) * (info->itext_num + 1)));
+  char** new_langtags = (char**)(lodepng_realloc(info->itext_langtags, sizeof(char*) * (info->itext_num + 1)));
+  char** new_transkeys = (char**)(lodepng_realloc(info->itext_transkeys, sizeof(char*) * (info->itext_num + 1)));
+  char** new_strings = (char**)(lodepng_realloc(info->itext_strings, sizeof(char*) * (info->itext_num + 1)));
+
+  if(new_keys) info->itext_keys = new_keys;
+  if(new_langtags) info->itext_langtags = new_langtags;
+  if(new_transkeys) info->itext_transkeys = new_transkeys;
+  if(new_strings) info->itext_strings = new_strings;
+
+  if(!new_keys || !new_langtags || !new_transkeys || !new_strings) return 83; /*alloc fail*/
+
+  ++info->itext_num;
+
+  info->itext_keys[info->itext_num - 1] = alloc_string(key);
+  info->itext_langtags[info->itext_num - 1] = alloc_string(langtag);
+  info->itext_transkeys[info->itext_num - 1] = alloc_string(transkey);
+  info->itext_strings[info->itext_num - 1] = alloc_string_sized(str, size);
+
+  return 0;
+}
+
+unsigned lodepng_add_itext(LodePNGInfo* info, const char* key, const char* langtag,
+                           const char* transkey, const char* str) {
+  return lodepng_add_itext_sized(info, key, langtag, transkey, str, lodepng_strlen(str));
+}
+
+/* same as set but does not delete */
+static unsigned lodepng_assign_icc(LodePNGInfo* info, const char* name, const unsigned char* profile, unsigned profile_size) {
+  if(profile_size == 0) return 100; /*invalid ICC profile size*/
+
+  info->iccp_name = alloc_string(name);
+  info->iccp_profile = (unsigned char*)lodepng_malloc(profile_size);
+
+  if(!info->iccp_name || !info->iccp_profile) return 83; /*alloc fail*/
+
+  lodepng_memcpy(info->iccp_profile, profile, profile_size);
+  info->iccp_profile_size = profile_size;
+
+  return 0; /*ok*/
+}
+
+unsigned lodepng_set_icc(LodePNGInfo* info, const char* name, const unsigned char* profile, unsigned profile_size) {
+  if(info->iccp_name) lodepng_clear_icc(info);
+  info->iccp_defined = 1;
+
+  return lodepng_assign_icc(info, name, profile, profile_size);
+}
+
+void lodepng_clear_icc(LodePNGInfo* info) {
+  string_cleanup(&info->iccp_name);
+  lodepng_free(info->iccp_profile);
+  info->iccp_profile = NULL;
+  info->iccp_profile_size = 0;
+  info->iccp_defined = 0;
+}
+#endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
+
+void lodepng_info_init(LodePNGInfo* info) {
+  lodepng_color_mode_init(&info->color);
+  info->interlace_method = 0;
+  info->compression_method = 0;
+  info->filter_method = 0;
+#ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
+  info->background_defined = 0;
+  info->background_r = info->background_g = info->background_b = 0;
+
+  LodePNGText_init(info);
+  LodePNGIText_init(info);
+
+  info->time_defined = 0;
+  info->phys_defined = 0;
+
+  info->gama_defined = 0;
+  info->chrm_defined = 0;
+  info->srgb_defined = 0;
+  info->iccp_defined = 0;
+  info->iccp_name = NULL;
+  info->iccp_profile = NULL;
+
+  LodePNGUnknownChunks_init(info);
+#endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
+}
+
+void lodepng_info_cleanup(LodePNGInfo* info) {
+  lodepng_color_mode_cleanup(&info->color);
+#ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
+  LodePNGText_cleanup(info);
+  LodePNGIText_cleanup(info);
+
+  lodepng_clear_icc(info);
+
+  LodePNGUnknownChunks_cleanup(info);
+#endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
+}
+
+unsigned lodepng_info_copy(LodePNGInfo* dest, const LodePNGInfo* source) {
+  lodepng_info_cleanup(dest);
+  lodepng_memcpy(dest, source, sizeof(LodePNGInfo));
+  lodepng_color_mode_init(&dest->color);
+  CERROR_TRY_RETURN(lodepng_color_mode_copy(&dest->color, &source->color));
+
+#ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
+  CERROR_TRY_RETURN(LodePNGText_copy(dest, source));
+  CERROR_TRY_RETURN(LodePNGIText_copy(dest, source));
+  if(source->iccp_defined) {
+    CERROR_TRY_RETURN(lodepng_assign_icc(dest, source->iccp_name, source->iccp_profile, source->iccp_profile_size));
+  }
+
+  LodePNGUnknownChunks_init(dest);
+  CERROR_TRY_RETURN(LodePNGUnknownChunks_copy(dest, source));
+#endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
+  return 0;
+}
+
+/* ////////////////////////////////////////////////////////////////////////// */
+
+/*index: bitgroup index, bits: bitgroup size(1, 2 or 4), in: bitgroup value, out: octet array to add bits to*/
+static void addColorBits(unsigned char* out, size_t index, unsigned bits, unsigned in) {
+  unsigned m = bits == 1 ? 7 : bits == 2 ? 3 : 1; /*8 / bits - 1*/
+  /*p = the partial index in the byte, e.g. with 4 palettebits it is 0 for first half or 1 for second half*/
+  unsigned p = index & m;
+  in &= (1u << bits) - 1u; /*filter out any other bits of the input value*/
+  in = in << (bits * (m - p));
+  if(p == 0) out[index * bits / 8u] = in;
+  else out[index * bits / 8u] |= in;
+}
+
+typedef struct ColorTree ColorTree;
+
+/*
+One node of a color tree
+This is the data structure used to count the number of unique colors and to get a palette
+index for a color. It's like an octree, but because the alpha channel is used too, each
+node has 16 instead of 8 children.
+*/
+struct ColorTree {
+  ColorTree* children[16]; /*up to 16 pointers to ColorTree of next level*/
+  int index; /*the payload. Only has a meaningful value if this is in the last level*/
+};
+
+static void color_tree_init(ColorTree* tree) {
+  lodepng_memset(tree->children, 0, 16 * sizeof(*tree->children));
+  tree->index = -1;
+}
+
+static void color_tree_cleanup(ColorTree* tree) {
+  int i;
+  for(i = 0; i != 16; ++i) {
+    if(tree->children[i]) {
+      color_tree_cleanup(tree->children[i]);
+      lodepng_free(tree->children[i]);
+    }
+  }
+}
+
+/*returns -1 if color not present, its index otherwise*/
+static int color_tree_get(ColorTree* tree, unsigned char r, unsigned char g, unsigned char b, unsigned char a) {
+  int bit = 0;
+  for(bit = 0; bit < 8; ++bit) {
+    int i = 8 * ((r >> bit) & 1) + 4 * ((g >> bit) & 1) + 2 * ((b >> bit) & 1) + 1 * ((a >> bit) & 1);
+    if(!tree->children[i]) return -1;
+    else tree = tree->children[i];
+  }
+  return tree ? tree->index : -1;
+}
+
+#ifdef LODEPNG_COMPILE_ENCODER
+static int color_tree_has(ColorTree* tree, unsigned char r, unsigned char g, unsigned char b, unsigned char a) {
+  return color_tree_get(tree, r, g, b, a) >= 0;
+}
+#endif /*LODEPNG_COMPILE_ENCODER*/
+
+/*color is not allowed to already exist.
+Index should be >= 0 (it's signed to be compatible with using -1 for "doesn't exist")
+Returns error code, or 0 if ok*/
+static unsigned color_tree_add(ColorTree* tree,
+                               unsigned char r, unsigned char g, unsigned char b, unsigned char a, unsigned index) {
+  int bit;
+  for(bit = 0; bit < 8; ++bit) {
+    int i = 8 * ((r >> bit) & 1) + 4 * ((g >> bit) & 1) + 2 * ((b >> bit) & 1) + 1 * ((a >> bit) & 1);
+    if(!tree->children[i]) {
+      tree->children[i] = (ColorTree*)lodepng_malloc(sizeof(ColorTree));
+      if(!tree->children[i]) return 83; /*alloc fail*/
+      color_tree_init(tree->children[i]);
+    }
+    tree = tree->children[i];
+  }
+  tree->index = (int)index;
+  return 0;
+}
+
+/*put a pixel, given its RGBA color, into image of any color type*/
+static unsigned rgba8ToPixel(unsigned char* out, size_t i,
+                             const LodePNGColorMode* mode, ColorTree* tree /*for palette*/,
+                             unsigned char r, unsigned char g, unsigned char b, unsigned char a) {
+  if(mode->colortype == LCT_GREY) {
+    unsigned char gray = r; /*((unsigned short)r + g + b) / 3u;*/
+    if(mode->bitdepth == 8) out[i] = gray;
+    else if(mode->bitdepth == 16) out[i * 2 + 0] = out[i * 2 + 1] = gray;
+    else {
+      /*take the most significant bits of gray*/
+      gray = ((unsigned)gray >> (8u - mode->bitdepth)) & ((1u << mode->bitdepth) - 1u);
+      addColorBits(out, i, mode->bitdepth, gray);
+    }
+  } else if(mode->colortype == LCT_RGB) {
+    if(mode->bitdepth == 8) {
+      out[i * 3 + 0] = r;
+      out[i * 3 + 1] = g;
+      out[i * 3 + 2] = b;
+    } else {
+      out[i * 6 + 0] = out[i * 6 + 1] = r;
+      out[i * 6 + 2] = out[i * 6 + 3] = g;
+      out[i * 6 + 4] = out[i * 6 + 5] = b;
+    }
+  } else if(mode->colortype == LCT_PALETTE) {
+    int index = color_tree_get(tree, r, g, b, a);
+    if(index < 0) return 82; /*color not in palette*/
+    if(mode->bitdepth == 8) out[i] = index;
+    else addColorBits(out, i, mode->bitdepth, (unsigned)index);
+  } else if(mode->colortype == LCT_GREY_ALPHA) {
+    unsigned char gray = r; /*((unsigned short)r + g + b) / 3u;*/
+    if(mode->bitdepth == 8) {
+      out[i * 2 + 0] = gray;
+      out[i * 2 + 1] = a;
+    } else if(mode->bitdepth == 16) {
+      out[i * 4 + 0] = out[i * 4 + 1] = gray;
+      out[i * 4 + 2] = out[i * 4 + 3] = a;
+    }
+  } else if(mode->colortype == LCT_RGBA) {
+    if(mode->bitdepth == 8) {
+      out[i * 4 + 0] = r;
+      out[i * 4 + 1] = g;
+      out[i * 4 + 2] = b;
+      out[i * 4 + 3] = a;
+    } else {
+      out[i * 8 + 0] = out[i * 8 + 1] = r;
+      out[i * 8 + 2] = out[i * 8 + 3] = g;
+      out[i * 8 + 4] = out[i * 8 + 5] = b;
+      out[i * 8 + 6] = out[i * 8 + 7] = a;
+    }
+  }
+
+  return 0; /*no error*/
+}
+
+/*put a pixel, given its RGBA16 color, into image of any color 16-bitdepth type*/
+static void rgba16ToPixel(unsigned char* out, size_t i,
+                         const LodePNGColorMode* mode,
+                         unsigned short r, unsigned short g, unsigned short b, unsigned short a) {
+  if(mode->colortype == LCT_GREY) {
+    unsigned short gray = r; /*((unsigned)r + g + b) / 3u;*/
+    out[i * 2 + 0] = (gray >> 8) & 255;
+    out[i * 2 + 1] = gray & 255;
+  } else if(mode->colortype == LCT_RGB) {
+    out[i * 6 + 0] = (r >> 8) & 255;
+    out[i * 6 + 1] = r & 255;
+    out[i * 6 + 2] = (g >> 8) & 255;
+    out[i * 6 + 3] = g & 255;
+    out[i * 6 + 4] = (b >> 8) & 255;
+    out[i * 6 + 5] = b & 255;
+  } else if(mode->colortype == LCT_GREY_ALPHA) {
+    unsigned short gray = r; /*((unsigned)r + g + b) / 3u;*/
+    out[i * 4 + 0] = (gray >> 8) & 255;
+    out[i * 4 + 1] = gray & 255;
+    out[i * 4 + 2] = (a >> 8) & 255;
+    out[i * 4 + 3] = a & 255;
+  } else if(mode->colortype == LCT_RGBA) {
+    out[i * 8 + 0] = (r >> 8) & 255;
+    out[i * 8 + 1] = r & 255;
+    out[i * 8 + 2] = (g >> 8) & 255;
+    out[i * 8 + 3] = g & 255;
+    out[i * 8 + 4] = (b >> 8) & 255;
+    out[i * 8 + 5] = b & 255;
+    out[i * 8 + 6] = (a >> 8) & 255;
+    out[i * 8 + 7] = a & 255;
+  }
+}
+
+/*Get RGBA8 color of pixel with index i (y * width + x) from the raw image with given color type.*/
+static void getPixelColorRGBA8(unsigned char* r, unsigned char* g,
+                               unsigned char* b, unsigned char* a,
+                               const unsigned char* in, size_t i,
+                               const LodePNGColorMode* mode) {
+  if(mode->colortype == LCT_GREY) {
+    if(mode->bitdepth == 8) {
+      *r = *g = *b = in[i];
+      if(mode->key_defined && *r == mode->key_r) *a = 0;
+      else *a = 255;
+    } else if(mode->bitdepth == 16) {
+      *r = *g = *b = in[i * 2 + 0];
+      if(mode->key_defined && 256U * in[i * 2 + 0] + in[i * 2 + 1] == mode->key_r) *a = 0;
+      else *a = 255;
+    } else {
+      unsigned highest = ((1U << mode->bitdepth) - 1U); /*highest possible value for this bit depth*/
+      size_t j = i * mode->bitdepth;
+      unsigned value = readBitsFromReversedStream(&j, in, mode->bitdepth);
+      *r = *g = *b = (value * 255) / highest;
+      if(mode->key_defined && value == mode->key_r) *a = 0;
+      else *a = 255;
+    }
+  } else if(mode->colortype == LCT_RGB) {
+    if(mode->bitdepth == 8) {
+      *r = in[i * 3 + 0]; *g = in[i * 3 + 1]; *b = in[i * 3 + 2];
+      if(mode->key_defined && *r == mode->key_r && *g == mode->key_g && *b == mode->key_b) *a = 0;
+      else *a = 255;
+    } else {
+      *r = in[i * 6 + 0];
+      *g = in[i * 6 + 2];
+      *b = in[i * 6 + 4];
+      if(mode->key_defined && 256U * in[i * 6 + 0] + in[i * 6 + 1] == mode->key_r
+         && 256U * in[i * 6 + 2] + in[i * 6 + 3] == mode->key_g
+         && 256U * in[i * 6 + 4] + in[i * 6 + 5] == mode->key_b) *a = 0;
+      else *a = 255;
+    }
+  } else if(mode->colortype == LCT_PALETTE) {
+    unsigned index;
+    if(mode->bitdepth == 8) index = in[i];
+    else {
+      size_t j = i * mode->bitdepth;
+      index = readBitsFromReversedStream(&j, in, mode->bitdepth);
+    }
+    /*out of bounds of palette not checked: see lodepng_color_mode_alloc_palette.*/
+    *r = mode->palette[index * 4 + 0];
+    *g = mode->palette[index * 4 + 1];
+    *b = mode->palette[index * 4 + 2];
+    *a = mode->palette[index * 4 + 3];
+  } else if(mode->colortype == LCT_GREY_ALPHA) {
+    if(mode->bitdepth == 8) {
+      *r = *g = *b = in[i * 2 + 0];
+      *a = in[i * 2 + 1];
+    } else {
+      *r = *g = *b = in[i * 4 + 0];
+      *a = in[i * 4 + 2];
+    }
+  } else if(mode->colortype == LCT_RGBA) {
+    if(mode->bitdepth == 8) {
+      *r = in[i * 4 + 0];
+      *g = in[i * 4 + 1];
+      *b = in[i * 4 + 2];
+      *a = in[i * 4 + 3];
+    } else {
+      *r = in[i * 8 + 0];
+      *g = in[i * 8 + 2];
+      *b = in[i * 8 + 4];
+      *a = in[i * 8 + 6];
+    }
+  }
+}
+
+/*Similar to getPixelColorRGBA8, but with all the for loops inside of the color
+mode test cases, optimized to convert the colors much faster, when converting
+to the common case of RGBA with 8 bit per channel. buffer must be RGBA with
+enough memory.*/
+static void getPixelColorsRGBA8(unsigned char* LODEPNG_RESTRICT buffer, size_t numpixels,
+                                const unsigned char* LODEPNG_RESTRICT in,
+                                const LodePNGColorMode* mode) {
+  unsigned num_channels = 4;
+  size_t i;
+  if(mode->colortype == LCT_GREY) {
+    if(mode->bitdepth == 8) {
+      for(i = 0; i != numpixels; ++i, buffer += num_channels) {
+        buffer[0] = buffer[1] = buffer[2] = in[i];
+        buffer[3] = 255;
+      }
+      if(mode->key_defined) {
+        buffer -= numpixels * num_channels;
+        for(i = 0; i != numpixels; ++i, buffer += num_channels) {
+          if(buffer[0] == mode->key_r) buffer[3] = 0;
+        }
+      }
+    } else if(mode->bitdepth == 16) {
+      for(i = 0; i != numpixels; ++i, buffer += num_channels) {
+        buffer[0] = buffer[1] = buffer[2] = in[i * 2];
+        buffer[3] = mode->key_defined && 256U * in[i * 2 + 0] + in[i * 2 + 1] == mode->key_r ? 0 : 255;
+      }
+    } else {
+      unsigned highest = ((1U << mode->bitdepth) - 1U); /*highest possible value for this bit depth*/
+      size_t j = 0;
+      for(i = 0; i != numpixels; ++i, buffer += num_channels) {
+        unsigned value = readBitsFromReversedStream(&j, in, mode->bitdepth);
+        buffer[0] = buffer[1] = buffer[2] = (value * 255) / highest;
+        buffer[3] = mode->key_defined && value == mode->key_r ? 0 : 255;
+      }
+    }
+  } else if(mode->colortype == LCT_RGB) {
+    if(mode->bitdepth == 8) {
+      for(i = 0; i != numpixels; ++i, buffer += num_channels) {
+        lodepng_memcpy(buffer, &in[i * 3], 3);
+        buffer[3] = 255;
+      }
+      if(mode->key_defined) {
+        buffer -= numpixels * num_channels;
+        for(i = 0; i != numpixels; ++i, buffer += num_channels) {
+          if(buffer[0] == mode->key_r && buffer[1]== mode->key_g && buffer[2] == mode->key_b) buffer[3] = 0;
+        }
+      }
+    } else {
+      for(i = 0; i != numpixels; ++i, buffer += num_channels) {
+        buffer[0] = in[i * 6 + 0];
+        buffer[1] = in[i * 6 + 2];
+        buffer[2] = in[i * 6 + 4];
+        buffer[3] = mode->key_defined
+           && 256U * in[i * 6 + 0] + in[i * 6 + 1] == mode->key_r
+           && 256U * in[i * 6 + 2] + in[i * 6 + 3] == mode->key_g
+           && 256U * in[i * 6 + 4] + in[i * 6 + 5] == mode->key_b ? 0 : 255;
+      }
+    }
+  } else if(mode->colortype == LCT_PALETTE) {
+    if(mode->bitdepth == 8) {
+      for(i = 0; i != numpixels; ++i, buffer += num_channels) {
+        unsigned index = in[i];
+        /*out of bounds of palette not checked: see lodepng_color_mode_alloc_palette.*/
+        lodepng_memcpy(buffer, &mode->palette[index * 4], 4);
+      }
+    } else {
+      size_t j = 0;
+      for(i = 0; i != numpixels; ++i, buffer += num_channels) {
+        unsigned index = readBitsFromReversedStream(&j, in, mode->bitdepth);
+        /*out of bounds of palette not checked: see lodepng_color_mode_alloc_palette.*/
+        lodepng_memcpy(buffer, &mode->palette[index * 4], 4);
+      }
+    }
+  } else if(mode->colortype == LCT_GREY_ALPHA) {
+    if(mode->bitdepth == 8) {
+      for(i = 0; i != numpixels; ++i, buffer += num_channels) {
+        buffer[0] = buffer[1] = buffer[2] = in[i * 2 + 0];
+        buffer[3] = in[i * 2 + 1];
+      }
+    } else {
+      for(i = 0; i != numpixels; ++i, buffer += num_channels) {
+        buffer[0] = buffer[1] = buffer[2] = in[i * 4 + 0];
+        buffer[3] = in[i * 4 + 2];
+      }
+    }
+  } else if(mode->colortype == LCT_RGBA) {
+    if(mode->bitdepth == 8) {
+      lodepng_memcpy(buffer, in, numpixels * 4);
+    } else {
+      for(i = 0; i != numpixels; ++i, buffer += num_channels) {
+        buffer[0] = in[i * 8 + 0];
+        buffer[1] = in[i * 8 + 2];
+        buffer[2] = in[i * 8 + 4];
+        buffer[3] = in[i * 8 + 6];
+      }
+    }
+  }
+}
+
+/*Similar to getPixelColorsRGBA8, but with 3-channel RGB output.*/
+static void getPixelColorsRGB8(unsigned char* LODEPNG_RESTRICT buffer, size_t numpixels,
+                               const unsigned char* LODEPNG_RESTRICT in,
+                               const LodePNGColorMode* mode) {
+  const unsigned num_channels = 3;
+  size_t i;
+  if(mode->colortype == LCT_GREY) {
+    if(mode->bitdepth == 8) {
+      for(i = 0; i != numpixels; ++i, buffer += num_channels) {
+        buffer[0] = buffer[1] = buffer[2] = in[i];
+      }
+    } else if(mode->bitdepth == 16) {
+      for(i = 0; i != numpixels; ++i, buffer += num_channels) {
+        buffer[0] = buffer[1] = buffer[2] = in[i * 2];
+      }
+    } else {
+      unsigned highest = ((1U << mode->bitdepth) - 1U); /*highest possible value for this bit depth*/
+      size_t j = 0;
+      for(i = 0; i != numpixels; ++i, buffer += num_channels) {
+        unsigned value = readBitsFromReversedStream(&j, in, mode->bitdepth);
+        buffer[0] = buffer[1] = buffer[2] = (value * 255) / highest;
+      }
+    }
+  } else if(mode->colortype == LCT_RGB) {
+    if(mode->bitdepth == 8) {
+      lodepng_memcpy(buffer, in, numpixels * 3);
+    } else {
+      for(i = 0; i != numpixels; ++i, buffer += num_channels) {
+        buffer[0] = in[i * 6 + 0];
+        buffer[1] = in[i * 6 + 2];
+        buffer[2] = in[i * 6 + 4];
+      }
+    }
+  } else if(mode->colortype == LCT_PALETTE) {
+    if(mode->bitdepth == 8) {
+      for(i = 0; i != numpixels; ++i, buffer += num_channels) {
+        unsigned index = in[i];
+        /*out of bounds of palette not checked: see lodepng_color_mode_alloc_palette.*/
+        lodepng_memcpy(buffer, &mode->palette[index * 4], 3);
+      }
+    } else {
+      size_t j = 0;
+      for(i = 0; i != numpixels; ++i, buffer += num_channels) {
+        unsigned index = readBitsFromReversedStream(&j, in, mode->bitdepth);
+        /*out of bounds of palette not checked: see lodepng_color_mode_alloc_palette.*/
+        lodepng_memcpy(buffer, &mode->palette[index * 4], 3);
+      }
+    }
+  } else if(mode->colortype == LCT_GREY_ALPHA) {
+    if(mode->bitdepth == 8) {
+      for(i = 0; i != numpixels; ++i, buffer += num_channels) {
+        buffer[0] = buffer[1] = buffer[2] = in[i * 2 + 0];
+      }
+    } else {
+      for(i = 0; i != numpixels; ++i, buffer += num_channels) {
+        buffer[0] = buffer[1] = buffer[2] = in[i * 4 + 0];
+      }
+    }
+  } else if(mode->colortype == LCT_RGBA) {
+    if(mode->bitdepth == 8) {
+      for(i = 0; i != numpixels; ++i, buffer += num_channels) {
+        lodepng_memcpy(buffer, &in[i * 4], 3);
+      }
+    } else {
+      for(i = 0; i != numpixels; ++i, buffer += num_channels) {
+        buffer[0] = in[i * 8 + 0];
+        buffer[1] = in[i * 8 + 2];
+        buffer[2] = in[i * 8 + 4];
+      }
+    }
+  }
+}
+
+/*Get RGBA16 color of pixel with index i (y * width + x) from the raw image with
+given color type, but the given color type must be 16-bit itself.*/
+static void getPixelColorRGBA16(unsigned short* r, unsigned short* g, unsigned short* b, unsigned short* a,
+                                const unsigned char* in, size_t i, const LodePNGColorMode* mode) {
+  if(mode->colortype == LCT_GREY) {
+    *r = *g = *b = 256 * in[i * 2 + 0] + in[i * 2 + 1];
+    if(mode->key_defined && 256U * in[i * 2 + 0] + in[i * 2 + 1] == mode->key_r) *a = 0;
+    else *a = 65535;
+  } else if(mode->colortype == LCT_RGB) {
+    *r = 256u * in[i * 6 + 0] + in[i * 6 + 1];
+    *g = 256u * in[i * 6 + 2] + in[i * 6 + 3];
+    *b = 256u * in[i * 6 + 4] + in[i * 6 + 5];
+    if(mode->key_defined
+       && 256u * in[i * 6 + 0] + in[i * 6 + 1] == mode->key_r
+       && 256u * in[i * 6 + 2] + in[i * 6 + 3] == mode->key_g
+       && 256u * in[i * 6 + 4] + in[i * 6 + 5] == mode->key_b) *a = 0;
+    else *a = 65535;
+  } else if(mode->colortype == LCT_GREY_ALPHA) {
+    *r = *g = *b = 256u * in[i * 4 + 0] + in[i * 4 + 1];
+    *a = 256u * in[i * 4 + 2] + in[i * 4 + 3];
+  } else if(mode->colortype == LCT_RGBA) {
+    *r = 256u * in[i * 8 + 0] + in[i * 8 + 1];
+    *g = 256u * in[i * 8 + 2] + in[i * 8 + 3];
+    *b = 256u * in[i * 8 + 4] + in[i * 8 + 5];
+    *a = 256u * in[i * 8 + 6] + in[i * 8 + 7];
+  }
+}
+
+unsigned lodepng_convert(unsigned char* out, const unsigned char* in,
+                         const LodePNGColorMode* mode_out, const LodePNGColorMode* mode_in,
+                         unsigned w, unsigned h) {
+  size_t i;
+  ColorTree tree;
+  size_t numpixels = (size_t)w * (size_t)h;
+  unsigned error = 0;
+
+  if(mode_in->colortype == LCT_PALETTE && !mode_in->palette) {
+    return 107; /* error: must provide palette if input mode is palette */
+  }
+
+  if(lodepng_color_mode_equal(mode_out, mode_in)) {
+    size_t numbytes = lodepng_get_raw_size(w, h, mode_in);
+    lodepng_memcpy(out, in, numbytes);
+    return 0;
+  }
+
+  if(mode_out->colortype == LCT_PALETTE) {
+    size_t palettesize = mode_out->palettesize;
+    const unsigned char* palette = mode_out->palette;
+    size_t palsize = (size_t)1u << mode_out->bitdepth;
+    /*if the user specified output palette but did not give the values, assume
+    they want the values of the input color type (assuming that one is palette).
+    Note that we never create a new palette ourselves.*/
+    if(palettesize == 0) {
+      palettesize = mode_in->palettesize;
+      palette = mode_in->palette;
+      /*if the input was also palette with same bitdepth, then the color types are also
+      equal, so copy literally. This to preserve the exact indices that were in the PNG
+      even in case there are duplicate colors in the palette.*/
+      if(mode_in->colortype == LCT_PALETTE && mode_in->bitdepth == mode_out->bitdepth) {
+        size_t numbytes = lodepng_get_raw_size(w, h, mode_in);
+        lodepng_memcpy(out, in, numbytes);
+        return 0;
+      }
+    }
+    if(palettesize < palsize) palsize = palettesize;
+    color_tree_init(&tree);
+    for(i = 0; i != palsize; ++i) {
+      const unsigned char* p = &palette[i * 4];
+      error = color_tree_add(&tree, p[0], p[1], p[2], p[3], (unsigned)i);
+      if(error) break;
+    }
+  }
+
+  if(!error) {
+    if(mode_in->bitdepth == 16 && mode_out->bitdepth == 16) {
+      for(i = 0; i != numpixels; ++i) {
+        unsigned short r = 0, g = 0, b = 0, a = 0;
+        getPixelColorRGBA16(&r, &g, &b, &a, in, i, mode_in);
+        rgba16ToPixel(out, i, mode_out, r, g, b, a);
+      }
+    } else if(mode_out->bitdepth == 8 && mode_out->colortype == LCT_RGBA) {
+      getPixelColorsRGBA8(out, numpixels, in, mode_in);
+    } else if(mode_out->bitdepth == 8 && mode_out->colortype == LCT_RGB) {
+      getPixelColorsRGB8(out, numpixels, in, mode_in);
+    } else {
+      unsigned char r = 0, g = 0, b = 0, a = 0;
+      for(i = 0; i != numpixels; ++i) {
+        getPixelColorRGBA8(&r, &g, &b, &a, in, i, mode_in);
+        error = rgba8ToPixel(out, i, mode_out, &tree, r, g, b, a);
+        if(error) break;
+      }
+    }
+  }
+
+  if(mode_out->colortype == LCT_PALETTE) {
+    color_tree_cleanup(&tree);
+  }
+
+  return error;
+}
+
+
+/* Converts a single rgb color without alpha from one type to another, color bits truncated to
+their bitdepth. In case of single channel (gray or palette), only the r channel is used. Slow
+function, do not use to process all pixels of an image. Alpha channel not supported on purpose:
+this is for bKGD, supporting alpha may prevent it from finding a color in the palette, from the
+specification it looks like bKGD should ignore the alpha values of the palette since it can use
+any palette index but doesn't have an alpha channel. Idem with ignoring color key. */
+unsigned lodepng_convert_rgb(
+    unsigned* r_out, unsigned* g_out, unsigned* b_out,
+    unsigned r_in, unsigned g_in, unsigned b_in,
+    const LodePNGColorMode* mode_out, const LodePNGColorMode* mode_in) {
+  unsigned r = 0, g = 0, b = 0;
+  unsigned mul = 65535 / ((1u << mode_in->bitdepth) - 1u); /*65535, 21845, 4369, 257, 1*/
+  unsigned shift = 16 - mode_out->bitdepth;
+
+  if(mode_in->colortype == LCT_GREY || mode_in->colortype == LCT_GREY_ALPHA) {
+    r = g = b = r_in * mul;
+  } else if(mode_in->colortype == LCT_RGB || mode_in->colortype == LCT_RGBA) {
+    r = r_in * mul;
+    g = g_in * mul;
+    b = b_in * mul;
+  } else if(mode_in->colortype == LCT_PALETTE) {
+    if(r_in >= mode_in->palettesize) return 82;
+    r = mode_in->palette[r_in * 4 + 0] * 257u;
+    g = mode_in->palette[r_in * 4 + 1] * 257u;
+    b = mode_in->palette[r_in * 4 + 2] * 257u;
+  } else {
+    return 31;
+  }
+
+  /* now convert to output format */
+  if(mode_out->colortype == LCT_GREY || mode_out->colortype == LCT_GREY_ALPHA) {
+    *r_out = r >> shift ;
+  } else if(mode_out->colortype == LCT_RGB || mode_out->colortype == LCT_RGBA) {
+    *r_out = r >> shift ;
+    *g_out = g >> shift ;
+    *b_out = b >> shift ;
+  } else if(mode_out->colortype == LCT_PALETTE) {
+    unsigned i;
+    /* a 16-bit color cannot be in the palette */
+    if((r >> 8) != (r & 255) || (g >> 8) != (g & 255) || (b >> 8) != (b & 255)) return 82;
+    for(i = 0; i < mode_out->palettesize; i++) {
+      unsigned j = i * 4;
+      if((r >> 8) == mode_out->palette[j + 0] && (g >> 8) == mode_out->palette[j + 1] &&
+          (b >> 8) == mode_out->palette[j + 2]) {
+        *r_out = i;
+        return 0;
+      }
+    }
+    return 82;
+  } else {
+    return 31;
+  }
+
+  return 0;
+}
+
+#ifdef LODEPNG_COMPILE_ENCODER
+
+void lodepng_color_stats_init(LodePNGColorStats* stats) {
+  /*stats*/
+  stats->colored = 0;
+  stats->key = 0;
+  stats->key_r = stats->key_g = stats->key_b = 0;
+  stats->alpha = 0;
+  stats->numcolors = 0;
+  stats->bits = 1;
+  stats->numpixels = 0;
+  /*settings*/
+  stats->allow_palette = 1;
+  stats->allow_greyscale = 1;
+}
+
+/*function used for debug purposes with C++*/
+/*void printColorStats(LodePNGColorStats* p) {
+  std::cout << "colored: " << (int)p->colored << ", ";
+  std::cout << "key: " << (int)p->key << ", ";
+  std::cout << "key_r: " << (int)p->key_r << ", ";
+  std::cout << "key_g: " << (int)p->key_g << ", ";
+  std::cout << "key_b: " << (int)p->key_b << ", ";
+  std::cout << "alpha: " << (int)p->alpha << ", ";
+  std::cout << "numcolors: " << (int)p->numcolors << ", ";
+  std::cout << "bits: " << (int)p->bits << std::endl;
+}*/
+
+/*Returns how many bits needed to represent given value (max 8 bit)*/
+static unsigned getValueRequiredBits(unsigned char value) {
+  if(value == 0 || value == 255) return 1;
+  /*The scaling of 2-bit and 4-bit values uses multiples of 85 and 17*/
+  if(value % 17 == 0) return value % 85 == 0 ? 2 : 4;
+  return 8;
+}
+
+/*stats must already have been inited. */
+unsigned lodepng_compute_color_stats(LodePNGColorStats* stats,
+                                     const unsigned char* in, unsigned w, unsigned h,
+                                     const LodePNGColorMode* mode_in) {
+  size_t i;
+  ColorTree tree;
+  size_t numpixels = (size_t)w * (size_t)h;
+  unsigned error = 0;
+
+  /* mark things as done already if it would be impossible to have a more expensive case */
+  unsigned colored_done = lodepng_is_greyscale_type(mode_in) ? 1 : 0;
+  unsigned alpha_done = lodepng_can_have_alpha(mode_in) ? 0 : 1;
+  unsigned numcolors_done = 0;
+  unsigned bpp = lodepng_get_bpp(mode_in);
+  unsigned bits_done = (stats->bits == 1 && bpp == 1) ? 1 : 0;
+  unsigned sixteen = 0; /* whether the input image is 16 bit */
+  unsigned maxnumcolors = 257;
+  if(bpp <= 8) maxnumcolors = LODEPNG_MIN(257, stats->numcolors + (1u << bpp));
+
+  stats->numpixels += numpixels;
+
+  /*if palette not allowed, no need to compute numcolors*/
+  if(!stats->allow_palette) numcolors_done = 1;
+
+  color_tree_init(&tree);
+
+  /*If the stats was already filled in from previous data, fill its palette in tree
+  and mark things as done already if we know they are the most expensive case already*/
+  if(stats->alpha) alpha_done = 1;
+  if(stats->colored) colored_done = 1;
+  if(stats->bits == 16) numcolors_done = 1;
+  if(stats->bits >= bpp) bits_done = 1;
+  if(stats->numcolors >= maxnumcolors) numcolors_done = 1;
+
+  if(!numcolors_done) {
+    for(i = 0; i < stats->numcolors; i++) {
+      const unsigned char* color = &stats->palette[i * 4];
+      error = color_tree_add(&tree, color[0], color[1], color[2], color[3], i);
+      if(error) goto cleanup;
+    }
+  }
+
+  /*Check if the 16-bit input is truly 16-bit*/
+  if(mode_in->bitdepth == 16 && !sixteen) {
+    unsigned short r = 0, g = 0, b = 0, a = 0;
+    for(i = 0; i != numpixels; ++i) {
+      getPixelColorRGBA16(&r, &g, &b, &a, in, i, mode_in);
+      if((r & 255) != ((r >> 8) & 255) || (g & 255) != ((g >> 8) & 255) ||
+         (b & 255) != ((b >> 8) & 255) || (a & 255) != ((a >> 8) & 255)) /*first and second byte differ*/ {
+        stats->bits = 16;
+        sixteen = 1;
+        bits_done = 1;
+        numcolors_done = 1; /*counting colors no longer useful, palette doesn't support 16-bit*/
+        break;
+      }
+    }
+  }
+
+  if(sixteen) {
+    unsigned short r = 0, g = 0, b = 0, a = 0;
+
+    for(i = 0; i != numpixels; ++i) {
+      getPixelColorRGBA16(&r, &g, &b, &a, in, i, mode_in);
+
+      if(!colored_done && (r != g || r != b)) {
+        stats->colored = 1;
+        colored_done = 1;
+      }
+
+      if(!alpha_done) {
+        unsigned matchkey = (r == stats->key_r && g == stats->key_g && b == stats->key_b);
+        if(a != 65535 && (a != 0 || (stats->key && !matchkey))) {
+          stats->alpha = 1;
+          stats->key = 0;
+          alpha_done = 1;
+        } else if(a == 0 && !stats->alpha && !stats->key) {
+          stats->key = 1;
+          stats->key_r = r;
+          stats->key_g = g;
+          stats->key_b = b;
+        } else if(a == 65535 && stats->key && matchkey) {
+          /* Color key cannot be used if an opaque pixel also has that RGB color. */
+          stats->alpha = 1;
+          stats->key = 0;
+          alpha_done = 1;
+        }
+      }
+      if(alpha_done && numcolors_done && colored_done && bits_done) break;
+    }
+
+    if(stats->key && !stats->alpha) {
+      for(i = 0; i != numpixels; ++i) {
+        getPixelColorRGBA16(&r, &g, &b, &a, in, i, mode_in);
+        if(a != 0 && r == stats->key_r && g == stats->key_g && b == stats->key_b) {
+          /* Color key cannot be used if an opaque pixel also has that RGB color. */
+          stats->alpha = 1;
+          stats->key = 0;
+          alpha_done = 1;
+        }
+      }
+    }
+  } else /* < 16-bit */ {
+    unsigned char r = 0, g = 0, b = 0, a = 0;
+    for(i = 0; i != numpixels; ++i) {
+      getPixelColorRGBA8(&r, &g, &b, &a, in, i, mode_in);
+
+      if(!bits_done && stats->bits < 8) {
+        /*only r is checked, < 8 bits is only relevant for grayscale*/
+        unsigned bits = getValueRequiredBits(r);
+        if(bits > stats->bits) stats->bits = bits;
+      }
+      bits_done = (stats->bits >= bpp);
+
+      if(!colored_done && (r != g || r != b)) {
+        stats->colored = 1;
+        colored_done = 1;
+        if(stats->bits < 8) stats->bits = 8; /*PNG has no colored modes with less than 8-bit per channel*/
+      }
+
+      if(!alpha_done) {
+        unsigned matchkey = (r == stats->key_r && g == stats->key_g && b == stats->key_b);
+        if(a != 255 && (a != 0 || (stats->key && !matchkey))) {
+          stats->alpha = 1;
+          stats->key = 0;
+          alpha_done = 1;
+          if(stats->bits < 8) stats->bits = 8; /*PNG has no alphachannel modes with less than 8-bit per channel*/
+        } else if(a == 0 && !stats->alpha && !stats->key) {
+          stats->key = 1;
+          stats->key_r = r;
+          stats->key_g = g;
+          stats->key_b = b;
+        } else if(a == 255 && stats->key && matchkey) {
+          /* Color key cannot be used if an opaque pixel also has that RGB color. */
+          stats->alpha = 1;
+          stats->key = 0;
+          alpha_done = 1;
+          if(stats->bits < 8) stats->bits = 8; /*PNG has no alphachannel modes with less than 8-bit per channel*/
+        }
+      }
+
+      if(!numcolors_done) {
+        if(!color_tree_has(&tree, r, g, b, a)) {
+          error = color_tree_add(&tree, r, g, b, a, stats->numcolors);
+          if(error) goto cleanup;
+          if(stats->numcolors < 256) {
+            unsigned char* p = stats->palette;
+            unsigned n = stats->numcolors;
+            p[n * 4 + 0] = r;
+            p[n * 4 + 1] = g;
+            p[n * 4 + 2] = b;
+            p[n * 4 + 3] = a;
+          }
+          ++stats->numcolors;
+          numcolors_done = stats->numcolors >= maxnumcolors;
+        }
+      }
+
+      if(alpha_done && numcolors_done && colored_done && bits_done) break;
+    }
+
+    if(stats->key && !stats->alpha) {
+      for(i = 0; i != numpixels; ++i) {
+        getPixelColorRGBA8(&r, &g, &b, &a, in, i, mode_in);
+        if(a != 0 && r == stats->key_r && g == stats->key_g && b == stats->key_b) {
+          /* Color key cannot be used if an opaque pixel also has that RGB color. */
+          stats->alpha = 1;
+          stats->key = 0;
+          alpha_done = 1;
+          if(stats->bits < 8) stats->bits = 8; /*PNG has no alphachannel modes with less than 8-bit per channel*/
+        }
+      }
+    }
+
+    /*make the stats's key always 16-bit for consistency - repeat each byte twice*/
+    stats->key_r += (stats->key_r << 8);
+    stats->key_g += (stats->key_g << 8);
+    stats->key_b += (stats->key_b << 8);
+  }
+
+cleanup:
+  color_tree_cleanup(&tree);
+  return error;
+}
+
+#ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
+/*Adds a single color to the color stats. The stats must already have been inited. The color must be given as 16-bit
+(with 2 bytes repeating for 8-bit and 65535 for opaque alpha channel). This function is expensive, do not call it for
+all pixels of an image but only for a few additional values. */
+static unsigned lodepng_color_stats_add(LodePNGColorStats* stats,
+                                        unsigned r, unsigned g, unsigned b, unsigned a) {
+  unsigned error = 0;
+  unsigned char image[8];
+  LodePNGColorMode mode;
+  lodepng_color_mode_init(&mode);
+  image[0] = r >> 8; image[1] = r; image[2] = g >> 8; image[3] = g;
+  image[4] = b >> 8; image[5] = b; image[6] = a >> 8; image[7] = a;
+  mode.bitdepth = 16;
+  mode.colortype = LCT_RGBA;
+  error = lodepng_compute_color_stats(stats, image, 1, 1, &mode);
+  lodepng_color_mode_cleanup(&mode);
+  return error;
+}
+#endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
+
+/*Computes a minimal PNG color model that can contain all colors as indicated by the stats.
+The stats should be computed with lodepng_compute_color_stats.
+mode_in is raw color profile of the image the stats were computed on, to copy palette order from when relevant.
+Minimal PNG color model means the color type and bit depth that gives smallest amount of bits in the output image,
+e.g. gray if only grayscale pixels, palette if less than 256 colors, color key if only single transparent color, ...
+This is used if auto_convert is enabled (it is by default).
+*/
+static unsigned auto_choose_color(LodePNGColorMode* mode_out,
+                                  const LodePNGColorMode* mode_in,
+                                  const LodePNGColorStats* stats) {
+  unsigned error = 0;
+  unsigned palettebits;
+  size_t i, n;
+  size_t numpixels = stats->numpixels;
+  unsigned palette_ok, gray_ok;
+
+  unsigned alpha = stats->alpha;
+  unsigned key = stats->key;
+  unsigned bits = stats->bits;
+
+  mode_out->key_defined = 0;
+
+  if(key && numpixels <= 16) {
+    alpha = 1; /*too few pixels to justify tRNS chunk overhead*/
+    key = 0;
+    if(bits < 8) bits = 8; /*PNG has no alphachannel modes with less than 8-bit per channel*/
+  }
+
+  gray_ok = !stats->colored;
+  if(!stats->allow_greyscale) gray_ok = 0;
+  if(!gray_ok && bits < 8) bits = 8;
+
+  n = stats->numcolors;
+  palettebits = n <= 2 ? 1 : (n <= 4 ? 2 : (n <= 16 ? 4 : 8));
+  palette_ok = n <= 256 && bits <= 8 && n != 0; /*n==0 means likely numcolors wasn't computed*/
+  if(numpixels < n * 2) palette_ok = 0; /*don't add palette overhead if image has only a few pixels*/
+  if(gray_ok && !alpha && bits <= palettebits) palette_ok = 0; /*gray is less overhead*/
+  if(!stats->allow_palette) palette_ok = 0;
+
+  if(palette_ok) {
+    const unsigned char* p = stats->palette;
+    lodepng_palette_clear(mode_out); /*remove potential earlier palette*/
+    for(i = 0; i != stats->numcolors; ++i) {
+      error = lodepng_palette_add(mode_out, p[i * 4 + 0], p[i * 4 + 1], p[i * 4 + 2], p[i * 4 + 3]);
+      if(error) break;
+    }
+
+    mode_out->colortype = LCT_PALETTE;
+    mode_out->bitdepth = palettebits;
+
+    if(mode_in->colortype == LCT_PALETTE && mode_in->palettesize >= mode_out->palettesize
+        && mode_in->bitdepth == mode_out->bitdepth) {
+      /*If input should have same palette colors, keep original to preserve its order and prevent conversion*/
+      lodepng_color_mode_cleanup(mode_out);
+      lodepng_color_mode_copy(mode_out, mode_in);
+    }
+  } else /*8-bit or 16-bit per channel*/ {
+    mode_out->bitdepth = bits;
+    mode_out->colortype = alpha ? (gray_ok ? LCT_GREY_ALPHA : LCT_RGBA)
+                                : (gray_ok ? LCT_GREY : LCT_RGB);
+    if(key) {
+      unsigned mask = (1u << mode_out->bitdepth) - 1u; /*stats always uses 16-bit, mask converts it*/
+      mode_out->key_r = stats->key_r & mask;
+      mode_out->key_g = stats->key_g & mask;
+      mode_out->key_b = stats->key_b & mask;
+      mode_out->key_defined = 1;
+    }
+  }
+
+  return error;
+}
+
+#endif /* #ifdef LODEPNG_COMPILE_ENCODER */
+
+/*
+Paeth predictor, used by PNG filter type 4
+The parameters are of type short, but should come from unsigned chars, the shorts
+are only needed to make the paeth calculation correct.
+*/
+static unsigned char paethPredictor(short a, short b, short c) {
+  short pa = LODEPNG_ABS(b - c);
+  short pb = LODEPNG_ABS(a - c);
+  short pc = LODEPNG_ABS(a + b - c - c);
+  /* return input value associated with smallest of pa, pb, pc (with certain priority if equal) */
+  if(pb < pa) { a = b; pa = pb; }
+  return (pc < pa) ? c : a;
+}
+
+/*shared values used by multiple Adam7 related functions*/
+
+static const unsigned ADAM7_IX[7] = { 0, 4, 0, 2, 0, 1, 0 }; /*x start values*/
+static const unsigned ADAM7_IY[7] = { 0, 0, 4, 0, 2, 0, 1 }; /*y start values*/
+static const unsigned ADAM7_DX[7] = { 8, 8, 4, 4, 2, 2, 1 }; /*x delta values*/
+static const unsigned ADAM7_DY[7] = { 8, 8, 8, 4, 4, 2, 2 }; /*y delta values*/
+
+/*
+Outputs various dimensions and positions in the image related to the Adam7 reduced images.
+passw: output containing the width of the 7 passes
+passh: output containing the height of the 7 passes
+filter_passstart: output containing the index of the start and end of each
+ reduced image with filter bytes
+padded_passstart output containing the index of the start and end of each
+ reduced image when without filter bytes but with padded scanlines
+passstart: output containing the index of the start and end of each reduced
+ image without padding between scanlines, but still padding between the images
+w, h: width and height of non-interlaced image
+bpp: bits per pixel
+"padded" is only relevant if bpp is less than 8 and a scanline or image does not
+ end at a full byte
+*/
+static void Adam7_getpassvalues(unsigned passw[7], unsigned passh[7], size_t filter_passstart[8],
+                                size_t padded_passstart[8], size_t passstart[8], unsigned w, unsigned h, unsigned bpp) {
+  /*the passstart values have 8 values: the 8th one indicates the byte after the end of the 7th (= last) pass*/
+  unsigned i;
+
+  /*calculate width and height in pixels of each pass*/
+  for(i = 0; i != 7; ++i) {
+    passw[i] = (w + ADAM7_DX[i] - ADAM7_IX[i] - 1) / ADAM7_DX[i];
+    passh[i] = (h + ADAM7_DY[i] - ADAM7_IY[i] - 1) / ADAM7_DY[i];
+    if(passw[i] == 0) passh[i] = 0;
+    if(passh[i] == 0) passw[i] = 0;
+  }
+
+  filter_passstart[0] = padded_passstart[0] = passstart[0] = 0;
+  for(i = 0; i != 7; ++i) {
+    /*if passw[i] is 0, it's 0 bytes, not 1 (no filtertype-byte)*/
+    filter_passstart[i + 1] = filter_passstart[i]
+                            + ((passw[i] && passh[i]) ? passh[i] * (1u + (passw[i] * bpp + 7u) / 8u) : 0);
+    /*bits padded if needed to fill full byte at end of each scanline*/
+    padded_passstart[i + 1] = padded_passstart[i] + passh[i] * ((passw[i] * bpp + 7u) / 8u);
+    /*only padded at end of reduced image*/
+    passstart[i + 1] = passstart[i] + (passh[i] * passw[i] * bpp + 7u) / 8u;
+  }
+}
+
+#ifdef LODEPNG_COMPILE_DECODER
+
+/* ////////////////////////////////////////////////////////////////////////// */
+/* / PNG Decoder                                                            / */
+/* ////////////////////////////////////////////////////////////////////////// */
+
+/*read the information from the header and store it in the LodePNGInfo. return value is error*/
+unsigned lodepng_inspect(unsigned* w, unsigned* h, LodePNGState* state,
+                         const unsigned char* in, size_t insize) {
+  unsigned width, height;
+  LodePNGInfo* info = &state->info_png;
+  if(insize == 0 || in == 0) {
+    CERROR_RETURN_ERROR(state->error, 48); /*error: the given data is empty*/
+  }
+  if(insize < 33) {
+    CERROR_RETURN_ERROR(state->error, 27); /*error: the data length is smaller than the length of a PNG header*/
+  }
+
+  /*when decoding a new PNG image, make sure all parameters created after previous decoding are reset*/
+  /* TODO: remove this. One should use a new LodePNGState for new sessions */
+  lodepng_info_cleanup(info);
+  lodepng_info_init(info);
+
+  if(in[0] != 137 || in[1] != 80 || in[2] != 78 || in[3] != 71
+     || in[4] != 13 || in[5] != 10 || in[6] != 26 || in[7] != 10) {
+    CERROR_RETURN_ERROR(state->error, 28); /*error: the first 8 bytes are not the correct PNG signature*/
+  }
+  if(lodepng_chunk_length(in + 8) != 13) {
+    CERROR_RETURN_ERROR(state->error, 94); /*error: header size must be 13 bytes*/
+  }
+  if(!lodepng_chunk_type_equals(in + 8, "IHDR")) {
+    CERROR_RETURN_ERROR(state->error, 29); /*error: it doesn't start with a IHDR chunk!*/
+  }
+
+  /*read the values given in the header*/
+  width = lodepng_read32bitInt(&in[16]);
+  height = lodepng_read32bitInt(&in[20]);
+  /*TODO: remove the undocumented feature that allows to give null pointers to width or height*/
+  if(w) *w = width;
+  if(h) *h = height;
+  info->color.bitdepth = in[24];
+  info->color.colortype = (LodePNGColorType)in[25];
+  info->compression_method = in[26];
+  info->filter_method = in[27];
+  info->interlace_method = in[28];
+
+  /*errors returned only after the parsing so other values are still output*/
+
+  /*error: invalid image size*/
+  if(width == 0 || height == 0) CERROR_RETURN_ERROR(state->error, 93);
+  /*error: invalid colortype or bitdepth combination*/
+  state->error = checkColorValidity(info->color.colortype, info->color.bitdepth);
+  if(state->error) return state->error;
+  /*error: only compression method 0 is allowed in the specification*/
+  if(info->compression_method != 0) CERROR_RETURN_ERROR(state->error, 32);
+  /*error: only filter method 0 is allowed in the specification*/
+  if(info->filter_method != 0) CERROR_RETURN_ERROR(state->error, 33);
+  /*error: only interlace methods 0 and 1 exist in the specification*/
+  if(info->interlace_method > 1) CERROR_RETURN_ERROR(state->error, 34);
+
+  if(!state->decoder.ignore_crc) {
+    unsigned CRC = lodepng_read32bitInt(&in[29]);
+    unsigned checksum = lodepng_crc32(&in[12], 17);
+    if(CRC != checksum) {
+      CERROR_RETURN_ERROR(state->error, 57); /*invalid CRC*/
+    }
+  }
+
+  return state->error;
+}
+
+static unsigned unfilterScanline(unsigned char* recon, const unsigned char* scanline, const unsigned char* precon,
+                                 size_t bytewidth, unsigned char filterType, size_t length) {
+  /*
+  For PNG filter method 0
+  unfilter a PNG image scanline by scanline. when the pixels are smaller than 1 byte,
+  the filter works byte per byte (bytewidth = 1)
+  precon is the previous unfiltered scanline, recon the result, scanline the current one
+  the incoming scanlines do NOT include the filtertype byte, that one is given in the parameter filterType instead
+  recon and scanline MAY be the same memory address! precon must be disjoint.
+  */
+
+  size_t i;
+  switch(filterType) {
+    case 0:
+      for(i = 0; i != length; ++i) recon[i] = scanline[i];
+      break;
+    case 1:
+      for(i = 0; i != bytewidth; ++i) recon[i] = scanline[i];
+      for(i = bytewidth; i < length; ++i) recon[i] = scanline[i] + recon[i - bytewidth];
+      break;
+    case 2:
+      if(precon) {
+        for(i = 0; i != length; ++i) recon[i] = scanline[i] + precon[i];
+      } else {
+        for(i = 0; i != length; ++i) recon[i] = scanline[i];
+      }
+      break;
+    case 3:
+      if(precon) {
+        for(i = 0; i != bytewidth; ++i) recon[i] = scanline[i] + (precon[i] >> 1u);
+        for(i = bytewidth; i < length; ++i) recon[i] = scanline[i] + ((recon[i - bytewidth] + precon[i]) >> 1u);
+      } else {
+        for(i = 0; i != bytewidth; ++i) recon[i] = scanline[i];
+        for(i = bytewidth; i < length; ++i) recon[i] = scanline[i] + (recon[i - bytewidth] >> 1u);
+      }
+      break;
+    case 4:
+      if(precon) {
+        for(i = 0; i != bytewidth; ++i) {
+          recon[i] = (scanline[i] + precon[i]); /*paethPredictor(0, precon[i], 0) is always precon[i]*/
+        }
+
+        /* Unroll independent paths of the paeth predictor. A 6x and 8x version would also be possible but that
+        adds too much code. Whether this actually speeds anything up at all depends on compiler and settings. */
+        if(bytewidth >= 4) {
+          for(; i + 3 < length; i += 4) {
+            size_t j = i - bytewidth;
+            unsigned char s0 = scanline[i + 0], s1 = scanline[i + 1], s2 = scanline[i + 2], s3 = scanline[i + 3];
+            unsigned char r0 = recon[j + 0], r1 = recon[j + 1], r2 = recon[j + 2], r3 = recon[j + 3];
+            unsigned char p0 = precon[i + 0], p1 = precon[i + 1], p2 = precon[i + 2], p3 = precon[i + 3];
+            unsigned char q0 = precon[j + 0], q1 = precon[j + 1], q2 = precon[j + 2], q3 = precon[j + 3];
+            recon[i + 0] = s0 + paethPredictor(r0, p0, q0);
+            recon[i + 1] = s1 + paethPredictor(r1, p1, q1);
+            recon[i + 2] = s2 + paethPredictor(r2, p2, q2);
+            recon[i + 3] = s3 + paethPredictor(r3, p3, q3);
+          }
+        } else if(bytewidth >= 3) {
+          for(; i + 2 < length; i += 3) {
+            size_t j = i - bytewidth;
+            unsigned char s0 = scanline[i + 0], s1 = scanline[i + 1], s2 = scanline[i + 2];
+            unsigned char r0 = recon[j + 0], r1 = recon[j + 1], r2 = recon[j + 2];
+            unsigned char p0 = precon[i + 0], p1 = precon[i + 1], p2 = precon[i + 2];
+            unsigned char q0 = precon[j + 0], q1 = precon[j + 1], q2 = precon[j + 2];
+            recon[i + 0] = s0 + paethPredictor(r0, p0, q0);
+            recon[i + 1] = s1 + paethPredictor(r1, p1, q1);
+            recon[i + 2] = s2 + paethPredictor(r2, p2, q2);
+          }
+        } else if(bytewidth >= 2) {
+          for(; i + 1 < length; i += 2) {
+            size_t j = i - bytewidth;
+            unsigned char s0 = scanline[i + 0], s1 = scanline[i + 1];
+            unsigned char r0 = recon[j + 0], r1 = recon[j + 1];
+            unsigned char p0 = precon[i + 0], p1 = precon[i + 1];
+            unsigned char q0 = precon[j + 0], q1 = precon[j + 1];
+            recon[i + 0] = s0 + paethPredictor(r0, p0, q0);
+            recon[i + 1] = s1 + paethPredictor(r1, p1, q1);
+          }
+        }
+
+        for(; i != length; ++i) {
+          recon[i] = (scanline[i] + paethPredictor(recon[i - bytewidth], precon[i], precon[i - bytewidth]));
+        }
+      } else {
+        for(i = 0; i != bytewidth; ++i) {
+          recon[i] = scanline[i];
+        }
+        for(i = bytewidth; i < length; ++i) {
+          /*paethPredictor(recon[i - bytewidth], 0, 0) is always recon[i - bytewidth]*/
+          recon[i] = (scanline[i] + recon[i - bytewidth]);
+        }
+      }
+      break;
+    default: return 36; /*error: invalid filter type given*/
+  }
+  return 0;
+}
+
+static unsigned unfilter(unsigned char* out, const unsigned char* in, unsigned w, unsigned h, unsigned bpp) {
+  /*
+  For PNG filter method 0
+  this function unfilters a single image (e.g. without interlacing this is called once, with Adam7 seven times)
+  out must have enough bytes allocated already, in must have the scanlines + 1 filtertype byte per scanline
+  w and h are image dimensions or dimensions of reduced image, bpp is bits per pixel
+  in and out are allowed to be the same memory address (but aren't the same size since in has the extra filter bytes)
+  */
+
+  unsigned y;
+  unsigned char* prevline = 0;
+
+  /*bytewidth is used for filtering, is 1 when bpp < 8, number of bytes per pixel otherwise*/
+  size_t bytewidth = (bpp + 7u) / 8u;
+  /*the width of a scanline in bytes, not including the filter type*/
+  size_t linebytes = lodepng_get_raw_size_idat(w, 1, bpp) - 1u;
+
+  for(y = 0; y < h; ++y) {
+    size_t outindex = linebytes * y;
+    size_t inindex = (1 + linebytes) * y; /*the extra filterbyte added to each row*/
+    unsigned char filterType = in[inindex];
+
+    CERROR_TRY_RETURN(unfilterScanline(&out[outindex], &in[inindex + 1], prevline, bytewidth, filterType, linebytes));
+
+    prevline = &out[outindex];
+  }
+
+  return 0;
+}
+
+/*
+in: Adam7 interlaced image, with no padding bits between scanlines, but between
+ reduced images so that each reduced image starts at a byte.
+out: the same pixels, but re-ordered so that they're now a non-interlaced image with size w*h
+bpp: bits per pixel
+out has the following size in bits: w * h * bpp.
+in is possibly bigger due to padding bits between reduced images.
+out must be big enough AND must be 0 everywhere if bpp < 8 in the current implementation
+(because that's likely a little bit faster)
+NOTE: comments about padding bits are only relevant if bpp < 8
+*/
+static void Adam7_deinterlace(unsigned char* out, const unsigned char* in, unsigned w, unsigned h, unsigned bpp) {
+  unsigned passw[7], passh[7];
+  size_t filter_passstart[8], padded_passstart[8], passstart[8];
+  unsigned i;
+
+  Adam7_getpassvalues(passw, passh, filter_passstart, padded_passstart, passstart, w, h, bpp);
+
+  if(bpp >= 8) {
+    for(i = 0; i != 7; ++i) {
+      unsigned x, y, b;
+      size_t bytewidth = bpp / 8u;
+      for(y = 0; y < passh[i]; ++y)
+      for(x = 0; x < passw[i]; ++x) {
+        size_t pixelinstart = passstart[i] + (y * passw[i] + x) * bytewidth;
+        size_t pixeloutstart = ((ADAM7_IY[i] + (size_t)y * ADAM7_DY[i]) * (size_t)w
+                             + ADAM7_IX[i] + (size_t)x * ADAM7_DX[i]) * bytewidth;
+        for(b = 0; b < bytewidth; ++b) {
+          out[pixeloutstart + b] = in[pixelinstart + b];
+        }
+      }
+    }
+  } else /*bpp < 8: Adam7 with pixels < 8 bit is a bit trickier: with bit pointers*/ {
+    for(i = 0; i != 7; ++i) {
+      unsigned x, y, b;
+      unsigned ilinebits = bpp * passw[i];
+      unsigned olinebits = bpp * w;
+      size_t obp, ibp; /*bit pointers (for out and in buffer)*/
+      for(y = 0; y < passh[i]; ++y)
+      for(x = 0; x < passw[i]; ++x) {
+        ibp = (8 * passstart[i]) + (y * ilinebits + x * bpp);
+        obp = (ADAM7_IY[i] + (size_t)y * ADAM7_DY[i]) * olinebits + (ADAM7_IX[i] + (size_t)x * ADAM7_DX[i]) * bpp;
+        for(b = 0; b < bpp; ++b) {
+          unsigned char bit = readBitFromReversedStream(&ibp, in);
+          setBitOfReversedStream(&obp, out, bit);
+        }
+      }
+    }
+  }
+}
+
+static void removePaddingBits(unsigned char* out, const unsigned char* in,
+                              size_t olinebits, size_t ilinebits, unsigned h) {
+  /*
+  After filtering there are still padding bits if scanlines have non multiple of 8 bit amounts. They need
+  to be removed (except at last scanline of (Adam7-reduced) image) before working with pure image buffers
+  for the Adam7 code, the color convert code and the output to the user.
+  in and out are allowed to be the same buffer, in may also be higher but still overlapping; in must
+  have >= ilinebits*h bits, out must have >= olinebits*h bits, olinebits must be <= ilinebits
+  also used to move bits after earlier such operations happened, e.g. in a sequence of reduced images from Adam7
+  only useful if (ilinebits - olinebits) is a value in the range 1..7
+  */
+  unsigned y;
+  size_t diff = ilinebits - olinebits;
+  size_t ibp = 0, obp = 0; /*input and output bit pointers*/
+  for(y = 0; y < h; ++y) {
+    size_t x;
+    for(x = 0; x < olinebits; ++x) {
+      unsigned char bit = readBitFromReversedStream(&ibp, in);
+      setBitOfReversedStream(&obp, out, bit);
+    }
+    ibp += diff;
+  }
+}
+
+/*out must be buffer big enough to contain full image, and in must contain the full decompressed data from
+the IDAT chunks (with filter index bytes and possible padding bits)
+return value is error*/
+static unsigned postProcessScanlines(unsigned char* out, unsigned char* in,
+                                     unsigned w, unsigned h, const LodePNGInfo* info_png) {
+  /*
+  This function converts the filtered-padded-interlaced data into pure 2D image buffer with the PNG's colortype.
+  Steps:
+  *) if no Adam7: 1) unfilter 2) remove padding bits (= possible extra bits per scanline if bpp < 8)
+  *) if adam7: 1) 7x unfilter 2) 7x remove padding bits 3) Adam7_deinterlace
+  NOTE: the in buffer will be overwritten with intermediate data!
+  */
+  unsigned bpp = lodepng_get_bpp(&info_png->color);
+  if(bpp == 0) return 31; /*error: invalid colortype*/
+
+  if(info_png->interlace_method == 0) {
+    if(bpp < 8 && w * bpp != ((w * bpp + 7u) / 8u) * 8u) {
+      CERROR_TRY_RETURN(unfilter(in, in, w, h, bpp));
+      removePaddingBits(out, in, w * bpp, ((w * bpp + 7u) / 8u) * 8u, h);
+    }
+    /*we can immediately filter into the out buffer, no other steps needed*/
+    else CERROR_TRY_RETURN(unfilter(out, in, w, h, bpp));
+  } else /*interlace_method is 1 (Adam7)*/ {
+    unsigned passw[7], passh[7]; size_t filter_passstart[8], padded_passstart[8], passstart[8];
+    unsigned i;
+
+    Adam7_getpassvalues(passw, passh, filter_passstart, padded_passstart, passstart, w, h, bpp);
+
+    for(i = 0; i != 7; ++i) {
+      CERROR_TRY_RETURN(unfilter(&in[padded_passstart[i]], &in[filter_passstart[i]], passw[i], passh[i], bpp));
+      /*TODO: possible efficiency improvement: if in this reduced image the bits fit nicely in 1 scanline,
+      move bytes instead of bits or move not at all*/
+      if(bpp < 8) {
+        /*remove padding bits in scanlines; after this there still may be padding
+        bits between the different reduced images: each reduced image still starts nicely at a byte*/
+        removePaddingBits(&in[passstart[i]], &in[padded_passstart[i]], passw[i] * bpp,
+                          ((passw[i] * bpp + 7u) / 8u) * 8u, passh[i]);
+      }
+    }
+
+    Adam7_deinterlace(out, in, w, h, bpp);
+  }
+
+  return 0;
+}
+
+static unsigned readChunk_PLTE(LodePNGColorMode* color, const unsigned char* data, size_t chunkLength) {
+  unsigned pos = 0, i;
+  color->palettesize = chunkLength / 3u;
+  if(color->palettesize == 0 || color->palettesize > 256) return 38; /*error: palette too small or big*/
+  lodepng_color_mode_alloc_palette(color);
+  if(!color->palette && color->palettesize) {
+    color->palettesize = 0;
+    return 83; /*alloc fail*/
+  }
+
+  for(i = 0; i != color->palettesize; ++i) {
+    color->palette[4 * i + 0] = data[pos++]; /*R*/
+    color->palette[4 * i + 1] = data[pos++]; /*G*/
+    color->palette[4 * i + 2] = data[pos++]; /*B*/
+    color->palette[4 * i + 3] = 255; /*alpha*/
+  }
+
+  return 0; /* OK */
+}
+
+static unsigned readChunk_tRNS(LodePNGColorMode* color, const unsigned char* data, size_t chunkLength) {
+  unsigned i;
+  if(color->colortype == LCT_PALETTE) {
+    /*error: more alpha values given than there are palette entries*/
+    if(chunkLength > color->palettesize) return 39;
+
+    for(i = 0; i != chunkLength; ++i) color->palette[4 * i + 3] = data[i];
+  } else if(color->colortype == LCT_GREY) {
+    /*error: this chunk must be 2 bytes for grayscale image*/
+    if(chunkLength != 2) return 30;
+
+    color->key_defined = 1;
+    color->key_r = color->key_g = color->key_b = 256u * data[0] + data[1];
+  } else if(color->colortype == LCT_RGB) {
+    /*error: this chunk must be 6 bytes for RGB image*/
+    if(chunkLength != 6) return 41;
+
+    color->key_defined = 1;
+    color->key_r = 256u * data[0] + data[1];
+    color->key_g = 256u * data[2] + data[3];
+    color->key_b = 256u * data[4] + data[5];
+  }
+  else return 42; /*error: tRNS chunk not allowed for other color models*/
+
+  return 0; /* OK */
+}
+
+
+#ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
+/*background color chunk (bKGD)*/
+static unsigned readChunk_bKGD(LodePNGInfo* info, const unsigned char* data, size_t chunkLength) {
+  if(info->color.colortype == LCT_PALETTE) {
+    /*error: this chunk must be 1 byte for indexed color image*/
+    if(chunkLength != 1) return 43;
+
+    /*error: invalid palette index, or maybe this chunk appeared before PLTE*/
+    if(data[0] >= info->color.palettesize) return 103;
+
+    info->background_defined = 1;
+    info->background_r = info->background_g = info->background_b = data[0];
+  } else if(info->color.colortype == LCT_GREY || info->color.colortype == LCT_GREY_ALPHA) {
+    /*error: this chunk must be 2 bytes for grayscale image*/
+    if(chunkLength != 2) return 44;
+
+    /*the values are truncated to bitdepth in the PNG file*/
+    info->background_defined = 1;
+    info->background_r = info->background_g = info->background_b = 256u * data[0] + data[1];
+  } else if(info->color.colortype == LCT_RGB || info->color.colortype == LCT_RGBA) {
+    /*error: this chunk must be 6 bytes for grayscale image*/
+    if(chunkLength != 6) return 45;
+
+    /*the values are truncated to bitdepth in the PNG file*/
+    info->background_defined = 1;
+    info->background_r = 256u * data[0] + data[1];
+    info->background_g = 256u * data[2] + data[3];
+    info->background_b = 256u * data[4] + data[5];
+  }
+
+  return 0; /* OK */
+}
+
+/*text chunk (tEXt)*/
+static unsigned readChunk_tEXt(LodePNGInfo* info, const unsigned char* data, size_t chunkLength) {
+  unsigned error = 0;
+  char *key = 0, *str = 0;
+
+  while(!error) /*not really a while loop, only used to break on error*/ {
+    unsigned length, string2_begin;
+
+    length = 0;
+    while(length < chunkLength && data[length] != 0) ++length;
+    /*even though it's not allowed by the standard, no error is thrown if
+    there's no null termination char, if the text is empty*/
+    if(length < 1 || length > 79) CERROR_BREAK(error, 89); /*keyword too short or long*/
+
+    key = (char*)lodepng_malloc(length + 1);
+    if(!key) CERROR_BREAK(error, 83); /*alloc fail*/
+
+    lodepng_memcpy(key, data, length);
+    key[length] = 0;
+
+    string2_begin = length + 1; /*skip keyword null terminator*/
+
+    length = (unsigned)(chunkLength < string2_begin ? 0 : chunkLength - string2_begin);
+    str = (char*)lodepng_malloc(length + 1);
+    if(!str) CERROR_BREAK(error, 83); /*alloc fail*/
+
+    lodepng_memcpy(str, data + string2_begin, length);
+    str[length] = 0;
+
+    error = lodepng_add_text(info, key, str);
+
+    break;
+  }
+
+  lodepng_free(key);
+  lodepng_free(str);
+
+  return error;
+}
+
+/*compressed text chunk (zTXt)*/
+static unsigned readChunk_zTXt(LodePNGInfo* info, const LodePNGDecompressSettings* zlibsettings,
+                               const unsigned char* data, size_t chunkLength) {
+  unsigned error = 0;
+
+  unsigned length, string2_begin;
+  char *key = 0;
+  unsigned char* str = 0;
+  size_t size = 0;
+
+  while(!error) /*not really a while loop, only used to break on error*/ {
+    for(length = 0; length < chunkLength && data[length] != 0; ++length) ;
+    if(length + 2 >= chunkLength) CERROR_BREAK(error, 75); /*no null termination, corrupt?*/
+    if(length < 1 || length > 79) CERROR_BREAK(error, 89); /*keyword too short or long*/
+
+    key = (char*)lodepng_malloc(length + 1);
+    if(!key) CERROR_BREAK(error, 83); /*alloc fail*/
+
+    lodepng_memcpy(key, data, length);
+    key[length] = 0;
+
+    if(data[length + 1] != 0) CERROR_BREAK(error, 72); /*the 0 byte indicating compression must be 0*/
+
+    string2_begin = length + 2;
+    if(string2_begin > chunkLength) CERROR_BREAK(error, 75); /*no null termination, corrupt?*/
+
+    length = (unsigned)chunkLength - string2_begin;
+    /*will fail if zlib error, e.g. if length is too small*/
+    error = zlib_decompress(&str, &size, 0, &data[string2_begin],
+                            length, zlibsettings);
+    if(error) break;
+    error = lodepng_add_text_sized(info, key, (char*)str, size);
+
+    break;
+  }
+
+  lodepng_free(key);
+  lodepng_free(str);
+
+  return error;
+}
+
+/*international text chunk (iTXt)*/
+static unsigned readChunk_iTXt(LodePNGInfo* info, const LodePNGDecompressSettings* zlibsettings,
+                               const unsigned char* data, size_t chunkLength) {
+  unsigned error = 0;
+  unsigned i;
+
+  unsigned length, begin, compressed;
+  char *key = 0, *langtag = 0, *transkey = 0;
+
+  while(!error) /*not really a while loop, only used to break on error*/ {
+    /*Quick check if the chunk length isn't too small. Even without check
+    it'd still fail with other error checks below if it's too short. This just gives a different error code.*/
+    if(chunkLength < 5) CERROR_BREAK(error, 30); /*iTXt chunk too short*/
+
+    /*read the key*/
+    for(length = 0; length < chunkLength && data[length] != 0; ++length) ;
+    if(length + 3 >= chunkLength) CERROR_BREAK(error, 75); /*no null termination char, corrupt?*/
+    if(length < 1 || length > 79) CERROR_BREAK(error, 89); /*keyword too short or long*/
+
+    key = (char*)lodepng_malloc(length + 1);
+    if(!key) CERROR_BREAK(error, 83); /*alloc fail*/
+
+    lodepng_memcpy(key, data, length);
+    key[length] = 0;
+
+    /*read the compression method*/
+    compressed = data[length + 1];
+    if(data[length + 2] != 0) CERROR_BREAK(error, 72); /*the 0 byte indicating compression must be 0*/
+
+    /*even though it's not allowed by the standard, no error is thrown if
+    there's no null termination char, if the text is empty for the next 3 texts*/
+
+    /*read the langtag*/
+    begin = length + 3;
+    length = 0;
+    for(i = begin; i < chunkLength && data[i] != 0; ++i) ++length;
+
+    langtag = (char*)lodepng_malloc(length + 1);
+    if(!langtag) CERROR_BREAK(error, 83); /*alloc fail*/
+
+    lodepng_memcpy(langtag, data + begin, length);
+    langtag[length] = 0;
+
+    /*read the transkey*/
+    begin += length + 1;
+    length = 0;
+    for(i = begin; i < chunkLength && data[i] != 0; ++i) ++length;
+
+    transkey = (char*)lodepng_malloc(length + 1);
+    if(!transkey) CERROR_BREAK(error, 83); /*alloc fail*/
+
+    lodepng_memcpy(transkey, data + begin, length);
+    transkey[length] = 0;
+
+    /*read the actual text*/
+    begin += length + 1;
+
+    length = (unsigned)chunkLength < begin ? 0 : (unsigned)chunkLength - begin;
+
+    if(compressed) {
+      unsigned char* str = 0;
+      size_t size = 0;
+      /*will fail if zlib error, e.g. if length is too small*/
+      error = zlib_decompress(&str, &size, 0, &data[begin],
+                              length, zlibsettings);
+      if(!error) error = lodepng_add_itext_sized(info, key, langtag, transkey, (char*)str, size);
+      lodepng_free(str);
+    } else {
+      error = lodepng_add_itext_sized(info, key, langtag, transkey, (char*)(data + begin), length);
+    }
+
+    break;
+  }
+
+  lodepng_free(key);
+  lodepng_free(langtag);
+  lodepng_free(transkey);
+
+  return error;
+}
+
+static unsigned readChunk_tIME(LodePNGInfo* info, const unsigned char* data, size_t chunkLength) {
+  if(chunkLength != 7) return 73; /*invalid tIME chunk size*/
+
+  info->time_defined = 1;
+  info->time.year = 256u * data[0] + data[1];
+  info->time.month = data[2];
+  info->time.day = data[3];
+  info->time.hour = data[4];
+  info->time.minute = data[5];
+  info->time.second = data[6];
+
+  return 0; /* OK */
+}
+
+static unsigned readChunk_pHYs(LodePNGInfo* info, const unsigned char* data, size_t chunkLength) {
+  if(chunkLength != 9) return 74; /*invalid pHYs chunk size*/
+
+  info->phys_defined = 1;
+  info->phys_x = 16777216u * data[0] + 65536u * data[1] + 256u * data[2] + data[3];
+  info->phys_y = 16777216u * data[4] + 65536u * data[5] + 256u * data[6] + data[7];
+  info->phys_unit = data[8];
+
+  return 0; /* OK */
+}
+
+static unsigned readChunk_gAMA(LodePNGInfo* info, const unsigned char* data, size_t chunkLength) {
+  if(chunkLength != 4) return 96; /*invalid gAMA chunk size*/
+
+  info->gama_defined = 1;
+  info->gama_gamma = 16777216u * data[0] + 65536u * data[1] + 256u * data[2] + data[3];
+
+  return 0; /* OK */
+}
+
+static unsigned readChunk_cHRM(LodePNGInfo* info, const unsigned char* data, size_t chunkLength) {
+  if(chunkLength != 32) return 97; /*invalid cHRM chunk size*/
+
+  info->chrm_defined = 1;
+  info->chrm_white_x = 16777216u * data[ 0] + 65536u * data[ 1] + 256u * data[ 2] + data[ 3];
+  info->chrm_white_y = 16777216u * data[ 4] + 65536u * data[ 5] + 256u * data[ 6] + data[ 7];
+  info->chrm_red_x   = 16777216u * data[ 8] + 65536u * data[ 9] + 256u * data[10] + data[11];
+  info->chrm_red_y   = 16777216u * data[12] + 65536u * data[13] + 256u * data[14] + data[15];
+  info->chrm_green_x = 16777216u * data[16] + 65536u * data[17] + 256u * data[18] + data[19];
+  info->chrm_green_y = 16777216u * data[20] + 65536u * data[21] + 256u * data[22] + data[23];
+  info->chrm_blue_x  = 16777216u * data[24] + 65536u * data[25] + 256u * data[26] + data[27];
+  info->chrm_blue_y  = 16777216u * data[28] + 65536u * data[29] + 256u * data[30] + data[31];
+
+  return 0; /* OK */
+}
+
+static unsigned readChunk_sRGB(LodePNGInfo* info, const unsigned char* data, size_t chunkLength) {
+  if(chunkLength != 1) return 98; /*invalid sRGB chunk size (this one is never ignored)*/
+
+  info->srgb_defined = 1;
+  info->srgb_intent = data[0];
+
+  return 0; /* OK */
+}
+
+static unsigned readChunk_iCCP(LodePNGInfo* info, const LodePNGDecompressSettings* zlibsettings,
+                               const unsigned char* data, size_t chunkLength) {
+  unsigned error = 0;
+  unsigned i;
+  size_t size = 0;
+
+  unsigned length, string2_begin;
+
+  info->iccp_defined = 1;
+  if(info->iccp_name) lodepng_clear_icc(info);
+
+  for(length = 0; length < chunkLength && data[length] != 0; ++length) ;
+  if(length + 2 >= chunkLength) return 75; /*no null termination, corrupt?*/
+  if(length < 1 || length > 79) return 89; /*keyword too short or long*/
+
+  info->iccp_name = (char*)lodepng_malloc(length + 1);
+  if(!info->iccp_name) return 83; /*alloc fail*/
+
+  info->iccp_name[length] = 0;
+  for(i = 0; i != length; ++i) info->iccp_name[i] = (char)data[i];
+
+  if(data[length + 1] != 0) return 72; /*the 0 byte indicating compression must be 0*/
+
+  string2_begin = length + 2;
+  if(string2_begin > chunkLength) return 75; /*no null termination, corrupt?*/
+
+  length = (unsigned)chunkLength - string2_begin;
+  error = zlib_decompress(&info->iccp_profile, &size, 0,
+                          &data[string2_begin],
+                          length, zlibsettings);
+  info->iccp_profile_size = size;
+  if(!error && !info->iccp_profile_size) error = 100; /*invalid ICC profile size*/
+  return error;
+}
+#endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
+
+unsigned lodepng_inspect_chunk(LodePNGState* state, size_t pos,
+                               const unsigned char* in, size_t insize) {
+  const unsigned char* chunk = in + pos;
+  unsigned chunkLength;
+  const unsigned char* data;
+  unsigned unhandled = 0;
+  unsigned error = 0;
+
+  if(pos + 4 > insize) return 30;
+  chunkLength = lodepng_chunk_length(chunk);
+  if(chunkLength > 2147483647) return 63;
+  data = lodepng_chunk_data_const(chunk);
+  if(data + chunkLength + 4 > in + insize) return 30;
+
+  if(lodepng_chunk_type_equals(chunk, "PLTE")) {
+    error = readChunk_PLTE(&state->info_png.color, data, chunkLength);
+  } else if(lodepng_chunk_type_equals(chunk, "tRNS")) {
+    error = readChunk_tRNS(&state->info_png.color, data, chunkLength);
+#ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
+  } else if(lodepng_chunk_type_equals(chunk, "bKGD")) {
+    error = readChunk_bKGD(&state->info_png, data, chunkLength);
+  } else if(lodepng_chunk_type_equals(chunk, "tEXt")) {
+    error = readChunk_tEXt(&state->info_png, data, chunkLength);
+  } else if(lodepng_chunk_type_equals(chunk, "zTXt")) {
+    error = readChunk_zTXt(&state->info_png, &state->decoder.zlibsettings, data, chunkLength);
+  } else if(lodepng_chunk_type_equals(chunk, "iTXt")) {
+    error = readChunk_iTXt(&state->info_png, &state->decoder.zlibsettings, data, chunkLength);
+  } else if(lodepng_chunk_type_equals(chunk, "tIME")) {
+    error = readChunk_tIME(&state->info_png, data, chunkLength);
+  } else if(lodepng_chunk_type_equals(chunk, "pHYs")) {
+    error = readChunk_pHYs(&state->info_png, data, chunkLength);
+  } else if(lodepng_chunk_type_equals(chunk, "gAMA")) {
+    error = readChunk_gAMA(&state->info_png, data, chunkLength);
+  } else if(lodepng_chunk_type_equals(chunk, "cHRM")) {
+    error = readChunk_cHRM(&state->info_png, data, chunkLength);
+  } else if(lodepng_chunk_type_equals(chunk, "sRGB")) {
+    error = readChunk_sRGB(&state->info_png, data, chunkLength);
+  } else if(lodepng_chunk_type_equals(chunk, "iCCP")) {
+    error = readChunk_iCCP(&state->info_png, &state->decoder.zlibsettings, data, chunkLength);
+#endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
+  } else {
+    /* unhandled chunk is ok (is not an error) */
+    unhandled = 1;
+  }
+
+  if(!error && !unhandled && !state->decoder.ignore_crc) {
+    if(lodepng_chunk_check_crc(chunk)) return 57; /*invalid CRC*/
+  }
+
+  return error;
+}
+
+/*read a PNG, the result will be in the same color type as the PNG (hence "generic")*/
+static void decodeGeneric(unsigned char** out, unsigned* w, unsigned* h,
+                          LodePNGState* state,
+                          const unsigned char* in, size_t insize) {
+  unsigned char IEND = 0;
+  const unsigned char* chunk;
+  unsigned char* idat; /*the data from idat chunks, zlib compressed*/
+  size_t idatsize = 0;
+  unsigned char* scanlines = 0;
+  size_t scanlines_size = 0, expected_size = 0;
+  size_t outsize = 0;
+
+  /*for unknown chunk order*/
+  unsigned unknown = 0;
+#ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
+  unsigned critical_pos = 1; /*1 = after IHDR, 2 = after PLTE, 3 = after IDAT*/
+#endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
+
+
+  /* safe output values in case error happens */
+  *out = 0;
+  *w = *h = 0;
+
+  state->error = lodepng_inspect(w, h, state, in, insize); /*reads header and resets other parameters in state->info_png*/
+  if(state->error) return;
+
+  if(lodepng_pixel_overflow(*w, *h, &state->info_png.color, &state->info_raw)) {
+    CERROR_RETURN(state->error, 92); /*overflow possible due to amount of pixels*/
+  }
+
+  /*the input filesize is a safe upper bound for the sum of idat chunks size*/
+  idat = (unsigned char*)lodepng_malloc(insize);
+  if(!idat) CERROR_RETURN(state->error, 83); /*alloc fail*/
+
+  chunk = &in[33]; /*first byte of the first chunk after the header*/
+
+  /*loop through the chunks, ignoring unknown chunks and stopping at IEND chunk.
+  IDAT data is put at the start of the in buffer*/
+  while(!IEND && !state->error) {
+    unsigned chunkLength;
+    const unsigned char* data; /*the data in the chunk*/
+
+    /*error: size of the in buffer too small to contain next chunk*/
+    if((size_t)((chunk - in) + 12) > insize || chunk < in) {
+      if(state->decoder.ignore_end) break; /*other errors may still happen though*/
+      CERROR_BREAK(state->error, 30);
+    }
+
+    /*length of the data of the chunk, excluding the length bytes, chunk type and CRC bytes*/
+    chunkLength = lodepng_chunk_length(chunk);
+    /*error: chunk length larger than the max PNG chunk size*/
+    if(chunkLength > 2147483647) {
+      if(state->decoder.ignore_end) break; /*other errors may still happen though*/
+      CERROR_BREAK(state->error, 63);
+    }
+
+    if((size_t)((chunk - in) + chunkLength + 12) > insize || (chunk + chunkLength + 12) < in) {
+      CERROR_BREAK(state->error, 64); /*error: size of the in buffer too small to contain next chunk*/
+    }
+
+    data = lodepng_chunk_data_const(chunk);
+
+    unknown = 0;
+
+    /*IDAT chunk, containing compressed image data*/
+    if(lodepng_chunk_type_equals(chunk, "IDAT")) {
+      size_t newsize;
+      if(lodepng_addofl(idatsize, chunkLength, &newsize)) CERROR_BREAK(state->error, 95);
+      if(newsize > insize) CERROR_BREAK(state->error, 95);
+      lodepng_memcpy(idat + idatsize, data, chunkLength);
+      idatsize += chunkLength;
+#ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
+      critical_pos = 3;
+#endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
+    } else if(lodepng_chunk_type_equals(chunk, "IEND")) {
+      /*IEND chunk*/
+      IEND = 1;
+    } else if(lodepng_chunk_type_equals(chunk, "PLTE")) {
+      /*palette chunk (PLTE)*/
+      state->error = readChunk_PLTE(&state->info_png.color, data, chunkLength);
+      if(state->error) break;
+#ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
+      critical_pos = 2;
+#endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
+    } else if(lodepng_chunk_type_equals(chunk, "tRNS")) {
+      /*palette transparency chunk (tRNS). Even though this one is an ancillary chunk , it is still compiled
+      in without 'LODEPNG_COMPILE_ANCILLARY_CHUNKS' because it contains essential color information that
+      affects the alpha channel of pixels. */
+      state->error = readChunk_tRNS(&state->info_png.color, data, chunkLength);
+      if(state->error) break;
+#ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
+      /*background color chunk (bKGD)*/
+    } else if(lodepng_chunk_type_equals(chunk, "bKGD")) {
+      state->error = readChunk_bKGD(&state->info_png, data, chunkLength);
+      if(state->error) break;
+    } else if(lodepng_chunk_type_equals(chunk, "tEXt")) {
+      /*text chunk (tEXt)*/
+      if(state->decoder.read_text_chunks) {
+        state->error = readChunk_tEXt(&state->info_png, data, chunkLength);
+        if(state->error) break;
+      }
+    } else if(lodepng_chunk_type_equals(chunk, "zTXt")) {
+      /*compressed text chunk (zTXt)*/
+      if(state->decoder.read_text_chunks) {
+        state->error = readChunk_zTXt(&state->info_png, &state->decoder.zlibsettings, data, chunkLength);
+        if(state->error) break;
+      }
+    } else if(lodepng_chunk_type_equals(chunk, "iTXt")) {
+      /*international text chunk (iTXt)*/
+      if(state->decoder.read_text_chunks) {
+        state->error = readChunk_iTXt(&state->info_png, &state->decoder.zlibsettings, data, chunkLength);
+        if(state->error) break;
+      }
+    } else if(lodepng_chunk_type_equals(chunk, "tIME")) {
+      state->error = readChunk_tIME(&state->info_png, data, chunkLength);
+      if(state->error) break;
+    } else if(lodepng_chunk_type_equals(chunk, "pHYs")) {
+      state->error = readChunk_pHYs(&state->info_png, data, chunkLength);
+      if(state->error) break;
+    } else if(lodepng_chunk_type_equals(chunk, "gAMA")) {
+      state->error = readChunk_gAMA(&state->info_png, data, chunkLength);
+      if(state->error) break;
+    } else if(lodepng_chunk_type_equals(chunk, "cHRM")) {
+      state->error = readChunk_cHRM(&state->info_png, data, chunkLength);
+      if(state->error) break;
+    } else if(lodepng_chunk_type_equals(chunk, "sRGB")) {
+      state->error = readChunk_sRGB(&state->info_png, data, chunkLength);
+      if(state->error) break;
+    } else if(lodepng_chunk_type_equals(chunk, "iCCP")) {
+      state->error = readChunk_iCCP(&state->info_png, &state->decoder.zlibsettings, data, chunkLength);
+      if(state->error) break;
+#endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
+    } else /*it's not an implemented chunk type, so ignore it: skip over the data*/ {
+      /*error: unknown critical chunk (5th bit of first byte of chunk type is 0)*/
+      if(!state->decoder.ignore_critical && !lodepng_chunk_ancillary(chunk)) {
+        CERROR_BREAK(state->error, 69);
+      }
+
+      unknown = 1;
+#ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
+      if(state->decoder.remember_unknown_chunks) {
+        state->error = lodepng_chunk_append(&state->info_png.unknown_chunks_data[critical_pos - 1],
+                                            &state->info_png.unknown_chunks_size[critical_pos - 1], chunk);
+        if(state->error) break;
+      }
+#endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
+    }
+
+    if(!state->decoder.ignore_crc && !unknown) /*check CRC if wanted, only on known chunk types*/ {
+      if(lodepng_chunk_check_crc(chunk)) CERROR_BREAK(state->error, 57); /*invalid CRC*/
+    }
+
+    if(!IEND) chunk = lodepng_chunk_next_const(chunk, in + insize);
+  }
+
+  if(state->info_png.color.colortype == LCT_PALETTE && !state->info_png.color.palette) {
+    state->error = 106; /* error: PNG file must have PLTE chunk if color type is palette */
+  }
+
+  if(!state->error) {
+    /*predict output size, to allocate exact size for output buffer to avoid more dynamic allocation.
+    If the decompressed size does not match the prediction, the image must be corrupt.*/
+    if(state->info_png.interlace_method == 0) {
+      size_t bpp = lodepng_get_bpp(&state->info_png.color);
+      expected_size = lodepng_get_raw_size_idat(*w, *h, bpp);
+    } else {
+      size_t bpp = lodepng_get_bpp(&state->info_png.color);
+      /*Adam-7 interlaced: expected size is the sum of the 7 sub-images sizes*/
+      expected_size = 0;
+      expected_size += lodepng_get_raw_size_idat((*w + 7) >> 3, (*h + 7) >> 3, bpp);
+      if(*w > 4) expected_size += lodepng_get_raw_size_idat((*w + 3) >> 3, (*h + 7) >> 3, bpp);
+      expected_size += lodepng_get_raw_size_idat((*w + 3) >> 2, (*h + 3) >> 3, bpp);
+      if(*w > 2) expected_size += lodepng_get_raw_size_idat((*w + 1) >> 2, (*h + 3) >> 2, bpp);
+      expected_size += lodepng_get_raw_size_idat((*w + 1) >> 1, (*h + 1) >> 2, bpp);
+      if(*w > 1) expected_size += lodepng_get_raw_size_idat((*w + 0) >> 1, (*h + 1) >> 1, bpp);
+      expected_size += lodepng_get_raw_size_idat((*w + 0), (*h + 0) >> 1, bpp);
+    }
+
+    state->error = zlib_decompress(&scanlines, &scanlines_size, expected_size, idat, idatsize, &state->decoder.zlibsettings);
+  }
+  if(!state->error && scanlines_size != expected_size) state->error = 91; /*decompressed size doesn't match prediction*/
+  lodepng_free(idat);
+
+  if(!state->error) {
+    outsize = lodepng_get_raw_size(*w, *h, &state->info_png.color);
+    *out = (unsigned char*)lodepng_malloc(outsize);
+    if(!*out) state->error = 83; /*alloc fail*/
+  }
+  if(!state->error) {
+    lodepng_memset(*out, 0, outsize);
+    state->error = postProcessScanlines(*out, scanlines, *w, *h, &state->info_png);
+  }
+  lodepng_free(scanlines);
+}
+
+unsigned lodepng_decode(unsigned char** out, unsigned* w, unsigned* h,
+                        LodePNGState* state,
+                        const unsigned char* in, size_t insize) {
+  *out = 0;
+  decodeGeneric(out, w, h, state, in, insize);
+  if(state->error) return state->error;
+  if(!state->decoder.color_convert || lodepng_color_mode_equal(&state->info_raw, &state->info_png.color)) {
+    /*same color type, no copying or converting of data needed*/
+    /*store the info_png color settings on the info_raw so that the info_raw still reflects what colortype
+    the raw image has to the end user*/
+    if(!state->decoder.color_convert) {
+      state->error = lodepng_color_mode_copy(&state->info_raw, &state->info_png.color);
+      if(state->error) return state->error;
+    }
+  } else { /*color conversion needed*/
+    unsigned char* data = *out;
+    size_t outsize;
+
+    /*TODO: check if this works according to the statement in the documentation: "The converter can convert
+    from grayscale input color type, to 8-bit grayscale or grayscale with alpha"*/
+    if(!(state->info_raw.colortype == LCT_RGB || state->info_raw.colortype == LCT_RGBA)
+       && !(state->info_raw.bitdepth == 8)) {
+      return 56; /*unsupported color mode conversion*/
+    }
+
+    outsize = lodepng_get_raw_size(*w, *h, &state->info_raw);
+    *out = (unsigned char*)lodepng_malloc(outsize);
+    if(!(*out)) {
+      state->error = 83; /*alloc fail*/
+    }
+    else state->error = lodepng_convert(*out, data, &state->info_raw,
+                                        &state->info_png.color, *w, *h);
+    lodepng_free(data);
+  }
+  return state->error;
+}
+
+unsigned lodepng_decode_memory(unsigned char** out, unsigned* w, unsigned* h, const unsigned char* in,
+                               size_t insize, LodePNGColorType colortype, unsigned bitdepth) {
+  unsigned error;
+  LodePNGState state;
+  lodepng_state_init(&state);
+  state.info_raw.colortype = colortype;
+  state.info_raw.bitdepth = bitdepth;
+  error = lodepng_decode(out, w, h, &state, in, insize);
+  lodepng_state_cleanup(&state);
+  return error;
+}
+
+unsigned lodepng_decode32(unsigned char** out, unsigned* w, unsigned* h, const unsigned char* in, size_t insize) {
+  return lodepng_decode_memory(out, w, h, in, insize, LCT_RGBA, 8);
+}
+
+unsigned lodepng_decode24(unsigned char** out, unsigned* w, unsigned* h, const unsigned char* in, size_t insize) {
+  return lodepng_decode_memory(out, w, h, in, insize, LCT_RGB, 8);
+}
+
+#ifdef LODEPNG_COMPILE_DISK
+unsigned lodepng_decode_file(unsigned char** out, unsigned* w, unsigned* h, const char* filename,
+                             LodePNGColorType colortype, unsigned bitdepth) {
+  unsigned char* buffer = 0;
+  size_t buffersize;
+  unsigned error;
+  /* safe output values in case error happens */
+  *out = 0;
+  *w = *h = 0;
+  error = lodepng_load_file(&buffer, &buffersize, filename);
+  if(!error) error = lodepng_decode_memory(out, w, h, buffer, buffersize, colortype, bitdepth);
+  lodepng_free(buffer);
+  return error;
+}
+
+unsigned lodepng_decode32_file(unsigned char** out, unsigned* w, unsigned* h, const char* filename) {
+  return lodepng_decode_file(out, w, h, filename, LCT_RGBA, 8);
+}
+
+unsigned lodepng_decode24_file(unsigned char** out, unsigned* w, unsigned* h, const char* filename) {
+  return lodepng_decode_file(out, w, h, filename, LCT_RGB, 8);
+}
+#endif /*LODEPNG_COMPILE_DISK*/
+
+void lodepng_decoder_settings_init(LodePNGDecoderSettings* settings) {
+  settings->color_convert = 1;
+#ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
+  settings->read_text_chunks = 1;
+  settings->remember_unknown_chunks = 0;
+#endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
+  settings->ignore_crc = 0;
+  settings->ignore_critical = 0;
+  settings->ignore_end = 0;
+  lodepng_decompress_settings_init(&settings->zlibsettings);
+}
+
+#endif /*LODEPNG_COMPILE_DECODER*/
+
+#if defined(LODEPNG_COMPILE_DECODER) || defined(LODEPNG_COMPILE_ENCODER)
+
+void lodepng_state_init(LodePNGState* state) {
+#ifdef LODEPNG_COMPILE_DECODER
+  lodepng_decoder_settings_init(&state->decoder);
+#endif /*LODEPNG_COMPILE_DECODER*/
+#ifdef LODEPNG_COMPILE_ENCODER
+  lodepng_encoder_settings_init(&state->encoder);
+#endif /*LODEPNG_COMPILE_ENCODER*/
+  lodepng_color_mode_init(&state->info_raw);
+  lodepng_info_init(&state->info_png);
+  state->error = 1;
+}
+
+void lodepng_state_cleanup(LodePNGState* state) {
+  lodepng_color_mode_cleanup(&state->info_raw);
+  lodepng_info_cleanup(&state->info_png);
+}
+
+void lodepng_state_copy(LodePNGState* dest, const LodePNGState* source) {
+  lodepng_state_cleanup(dest);
+  *dest = *source;
+  lodepng_color_mode_init(&dest->info_raw);
+  lodepng_info_init(&dest->info_png);
+  dest->error = lodepng_color_mode_copy(&dest->info_raw, &source->info_raw); if(dest->error) return;
+  dest->error = lodepng_info_copy(&dest->info_png, &source->info_png); if(dest->error) return;
+}
+
+#endif /* defined(LODEPNG_COMPILE_DECODER) || defined(LODEPNG_COMPILE_ENCODER) */
+
+#ifdef LODEPNG_COMPILE_ENCODER
+
+/* ////////////////////////////////////////////////////////////////////////// */
+/* / PNG Encoder                                                            / */
+/* ////////////////////////////////////////////////////////////////////////// */
+
+
+static unsigned writeSignature(ucvector* out) {
+  size_t pos = out->size;
+  const unsigned char signature[] = {137, 80, 78, 71, 13, 10, 26, 10};
+  /*8 bytes PNG signature, aka the magic bytes*/
+  if(!ucvector_resize(out, out->size + 8)) return 83; /*alloc fail*/
+  lodepng_memcpy(out->data + pos, signature, 8);
+  return 0;
+}
+
+static unsigned addChunk_IHDR(ucvector* out, unsigned w, unsigned h,
+                              LodePNGColorType colortype, unsigned bitdepth, unsigned interlace_method) {
+  unsigned char *chunk, *data;
+  CERROR_TRY_RETURN(lodepng_chunk_init(&chunk, out, 13, "IHDR"));
+  data = chunk + 8;
+
+  lodepng_set32bitInt(data + 0, w); /*width*/
+  lodepng_set32bitInt(data + 4, h); /*height*/
+  data[8] = (unsigned char)bitdepth; /*bit depth*/
+  data[9] = (unsigned char)colortype; /*color type*/
+  data[10] = 0; /*compression method*/
+  data[11] = 0; /*filter method*/
+  data[12] = interlace_method; /*interlace method*/
+
+  lodepng_chunk_generate_crc(chunk);
+  return 0;
+}
+
+/* only adds the chunk if needed (there is a key or palette with alpha) */
+static unsigned addChunk_PLTE(ucvector* out, const LodePNGColorMode* info) {
+  unsigned char* chunk;
+  size_t i, j = 8;
+
+  CERROR_TRY_RETURN(lodepng_chunk_init(&chunk, out, info->palettesize * 3, "PLTE"));
+
+  for(i = 0; i != info->palettesize; ++i) {
+    /*add all channels except alpha channel*/
+    chunk[j++] = info->palette[i * 4 + 0];
+    chunk[j++] = info->palette[i * 4 + 1];
+    chunk[j++] = info->palette[i * 4 + 2];
+  }
+
+  lodepng_chunk_generate_crc(chunk);
+  return 0;
+}
+
+static unsigned addChunk_tRNS(ucvector* out, const LodePNGColorMode* info) {
+  unsigned char* chunk = 0;
+
+  if(info->colortype == LCT_PALETTE) {
+    size_t i, amount = info->palettesize;
+    /*the tail of palette values that all have 255 as alpha, does not have to be encoded*/
+    for(i = info->palettesize; i != 0; --i) {
+      if(info->palette[4 * (i - 1) + 3] != 255) break;
+      --amount;
+    }
+    if(amount) {
+      CERROR_TRY_RETURN(lodepng_chunk_init(&chunk, out, amount, "tRNS"));
+      /*add the alpha channel values from the palette*/
+      for(i = 0; i != amount; ++i) chunk[8 + i] = info->palette[4 * i + 3];
+    }
+  } else if(info->colortype == LCT_GREY) {
+    if(info->key_defined) {
+      CERROR_TRY_RETURN(lodepng_chunk_init(&chunk, out, 2, "tRNS"));
+      chunk[8] = (unsigned char)(info->key_r >> 8);
+      chunk[9] = (unsigned char)(info->key_r & 255);
+    }
+  } else if(info->colortype == LCT_RGB) {
+    if(info->key_defined) {
+      CERROR_TRY_RETURN(lodepng_chunk_init(&chunk, out, 6, "tRNS"));
+      chunk[8] = (unsigned char)(info->key_r >> 8);
+      chunk[9] = (unsigned char)(info->key_r & 255);
+      chunk[10] = (unsigned char)(info->key_g >> 8);
+      chunk[11] = (unsigned char)(info->key_g & 255);
+      chunk[12] = (unsigned char)(info->key_b >> 8);
+      chunk[13] = (unsigned char)(info->key_b & 255);
+    }
+  }
+
+  if(chunk) lodepng_chunk_generate_crc(chunk);
+  return 0;
+}
+
+static unsigned addChunk_IDAT(ucvector* out, const unsigned char* data, size_t datasize,
+                              LodePNGCompressSettings* zlibsettings) {
+  unsigned error = 0;
+  unsigned char* zlib = 0;
+  size_t zlibsize = 0;
+
+  error = zlib_compress(&zlib, &zlibsize, data, datasize, zlibsettings);
+  if(!error) {
+    error = lodepng_chunk_createv(out, zlibsize, "IDAT", zlib);
+  }
+  lodepng_free(zlib);
+  return error;
+}
+
+static unsigned addChunk_IEND(ucvector* out) {
+  return lodepng_chunk_createv(out, 0, "IEND", 0);
+}
+
+#ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
+
+static unsigned addChunk_tEXt(ucvector* out, const char* keyword, const char* textstring) {
+  unsigned char* chunk = 0;
+  size_t keysize = lodepng_strlen(keyword), textsize = lodepng_strlen(textstring);
+  size_t size = keysize + 1 + textsize;
+  if(keysize < 1 || keysize > 79) return 89; /*error: invalid keyword size*/
+  CERROR_TRY_RETURN(lodepng_chunk_init(&chunk, out, size, "tEXt"));
+  lodepng_memcpy(chunk + 8, keyword, keysize);
+  chunk[8 + keysize] = 0; /*null termination char*/
+  lodepng_memcpy(chunk + 9 + keysize, textstring, textsize);
+  lodepng_chunk_generate_crc(chunk);
+  return 0;
+}
+
+static unsigned addChunk_zTXt(ucvector* out, const char* keyword, const char* textstring,
+                              LodePNGCompressSettings* zlibsettings) {
+  unsigned error = 0;
+  unsigned char* chunk = 0;
+  unsigned char* compressed = 0;
+  size_t compressedsize = 0;
+  size_t textsize = lodepng_strlen(textstring);
+  size_t keysize = lodepng_strlen(keyword);
+  if(keysize < 1 || keysize > 79) return 89; /*error: invalid keyword size*/
+
+  error = zlib_compress(&compressed, &compressedsize,
+                        (const unsigned char*)textstring, textsize, zlibsettings);
+  if(!error) {
+    size_t size = keysize + 2 + compressedsize;
+    error = lodepng_chunk_init(&chunk, out, size, "zTXt");
+  }
+  if(!error) {
+    lodepng_memcpy(chunk + 8, keyword, keysize);
+    chunk[8 + keysize] = 0; /*null termination char*/
+    chunk[9 + keysize] = 0; /*compression method: 0*/
+    lodepng_memcpy(chunk + 10 + keysize, compressed, compressedsize);
+    lodepng_chunk_generate_crc(chunk);
+  }
+
+  lodepng_free(compressed);
+  return error;
+}
+
+static unsigned addChunk_iTXt(ucvector* out, unsigned compress, const char* keyword, const char* langtag,
+                              const char* transkey, const char* textstring, LodePNGCompressSettings* zlibsettings) {
+  unsigned error = 0;
+  unsigned char* chunk = 0;
+  unsigned char* compressed = 0;
+  size_t compressedsize = 0;
+  size_t textsize = lodepng_strlen(textstring);
+  size_t keysize = lodepng_strlen(keyword), langsize = lodepng_strlen(langtag), transsize = lodepng_strlen(transkey);
+
+  if(keysize < 1 || keysize > 79) return 89; /*error: invalid keyword size*/
+
+  if(compress) {
+    error = zlib_compress(&compressed, &compressedsize,
+                          (const unsigned char*)textstring, textsize, zlibsettings);
+  }
+  if(!error) {
+    size_t size = keysize + 3 + langsize + 1 + transsize + 1 + (compress ? compressedsize : textsize);
+    error = lodepng_chunk_init(&chunk, out, size, "iTXt");
+  }
+  if(!error) {
+    size_t pos = 8;
+    lodepng_memcpy(chunk + pos, keyword, keysize);
+    pos += keysize;
+    chunk[pos++] = 0; /*null termination char*/
+    chunk[pos++] = (compress ? 1 : 0); /*compression flag*/
+    chunk[pos++] = 0; /*compression method: 0*/
+    lodepng_memcpy(chunk + pos, langtag, langsize);
+    pos += langsize;
+    chunk[pos++] = 0; /*null termination char*/
+    lodepng_memcpy(chunk + pos, transkey, transsize);
+    pos += transsize;
+    chunk[pos++] = 0; /*null termination char*/
+    if(compress) {
+      lodepng_memcpy(chunk + pos, compressed, compressedsize);
+    } else {
+      lodepng_memcpy(chunk + pos, textstring, textsize);
+    }
+    lodepng_chunk_generate_crc(chunk);
+  }
+
+  lodepng_free(compressed);
+  return error;
+}
+
+static unsigned addChunk_bKGD(ucvector* out, const LodePNGInfo* info) {
+  unsigned char* chunk = 0;
+  if(info->color.colortype == LCT_GREY || info->color.colortype == LCT_GREY_ALPHA) {
+    CERROR_TRY_RETURN(lodepng_chunk_init(&chunk, out, 2, "bKGD"));
+    chunk[8] = (unsigned char)(info->background_r >> 8);
+    chunk[9] = (unsigned char)(info->background_r & 255);
+  } else if(info->color.colortype == LCT_RGB || info->color.colortype == LCT_RGBA) {
+    CERROR_TRY_RETURN(lodepng_chunk_init(&chunk, out, 6, "bKGD"));
+    chunk[8] = (unsigned char)(info->background_r >> 8);
+    chunk[9] = (unsigned char)(info->background_r & 255);
+    chunk[10] = (unsigned char)(info->background_g >> 8);
+    chunk[11] = (unsigned char)(info->background_g & 255);
+    chunk[12] = (unsigned char)(info->background_b >> 8);
+    chunk[13] = (unsigned char)(info->background_b & 255);
+  } else if(info->color.colortype == LCT_PALETTE) {
+    CERROR_TRY_RETURN(lodepng_chunk_init(&chunk, out, 1, "bKGD"));
+    chunk[8] = (unsigned char)(info->background_r & 255); /*palette index*/
+  }
+  if(chunk) lodepng_chunk_generate_crc(chunk);
+  return 0;
+}
+
+static unsigned addChunk_tIME(ucvector* out, const LodePNGTime* time) {
+  unsigned char* chunk;
+  CERROR_TRY_RETURN(lodepng_chunk_init(&chunk, out, 7, "tIME"));
+  chunk[8] = (unsigned char)(time->year >> 8);
+  chunk[9] = (unsigned char)(time->year & 255);
+  chunk[10] = (unsigned char)time->month;
+  chunk[11] = (unsigned char)time->day;
+  chunk[12] = (unsigned char)time->hour;
+  chunk[13] = (unsigned char)time->minute;
+  chunk[14] = (unsigned char)time->second;
+  lodepng_chunk_generate_crc(chunk);
+  return 0;
+}
+
+static unsigned addChunk_pHYs(ucvector* out, const LodePNGInfo* info) {
+  unsigned char* chunk;
+  CERROR_TRY_RETURN(lodepng_chunk_init(&chunk, out, 9, "pHYs"));
+  lodepng_set32bitInt(chunk + 8, info->phys_x);
+  lodepng_set32bitInt(chunk + 12, info->phys_y);
+  chunk[16] = info->phys_unit;
+  lodepng_chunk_generate_crc(chunk);
+  return 0;
+}
+
+static unsigned addChunk_gAMA(ucvector* out, const LodePNGInfo* info) {
+  unsigned char* chunk;
+  CERROR_TRY_RETURN(lodepng_chunk_init(&chunk, out, 4, "gAMA"));
+  lodepng_set32bitInt(chunk + 8, info->gama_gamma);
+  lodepng_chunk_generate_crc(chunk);
+  return 0;
+}
+
+static unsigned addChunk_cHRM(ucvector* out, const LodePNGInfo* info) {
+  unsigned char* chunk;
+  CERROR_TRY_RETURN(lodepng_chunk_init(&chunk, out, 32, "cHRM"));
+  lodepng_set32bitInt(chunk + 8, info->chrm_white_x);
+  lodepng_set32bitInt(chunk + 12, info->chrm_white_y);
+  lodepng_set32bitInt(chunk + 16, info->chrm_red_x);
+  lodepng_set32bitInt(chunk + 20, info->chrm_red_y);
+  lodepng_set32bitInt(chunk + 24, info->chrm_green_x);
+  lodepng_set32bitInt(chunk + 28, info->chrm_green_y);
+  lodepng_set32bitInt(chunk + 32, info->chrm_blue_x);
+  lodepng_set32bitInt(chunk + 36, info->chrm_blue_y);
+  lodepng_chunk_generate_crc(chunk);
+  return 0;
+}
+
+static unsigned addChunk_sRGB(ucvector* out, const LodePNGInfo* info) {
+  unsigned char data = info->srgb_intent;
+  return lodepng_chunk_createv(out, 1, "sRGB", &data);
+}
+
+static unsigned addChunk_iCCP(ucvector* out, const LodePNGInfo* info, LodePNGCompressSettings* zlibsettings) {
+  unsigned error = 0;
+  unsigned char* chunk = 0;
+  unsigned char* compressed = 0;
+  size_t compressedsize = 0;
+  size_t keysize = lodepng_strlen(info->iccp_name);
+
+  if(keysize < 1 || keysize > 79) return 89; /*error: invalid keyword size*/
+  error = zlib_compress(&compressed, &compressedsize,
+                        info->iccp_profile, info->iccp_profile_size, zlibsettings);
+  if(!error) {
+    size_t size = keysize + 2 + compressedsize;
+    error = lodepng_chunk_init(&chunk, out, size, "iCCP");
+  }
+  if(!error) {
+    lodepng_memcpy(chunk + 8, info->iccp_name, keysize);
+    chunk[8 + keysize] = 0; /*null termination char*/
+    chunk[9 + keysize] = 0; /*compression method: 0*/
+    lodepng_memcpy(chunk + 10 + keysize, compressed, compressedsize);
+    lodepng_chunk_generate_crc(chunk);
+  }
+
+  lodepng_free(compressed);
+  return error;
+}
+
+#endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
+
+static void filterScanline(unsigned char* out, const unsigned char* scanline, const unsigned char* prevline,
+                           size_t length, size_t bytewidth, unsigned char filterType) {
+  size_t i;
+  switch(filterType) {
+    case 0: /*None*/
+      for(i = 0; i != length; ++i) out[i] = scanline[i];
+      break;
+    case 1: /*Sub*/
+      for(i = 0; i != bytewidth; ++i) out[i] = scanline[i];
+      for(i = bytewidth; i < length; ++i) out[i] = scanline[i] - scanline[i - bytewidth];
+      break;
+    case 2: /*Up*/
+      if(prevline) {
+        for(i = 0; i != length; ++i) out[i] = scanline[i] - prevline[i];
+      } else {
+        for(i = 0; i != length; ++i) out[i] = scanline[i];
+      }
+      break;
+    case 3: /*Average*/
+      if(prevline) {
+        for(i = 0; i != bytewidth; ++i) out[i] = scanline[i] - (prevline[i] >> 1);
+        for(i = bytewidth; i < length; ++i) out[i] = scanline[i] - ((scanline[i - bytewidth] + prevline[i]) >> 1);
+      } else {
+        for(i = 0; i != bytewidth; ++i) out[i] = scanline[i];
+        for(i = bytewidth; i < length; ++i) out[i] = scanline[i] - (scanline[i - bytewidth] >> 1);
+      }
+      break;
+    case 4: /*Paeth*/
+      if(prevline) {
+        /*paethPredictor(0, prevline[i], 0) is always prevline[i]*/
+        for(i = 0; i != bytewidth; ++i) out[i] = (scanline[i] - prevline[i]);
+        for(i = bytewidth; i < length; ++i) {
+          out[i] = (scanline[i] - paethPredictor(scanline[i - bytewidth], prevline[i], prevline[i - bytewidth]));
+        }
+      } else {
+        for(i = 0; i != bytewidth; ++i) out[i] = scanline[i];
+        /*paethPredictor(scanline[i - bytewidth], 0, 0) is always scanline[i - bytewidth]*/
+        for(i = bytewidth; i < length; ++i) out[i] = (scanline[i] - scanline[i - bytewidth]);
+      }
+      break;
+    default: return; /*invalid filter type given*/
+  }
+}
+
+/* integer binary logarithm, max return value is 31 */
+static size_t ilog2(size_t i) {
+  size_t result = 0;
+  if(i >= 65536) { result += 16; i >>= 16; }
+  if(i >= 256) { result += 8; i >>= 8; }
+  if(i >= 16) { result += 4; i >>= 4; }
+  if(i >= 4) { result += 2; i >>= 2; }
+  if(i >= 2) { result += 1; /*i >>= 1;*/ }
+  return result;
+}
+
+/* integer approximation for i * log2(i), helper function for LFS_ENTROPY */
+static size_t ilog2i(size_t i) {
+  size_t l;
+  if(i == 0) return 0;
+  l = ilog2(i);
+  /* approximate i*log2(i): l is integer logarithm, ((i - (1u << l)) << 1u)
+  linearly approximates the missing fractional part multiplied by i */
+  return i * l + ((i - (1u << l)) << 1u);
+}
+
+static unsigned filter(unsigned char* out, const unsigned char* in, unsigned w, unsigned h,
+                       const LodePNGColorMode* color, const LodePNGEncoderSettings* settings) {
+  /*
+  For PNG filter method 0
+  out must be a buffer with as size: h + (w * h * bpp + 7u) / 8u, because there are
+  the scanlines with 1 extra byte per scanline
+  */
+
+  unsigned bpp = lodepng_get_bpp(color);
+  /*the width of a scanline in bytes, not including the filter type*/
+  size_t linebytes = lodepng_get_raw_size_idat(w, 1, bpp) - 1u;
+
+  /*bytewidth is used for filtering, is 1 when bpp < 8, number of bytes per pixel otherwise*/
+  size_t bytewidth = (bpp + 7u) / 8u;
+  const unsigned char* prevline = 0;
+  unsigned x, y;
+  unsigned error = 0;
+  LodePNGFilterStrategy strategy = settings->filter_strategy;
+
+  /*
+  There is a heuristic called the minimum sum of absolute differences heuristic, suggested by the PNG standard:
+   *  If the image type is Palette, or the bit depth is smaller than 8, then do not filter the image (i.e.
+      use fixed filtering, with the filter None).
+   * (The other case) If the image type is Grayscale or RGB (with or without Alpha), and the bit depth is
+     not smaller than 8, then use adaptive filtering heuristic as follows: independently for each row, apply
+     all five filters and select the filter that produces the smallest sum of absolute values per row.
+  This heuristic is used if filter strategy is LFS_MINSUM and filter_palette_zero is true.
+
+  If filter_palette_zero is true and filter_strategy is not LFS_MINSUM, the above heuristic is followed,
+  but for "the other case", whatever strategy filter_strategy is set to instead of the minimum sum
+  heuristic is used.
+  */
+  if(settings->filter_palette_zero &&
+     (color->colortype == LCT_PALETTE || color->bitdepth < 8)) strategy = LFS_ZERO;
+
+  if(bpp == 0) return 31; /*error: invalid color type*/
+
+  if(strategy >= LFS_ZERO && strategy <= LFS_FOUR) {
+    unsigned char type = (unsigned char)strategy;
+    for(y = 0; y != h; ++y) {
+      size_t outindex = (1 + linebytes) * y; /*the extra filterbyte added to each row*/
+      size_t inindex = linebytes * y;
+      out[outindex] = type; /*filter type byte*/
+      filterScanline(&out[outindex + 1], &in[inindex], prevline, linebytes, bytewidth, type);
+      prevline = &in[inindex];
+    }
+  } else if(strategy == LFS_MINSUM) {
+    /*adaptive filtering*/
+    unsigned char* attempt[5]; /*five filtering attempts, one for each filter type*/
+    size_t smallest = 0;
+    unsigned char type, bestType = 0;
+
+    for(type = 0; type != 5; ++type) {
+      attempt[type] = (unsigned char*)lodepng_malloc(linebytes);
+      if(!attempt[type]) error = 83; /*alloc fail*/
+    }
+
+    if(!error) {
+      for(y = 0; y != h; ++y) {
+        /*try the 5 filter types*/
+        for(type = 0; type != 5; ++type) {
+          size_t sum = 0;
+          filterScanline(attempt[type], &in[y * linebytes], prevline, linebytes, bytewidth, type);
+
+          /*calculate the sum of the result*/
+          if(type == 0) {
+            for(x = 0; x != linebytes; ++x) sum += (unsigned char)(attempt[type][x]);
+          } else {
+            for(x = 0; x != linebytes; ++x) {
+              /*For differences, each byte should be treated as signed, values above 127 are negative
+              (converted to signed char). Filtertype 0 isn't a difference though, so use unsigned there.
+              This means filtertype 0 is almost never chosen, but that is justified.*/
+              unsigned char s = attempt[type][x];
+              sum += s < 128 ? s : (255U - s);
+            }
+          }
+
+          /*check if this is smallest sum (or if type == 0 it's the first case so always store the values)*/
+          if(type == 0 || sum < smallest) {
+            bestType = type;
+            smallest = sum;
+          }
+        }
+
+        prevline = &in[y * linebytes];
+
+        /*now fill the out values*/
+        out[y * (linebytes + 1)] = bestType; /*the first byte of a scanline will be the filter type*/
+        for(x = 0; x != linebytes; ++x) out[y * (linebytes + 1) + 1 + x] = attempt[bestType][x];
+      }
+    }
+
+    for(type = 0; type != 5; ++type) lodepng_free(attempt[type]);
+  } else if(strategy == LFS_ENTROPY) {
+    unsigned char* attempt[5]; /*five filtering attempts, one for each filter type*/
+    size_t bestSum = 0;
+    unsigned type, bestType = 0;
+    unsigned count[256];
+
+    for(type = 0; type != 5; ++type) {
+      attempt[type] = (unsigned char*)lodepng_malloc(linebytes);
+      if(!attempt[type]) error = 83; /*alloc fail*/
+    }
+
+    if(!error) {
+      for(y = 0; y != h; ++y) {
+        /*try the 5 filter types*/
+        for(type = 0; type != 5; ++type) {
+          size_t sum = 0;
+          filterScanline(attempt[type], &in[y * linebytes], prevline, linebytes, bytewidth, type);
+          lodepng_memset(count, 0, 256 * sizeof(*count));
+          for(x = 0; x != linebytes; ++x) ++count[attempt[type][x]];
+          ++count[type]; /*the filter type itself is part of the scanline*/
+          for(x = 0; x != 256; ++x) {
+            sum += ilog2i(count[x]);
+          }
+          /*check if this is smallest sum (or if type == 0 it's the first case so always store the values)*/
+          if(type == 0 || sum > bestSum) {
+            bestType = type;
+            bestSum = sum;
+          }
+        }
+
+        prevline = &in[y * linebytes];
+
+        /*now fill the out values*/
+        out[y * (linebytes + 1)] = bestType; /*the first byte of a scanline will be the filter type*/
+        for(x = 0; x != linebytes; ++x) out[y * (linebytes + 1) + 1 + x] = attempt[bestType][x];
+      }
+    }
+
+    for(type = 0; type != 5; ++type) lodepng_free(attempt[type]);
+  } else if(strategy == LFS_PREDEFINED) {
+    for(y = 0; y != h; ++y) {
+      size_t outindex = (1 + linebytes) * y; /*the extra filterbyte added to each row*/
+      size_t inindex = linebytes * y;
+      unsigned char type = settings->predefined_filters[y];
+      out[outindex] = type; /*filter type byte*/
+      filterScanline(&out[outindex + 1], &in[inindex], prevline, linebytes, bytewidth, type);
+      prevline = &in[inindex];
+    }
+  } else if(strategy == LFS_BRUTE_FORCE) {
+    /*brute force filter chooser.
+    deflate the scanline after every filter attempt to see which one deflates best.
+    This is very slow and gives only slightly smaller, sometimes even larger, result*/
+    size_t size[5];
+    unsigned char* attempt[5]; /*five filtering attempts, one for each filter type*/
+    size_t smallest = 0;
+    unsigned type = 0, bestType = 0;
+    unsigned char* dummy;
+    LodePNGCompressSettings zlibsettings;
+    lodepng_memcpy(&zlibsettings, &settings->zlibsettings, sizeof(LodePNGCompressSettings));
+    /*use fixed tree on the attempts so that the tree is not adapted to the filtertype on purpose,
+    to simulate the true case where the tree is the same for the whole image. Sometimes it gives
+    better result with dynamic tree anyway. Using the fixed tree sometimes gives worse, but in rare
+    cases better compression. It does make this a bit less slow, so it's worth doing this.*/
+    zlibsettings.btype = 1;
+    /*a custom encoder likely doesn't read the btype setting and is optimized for complete PNG
+    images only, so disable it*/
+    zlibsettings.custom_zlib = 0;
+    zlibsettings.custom_deflate = 0;
+    for(type = 0; type != 5; ++type) {
+      attempt[type] = (unsigned char*)lodepng_malloc(linebytes);
+      if(!attempt[type]) error = 83; /*alloc fail*/
+    }
+    if(!error) {
+      for(y = 0; y != h; ++y) /*try the 5 filter types*/ {
+        for(type = 0; type != 5; ++type) {
+          unsigned testsize = (unsigned)linebytes;
+          /*if(testsize > 8) testsize /= 8;*/ /*it already works good enough by testing a part of the row*/
+
+          filterScanline(attempt[type], &in[y * linebytes], prevline, linebytes, bytewidth, type);
+          size[type] = 0;
+          dummy = 0;
+          zlib_compress(&dummy, &size[type], attempt[type], testsize, &zlibsettings);
+          lodepng_free(dummy);
+          /*check if this is smallest size (or if type == 0 it's the first case so always store the values)*/
+          if(type == 0 || size[type] < smallest) {
+            bestType = type;
+            smallest = size[type];
+          }
+        }
+        prevline = &in[y * linebytes];
+        out[y * (linebytes + 1)] = bestType; /*the first byte of a scanline will be the filter type*/
+        for(x = 0; x != linebytes; ++x) out[y * (linebytes + 1) + 1 + x] = attempt[bestType][x];
+      }
+    }
+    for(type = 0; type != 5; ++type) lodepng_free(attempt[type]);
+  }
+  else return 88; /* unknown filter strategy */
+
+  return error;
+}
+
+static void addPaddingBits(unsigned char* out, const unsigned char* in,
+                           size_t olinebits, size_t ilinebits, unsigned h) {
+  /*The opposite of the removePaddingBits function
+  olinebits must be >= ilinebits*/
+  unsigned y;
+  size_t diff = olinebits - ilinebits;
+  size_t obp = 0, ibp = 0; /*bit pointers*/
+  for(y = 0; y != h; ++y) {
+    size_t x;
+    for(x = 0; x < ilinebits; ++x) {
+      unsigned char bit = readBitFromReversedStream(&ibp, in);
+      setBitOfReversedStream(&obp, out, bit);
+    }
+    /*obp += diff; --> no, fill in some value in the padding bits too, to avoid
+    "Use of uninitialised value of size ###" warning from valgrind*/
+    for(x = 0; x != diff; ++x) setBitOfReversedStream(&obp, out, 0);
+  }
+}
+
+/*
+in: non-interlaced image with size w*h
+out: the same pixels, but re-ordered according to PNG's Adam7 interlacing, with
+ no padding bits between scanlines, but between reduced images so that each
+ reduced image starts at a byte.
+bpp: bits per pixel
+there are no padding bits, not between scanlines, not between reduced images
+in has the following size in bits: w * h * bpp.
+out is possibly bigger due to padding bits between reduced images
+NOTE: comments about padding bits are only relevant if bpp < 8
+*/
+static void Adam7_interlace(unsigned char* out, const unsigned char* in, unsigned w, unsigned h, unsigned bpp) {
+  unsigned passw[7], passh[7];
+  size_t filter_passstart[8], padded_passstart[8], passstart[8];
+  unsigned i;
+
+  Adam7_getpassvalues(passw, passh, filter_passstart, padded_passstart, passstart, w, h, bpp);
+
+  if(bpp >= 8) {
+    for(i = 0; i != 7; ++i) {
+      unsigned x, y, b;
+      size_t bytewidth = bpp / 8u;
+      for(y = 0; y < passh[i]; ++y)
+      for(x = 0; x < passw[i]; ++x) {
+        size_t pixelinstart = ((ADAM7_IY[i] + y * ADAM7_DY[i]) * w + ADAM7_IX[i] + x * ADAM7_DX[i]) * bytewidth;
+        size_t pixeloutstart = passstart[i] + (y * passw[i] + x) * bytewidth;
+        for(b = 0; b < bytewidth; ++b) {
+          out[pixeloutstart + b] = in[pixelinstart + b];
+        }
+      }
+    }
+  } else /*bpp < 8: Adam7 with pixels < 8 bit is a bit trickier: with bit pointers*/ {
+    for(i = 0; i != 7; ++i) {
+      unsigned x, y, b;
+      unsigned ilinebits = bpp * passw[i];
+      unsigned olinebits = bpp * w;
+      size_t obp, ibp; /*bit pointers (for out and in buffer)*/
+      for(y = 0; y < passh[i]; ++y)
+      for(x = 0; x < passw[i]; ++x) {
+        ibp = (ADAM7_IY[i] + y * ADAM7_DY[i]) * olinebits + (ADAM7_IX[i] + x * ADAM7_DX[i]) * bpp;
+        obp = (8 * passstart[i]) + (y * ilinebits + x * bpp);
+        for(b = 0; b < bpp; ++b) {
+          unsigned char bit = readBitFromReversedStream(&ibp, in);
+          setBitOfReversedStream(&obp, out, bit);
+        }
+      }
+    }
+  }
+}
+
+/*out must be buffer big enough to contain uncompressed IDAT chunk data, and in must contain the full image.
+return value is error**/
+static unsigned preProcessScanlines(unsigned char** out, size_t* outsize, const unsigned char* in,
+                                    unsigned w, unsigned h,
+                                    const LodePNGInfo* info_png, const LodePNGEncoderSettings* settings) {
+  /*
+  This function converts the pure 2D image with the PNG's colortype, into filtered-padded-interlaced data. Steps:
+  *) if no Adam7: 1) add padding bits (= possible extra bits per scanline if bpp < 8) 2) filter
+  *) if adam7: 1) Adam7_interlace 2) 7x add padding bits 3) 7x filter
+  */
+  unsigned bpp = lodepng_get_bpp(&info_png->color);
+  unsigned error = 0;
+
+  if(info_png->interlace_method == 0) {
+    *outsize = h + (h * ((w * bpp + 7u) / 8u)); /*image size plus an extra byte per scanline + possible padding bits*/
+    *out = (unsigned char*)lodepng_malloc(*outsize);
+    if(!(*out) && (*outsize)) error = 83; /*alloc fail*/
+
+    if(!error) {
+      /*non multiple of 8 bits per scanline, padding bits needed per scanline*/
+      if(bpp < 8 && w * bpp != ((w * bpp + 7u) / 8u) * 8u) {
+        unsigned char* padded = (unsigned char*)lodepng_malloc(h * ((w * bpp + 7u) / 8u));
+        if(!padded) error = 83; /*alloc fail*/
+        if(!error) {
+          addPaddingBits(padded, in, ((w * bpp + 7u) / 8u) * 8u, w * bpp, h);
+          error = filter(*out, padded, w, h, &info_png->color, settings);
+        }
+        lodepng_free(padded);
+      } else {
+        /*we can immediately filter into the out buffer, no other steps needed*/
+        error = filter(*out, in, w, h, &info_png->color, settings);
+      }
+    }
+  } else /*interlace_method is 1 (Adam7)*/ {
+    unsigned passw[7], passh[7];
+    size_t filter_passstart[8], padded_passstart[8], passstart[8];
+    unsigned char* adam7;
+
+    Adam7_getpassvalues(passw, passh, filter_passstart, padded_passstart, passstart, w, h, bpp);
+
+    *outsize = filter_passstart[7]; /*image size plus an extra byte per scanline + possible padding bits*/
+    *out = (unsigned char*)lodepng_malloc(*outsize);
+    if(!(*out)) error = 83; /*alloc fail*/
+
+    adam7 = (unsigned char*)lodepng_malloc(passstart[7]);
+    if(!adam7 && passstart[7]) error = 83; /*alloc fail*/
+
+    if(!error) {
+      unsigned i;
+
+      Adam7_interlace(adam7, in, w, h, bpp);
+      for(i = 0; i != 7; ++i) {
+        if(bpp < 8) {
+          unsigned char* padded = (unsigned char*)lodepng_malloc(padded_passstart[i + 1] - padded_passstart[i]);
+          if(!padded) ERROR_BREAK(83); /*alloc fail*/
+          addPaddingBits(padded, &adam7[passstart[i]],
+                         ((passw[i] * bpp + 7u) / 8u) * 8u, passw[i] * bpp, passh[i]);
+          error = filter(&(*out)[filter_passstart[i]], padded,
+                         passw[i], passh[i], &info_png->color, settings);
+          lodepng_free(padded);
+        } else {
+          error = filter(&(*out)[filter_passstart[i]], &adam7[padded_passstart[i]],
+                         passw[i], passh[i], &info_png->color, settings);
+        }
+
+        if(error) break;
+      }
+    }
+
+    lodepng_free(adam7);
+  }
+
+  return error;
+}
+
+#ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
+static unsigned addUnknownChunks(ucvector* out, unsigned char* data, size_t datasize) {
+  unsigned char* inchunk = data;
+  while((size_t)(inchunk - data) < datasize) {
+    CERROR_TRY_RETURN(lodepng_chunk_append(&out->data, &out->size, inchunk));
+    out->allocsize = out->size; /*fix the allocsize again*/
+    inchunk = lodepng_chunk_next(inchunk, data + datasize);
+  }
+  return 0;
+}
+
+static unsigned isGrayICCProfile(const unsigned char* profile, unsigned size) {
+  /*
+  It is a gray profile if bytes 16-19 are "GRAY", rgb profile if bytes 16-19
+  are "RGB ". We do not perform any full parsing of the ICC profile here, other
+  than check those 4 bytes to grayscale profile. Other than that, validity of
+  the profile is not checked. This is needed only because the PNG specification
+  requires using a non-gray color model if there is an ICC profile with "RGB "
+  (sadly limiting compression opportunities if the input data is grayscale RGB
+  data), and requires using a gray color model if it is "GRAY".
+  */
+  if(size < 20) return 0;
+  return profile[16] == 'G' &&  profile[17] == 'R' &&  profile[18] == 'A' &&  profile[19] == 'Y';
+}
+
+static unsigned isRGBICCProfile(const unsigned char* profile, unsigned size) {
+  /* See comment in isGrayICCProfile*/
+  if(size < 20) return 0;
+  return profile[16] == 'R' &&  profile[17] == 'G' &&  profile[18] == 'B' &&  profile[19] == ' ';
+}
+#endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
+
+unsigned lodepng_encode(unsigned char** out, size_t* outsize,
+                        const unsigned char* image, unsigned w, unsigned h,
+                        LodePNGState* state) {
+  unsigned char* data = 0; /*uncompressed version of the IDAT chunk data*/
+  size_t datasize = 0;
+  ucvector outv = ucvector_init(NULL, 0);
+  LodePNGInfo info;
+  const LodePNGInfo* info_png = &state->info_png;
+
+  lodepng_info_init(&info);
+
+  /*provide some proper output values if error will happen*/
+  *out = 0;
+  *outsize = 0;
+  state->error = 0;
+
+  /*check input values validity*/
+  if((info_png->color.colortype == LCT_PALETTE || state->encoder.force_palette)
+      && (info_png->color.palettesize == 0 || info_png->color.palettesize > 256)) {
+    state->error = 68; /*invalid palette size, it is only allowed to be 1-256*/
+    goto cleanup;
+  }
+  if(state->encoder.zlibsettings.btype > 2) {
+    state->error = 61; /*error: invalid btype*/
+    goto cleanup;
+  }
+  if(info_png->interlace_method > 1) {
+    state->error = 71; /*error: invalid interlace mode*/
+    goto cleanup;
+  }
+  state->error = checkColorValidity(info_png->color.colortype, info_png->color.bitdepth);
+  if(state->error) goto cleanup; /*error: invalid color type given*/
+  state->error = checkColorValidity(state->info_raw.colortype, state->info_raw.bitdepth);
+  if(state->error) goto cleanup; /*error: invalid color type given*/
+
+  /* color convert and compute scanline filter types */
+  lodepng_info_copy(&info, &state->info_png);
+  if(state->encoder.auto_convert) {
+    LodePNGColorStats stats;
+    lodepng_color_stats_init(&stats);
+#ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
+    if(info_png->iccp_defined &&
+        isGrayICCProfile(info_png->iccp_profile, info_png->iccp_profile_size)) {
+      /*the PNG specification does not allow to use palette with a GRAY ICC profile, even
+      if the palette has only gray colors, so disallow it.*/
+      stats.allow_palette = 0;
+    }
+    if(info_png->iccp_defined &&
+        isRGBICCProfile(info_png->iccp_profile, info_png->iccp_profile_size)) {
+      /*the PNG specification does not allow to use grayscale color with RGB ICC profile, so disallow gray.*/
+      stats.allow_greyscale = 0;
+    }
+#endif /* LODEPNG_COMPILE_ANCILLARY_CHUNKS */
+    state->error = lodepng_compute_color_stats(&stats, image, w, h, &state->info_raw);
+    if(state->error) goto cleanup;
+#ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
+    if(info_png->background_defined) {
+      /*the background chunk's color must be taken into account as well*/
+      unsigned r = 0, g = 0, b = 0;
+      LodePNGColorMode mode16 = lodepng_color_mode_make(LCT_RGB, 16);
+      lodepng_convert_rgb(&r, &g, &b, info_png->background_r, info_png->background_g, info_png->background_b, &mode16, &info_png->color);
+      state->error = lodepng_color_stats_add(&stats, r, g, b, 65535);
+      if(state->error) goto cleanup;
+    }
+#endif /* LODEPNG_COMPILE_ANCILLARY_CHUNKS */
+    state->error = auto_choose_color(&info.color, &state->info_raw, &stats);
+    if(state->error) goto cleanup;
+#ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
+    /*also convert the background chunk*/
+    if(info_png->background_defined) {
+      if(lodepng_convert_rgb(&info.background_r, &info.background_g, &info.background_b,
+          info_png->background_r, info_png->background_g, info_png->background_b, &info.color, &info_png->color)) {
+        state->error = 104;
+        goto cleanup;
+      }
+    }
+#endif /* LODEPNG_COMPILE_ANCILLARY_CHUNKS */
+  }
+#ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
+  if(info_png->iccp_defined) {
+    unsigned gray_icc = isGrayICCProfile(info_png->iccp_profile, info_png->iccp_profile_size);
+    unsigned rgb_icc = isRGBICCProfile(info_png->iccp_profile, info_png->iccp_profile_size);
+    unsigned gray_png = info.color.colortype == LCT_GREY || info.color.colortype == LCT_GREY_ALPHA;
+    if(!gray_icc && !rgb_icc) {
+      state->error = 100; /* Disallowed profile color type for PNG */
+      goto cleanup;
+    }
+    if(gray_icc != gray_png) {
+      /*Not allowed to use RGB/RGBA/palette with GRAY ICC profile or vice versa,
+      or in case of auto_convert, it wasn't possible to find appropriate model*/
+      state->error = state->encoder.auto_convert ? 102 : 101;
+      goto cleanup;
+    }
+  }
+#endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
+  if(!lodepng_color_mode_equal(&state->info_raw, &info.color)) {
+    unsigned char* converted;
+    size_t size = ((size_t)w * (size_t)h * (size_t)lodepng_get_bpp(&info.color) + 7u) / 8u;
+
+    converted = (unsigned char*)lodepng_malloc(size);
+    if(!converted && size) state->error = 83; /*alloc fail*/
+    if(!state->error) {
+      state->error = lodepng_convert(converted, image, &info.color, &state->info_raw, w, h);
+    }
+    if(!state->error) {
+      state->error = preProcessScanlines(&data, &datasize, converted, w, h, &info, &state->encoder);
+    }
+    lodepng_free(converted);
+    if(state->error) goto cleanup;
+  } else {
+    state->error = preProcessScanlines(&data, &datasize, image, w, h, &info, &state->encoder);
+    if(state->error) goto cleanup;
+  }
+
+  /* output all PNG chunks */ {
+#ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
+    size_t i;
+#endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
+    /*write signature and chunks*/
+    state->error = writeSignature(&outv);
+    if(state->error) goto cleanup;
+    /*IHDR*/
+    state->error = addChunk_IHDR(&outv, w, h, info.color.colortype, info.color.bitdepth, info.interlace_method);
+    if(state->error) goto cleanup;
+#ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
+    /*unknown chunks between IHDR and PLTE*/
+    if(info.unknown_chunks_data[0]) {
+      state->error = addUnknownChunks(&outv, info.unknown_chunks_data[0], info.unknown_chunks_size[0]);
+      if(state->error) goto cleanup;
+    }
+    /*color profile chunks must come before PLTE */
+    if(info.iccp_defined) {
+      state->error = addChunk_iCCP(&outv, &info, &state->encoder.zlibsettings);
+      if(state->error) goto cleanup;
+    }
+    if(info.srgb_defined) {
+      state->error = addChunk_sRGB(&outv, &info);
+      if(state->error) goto cleanup;
+    }
+    if(info.gama_defined) {
+      state->error = addChunk_gAMA(&outv, &info);
+      if(state->error) goto cleanup;
+    }
+    if(info.chrm_defined) {
+      state->error = addChunk_cHRM(&outv, &info);
+      if(state->error) goto cleanup;
+    }
+#endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
+    /*PLTE*/
+    if(info.color.colortype == LCT_PALETTE) {
+      state->error = addChunk_PLTE(&outv, &info.color);
+      if(state->error) goto cleanup;
+    }
+    if(state->encoder.force_palette && (info.color.colortype == LCT_RGB || info.color.colortype == LCT_RGBA)) {
+      /*force_palette means: write suggested palette for truecolor in PLTE chunk*/
+      state->error = addChunk_PLTE(&outv, &info.color);
+      if(state->error) goto cleanup;
+    }
+    /*tRNS (this will only add if when necessary) */
+    state->error = addChunk_tRNS(&outv, &info.color);
+    if(state->error) goto cleanup;
+#ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
+    /*bKGD (must come between PLTE and the IDAt chunks*/
+    if(info.background_defined) {
+      state->error = addChunk_bKGD(&outv, &info);
+      if(state->error) goto cleanup;
+    }
+    /*pHYs (must come before the IDAT chunks)*/
+    if(info.phys_defined) {
+      state->error = addChunk_pHYs(&outv, &info);
+      if(state->error) goto cleanup;
+    }
+
+    /*unknown chunks between PLTE and IDAT*/
+    if(info.unknown_chunks_data[1]) {
+      state->error = addUnknownChunks(&outv, info.unknown_chunks_data[1], info.unknown_chunks_size[1]);
+      if(state->error) goto cleanup;
+    }
+#endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
+    /*IDAT (multiple IDAT chunks must be consecutive)*/
+    state->error = addChunk_IDAT(&outv, data, datasize, &state->encoder.zlibsettings);
+    if(state->error) goto cleanup;
+#ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
+    /*tIME*/
+    if(info.time_defined) {
+      state->error = addChunk_tIME(&outv, &info.time);
+      if(state->error) goto cleanup;
+    }
+    /*tEXt and/or zTXt*/
+    for(i = 0; i != info.text_num; ++i) {
+      if(lodepng_strlen(info.text_keys[i]) > 79) {
+        state->error = 66; /*text chunk too large*/
+        goto cleanup;
+      }
+      if(lodepng_strlen(info.text_keys[i]) < 1) {
+        state->error = 67; /*text chunk too small*/
+        goto cleanup;
+      }
+      if(state->encoder.text_compression) {
+        state->error = addChunk_zTXt(&outv, info.text_keys[i], info.text_strings[i], &state->encoder.zlibsettings);
+        if(state->error) goto cleanup;
+      } else {
+        state->error = addChunk_tEXt(&outv, info.text_keys[i], info.text_strings[i]);
+        if(state->error) goto cleanup;
+      }
+    }
+    /*LodePNG version id in text chunk*/
+    if(state->encoder.add_id) {
+      unsigned already_added_id_text = 0;
+      for(i = 0; i != info.text_num; ++i) {
+        const char* k = info.text_keys[i];
+        /* Could use strcmp, but we're not calling or reimplementing this C library function for this use only */
+        if(k[0] == 'L' && k[1] == 'o' && k[2] == 'd' && k[3] == 'e' &&
+           k[4] == 'P' && k[5] == 'N' && k[6] == 'G' && k[7] == '\0') {
+          already_added_id_text = 1;
+          break;
+        }
+      }
+      if(already_added_id_text == 0) {
+        state->error = addChunk_tEXt(&outv, "LodePNG", LODEPNG_VERSION_STRING); /*it's shorter as tEXt than as zTXt chunk*/
+        if(state->error) goto cleanup;
+      }
+    }
+    /*iTXt*/
+    for(i = 0; i != info.itext_num; ++i) {
+      if(lodepng_strlen(info.itext_keys[i]) > 79) {
+        state->error = 66; /*text chunk too large*/
+        goto cleanup;
+      }
+      if(lodepng_strlen(info.itext_keys[i]) < 1) {
+        state->error = 67; /*text chunk too small*/
+        goto cleanup;
+      }
+      state->error = addChunk_iTXt(
+          &outv, state->encoder.text_compression,
+          info.itext_keys[i], info.itext_langtags[i], info.itext_transkeys[i], info.itext_strings[i],
+          &state->encoder.zlibsettings);
+      if(state->error) goto cleanup;
+    }
+
+    /*unknown chunks between IDAT and IEND*/
+    if(info.unknown_chunks_data[2]) {
+      state->error = addUnknownChunks(&outv, info.unknown_chunks_data[2], info.unknown_chunks_size[2]);
+      if(state->error) goto cleanup;
+    }
+#endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
+    state->error = addChunk_IEND(&outv);
+    if(state->error) goto cleanup;
+  }
+
+cleanup:
+  lodepng_info_cleanup(&info);
+  lodepng_free(data);
+
+  /*instead of cleaning the vector up, give it to the output*/
+  *out = outv.data;
+  *outsize = outv.size;
+
+  return state->error;
+}
+
+unsigned lodepng_encode_memory(unsigned char** out, size_t* outsize, const unsigned char* image,
+                               unsigned w, unsigned h, LodePNGColorType colortype, unsigned bitdepth) {
+  unsigned error;
+  LodePNGState state;
+  lodepng_state_init(&state);
+  state.info_raw.colortype = colortype;
+  state.info_raw.bitdepth = bitdepth;
+  state.info_png.color.colortype = colortype;
+  state.info_png.color.bitdepth = bitdepth;
+  lodepng_encode(out, outsize, image, w, h, &state);
+  error = state.error;
+  lodepng_state_cleanup(&state);
+  return error;
+}
+
+unsigned lodepng_encode32(unsigned char** out, size_t* outsize, const unsigned char* image, unsigned w, unsigned h) {
+  return lodepng_encode_memory(out, outsize, image, w, h, LCT_RGBA, 8);
+}
+
+unsigned lodepng_encode24(unsigned char** out, size_t* outsize, const unsigned char* image, unsigned w, unsigned h) {
+  return lodepng_encode_memory(out, outsize, image, w, h, LCT_RGB, 8);
+}
+
+#ifdef LODEPNG_COMPILE_DISK
+unsigned lodepng_encode_file(const char* filename, const unsigned char* image, unsigned w, unsigned h,
+                             LodePNGColorType colortype, unsigned bitdepth) {
+  unsigned char* buffer;
+  size_t buffersize;
+  unsigned error = lodepng_encode_memory(&buffer, &buffersize, image, w, h, colortype, bitdepth);
+  if(!error) error = lodepng_save_file(buffer, buffersize, filename);
+  lodepng_free(buffer);
+  return error;
+}
+
+unsigned lodepng_encode32_file(const char* filename, const unsigned char* image, unsigned w, unsigned h) {
+  return lodepng_encode_file(filename, image, w, h, LCT_RGBA, 8);
+}
+
+unsigned lodepng_encode24_file(const char* filename, const unsigned char* image, unsigned w, unsigned h) {
+  return lodepng_encode_file(filename, image, w, h, LCT_RGB, 8);
+}
+#endif /*LODEPNG_COMPILE_DISK*/
+
+void lodepng_encoder_settings_init(LodePNGEncoderSettings* settings) {
+  lodepng_compress_settings_init(&settings->zlibsettings);
+  settings->filter_palette_zero = 1;
+  settings->filter_strategy = LFS_MINSUM;
+  settings->auto_convert = 1;
+  settings->force_palette = 0;
+  settings->predefined_filters = 0;
+#ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
+  settings->add_id = 0;
+  settings->text_compression = 1;
+#endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
+}
+
+#endif /*LODEPNG_COMPILE_ENCODER*/
+#endif /*LODEPNG_COMPILE_PNG*/
+
+#ifdef LODEPNG_COMPILE_ERROR_TEXT
+/*
+This returns the description of a numerical error code in English. This is also
+the documentation of all the error codes.
+*/
+const char* lodepng_error_text(unsigned code) {
+  switch(code) {
+    case 0: return "no error, everything went ok";
+    case 1: return "nothing done yet"; /*the Encoder/Decoder has done nothing yet, error checking makes no sense yet*/
+    case 10: return "end of input memory reached without huffman end code"; /*while huffman decoding*/
+    case 11: return "error in code tree made it jump outside of huffman tree"; /*while huffman decoding*/
+    case 13: return "problem while processing dynamic deflate block";
+    case 14: return "problem while processing dynamic deflate block";
+    case 15: return "problem while processing dynamic deflate block";
+    /*this error could happen if there are only 0 or 1 symbols present in the huffman code:*/
+    case 16: return "invalid code while processing dynamic deflate block";
+    case 17: return "end of out buffer memory reached while inflating";
+    case 18: return "invalid distance code while inflating";
+    case 19: return "end of out buffer memory reached while inflating";
+    case 20: return "invalid deflate block BTYPE encountered while decoding";
+    case 21: return "NLEN is not ones complement of LEN in a deflate block";
+
+    /*end of out buffer memory reached while inflating:
+    This can happen if the inflated deflate data is longer than the amount of bytes required to fill up
+    all the pixels of the image, given the color depth and image dimensions. Something that doesn't
+    happen in a normal, well encoded, PNG image.*/
+    case 22: return "end of out buffer memory reached while inflating";
+    case 23: return "end of in buffer memory reached while inflating";
+    case 24: return "invalid FCHECK in zlib header";
+    case 25: return "invalid compression method in zlib header";
+    case 26: return "FDICT encountered in zlib header while it's not used for PNG";
+    case 27: return "PNG file is smaller than a PNG header";
+    /*Checks the magic file header, the first 8 bytes of the PNG file*/
+    case 28: return "incorrect PNG signature, it's no PNG or corrupted";
+    case 29: return "first chunk is not the header chunk";
+    case 30: return "chunk length too large, chunk broken off at end of file";
+    case 31: return "illegal PNG color type or bpp";
+    case 32: return "illegal PNG compression method";
+    case 33: return "illegal PNG filter method";
+    case 34: return "illegal PNG interlace method";
+    case 35: return "chunk length of a chunk is too large or the chunk too small";
+    case 36: return "illegal PNG filter type encountered";
+    case 37: return "illegal bit depth for this color type given";
+    case 38: return "the palette is too small or too big"; /*0, or more than 256 colors*/
+    case 39: return "tRNS chunk before PLTE or has more entries than palette size";
+    case 40: return "tRNS chunk has wrong size for grayscale image";
+    case 41: return "tRNS chunk has wrong size for RGB image";
+    case 42: return "tRNS chunk appeared while it was not allowed for this color type";
+    case 43: return "bKGD chunk has wrong size for palette image";
+    case 44: return "bKGD chunk has wrong size for grayscale image";
+    case 45: return "bKGD chunk has wrong size for RGB image";
+    case 48: return "empty input buffer given to decoder. Maybe caused by non-existing file?";
+    case 49: return "jumped past memory while generating dynamic huffman tree";
+    case 50: return "jumped past memory while generating dynamic huffman tree";
+    case 51: return "jumped past memory while inflating huffman block";
+    case 52: return "jumped past memory while inflating";
+    case 53: return "size of zlib data too small";
+    case 54: return "repeat symbol in tree while there was no value symbol yet";
+    /*jumped past tree while generating huffman tree, this could be when the
+    tree will have more leaves than symbols after generating it out of the
+    given lengths. They call this an oversubscribed dynamic bit lengths tree in zlib.*/
+    case 55: return "jumped past tree while generating huffman tree";
+    case 56: return "given output image colortype or bitdepth not supported for color conversion";
+    case 57: return "invalid CRC encountered (checking CRC can be disabled)";
+    case 58: return "invalid ADLER32 encountered (checking ADLER32 can be disabled)";
+    case 59: return "requested color conversion not supported";
+    case 60: return "invalid window size given in the settings of the encoder (must be 0-32768)";
+    case 61: return "invalid BTYPE given in the settings of the encoder (only 0, 1 and 2 are allowed)";
+    /*LodePNG leaves the choice of RGB to grayscale conversion formula to the user.*/
+    case 62: return "conversion from color to grayscale not supported";
+    /*(2^31-1)*/
+    case 63: return "length of a chunk too long, max allowed for PNG is 2147483647 bytes per chunk";
+    /*this would result in the inability of a deflated block to ever contain an end code. It must be at least 1.*/
+    case 64: return "the length of the END symbol 256 in the Huffman tree is 0";
+    case 66: return "the length of a text chunk keyword given to the encoder is longer than the maximum of 79 bytes";
+    case 67: return "the length of a text chunk keyword given to the encoder is smaller than the minimum of 1 byte";
+    case 68: return "tried to encode a PLTE chunk with a palette that has less than 1 or more than 256 colors";
+    case 69: return "unknown chunk type with 'critical' flag encountered by the decoder";
+    case 71: return "invalid interlace mode given to encoder (must be 0 or 1)";
+    case 72: return "while decoding, invalid compression method encountering in zTXt or iTXt chunk (it must be 0)";
+    case 73: return "invalid tIME chunk size";
+    case 74: return "invalid pHYs chunk size";
+    /*length could be wrong, or data chopped off*/
+    case 75: return "no null termination char found while decoding text chunk";
+    case 76: return "iTXt chunk too short to contain required bytes";
+    case 77: return "integer overflow in buffer size";
+    case 78: return "failed to open file for reading"; /*file doesn't exist or couldn't be opened for reading*/
+    case 79: return "failed to open file for writing";
+    case 80: return "tried creating a tree of 0 symbols";
+    case 81: return "lazy matching at pos 0 is impossible";
+    case 82: return "color conversion to palette requested while a color isn't in palette, or index out of bounds";
+    case 83: return "memory allocation failed";
+    case 84: return "given image too small to contain all pixels to be encoded";
+    case 86: return "impossible offset in lz77 encoding (internal bug)";
+    case 87: return "must provide custom zlib function pointer if LODEPNG_COMPILE_ZLIB is not defined";
+    case 88: return "invalid filter strategy given for LodePNGEncoderSettings.filter_strategy";
+    case 89: return "text chunk keyword too short or long: must have size 1-79";
+    /*the windowsize in the LodePNGCompressSettings. Requiring POT(==> & instead of %) makes encoding 12% faster.*/
+    case 90: return "windowsize must be a power of two";
+    case 91: return "invalid decompressed idat size";
+    case 92: return "integer overflow due to too many pixels";
+    case 93: return "zero width or height is invalid";
+    case 94: return "header chunk must have a size of 13 bytes";
+    case 95: return "integer overflow with combined idat chunk size";
+    case 96: return "invalid gAMA chunk size";
+    case 97: return "invalid cHRM chunk size";
+    case 98: return "invalid sRGB chunk size";
+    case 99: return "invalid sRGB rendering intent";
+    case 100: return "invalid ICC profile color type, the PNG specification only allows RGB or GRAY";
+    case 101: return "PNG specification does not allow RGB ICC profile on gray color types and vice versa";
+    case 102: return "not allowed to set grayscale ICC profile with colored pixels by PNG specification";
+    case 103: return "invalid palette index in bKGD chunk. Maybe it came before PLTE chunk?";
+    case 104: return "invalid bKGD color while encoding (e.g. palette index out of range)";
+    case 105: return "integer overflow of bitsize";
+    case 106: return "PNG file must have PLTE chunk if color type is palette";
+    case 107: return "color convert from palette mode requested without setting the palette data in it";
+    case 108: return "tried to add more than 256 values to a palette";
+  }
+  return "unknown error code";
+}
+#endif /*LODEPNG_COMPILE_ERROR_TEXT*/
+
+/* ////////////////////////////////////////////////////////////////////////// */
+/* ////////////////////////////////////////////////////////////////////////// */
+/* // C++ Wrapper                                                          // */
+/* ////////////////////////////////////////////////////////////////////////// */
+/* ////////////////////////////////////////////////////////////////////////// */
+
+#ifdef LODEPNG_COMPILE_CPP
+namespace lodepng {
+
+#ifdef LODEPNG_COMPILE_DISK
+unsigned load_file(std::vector<unsigned char>& buffer, const std::string& filename) {
+  long size = lodepng_filesize(filename.c_str());
+  if(size < 0) return 78;
+  buffer.resize((size_t)size);
+  return size == 0 ? 0 : lodepng_buffer_file(&buffer[0], (size_t)size, filename.c_str());
+}
+
+/*write given buffer to the file, overwriting the file, it doesn't append to it.*/
+unsigned save_file(const std::vector<unsigned char>& buffer, const std::string& filename) {
+  return lodepng_save_file(buffer.empty() ? 0 : &buffer[0], buffer.size(), filename.c_str());
+}
+#endif /* LODEPNG_COMPILE_DISK */
+
+#ifdef LODEPNG_COMPILE_ZLIB
+#ifdef LODEPNG_COMPILE_DECODER
+unsigned decompress(std::vector<unsigned char>& out, const unsigned char* in, size_t insize,
+                    const LodePNGDecompressSettings& settings) {
+  unsigned char* buffer = 0;
+  size_t buffersize = 0;
+  unsigned error = zlib_decompress(&buffer, &buffersize, 0, in, insize, &settings);
+  if(buffer) {
+    out.insert(out.end(), &buffer[0], &buffer[buffersize]);
+    lodepng_free(buffer);
+  }
+  return error;
+}
+
+unsigned decompress(std::vector<unsigned char>& out, const std::vector<unsigned char>& in,
+                    const LodePNGDecompressSettings& settings) {
+  return decompress(out, in.empty() ? 0 : &in[0], in.size(), settings);
+}
+#endif /* LODEPNG_COMPILE_DECODER */
+
+#ifdef LODEPNG_COMPILE_ENCODER
+unsigned compress(std::vector<unsigned char>& out, const unsigned char* in, size_t insize,
+                  const LodePNGCompressSettings& settings) {
+  unsigned char* buffer = 0;
+  size_t buffersize = 0;
+  unsigned error = zlib_compress(&buffer, &buffersize, in, insize, &settings);
+  if(buffer) {
+    out.insert(out.end(), &buffer[0], &buffer[buffersize]);
+    lodepng_free(buffer);
+  }
+  return error;
+}
+
+unsigned compress(std::vector<unsigned char>& out, const std::vector<unsigned char>& in,
+                  const LodePNGCompressSettings& settings) {
+  return compress(out, in.empty() ? 0 : &in[0], in.size(), settings);
+}
+#endif /* LODEPNG_COMPILE_ENCODER */
+#endif /* LODEPNG_COMPILE_ZLIB */
+
+
+#ifdef LODEPNG_COMPILE_PNG
+
+State::State() {
+  lodepng_state_init(this);
+}
+
+State::State(const State& other) {
+  lodepng_state_init(this);
+  lodepng_state_copy(this, &other);
+}
+
+State::~State() {
+  lodepng_state_cleanup(this);
+}
+
+State& State::operator=(const State& other) {
+  lodepng_state_copy(this, &other);
+  return *this;
+}
+
+#ifdef LODEPNG_COMPILE_DECODER
+
+unsigned decode(std::vector<unsigned char>& out, unsigned& w, unsigned& h, const unsigned char* in,
+                size_t insize, LodePNGColorType colortype, unsigned bitdepth) {
+  unsigned char* buffer = 0;
+  unsigned error = lodepng_decode_memory(&buffer, &w, &h, in, insize, colortype, bitdepth);
+  if(buffer && !error) {
+    State state;
+    state.info_raw.colortype = colortype;
+    state.info_raw.bitdepth = bitdepth;
+    size_t buffersize = lodepng_get_raw_size(w, h, &state.info_raw);
+    out.insert(out.end(), &buffer[0], &buffer[buffersize]);
+  }
+  lodepng_free(buffer);
+  return error;
+}
+
+unsigned decode(std::vector<unsigned char>& out, unsigned& w, unsigned& h,
+                const std::vector<unsigned char>& in, LodePNGColorType colortype, unsigned bitdepth) {
+  return decode(out, w, h, in.empty() ? 0 : &in[0], (unsigned)in.size(), colortype, bitdepth);
+}
+
+unsigned decode(std::vector<unsigned char>& out, unsigned& w, unsigned& h,
+                State& state,
+                const unsigned char* in, size_t insize) {
+  unsigned char* buffer = NULL;
+  unsigned error = lodepng_decode(&buffer, &w, &h, &state, in, insize);
+  if(buffer && !error) {
+    size_t buffersize = lodepng_get_raw_size(w, h, &state.info_raw);
+    out.insert(out.end(), &buffer[0], &buffer[buffersize]);
+  }
+  lodepng_free(buffer);
+  return error;
+}
+
+unsigned decode(std::vector<unsigned char>& out, unsigned& w, unsigned& h,
+                State& state,
+                const std::vector<unsigned char>& in) {
+  return decode(out, w, h, state, in.empty() ? 0 : &in[0], in.size());
+}
+
+#ifdef LODEPNG_COMPILE_DISK
+unsigned decode(std::vector<unsigned char>& out, unsigned& w, unsigned& h, const std::string& filename,
+                LodePNGColorType colortype, unsigned bitdepth) {
+  std::vector<unsigned char> buffer;
+  /* safe output values in case error happens */
+  w = h = 0;
+  unsigned error = load_file(buffer, filename);
+  if(error) return error;
+  return decode(out, w, h, buffer, colortype, bitdepth);
+}
+#endif /* LODEPNG_COMPILE_DECODER */
+#endif /* LODEPNG_COMPILE_DISK */
+
+#ifdef LODEPNG_COMPILE_ENCODER
+unsigned encode(std::vector<unsigned char>& out, const unsigned char* in, unsigned w, unsigned h,
+                LodePNGColorType colortype, unsigned bitdepth) {
+  unsigned char* buffer;
+  size_t buffersize;
+  unsigned error = lodepng_encode_memory(&buffer, &buffersize, in, w, h, colortype, bitdepth);
+  if(buffer) {
+    out.insert(out.end(), &buffer[0], &buffer[buffersize]);
+    lodepng_free(buffer);
+  }
+  return error;
+}
+
+unsigned encode(std::vector<unsigned char>& out,
+                const std::vector<unsigned char>& in, unsigned w, unsigned h,
+                LodePNGColorType colortype, unsigned bitdepth) {
+  if(lodepng_get_raw_size_lct(w, h, colortype, bitdepth) > in.size()) return 84;
+  return encode(out, in.empty() ? 0 : &in[0], w, h, colortype, bitdepth);
+}
+
+unsigned encode(std::vector<unsigned char>& out,
+                const unsigned char* in, unsigned w, unsigned h,
+                State& state) {
+  unsigned char* buffer;
+  size_t buffersize;
+  unsigned error = lodepng_encode(&buffer, &buffersize, in, w, h, &state);
+  if(buffer) {
+    out.insert(out.end(), &buffer[0], &buffer[buffersize]);
+    lodepng_free(buffer);
+  }
+  return error;
+}
+
+unsigned encode(std::vector<unsigned char>& out,
+                const std::vector<unsigned char>& in, unsigned w, unsigned h,
+                State& state) {
+  if(lodepng_get_raw_size(w, h, &state.info_raw) > in.size()) return 84;
+  return encode(out, in.empty() ? 0 : &in[0], w, h, state);
+}
+
+#ifdef LODEPNG_COMPILE_DISK
+unsigned encode(const std::string& filename,
+                const unsigned char* in, unsigned w, unsigned h,
+                LodePNGColorType colortype, unsigned bitdepth) {
+  std::vector<unsigned char> buffer;
+  unsigned error = encode(buffer, in, w, h, colortype, bitdepth);
+  if(!error) error = save_file(buffer, filename);
+  return error;
+}
+
+unsigned encode(const std::string& filename,
+                const std::vector<unsigned char>& in, unsigned w, unsigned h,
+                LodePNGColorType colortype, unsigned bitdepth) {
+  if(lodepng_get_raw_size_lct(w, h, colortype, bitdepth) > in.size()) return 84;
+  return encode(filename, in.empty() ? 0 : &in[0], w, h, colortype, bitdepth);
+}
+#endif /* LODEPNG_COMPILE_DISK */
+#endif /* LODEPNG_COMPILE_ENCODER */
+#endif /* LODEPNG_COMPILE_PNG */
+} /* namespace lodepng */
+#endif /*LODEPNG_COMPILE_CPP*/