blob: cf964d0555c2c6c69f2453aac2b17ea4aa0ae3b9 [file] [log] [blame]
/*
LodePNG version 20190210
Copyright (c) 2005-2019 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.
*/
#ifdef _MSC_VER
#pragma warning (disable : 4201)
#ifndef BASISU_NO_ITERATOR_DEBUG_LEVEL
#if defined(_DEBUG) || defined(DEBUG)
#define _ITERATOR_DEBUG_LEVEL 1
#define _SECURE_SCL 1
#else
#define _SECURE_SCL 0
#define _ITERATOR_DEBUG_LEVEL 0
#endif
#endif
#endif
#include "lodepng.h"
#include <limits.h> /* LONG_MAX */
#include <stdio.h> /* file handling */
#include <stdlib.h> /* allocations */
#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 = "20190210";
/*
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
*/
/*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);
}
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*/
void* lodepng_malloc(size_t size);
void* lodepng_realloc(void* ptr, size_t new_size);
void lodepng_free(void* ptr);
#endif /*LODEPNG_COMPILE_ALLOCATORS*/
/* ////////////////////////////////////////////////////////////////////////// */
/* ////////////////////////////////////////////////////////////////////////// */
/* // Tools for C, and common code for PNG and Zlib. // */
/* ////////////////////////////////////////////////////////////////////////// */
/* ////////////////////////////////////////////////////////////////////////// */
#define LODEPNG_MAX(a, b) (((a) > (b)) ? (a) : (b))
#define LODEPNG_MIN(a, b) (((a) < (b)) ? (a) : (b))
/*
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_resizev(&frequencies_ll, 286, 0)) 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
/*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_reserve(uivector* p, size_t allocsize) {
if(allocsize > p->allocsize) {
size_t newsize = (allocsize > p->allocsize * 2) ? allocsize : (allocsize * 3 / 2);
void* data = lodepng_realloc(p->data, newsize);
if(data) {
p->allocsize = newsize;
p->data = (unsigned*)data;
}
else return 0; /*error: not enough memory*/
}
return 1;
}
/*returns 1 if success, 0 if failure ==> nothing done*/
static unsigned uivector_resize(uivector* p, size_t size) {
if(!uivector_reserve(p, size * sizeof(unsigned))) return 0;
p->size = size;
return 1; /*success*/
}
/*resize and give all new elements the value*/
static unsigned uivector_resizev(uivector* p, size_t size, unsigned value) {
size_t oldsize = p->size, i;
if(!uivector_resize(p, size)) return 0;
for(i = oldsize; i < size; ++i) p->data[i] = value;
return 1;
}
static void uivector_init(uivector* p) {
p->data = NULL;
p->size = p->allocsize = 0;
}
#ifdef LODEPNG_COMPILE_ENCODER
/*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_reserve(ucvector* p, size_t allocsize) {
if(allocsize > p->allocsize) {
size_t newsize = (allocsize > p->allocsize * 2) ? allocsize : (allocsize * 3 / 2);
void* data = lodepng_realloc(p->data, newsize);
if(data) {
p->allocsize = newsize;
p->data = (unsigned char*)data;
}
else return 0; /*error: not enough memory*/
}
return 1;
}
/*returns 1 if success, 0 if failure ==> nothing done*/
static unsigned ucvector_resize(ucvector* p, size_t size) {
if(!ucvector_reserve(p, size * sizeof(unsigned char))) return 0;
p->size = size;
return 1; /*success*/
}
#ifdef LODEPNG_COMPILE_PNG
static void ucvector_cleanup(void* p) {
((ucvector*)p)->size = ((ucvector*)p)->allocsize = 0;
lodepng_free(((ucvector*)p)->data);
((ucvector*)p)->data = NULL;
}
static void ucvector_init(ucvector* p) {
p->data = NULL;
p->size = p->allocsize = 0;
}
#endif /*LODEPNG_COMPILE_PNG*/
#ifdef LODEPNG_COMPILE_ZLIB
/*you can both convert from vector to buffer&size and vica versa. If you use
init_buffer to take over a buffer and size, it is not needed to use cleanup*/
static void ucvector_init_buffer(ucvector* p, unsigned char* buffer, size_t size) {
p->data = buffer;
p->allocsize = p->size = size;
}
#endif /*LODEPNG_COMPILE_ZLIB*/
#if (defined(LODEPNG_COMPILE_PNG) && defined(LODEPNG_COMPILE_ANCILLARY_CHUNKS)) || defined(LODEPNG_COMPILE_ENCODER)
/*returns 1 if success, 0 if failure ==> nothing done*/
static unsigned ucvector_push_back(ucvector* p, unsigned char c) {
if(!ucvector_resize(p, p->size + 1)) return 0;
p->data[p->size - 1] = c;
return 1;
}
#endif /*defined(LODEPNG_COMPILE_PNG) || defined(LODEPNG_COMPILE_ENCODER)*/
/* ////////////////////////////////////////////////////////////////////////// */
#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;
}
/* dynamically allocates a new string with a copy of the null terminated input text */
static char* alloc_string(const char* in) {
size_t insize = strlen(in);
char* out = (char*)lodepng_malloc(insize + 1);
if(out) {
size_t i;
for(i = 0; i != insize; ++i) {
out[i] = in[i];
}
out[i] = 0;
}
return out;
}
#endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
#endif /*LODEPNG_COMPILE_PNG*/
/* ////////////////////////////////////////////////////////////////////////// */
unsigned lodepng_read32bitInt(const unsigned char* buffer) {
return (unsigned)((buffer[0] << 24) | (buffer[1] << 16) | (buffer[2] << 8) | buffer[3]);
}
#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)*/
#ifdef LODEPNG_COMPILE_ENCODER
static void lodepng_add32bitInt(ucvector* buffer, unsigned value) {
ucvector_resize(buffer, buffer->size + 4); /*todo: give error if resize failed*/
lodepng_set32bitInt(&buffer->data[buffer->size - 4], value);
}
#endif /*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
/*TODO: this ignores potential out of memory errors*/
#define addBitToStream(/*size_t**/ bitpointer, /*ucvector**/ bitstream, /*unsigned char*/ bit){\
/*add a new byte at the end*/\
if(((*bitpointer) & 7) == 0) ucvector_push_back(bitstream, (unsigned char)0);\
/*earlier bit of huffman code is in a lesser significant bit of an earlier byte*/\
(bitstream->data[bitstream->size - 1]) |= (bit << ((*bitpointer) & 0x7));\
++(*bitpointer);\
}
static void addBitsToStream(size_t* bitpointer, ucvector* bitstream, unsigned value, size_t nbits) {
size_t i;
for(i = 0; i != nbits; ++i) addBitToStream(bitpointer, bitstream, (unsigned char)((value >> i) & 1));
}
static void addBitsToStreamReversed(size_t* bitpointer, ucvector* bitstream, unsigned value, size_t nbits) {
size_t i;
for(i = 0; i != nbits; ++i) addBitToStream(bitpointer, bitstream, (unsigned char)((value >> (nbits - 1 - i)) & 1));
}
#endif /*LODEPNG_COMPILE_ENCODER*/
#ifdef LODEPNG_COMPILE_DECODER
#define READBIT(bitpointer, bitstream) ((bitstream[bitpointer >> 3] >> (bitpointer & 0x7)) & (unsigned char)1)
static unsigned char readBitFromStream(size_t* bitpointer, const unsigned char* bitstream) {
unsigned char result = (unsigned char)(READBIT(*bitpointer, bitstream));
++(*bitpointer);
return result;
}
static unsigned readBitsFromStream(size_t* bitpointer, const unsigned char* bitstream, size_t nbits) {
unsigned result = 0, i;
for(i = 0; i != nbits; ++i) {
result += ((unsigned)READBIT(*bitpointer, bitstream)) << i;
++(*bitpointer);
}
return result;
}
#endif /*LODEPNG_COMPILE_DECODER*/
/* ////////////////////////////////////////////////////////////////////////// */
/* / 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, 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* tree2d;
unsigned* tree1d;
unsigned* lengths; /*the lengths of the codes of the 1d-tree*/
unsigned maxbitlen; /*maximum number of bits a single code can get*/
unsigned numcodes; /*number of symbols in the alphabet = number of codes*/
} HuffmanTree;
/*function used for debug purposes to draw the tree in ascii art with C++*/
/*
static void HuffmanTree_draw(HuffmanTree* tree) {
std::cout << "tree. length: " << tree->numcodes << " maxbitlen: " << tree->maxbitlen << std::endl;
for(size_t i = 0; i != tree->tree1d.size; ++i) {
if(tree->lengths.data[i])
std::cout << i << " " << tree->tree1d.data[i] << " " << tree->lengths.data[i] << std::endl;
}
std::cout << std::endl;
}*/
static void HuffmanTree_init(HuffmanTree* tree) {
tree->tree2d = 0;
tree->tree1d = 0;
tree->lengths = 0;
}
static void HuffmanTree_cleanup(HuffmanTree* tree) {
lodepng_free(tree->tree2d);
lodepng_free(tree->tree1d);
lodepng_free(tree->lengths);
}
/*the tree representation used by the decoder. return value is error*/
static unsigned HuffmanTree_make2DTree(HuffmanTree* tree) {
unsigned nodefilled = 0; /*up to which node it is filled*/
unsigned treepos = 0; /*position in the tree (1 of the numcodes columns)*/
unsigned n, i;
tree->tree2d = (unsigned*)lodepng_malloc(tree->numcodes * 2 * sizeof(unsigned));
if(!tree->tree2d) return 83; /*alloc fail*/
/*
convert tree1d[] to tree2d[][]. In the 2D array, a value of 32767 means
uninited, a value >= numcodes is an address to another bit, a value < numcodes
is a code. The 2 rows are the 2 possible bit values (0 or 1), there are as
many columns as codes - 1.
A good huffman tree has N * 2 - 1 nodes, of which N - 1 are internal nodes.
Here, the internal nodes are stored (what their 0 and 1 option point to).
There is only memory for such good tree currently, if there are more nodes
(due to too long length codes), error 55 will happen
*/
for(n = 0; n < tree->numcodes * 2; ++n) {
tree->tree2d[n] = 32767; /*32767 here means the tree2d isn't filled there yet*/
}
for(n = 0; n < tree->numcodes; ++n) /*the codes*/ {
for(i = 0; i != tree->lengths[n]; ++i) /*the bits for this code*/ {
unsigned char bit = (unsigned char)((tree->tree1d[n] >> (tree->lengths[n] - i - 1)) & 1);
/*oversubscribed, see comment in lodepng_error_text*/
if(treepos > 2147483647 || treepos + 2 > tree->numcodes) return 55;
if(tree->tree2d[2 * treepos + bit] == 32767) /*not yet filled in*/ {
if(i + 1 == tree->lengths[n]) /*last bit*/ {
tree->tree2d[2 * treepos + bit] = n; /*put the current code in it*/
treepos = 0;
} else {
/*put address of the next step in here, first that address has to be found of course
(it's just nodefilled + 1)...*/
++nodefilled;
/*addresses encoded with numcodes added to it*/
tree->tree2d[2 * treepos + bit] = nodefilled + tree->numcodes;
treepos = nodefilled;
}
}
else treepos = tree->tree2d[2 * treepos + bit] - tree->numcodes;
}
}
for(n = 0; n < tree->numcodes * 2; ++n) {
if(tree->tree2d[n] == 32767) tree->tree2d[n] = 0; /*remove possible remaining 32767's*/
}
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) {
uivector blcount;
uivector nextcode;
unsigned error = 0;
unsigned bits, n;
uivector_init(&blcount);
uivector_init(&nextcode);
tree->tree1d = (unsigned*)lodepng_malloc(tree->numcodes * sizeof(unsigned));
if(!tree->tree1d) error = 83; /*alloc fail*/
if(!uivector_resizev(&blcount, tree->maxbitlen + 1, 0)
|| !uivector_resizev(&nextcode, tree->maxbitlen + 1, 0))
error = 83; /*alloc fail*/
if(!error) {
/*step 1: count number of instances of each code length*/
for(bits = 0; bits != tree->numcodes; ++bits) ++blcount.data[tree->lengths[bits]];
/*step 2: generate the nextcode values*/
for(bits = 1; bits <= tree->maxbitlen; ++bits) {
nextcode.data[bits] = (nextcode.data[bits - 1] + blcount.data[bits - 1]) << 1;
}
/*step 3: generate all the codes*/
for(n = 0; n != tree->numcodes; ++n) {
if(tree->lengths[n] != 0) tree->tree1d[n] = nextcode.data[tree->lengths[n]]++;
}
}
uivector_cleanup(&blcount);
uivector_cleanup(&nextcode);
if(!error) return HuffmanTree_make2DTree(tree);
else 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) 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;
}
}
for(i = 0; i != numcodes; ++i) lengths[i] = 0;
/*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 theoritical 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->maxbitlen = maxbitlen;
tree->numcodes = (unsigned)numcodes; /*number of symbols*/
tree->lengths = (unsigned*)lodepng_realloc(tree->lengths, numcodes * sizeof(unsigned));
if(!tree->lengths) return 83; /*alloc fail*/
/*initialize all lengths to 0*/
memset(tree->lengths, 0, numcodes * sizeof(unsigned));
error = lodepng_huffman_code_lengths(tree->lengths, frequencies, numcodes, maxbitlen);
if(!error) error = HuffmanTree_makeFromLengths2(tree);
return error;
}
static unsigned HuffmanTree_getCode(const HuffmanTree* tree, unsigned index) {
return tree->tree1d[index];
}
static unsigned HuffmanTree_getLength(const HuffmanTree* tree, unsigned index) {
return tree->lengths[index];
}
#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, or (unsigned)(-1) if error happened
inbitlength is the length of the complete buffer, in bits (so its byte length times 8)
*/
static unsigned huffmanDecodeSymbol(const unsigned char* in, size_t* bp,
const HuffmanTree* codetree, size_t inbitlength) {
unsigned treepos = 0, ct;
for(;;) {
if(*bp >= inbitlength) return (unsigned)(-1); /*error: end of input memory reached without endcode*/
/*
decode the symbol from the tree. The "readBitFromStream" code is inlined in
the expression below because this is the biggest bottleneck while decoding
*/
ct = codetree->tree2d[(treepos << 1) + READBIT(*bp, in)];
++(*bp);
if(ct < codetree->numcodes) return ct; /*the symbol is decoded, return it*/
else treepos = ct - codetree->numcodes; /*symbol not yet decoded, instead move tree position*/
if(treepos >= codetree->numcodes) return (unsigned)(-1); /*error: it appeared outside the codetree*/
}
}
#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*/
static void getTreeInflateFixed(HuffmanTree* tree_ll, HuffmanTree* tree_d) {
/*TODO: check for out of memory errors*/
generateFixedLitLenTree(tree_ll);
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,
const unsigned char* in, size_t* bp, size_t inlength) {
/*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;
size_t inbitlength = inlength * 8;
/*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((*bp) + 14 > (inlength << 3)) 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 = readBitsFromStream(bp, in, 5) + 257;
/*number of distance codes. Unlike the spec, the value 1 is added to it here already*/
HDIST = readBitsFromStream(bp, in, 5) + 1;
/*number of code length codes. Unlike the spec, the value 4 is added to it here already*/
HCLEN = readBitsFromStream(bp, in, 4) + 4;
if((*bp) + HCLEN * 3 > (inlength << 3)) return 50; /*error: the bit pointer is or will go past the memory*/
HuffmanTree_init(&tree_cl);
while(!error) {
/*read the code length codes out of 3 * (amount of code length codes) bits*/
bitlen_cl = (unsigned*)lodepng_malloc(NUM_CODE_LENGTH_CODES * sizeof(unsigned));
if(!bitlen_cl) ERROR_BREAK(83 /*alloc fail*/);
for(i = 0; i != NUM_CODE_LENGTH_CODES; ++i) {
if(i < HCLEN) bitlen_cl[CLCL_ORDER[i]] = readBitsFromStream(bp, in, 3);
else bitlen_cl[CLCL_ORDER[i]] = 0; /*if not, it must stay 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*/);
for(i = 0; i != NUM_DEFLATE_CODE_SYMBOLS; ++i) bitlen_ll[i] = 0;
for(i = 0; i != NUM_DISTANCE_SYMBOLS; ++i) bitlen_d[i] = 0;
/*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 = huffmanDecodeSymbol(in, bp, &tree_cl, inbitlength);
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*/
if((*bp + 2) > inbitlength) ERROR_BREAK(50); /*error, bit pointer jumps past memory*/
replength += readBitsFromStream(bp, in, 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*/
if((*bp + 3) > inbitlength) ERROR_BREAK(50); /*error, bit pointer jumps past memory*/
replength += readBitsFromStream(bp, in, 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*/
if((*bp + 7) > inbitlength) ERROR_BREAK(50); /*error, bit pointer jumps past memory*/
replength += readBitsFromStream(bp, in, 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 == (unsigned)(-1))*/ /*huffmanDecodeSymbol returns (unsigned)(-1) in case of error*/ {
if(code == (unsigned)(-1)) {
/*return error code 10 or 11 depending on the situation that happened in huffmanDecodeSymbol
(10=no endcode, 11=wrong jump outside of tree)*/
error = (*bp) > inbitlength ? 10 : 11;
}
else error = 16; /*unexisting code, this can never happen*/
break;
}
}
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*/
static unsigned inflateHuffmanBlock(ucvector* out, const unsigned char* in, size_t* bp,
size_t* pos, size_t inlength, 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*/
size_t inbitlength = inlength * 8;
HuffmanTree_init(&tree_ll);
HuffmanTree_init(&tree_d);
if(btype == 1) getTreeInflateFixed(&tree_ll, &tree_d);
else if(btype == 2) error = getTreeInflateDynamic(&tree_ll, &tree_d, in, bp, inlength);
while(!error) /*decode all symbols until end reached, breaks at end code*/ {
/*code_ll is literal, length or end code*/
unsigned code_ll = huffmanDecodeSymbol(in, bp, &tree_ll, inbitlength);
if(code_ll <= 255) /*literal symbol*/ {
/*ucvector_push_back would do the same, but for some reason the two lines below run 10% faster*/
if(!ucvector_resize(out, (*pos) + 1)) ERROR_BREAK(83 /*alloc fail*/);
out->data[*pos] = (unsigned char)code_ll;
++(*pos);
} 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, forward, 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((*bp + numextrabits_l) > inbitlength) ERROR_BREAK(51); /*error, bit pointer will jump past memory*/
length += readBitsFromStream(bp, in, numextrabits_l);
/*part 3: get distance code*/
code_d = huffmanDecodeSymbol(in, bp, &tree_d, inbitlength);
if(code_d > 29) {
if(code_d == (unsigned)(-1)) /*huffmanDecodeSymbol returns (unsigned)(-1) in case of error*/ {
/*return error code 10 or 11 depending on the situation that happened in huffmanDecodeSymbol
(10=no endcode, 11=wrong jump outside of tree)*/
error = (*bp) > inlength * 8 ? 10 : 11;
}
else error = 18; /*error: invalid distance code (30-31 are never used)*/
break;
}
distance = DISTANCEBASE[code_d];
/*part 4: get extra bits from distance*/
numextrabits_d = DISTANCEEXTRA[code_d];
if((*bp + numextrabits_d) > inbitlength) ERROR_BREAK(51); /*error, bit pointer will jump past memory*/
distance += readBitsFromStream(bp, in, numextrabits_d);
/*part 5: fill in all the out[n] values based on the length and dist*/
start = (*pos);
if(distance > start) ERROR_BREAK(52); /*too long backward distance*/
backward = start - distance;
if(!ucvector_resize(out, (*pos) + length)) ERROR_BREAK(83 /*alloc fail*/);
if (distance < length) {
for(forward = 0; forward < length; ++forward) {
out->data[(*pos)++] = out->data[backward++];
}
} else {
memcpy(out->data + *pos, out->data + backward, length);
*pos += length;
}
} else if(code_ll == 256) {
break; /*end code, break the loop*/
} else /*if(code == (unsigned)(-1))*/ /*huffmanDecodeSymbol returns (unsigned)(-1) in case of error*/ {
/*return error code 10 or 11 depending on the situation that happened in huffmanDecodeSymbol
(10=no endcode, 11=wrong jump outside of tree)*/
error = ((*bp) > inlength * 8) ? 10 : 11;
break;
}
}
HuffmanTree_cleanup(&tree_ll);
HuffmanTree_cleanup(&tree_d);
return error;
}
static unsigned inflateNoCompression(ucvector* out, const unsigned char* in, size_t* bp, size_t* pos, size_t inlength) {
size_t p;
unsigned LEN, NLEN, n, error = 0;
/*go to first boundary of byte*/
while(((*bp) & 0x7) != 0) ++(*bp);
p = (*bp) / 8; /*byte position*/
/*read LEN (2 bytes) and NLEN (2 bytes)*/
if(p + 4 >= inlength) return 52; /*error, bit pointer will jump past memory*/
LEN = in[p] + 256u * in[p + 1]; p += 2;
NLEN = in[p] + 256u * in[p + 1]; p += 2;
/*check if 16-bit NLEN is really the one's complement of LEN*/
if(LEN + NLEN != 65535) return 21; /*error: NLEN is not one's complement of LEN*/
if(!ucvector_resize(out, (*pos) + LEN)) return 83; /*alloc fail*/
/*read the literal data: LEN bytes are now stored in the out buffer*/
if(p + LEN > inlength) return 23; /*error: reading outside of in buffer*/
for(n = 0; n < LEN; ++n) out->data[(*pos)++] = in[p++];
(*bp) = p * 8;
return error;
}
static unsigned lodepng_inflatev(ucvector* out,
const unsigned char* in, size_t insize,
const LodePNGDecompressSettings* settings) {
/*bit pointer in the "in" data, current byte is bp >> 3, current bit is bp & 0x7 (from lsb to msb of the byte)*/
size_t bp = 0;
unsigned BFINAL = 0;
size_t pos = 0; /*byte position in the out buffer*/
unsigned error = 0;
(void)settings;
while(!BFINAL) {
unsigned BTYPE;
if(bp + 2 >= insize * 8) return 52; /*error, bit pointer will jump past memory*/
BFINAL = readBitFromStream(&bp, in);
BTYPE = 1u * readBitFromStream(&bp, in);
BTYPE += 2u * readBitFromStream(&bp, in);
if(BTYPE == 3) return 20; /*error: invalid BTYPE*/
else if(BTYPE == 0) error = inflateNoCompression(out, in, &bp, &pos, insize); /*no compression*/
else error = inflateHuffmanBlock(out, in, &bp, &pos, insize, 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) {
unsigned error;
ucvector v;
ucvector_init_buffer(&v, *out, *outsize);
error = lodepng_inflatev(&v, in, insize, settings);
*out = v.data;
*outsize = v.size;
return error;
}
static unsigned inflate(unsigned char** out, size_t* outsize,
const unsigned char* in, size_t insize,
const LodePNGDecompressSettings* settings) {
if(settings->custom_inflate) {
return settings->custom_inflate(out, outsize, in, insize, settings);
} else {
return lodepng_inflate(out, outsize, in, insize, settings);
}
}
#endif /*LODEPNG_COMPILE_DECODER*/
#ifdef LODEPNG_COMPILE_ENCODER
/* ////////////////////////////////////////////////////////////////////////// */
/* / Deflator (Compressor) / */
/* ////////////////////////////////////////////////////////////////////////// */
static const size_t MAX_SUPPORTED_DEFLATE_LENGTH = 258;
/*bitlen is the size in bits of the code*/
static void addHuffmanSymbol(size_t* bp, ucvector* compressed, unsigned code, unsigned bitlen) {
addBitsToStreamReversed(bp, compressed, code, bitlen);
}
/*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]);
uivector_push_back(values, length_code + FIRST_LENGTH_CODE_INDEX);
uivector_push_back(values, extra_length);
uivector_push_back(values, dist_code);
uivector_push_back(values, 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 / 8;
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, j, numdeflateblocks = (datasize + 65534) / 65535;
unsigned datapos = 0;
for(i = 0; i != numdeflateblocks; ++i) {
unsigned BFINAL, BTYPE, LEN, NLEN;
unsigned char firstbyte;
BFINAL = (i == numdeflateblocks - 1);
BTYPE = 0;
firstbyte = (unsigned char)(BFINAL + ((BTYPE & 1) << 1) + ((BTYPE & 2) << 1));
ucvector_push_back(out, firstbyte);
LEN = 65535;
if(datasize - datapos < 65535) LEN = (unsigned)datasize - datapos;
NLEN = 65535 - LEN;
ucvector_push_back(out, (unsigned char)(LEN & 255));
ucvector_push_back(out, (unsigned char)(LEN >> 8));
ucvector_push_back(out, (unsigned char)(NLEN & 255));
ucvector_push_back(out, (unsigned char)(NLEN >> 8));
/*Decompressed data*/
for(j = 0; j < 65535 && datapos < datasize; ++j) {
ucvector_push_back(out, data[datapos++]);
}
}
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(size_t* bp, ucvector* out, 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];
addHuffmanSymbol(bp, out, HuffmanTree_getCode(tree_ll, val), HuffmanTree_getLength(tree_ll, 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];
addBitsToStream(bp, out, length_extra_bits, n_length_extra_bits);
addHuffmanSymbol(bp, out, HuffmanTree_getCode(tree_d, distance_code),
HuffmanTree_getLength(tree_d, distance_code));
addBitsToStream(bp, out, 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(ucvector* out, size_t* bp, 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 lenghts 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*/
uivector frequencies_ll; /*frequency of lit,len codes*/
uivector frequencies_d; /*frequency of dist codes*/
uivector frequencies_cl; /*frequency of code length codes*/
uivector bitlen_lld; /*lit,len,dist code lenghts (int bits), literally (without repeat codes).*/
uivector bitlen_lld_e; /*bitlen_lld encoded with repeat codes (this is a rudemtary run length compression)*/
/*bitlen_cl is the code length code lengths ("clcl"). The bit lengths of codes to represent tree_cl
(these are written as is in the file, it would be crazy to compress these using yet another huffman
tree that needs to be represented by yet another set of code lengths)*/
uivector bitlen_cl;
size_t datasize = dataend - datapos;
/*
Due to the huffman compression of huffman tree representations ("two levels"), there are some anologies:
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 numcodes_ll, numcodes_d, i;
unsigned HLIT, HDIST, HCLEN;
uivector_init(&lz77_encoded);
HuffmanTree_init(&tree_ll);
HuffmanTree_init(&tree_d);
HuffmanTree_init(&tree_cl);
uivector_init(&frequencies_ll);
uivector_init(&frequencies_d);
uivector_init(&frequencies_cl);
uivector_init(&bitlen_lld);
uivector_init(&bitlen_lld_e);
uivector_init(&bitlen_cl);
/*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) {
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*/
}
if(!uivector_resizev(&frequencies_ll, 286, 0)) ERROR_BREAK(83 /*alloc fail*/);
if(!uivector_resizev(&frequencies_d, 30, 0)) ERROR_BREAK(83 /*alloc fail*/);
/*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.data[symbol];
if(symbol > 256) {
unsigned dist = lz77_encoded.data[i + 2];
++frequencies_d.data[dist];
i += 3;
}
}
frequencies_ll.data[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.data, 257, frequencies_ll.size, 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.data, 2, frequencies_d.size, 15);
if(error) break;
numcodes_ll = tree_ll.numcodes; if(numcodes_ll > 286) numcodes_ll = 286;
numcodes_d = tree_d.numcodes; if(numcodes_d > 30) numcodes_d = 30;
/*store the code lengths of both generated trees in bitlen_lld*/
for(i = 0; i != numcodes_ll; ++i) uivector_push_back(&bitlen_lld, HuffmanTree_getLength(&tree_ll, (unsigned)i));
for(i = 0; i != numcodes_d; ++i) uivector_push_back(&bitlen_lld, HuffmanTree_getLength(&tree_d, (unsigned)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 != (unsigned)bitlen_lld.size; ++i) {
unsigned j = 0; /*amount of repititions*/
while(i + j + 1 < (unsigned)bitlen_lld.size && bitlen_lld.data[i + j + 1] == bitlen_lld.data[i]) ++j;
if(bitlen_lld.data[i] == 0 && j >= 2) /*repeat code for zeroes*/ {
++j; /*include the first zero*/
if(j <= 10) /*repeat code 17 supports max 10 zeroes*/ {
uivector_push_back(&bitlen_lld_e, 17);
uivector_push_back(&bitlen_lld_e, j - 3);
} else /*repeat code 18 supports max 138 zeroes*/ {
if(j > 138) j = 138;
uivector_push_back(&bitlen_lld_e, 18);
uivector_push_back(&bitlen_lld_e, j - 11);
}
i += (j - 1);
} else if(j >= 3) /*repeat code for value other than zero*/ {
size_t k;
unsigned num = j / 6, rest = j % 6;
uivector_push_back(&bitlen_lld_e, bitlen_lld.data[i]);
for(k = 0; k < num; ++k) {
uivector_push_back(&bitlen_lld_e, 16);
uivector_push_back(&bitlen_lld_e, 6 - 3);
}
if(rest >= 3) {
uivector_push_back(&bitlen_lld_e, 16);
uivector_push_back(&bitlen_lld_e, rest - 3);
}
else j -= rest;
i += j;
} else /*too short to benefit from repeat code*/ {
uivector_push_back(&bitlen_lld_e, bitlen_lld.data[i]);
}
}
/*generate tree_cl, the huffmantree of huffmantrees*/
if(!uivector_resizev(&frequencies_cl, NUM_CODE_LENGTH_CODES, 0)) ERROR_BREAK(83 /*alloc fail*/);
for(i = 0; i != bitlen_lld_e.size; ++i) {
++frequencies_cl.data[bitlen_lld_e.data[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.data[i] >= 16) ++i;
}
error = HuffmanTree_makeFromFrequencies(&tree_cl, frequencies_cl.data,
frequencies_cl.size, frequencies_cl.size, 7);
if(error) break;
if(!uivector_resize(&bitlen_cl, tree_cl.numcodes)) ERROR_BREAK(83 /*alloc fail*/);
for(i = 0; i != tree_cl.numcodes; ++i) {
/*lenghts of code length tree is in the order as specified by deflate*/
bitlen_cl.data[i] = HuffmanTree_getLength(&tree_cl, CLCL_ORDER[i]);
}
while(bitlen_cl.data[bitlen_cl.size - 1] == 0 && bitlen_cl.size > 4) {
/*remove zeros at the end, but minimum size must be 4*/
if(!uivector_resize(&bitlen_cl, bitlen_cl.size - 1)) ERROR_BREAK(83 /*alloc fail*/);
}
if(error) break;
/*
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 lenghts 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*/
addBitToStream(bp, out, BFINAL);
addBitToStream(bp, out, 0); /*first bit of BTYPE "dynamic"*/
addBitToStream(bp, out, 1); /*second bit of BTYPE "dynamic"*/
/*write the HLIT, HDIST and HCLEN values*/
HLIT = (unsigned)(numcodes_ll - 257);
HDIST = (unsigned)(numcodes_d - 1);
HCLEN = (unsigned)bitlen_cl.size - 4;
/*trim zeroes for HCLEN. HLIT and HDIST were already trimmed at tree creation*/
while(!bitlen_cl.data[HCLEN + 4 - 1] && HCLEN > 0) --HCLEN;
addBitsToStream(bp, out, HLIT, 5);
addBitsToStream(bp, out, HDIST, 5);
addBitsToStream(bp, out, HCLEN, 4);
/*write the code lenghts of the code length alphabet*/
for(i = 0; i != HCLEN + 4; ++i) addBitsToStream(bp, out, bitlen_cl.data[i], 3);
/*write the lenghts of the lit/len AND the dist alphabet*/
for(i = 0; i != bitlen_lld_e.size; ++i) {
addHuffmanSymbol(bp, out, HuffmanTree_getCode(&tree_cl, bitlen_lld_e.data[i]),
HuffmanTree_getLength(&tree_cl, bitlen_lld_e.data[i]));
/*extra bits of repeat codes*/
if(bitlen_lld_e.data[i] == 16) addBitsToStream(bp, out, bitlen_lld_e.data[++i], 2);
else if(bitlen_lld_e.data[i] == 17) addBitsToStream(bp, out, bitlen_lld_e.data[++i], 3);
else if(bitlen_lld_e.data[i] == 18) addBitsToStream(bp, out, bitlen_lld_e.data[++i], 7);
}
/*write the compressed data symbols*/
writeLZ77data(bp, out, &lz77_encoded, &tree_ll, &tree_d);
/*error: the length of the end code 256 must be larger than 0*/
if(HuffmanTree_getLength(&tree_ll, 256) == 0) ERROR_BREAK(64);
/*write the end code*/
addHuffmanSymbol(bp, out, HuffmanTree_getCode(&tree_ll, 256), HuffmanTree_getLength(&tree_ll, 256));
break; /*end of error-while*/
}
/*cleanup*/
uivector_cleanup(&lz77_encoded);
HuffmanTree_cleanup(&tree_ll);
HuffmanTree_cleanup(&tree_d);
HuffmanTree_cleanup(&tree_cl);
uivector_cleanup(&frequencies_ll);
uivector_cleanup(&frequencies_d);
uivector_cleanup(&frequencies_cl);
uivector_cleanup(&bitlen_lld_e);
uivector_cleanup(&bitlen_lld);
uivector_cleanup(&bitlen_cl);
return error;
}
static unsigned deflateFixed(ucvector* out, size_t* bp, 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);
generateFixedLitLenTree(&tree_ll);
generateFixedDistanceTree(&tree_d);
addBitToStream(bp, out, BFINAL);
addBitToStream(bp, out, 1); /*first bit of BTYPE*/
addBitToStream(bp, out, 0); /*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(bp, out, &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) {
addHuffmanSymbol(bp, out, HuffmanTree_getCode(&tree_ll, data[i]), HuffmanTree_getLength(&tree_ll, data[i]));
}
}
/*add END code*/
if(!error) addHuffmanSymbol(bp, out, HuffmanTree_getCode(&tree_ll, 256), HuffmanTree_getLength(&tree_ll, 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;
size_t bp = 0; /*the bit pointer*/
Hash hash;
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 / 8 + 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) return 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(out, &bp, &hash, in, start, end, settings, final);
else if(settings->btype == 2) error = deflateDynamic(out, &bp, &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) {
unsigned error;
ucvector v;
ucvector_init_buffer(&v, *out, *outsize);
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 & 0xffff;
unsigned s2 = (adler >> 16) & 0xffff;
while(len > 0) {
/*at least 5552 sums can be done before the sums overflow, saving a lot of module divisions*/
unsigned amount = len > 5552 ? 5552 : len;
len -= amount;
while(amount > 0) {
s1 += (*data++);
s2 += s1;
--amount;
}
s1 %= 65521;
s2 %= 65521;
}
return (s2 << 16) | s1;
}
/*Return the adler32 of the bytes data[0..len-1]*/
static unsigned adler32(const unsigned char* data, unsigned len) {
return update_adler32(1L, data, len);
}
/* ////////////////////////////////////////////////////////////////////////// */
/* / Zlib / */
/* ////////////////////////////////////////////////////////////////////////// */
#ifdef LODEPNG_COMPILE_DECODER
unsigned lodepng_zlib_decompress(unsigned char** out, size_t* outsize, 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 = inflate(out, outsize, in + 2, insize - 2, settings);
if(error) return error;
if(!settings->ignore_adler32) {
unsigned ADLER32 = lodepng_read32bitInt(&in[insize - 4]);
unsigned checksum = adler32(*out, (unsigned)(*outsize));
if(checksum != ADLER32) return 58; /*error, adler checksum not correct, data must be corrupted*/
}
return 0; /*no error*/
}
static unsigned zlib_decompress(unsigned char** out, size_t* outsize, const unsigned char* in,
size_t insize, const LodePNGDecompressSettings* settings) {
if(settings->custom_zlib) {
return settings->custom_zlib(out, outsize, in, insize, settings);
} else {
return lodepng_zlib_decompress(out, outsize, in, insize, settings);
}
}
#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) {
/*initially, *out must be NULL and outsize 0, if you just give some random *out
that's pointing to a non allocated buffer, this'll crash*/
ucvector outv;
size_t i;
unsigned error;
unsigned char* deflatedata = 0;
size_t deflatesize = 0;
/*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;
/*ucvector-controlled version of the output buffer, for dynamic array*/
ucvector_init_buffer(&outv, *out, *outsize);
ucvector_push_back(&outv, (unsigned char)(CMFFLG >> 8));
ucvector_push_back(&outv, (unsigned char)(CMFFLG & 255));
error = deflate(&deflatedata, &deflatesize, in, insize, settings);
if(!error) {
unsigned ADLER32 = adler32(in, (unsigned)insize);
for(i = 0; i != deflatesize; ++i) ucvector_push_back(&outv, deflatedata[i]);
lodepng_free(deflatedata);
lodepng_add32bitInt(&outv, ADLER32);
}
*out = outv.data;
*outsize = outv.size;
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, const unsigned char* in,
size_t insize, const LodePNGDecompressSettings* settings) {
if(!settings->custom_zlib) return 87; /*no custom zlib function provided */
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->custom_zlib = 0;
settings->custom_inflate = 0;
settings->custom_context = 0;
}
const LodePNGDecompressSettings lodepng_default_decompress_settings = {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]) & 0xff] ^ (r >> 8);
}
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 single bits and bytes from/to stream for LodePNG / */
/* ////////////////////////////////////////////////////////////////////////// */
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;
}
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 <<= 1;
result |= (unsigned)readBitFromReversedStream(bitpointer, bitstream);
}
return result;
}
#ifdef LODEPNG_COMPILE_DECODER
static void setBitOfReversedStream0(size_t* bitpointer, unsigned char* bitstream, unsigned char bit) {
/*the current bit in bitstream must be 0 for this to work*/
if(bit) {
/*earlier bit of huffman code is in a lesser significant bit of an earlier byte*/
bitstream[(*bitpointer) >> 3] |= (bit << (7 - ((*bitpointer) & 0x7)));
}
++(*bitpointer);
}
#endif /*LODEPNG_COMPILE_DECODER*/
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) >> 3] &= (unsigned char)(~(1 << (7 - ((*bitpointer) & 0x7))));
else bitstream[(*bitpointer) >> 3] |= (1 << (7 - ((*bitpointer) & 0x7)));
++(*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(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) {
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 {
unsigned total_chunk_length = lodepng_chunk_length(chunk) + 12;
return chunk + total_chunk_length;
}
}
const unsigned char* lodepng_chunk_next_const(const unsigned char* 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 {
unsigned total_chunk_length = lodepng_chunk_length(chunk) + 12;
return chunk + total_chunk_length;
}
}
unsigned char* lodepng_chunk_find(unsigned char* chunk, const unsigned char* end, const char type[5]) {
for(;;) {
if(chunk + 12 >= end) return 0;
if(lodepng_chunk_type_equals(chunk, type)) return chunk;
chunk = lodepng_chunk_next(chunk);
}
}
const unsigned char* lodepng_chunk_find_const(const unsigned char* chunk, const unsigned char* end, const char type[5]) {
for(;;) {
if(chunk + 12 >= end) return 0;
if(lodepng_chunk_type_equals(chunk, type)) return chunk;
chunk = lodepng_chunk_next_const(chunk);
}
}
unsigned lodepng_chunk_append(unsigned char** out, size_t* outlength, const unsigned char* chunk) {
unsigned i;
unsigned total_chunk_length = lodepng_chunk_length(chunk) + 12;
unsigned char *chunk_start, *new_buffer;
size_t new_length = (*outlength) + total_chunk_length;
if(new_length < total_chunk_length || new_length < (*outlength)) return 77; /*integer overflow happened*/
new_buffer = (unsigned char*)lodepng_realloc(*out, new_length);
if(!new_buffer) return 83; /*alloc fail*/
(*out) = new_buffer;
(*outlength) = 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;
}
unsigned lodepng_chunk_create(unsigned char** out, size_t* outlength, unsigned length,
const char* type, const unsigned char* data) {
unsigned i;
unsigned char *chunk, *new_buffer;
size_t new_length = (*outlength) + length + 12;
if(new_length < length + 12 || new_length < (*outlength)) return 77; /*integer overflow happened*/
new_buffer = (unsigned char*)lodepng_realloc(*out, new_length);