Commit 8599c8390194ce9e3e7c296521d75a923f314be2 - plotter

pntlsm v0 Haldean Brown 2 years ago

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	1	pntlsm

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lib/lodepng.cpp less more

	0	/*
	1	LodePNG version 20191020
	2
	3	Copyright (c) 2005-2019 Lode Vandevenne
	4
	5	This software is provided 'as-is', without any express or implied
	6	warranty. In no event will the authors be held liable for any damages
	7	arising from the use of this software.
	8
	9	Permission is granted to anyone to use this software for any purpose,
	10	including commercial applications, and to alter it and redistribute it
	11	freely, subject to the following restrictions:
	12
	13	1. The origin of this software must not be misrepresented; you must not
	14	claim that you wrote the original software. If you use this software
	15	in a product, an acknowledgment in the product documentation would be
	16	appreciated but is not required.
	17
	18	2. Altered source versions must be plainly marked as such, and must not be
	19	misrepresented as being the original software.
	20
	21	3. This notice may not be removed or altered from any source
	22	distribution.
	23	*/
	24
	25	/*
	26	The manual and changelog are in the header file "lodepng.h"
	27	Rename this file to lodepng.cpp to use it for C++, or to lodepng.c to use it for C.
	28	*/
	29
	30	#include "lodepng.h"
	31
	32	#ifdef LODEPNG_COMPILE_DISK
	33	#include <limits.h> /* LONG_MAX */
	34	#include <stdio.h> /* file handling */
	35	#endif /* LODEPNG_COMPILE_DISK */
	36
	37	#ifdef LODEPNG_COMPILE_ALLOCATORS
	38	#include <stdlib.h> /* allocations */
	39	#endif /* LODEPNG_COMPILE_ALLOCATORS */
	40
	41	#if defined(_MSC_VER) && (_MSC_VER >= 1310) /Visual Studio: A few warning types are not desired here./
	42	#pragma warning( disable : 4244 ) /implicit conversions: not warned by gcc -Wall -Wextra and requires too much casts/
	43	#pragma warning( disable : 4996 ) /VS does not like fopen, but fopen_s is not standard C so unusable here/
	44	#endif /_MSC_VER /
	45
	46	const char* LODEPNG_VERSION_STRING = "20191020";
	47
	48	/*
	49	This source file is built up in the following large parts. The code sections
	50	with the "LODEPNG_COMPILE_" #defines divide this up further in an intermixed way.
	51	-Tools for C and common code for PNG and Zlib
	52	-C Code for Zlib (huffman, deflate, ...)
	53	-C Code for PNG (file format chunks, adam7, PNG filters, color conversions, ...)
	54	-The C++ wrapper around all of the above
	55	*/
	56
	57	/* ////////////////////////////////////////////////////////////////////////// */
	58	/* ////////////////////////////////////////////////////////////////////////// */
	59	/* // Tools for C, and common code for PNG and Zlib. // */
	60	/* ////////////////////////////////////////////////////////////////////////// */
	61	/* ////////////////////////////////////////////////////////////////////////// */
	62
	63	/*The malloc, realloc and free functions defined here with "lodepng_" in front
	64	of the name, so that you can easily change them to others related to your
	65	platform if needed. Everything else in the code calls these. Pass
	66	-DLODEPNG_NO_COMPILE_ALLOCATORS to the compiler, or comment out
	67	#define LODEPNG_COMPILE_ALLOCATORS in the header, to disable the ones here and
	68	define them in your own project's source files without needing to change
	69	lodepng source code. Don't forget to remove "static" if you copypaste them
	70	from here.*/
	71
	72	#ifdef LODEPNG_COMPILE_ALLOCATORS
	73	static void* lodepng_malloc(size_t size) {
	74	#ifdef LODEPNG_MAX_ALLOC
	75	if(size > LODEPNG_MAX_ALLOC) return 0;
	76	#endif
	77	return malloc(size);
	78	}
	79
	80	static void* lodepng_realloc(void* ptr, size_t new_size) {
	81	#ifdef LODEPNG_MAX_ALLOC
	82	if(new_size > LODEPNG_MAX_ALLOC) return 0;
	83	#endif
	84	return realloc(ptr, new_size);
	85	}
	86
	87	static void lodepng_free(void* ptr) {
	88	free(ptr);
	89	}
	90	#else /LODEPNG_COMPILE_ALLOCATORS/
	91	/* TODO: support giving additional void* payload to the custom allocators */
	92	void* lodepng_malloc(size_t size);
	93	void* lodepng_realloc(void* ptr, size_t new_size);
	94	void lodepng_free(void* ptr);
	95	#endif /LODEPNG_COMPILE_ALLOCATORS/
	96
	97	/* convince the compiler to inline a function, for use when this measurably improves performance */
	98	/* inline is not available in C90, but use it when supported by the compiler */
	99	#if (defined(__STDC_VERSION__) && (__STDC_VERSION__ >= 199901L)) \|\| (defined(__cplusplus) && (__cplusplus >= 199711L))
	100	#define LODEPNG_INLINE inline
	101	#else
	102	#define LODEPNG_INLINE /* not available */
	103	#endif
	104
	105	/* restrict is not available in C90, but use it when supported by the compiler */
	106	#if (defined(__GNUC__) && defined(__GNUC_MINOR__) && (__GNUC__ >= 3) && (__GNUC_MINOR__ >= 1)) \|\|\
	107	(defined(_MSC_VER) && (_MSC_VER >= 1400)) \|\| (defined(__WATCOMC__) && (__WATCOMC__ >= 1250))
	108	#define LODEPNG_RESTRICT __restrict
	109	#else
	110	#define LODEPNG_RESTRICT /* not available */
	111	#endif
	112
	113	/* Replacements for C library functions memcpy and strlen, to support those platforms
	114	where a full C library is not available. The compiler can recognize them and compile
	115	to something as fast. */
	116
	117	static void lodepng_memcpy(void* LODEPNG_RESTRICT dst,
	118	const void* LODEPNG_RESTRICT src, size_t size) {
	119	size_t i;
	120	for(i = 0; i < size; i++) ((char)dst)[i] = ((const char)src)[i];
	121	}
	122
	123	/* does not check memory out of bounds, do not use on untrusted data */
	124	static size_t lodepng_strlen(const char* a) {
	125	const char* orig = a;
	126	/* avoid warning about unused function in case of disabled COMPILE... macros */
	127	(void)lodepng_strlen;
	128	while(*a) a++;
	129	return (size_t)(a - orig);
	130	}
	131
	132	#define LODEPNG_MAX(a, b) (((a) > (b)) ? (a) : (b))
	133	#define LODEPNG_MIN(a, b) (((a) < (b)) ? (a) : (b))
	134	#define LODEPNG_ABS(x) ((x) < 0 ? -(x) : (x))
	135
	136
	137	#ifdef LODEPNG_COMPILE_DECODER
	138	/* Safely check if multiplying two integers will overflow (no undefined
	139	behavior, compiler removing the code, etc...) and output result. */
	140	static int lodepng_mulofl(size_t a, size_t b, size_t* result) {
	141	result = a b; /* Unsigned multiplication is well defined and safe in C90 */
	142	return (a != 0 && *result / a != b);
	143	}
	144
	145	/* Safely check if adding two integers will overflow (no undefined
	146	behavior, compiler removing the code, etc...) and output result. */
	147	static int lodepng_addofl(size_t a, size_t b, size_t* result) {
	148	result = a + b; / Unsigned addition is well defined and safe in C90 */
	149	return *result < a;
	150	}
	151
	152	#ifdef LODEPNG_COMPILE_ZLIB
	153	/* Safely check if a + b > c, even if overflow could happen. */
	154	static int lodepng_gtofl(size_t a, size_t b, size_t c) {
	155	size_t d;
	156	if(lodepng_addofl(a, b, &d)) return 1;
	157	return d > c;
	158	}
	159	#endif /LODEPNG_COMPILE_ZLIB/
	160	#endif /LODEPNG_COMPILE_DECODER/
	161
	162
	163	/*
	164	Often in case of an error a value is assigned to a variable and then it breaks
	165	out of a loop (to go to the cleanup phase of a function). This macro does that.
	166	It makes the error handling code shorter and more readable.
	167
	168	Example: if(!uivector_resizev(&frequencies_ll, 286, 0)) ERROR_BREAK(83);
	169	*/
	170	#define CERROR_BREAK(errorvar, code){\
	171	errorvar = code;\
	172	break;\
	173	}
	174
	175	/version of CERROR_BREAK that assumes the common case where the error variable is named "error"/
	176	#define ERROR_BREAK(code) CERROR_BREAK(error, code)
	177
	178	/Set error var to the error code, and return it./
	179	#define CERROR_RETURN_ERROR(errorvar, code){\
	180	errorvar = code;\
	181	return code;\
	182	}
	183
	184	/Try the code, if it returns error, also return the error./
	185	#define CERROR_TRY_RETURN(call){\
	186	unsigned error = call;\
	187	if(error) return error;\
	188	}
	189
	190	/Set error var to the error code, and return from the void function./
	191	#define CERROR_RETURN(errorvar, code){\
	192	errorvar = code;\
	193	return;\
	194	}
	195
	196	/*
	197	About uivector, ucvector and string:
	198	-All of them wrap dynamic arrays or text strings in a similar way.
	199	-LodePNG was originally written in C++. The vectors replace the std::vectors that were used in the C++ version.
	200	-The string tools are made to avoid problems with compilers that declare things like strncat as deprecated.
	201	-They're not used in the interface, only internally in this file as static functions.
	202	-As with many other structs in this file, the init and cleanup functions serve as ctor and dtor.
	203	*/
	204
	205	#ifdef LODEPNG_COMPILE_ZLIB
	206	#ifdef LODEPNG_COMPILE_ENCODER
	207	/dynamic vector of unsigned ints/
	208	typedef struct uivector {
	209	unsigned* data;
	210	size_t size; /size in number of unsigned longs/
	211	size_t allocsize; /allocated size in bytes/
	212	} uivector;
	213
	214	static void uivector_cleanup(void* p) {
	215	((uivector)p)->size = ((uivector)p)->allocsize = 0;
	216	lodepng_free(((uivector*)p)->data);
	217	((uivector*)p)->data = NULL;
	218	}
	219
	220	/returns 1 if success, 0 if failure ==> nothing done/
	221	static unsigned uivector_reserve(uivector* p, size_t allocsize) {
	222	if(allocsize > p->allocsize) {
	223	size_t newsize = (allocsize > p->allocsize * 2u) ? allocsize : ((allocsize * 3u) >> 1u);
	224	void* data = lodepng_realloc(p->data, newsize);
	225	if(data) {
	226	p->allocsize = newsize;
	227	p->data = (unsigned*)data;
	228	}
	229	else return 0; /error: not enough memory/
	230	}
	231	return 1;
	232	}
	233
	234	/returns 1 if success, 0 if failure ==> nothing done/
	235	static unsigned uivector_resize(uivector* p, size_t size) {
	236	if(!uivector_reserve(p, size * sizeof(unsigned))) return 0;
	237	p->size = size;
	238	return 1; /success/
	239	}
	240
	241	/resize and give all new elements the value/
	242	static unsigned uivector_resizev(uivector* p, size_t size, unsigned value) {
	243	size_t oldsize = p->size, i;
	244	if(!uivector_resize(p, size)) return 0;
	245	for(i = oldsize; i < size; ++i) p->data[i] = value;
	246	return 1;
	247	}
	248
	249	static void uivector_init(uivector* p) {
	250	p->data = NULL;
	251	p->size = p->allocsize = 0;
	252	}
	253
	254	/returns 1 if success, 0 if failure ==> nothing done/
	255	static unsigned uivector_push_back(uivector* p, unsigned c) {
	256	if(!uivector_resize(p, p->size + 1)) return 0;
	257	p->data[p->size - 1] = c;
	258	return 1;
	259	}
	260	#endif /LODEPNG_COMPILE_ENCODER/
	261	#endif /LODEPNG_COMPILE_ZLIB/
	262
	263	/* /////////////////////////////////////////////////////////////////////////// */
	264
	265	/dynamic vector of unsigned chars/
	266	typedef struct ucvector {
	267	unsigned char* data;
	268	size_t size; /used size/
	269	size_t allocsize; /allocated size/
	270	} ucvector;
	271
	272	/returns 1 if success, 0 if failure ==> nothing done/
	273	static unsigned ucvector_reserve(ucvector* p, size_t allocsize) {
	274	if(allocsize > p->allocsize) {
	275	size_t newsize = (allocsize > p->allocsize * 2u) ? allocsize : ((allocsize * 3u) >> 1u);
	276	void* data = lodepng_realloc(p->data, newsize);
	277	if(data) {
	278	p->allocsize = newsize;
	279	p->data = (unsigned char*)data;
	280	}
	281	else return 0; /error: not enough memory/
	282	}
	283	return 1;
	284	}
	285
	286	/returns 1 if success, 0 if failure ==> nothing done/
	287	static unsigned ucvector_resize(ucvector* p, size_t size) {
	288	if(!ucvector_reserve(p, size * sizeof(unsigned char))) return 0;
	289	p->size = size;
	290	return 1; /success/
	291	}
	292
	293	#ifdef LODEPNG_COMPILE_PNG
	294
	295	static void ucvector_cleanup(void* p) {
	296	((ucvector)p)->size = ((ucvector)p)->allocsize = 0;
	297	lodepng_free(((ucvector*)p)->data);
	298	((ucvector*)p)->data = NULL;
	299	}
	300
	301	static void ucvector_init(ucvector* p) {
	302	p->data = NULL;
	303	p->size = p->allocsize = 0;
	304	}
	305	#endif /LODEPNG_COMPILE_PNG/
	306
	307	#ifdef LODEPNG_COMPILE_ZLIB
	308	/*you can both convert from vector to buffer&size and vice versa. If you use
	309	init_buffer to take over a buffer and size, it is not needed to use cleanup*/
	310	static void ucvector_init_buffer(ucvector* p, unsigned char* buffer, size_t size) {
	311	p->data = buffer;
	312	p->allocsize = p->size = size;
	313	}
	314	#endif /LODEPNG_COMPILE_ZLIB/
	315
	316	#if (defined(LODEPNG_COMPILE_PNG) && defined(LODEPNG_COMPILE_ANCILLARY_CHUNKS)) \|\| defined(LODEPNG_COMPILE_ENCODER)
	317	/returns 1 if success, 0 if failure ==> nothing done/
	318	static unsigned ucvector_push_back(ucvector* p, unsigned char c) {
	319	if(!ucvector_resize(p, p->size + 1)) return 0;
	320	p->data[p->size - 1] = c;
	321	return 1;
	322	}
	323	#endif /defined(LODEPNG_COMPILE_PNG) \|\| defined(LODEPNG_COMPILE_ENCODER)/
	324
	325
	326	/* ////////////////////////////////////////////////////////////////////////// */
	327
	328	#ifdef LODEPNG_COMPILE_PNG
	329	#ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
	330
	331	/free string pointer and set it to NULL/
	332	static void string_cleanup(char** out) {
	333	lodepng_free(*out);
	334	*out = NULL;
	335	}
	336
	337	/* dynamically allocates a new string with a copy of the null terminated input text */
	338	static char* alloc_string(const char* in) {
	339	size_t insize = lodepng_strlen(in);
	340	char* out = (char*)lodepng_malloc(insize + 1);
	341	if(out) {
	342	size_t i;
	343	for(i = 0; i != insize; ++i) {
	344	out[i] = in[i];
	345	}
	346	out[i] = 0;
	347	}
	348	return out;
	349	}
	350	#endif /LODEPNG_COMPILE_ANCILLARY_CHUNKS/
	351	#endif /LODEPNG_COMPILE_PNG/
	352
	353	/* ////////////////////////////////////////////////////////////////////////// */
	354
	355	#if defined(LODEPNG_COMPILE_DECODER) \|\| defined(LODEPNG_COMPILE_PNG)
	356	static unsigned lodepng_read32bitInt(const unsigned char* buffer) {
	357	return (((unsigned)buffer[0] << 24u) \| ((unsigned)buffer[1] << 16u) \|
	358	((unsigned)buffer[2] << 8u) \| (unsigned)buffer[3]);
	359	}
	360	#endif /defined(LODEPNG_COMPILE_DECODER) \|\| defined(LODEPNG_COMPILE_PNG)/
	361
	362	#if defined(LODEPNG_COMPILE_PNG) \|\| defined(LODEPNG_COMPILE_ENCODER)
	363	/buffer must have at least 4 allocated bytes available/
	364	static void lodepng_set32bitInt(unsigned char* buffer, unsigned value) {
	365	buffer[0] = (unsigned char)((value >> 24) & 0xff);
	366	buffer[1] = (unsigned char)((value >> 16) & 0xff);
	367	buffer[2] = (unsigned char)((value >> 8) & 0xff);
	368	buffer[3] = (unsigned char)((value ) & 0xff);
	369	}
	370	#endif /defined(LODEPNG_COMPILE_PNG) \|\| defined(LODEPNG_COMPILE_ENCODER)/
	371
	372	/* ////////////////////////////////////////////////////////////////////////// */
	373	/* / File IO / */
	374	/* ////////////////////////////////////////////////////////////////////////// */
	375
	376	#ifdef LODEPNG_COMPILE_DISK
	377
	378	/* returns negative value on error. This should be pure C compatible, so no fstat. */
	379	static long lodepng_filesize(const char* filename) {
	380	FILE* file;
	381	long size;
	382	file = fopen(filename, "rb");
	383	if(!file) return -1;
	384
	385	if(fseek(file, 0, SEEK_END) != 0) {
	386	fclose(file);
	387	return -1;
	388	}
	389
	390	size = ftell(file);
	391	/* It may give LONG_MAX as directory size, this is invalid for us. */
	392	if(size == LONG_MAX) size = -1;
	393
	394	fclose(file);
	395	return size;
	396	}
	397
	398	/* load file into buffer that already has the correct allocated size. Returns error code.*/
	399	static unsigned lodepng_buffer_file(unsigned char* out, size_t size, const char* filename) {
	400	FILE* file;
	401	size_t readsize;
	402	file = fopen(filename, "rb");
	403	if(!file) return 78;
	404
	405	readsize = fread(out, 1, size, file);
	406	fclose(file);
	407
	408	if (readsize != size) return 78;
	409	return 0;
	410	}
	411
	412	unsigned lodepng_load_file(unsigned char** out, size_t* outsize, const char* filename) {
	413	long size = lodepng_filesize(filename);
	414	if (size < 0) return 78;
	415	*outsize = (size_t)size;
	416
	417	out = (unsigned char)lodepng_malloc((size_t)size);
	418	if(!(out) && size > 0) return 83; /the above malloc failed*/
	419
	420	return lodepng_buffer_file(*out, (size_t)size, filename);
	421	}
	422
	423	/write given buffer to the file, overwriting the file, it doesn't append to it./
	424	unsigned lodepng_save_file(const unsigned char* buffer, size_t buffersize, const char* filename) {
	425	FILE* file;
	426	file = fopen(filename, "wb" );
	427	if(!file) return 79;
	428	fwrite(buffer, 1, buffersize, file);
	429	fclose(file);
	430	return 0;
	431	}
	432
	433	#endif /LODEPNG_COMPILE_DISK/
	434
	435	/* ////////////////////////////////////////////////////////////////////////// */
	436	/* ////////////////////////////////////////////////////////////////////////// */
	437	/* // End of common code and tools. Begin of Zlib related code. // */
	438	/* ////////////////////////////////////////////////////////////////////////// */
	439	/* ////////////////////////////////////////////////////////////////////////// */
	440
	441	#ifdef LODEPNG_COMPILE_ZLIB
	442	#ifdef LODEPNG_COMPILE_ENCODER
	443
	444	typedef struct {
	445	ucvector* data;
	446	size_t bp;
	447	} LodePNGBitWriter;
	448
	449	void LodePNGBitWriter_init(LodePNGBitWriter* writer, ucvector* data) {
	450	writer->data = data;
	451	writer->bp = 0;
	452	}
	453
	454	/TODO: this ignores potential out of memory errors/
	455	#define WRITEBIT(/size_t/ writer, /unsigned char*/ bit){\
	456	/* append new byte */\
	457	if(((writer->bp) & 7u) == 0) ucvector_push_back(writer->data, (unsigned char)0);\
	458	(writer->data->data[writer->data->size - 1]) \|= (bit << ((writer->bp) & 7u));\
	459	++writer->bp;\
	460	}
	461
	462	/* LSB of value is written first, and LSB of bytes is used first */
	463	static void writeBits(LodePNGBitWriter* writer, unsigned value, size_t nbits) {
	464	if(nbits == 1) { /* compiler should statically compile this case if nbits == 1 */
	465	WRITEBIT(writer, value);
	466	} else {
	467	/* TODO: increase output size nly once here rather than in each WRITEBIT */
	468	size_t i;
	469	for(i = 0; i != nbits; ++i) {
	470	WRITEBIT(writer, (unsigned char)((value >> i) & 1));
	471	}
	472	}
	473	}
	474
	475	/* This one is to use for adding huffman symbol, the value bits are written MSB first */
	476	static void writeBitsReversed(LodePNGBitWriter* writer, unsigned value, size_t nbits) {
	477	size_t i;
	478	for(i = 0; i != nbits; ++i) {
	479	/* TODO: increase output size only once here rather than in each WRITEBIT */
	480	WRITEBIT(writer, (unsigned char)((value >> (nbits - 1u - i)) & 1u));
	481	}
	482	}
	483	#endif /LODEPNG_COMPILE_ENCODER/
	484
	485	#ifdef LODEPNG_COMPILE_DECODER
	486
	487	typedef struct {
	488	const unsigned char* data;
	489	size_t size; /size of data in bytes/
	490	size_t bitsize; /size of data in bits, end of valid bp values, should be 8size*/
	491	size_t bp;
	492	unsigned buffer; /buffer for reading bits. NOTE: 'unsigned' must support at least 32 bits/
	493	} LodePNGBitReader;
	494
	495	/* data size argument is in bytes. Returns error if size too large causing overflow */
	496	static unsigned LodePNGBitReader_init(LodePNGBitReader* reader, const unsigned char* data, size_t size) {
	497	size_t temp;
	498	reader->data = data;
	499	reader->size = size;
	500	/* size in bits, return error if overflow (if size_t is 32 bit this supports up to 500MB) */
	501	if(lodepng_mulofl(size, 8u, &reader->bitsize)) return 105;
	502	/*ensure incremented bp can be compared to bitsize without overflow even when it would be incremented 32 too much and
	503	trying to ensure 32 more bits*/
	504	if(lodepng_addofl(reader->bitsize, 64u, &temp)) return 105;
	505	reader->bp = 0;
	506	reader->buffer = 0;
	507	return 0; /ok/
	508	}
	509
	510	/*
	511	ensureBits functions:
	512	Ensures the reader can at least read nbits bits in one or more readBits calls,
	513	safely even if not enough bits are available.
	514	Returns 1 if there are enough bits available, 0 if not.
	515	*/
	516
	517	/See ensureBits documentation above. This one ensures exactly 1 bit /
	518	/static unsigned ensureBits1(LodePNGBitReader reader) {
	519	if(reader->bp >= reader->bitsize) return 0;
	520	reader->buffer = (unsigned)reader->data[reader->bp >> 3u] >> (reader->bp & 7u);
	521	return 1;
	522	}*/
	523
	524	/See ensureBits documentation above. This one ensures up to 9 bits /
	525	static unsigned ensureBits9(LodePNGBitReader* reader, size_t nbits) {
	526	size_t start = reader->bp >> 3u;
	527	size_t size = reader->size;
	528	if(start + 1u < size) {
	529	reader->buffer = (unsigned)(reader->data[start + 0]) \| (unsigned)(reader->data[start + 1] << 8u);
	530	reader->buffer >>= (reader->bp & 7u);
	531	return 1;
	532	} else {
	533	reader->buffer = 0;
	534	if(start + 0u < size) reader->buffer \|= reader->data[start + 0];
	535	reader->buffer >>= (reader->bp & 7u);
	536	return reader->bp + nbits < reader->bitsize;
	537	}
	538	}
	539
	540	/See ensureBits documentation above. This one ensures up to 17 bits /
	541	static unsigned ensureBits17(LodePNGBitReader* reader, size_t nbits) {
	542	size_t start = reader->bp >> 3u;
	543	size_t size = reader->size;
	544	if(start + 2u < size) {
	545	reader->buffer = (unsigned)(reader->data[start + 0]) \| (unsigned)(reader->data[start + 1] << 8u) \|
	546	(unsigned)(reader->data[start + 2] << 16u);
	547	reader->buffer >>= (reader->bp & 7u);
	548	return 1;
	549	} else {
	550	reader->buffer = 0;
	551	if(start + 0u < size) reader->buffer \|= reader->data[start + 0];
	552	if(start + 1u < size) reader->buffer \|= (unsigned)(reader->data[start + 1] << 8u);
	553	reader->buffer >>= (reader->bp & 7u);
	554	return reader->bp + nbits < reader->bitsize;
	555	}
	556	}
	557
	558	/See ensureBits documentation above. This one ensures up to 25 bits /
	559	static LODEPNG_INLINE unsigned ensureBits25(LodePNGBitReader* reader, size_t nbits) {
	560	size_t start = reader->bp >> 3u;
	561	size_t size = reader->size;
	562	if(start + 3u < size) {
	563	reader->buffer = (unsigned)(reader->data[start + 0]) \| (unsigned)(reader->data[start + 1] << 8u) \|
	564	(unsigned)(reader->data[start + 2] << 16u) \| (unsigned)(reader->data[start + 3] << 24u);
	565	reader->buffer >>= (reader->bp & 7u);
	566	return 1;
	567	} else {
	568	reader->buffer = 0;
	569	if(start + 0u < size) reader->buffer \|= reader->data[start + 0];
	570	if(start + 1u < size) reader->buffer \|= (unsigned)(reader->data[start + 1] << 8u);
	571	if(start + 2u < size) reader->buffer \|= (unsigned)(reader->data[start + 2] << 16u);
	572	reader->buffer >>= (reader->bp & 7u);
	573	return reader->bp + nbits < reader->bitsize;
	574	}
	575	}
	576
	577	/See ensureBits documentation above. This one ensures up to 32 bits /
	578	static LODEPNG_INLINE unsigned ensureBits32(LodePNGBitReader* reader, size_t nbits) {
	579	size_t start = reader->bp >> 3u;
	580	size_t size = reader->size;
	581	if(start + 4u < size) {
	582	reader->buffer = (unsigned)(reader->data[start + 0]) \| (unsigned)(reader->data[start + 1] << 8u) \|
	583	(unsigned)(reader->data[start + 2] << 16u) \| (unsigned)(reader->data[start + 3] << 24u);
	584	reader->buffer >>= (reader->bp & 7u);
	585	reader->buffer \|= ((unsigned)(reader->data[start + 4] << 24u) << (7u - (reader->bp & 7u)));
	586	return 1;
	587	} else {
	588	reader->buffer = 0;
	589	if(start + 0u < size) reader->buffer \|= reader->data[start + 0];
	590	if(start + 1u < size) reader->buffer \|= (unsigned)(reader->data[start + 1] << 8u);
	591	if(start + 2u < size) reader->buffer \|= (unsigned)(reader->data[start + 2] << 16u);
	592	if(start + 3u < size) reader->buffer \|= (unsigned)(reader->data[start + 3] << 24u);
	593	reader->buffer >>= (reader->bp & 7u);
	594	return reader->bp + nbits < reader->bitsize;
	595	}
	596	}
	597
	598	/* Get bits without advancing the bit pointer. Must have enough bits available with ensureBits */
	599	static unsigned peekBits(LodePNGBitReader* reader, size_t nbits) {
	600	return reader->buffer & ((1u << nbits) - 1u);
	601	}
	602
	603	/* Must have enough bits available with ensureBits */
	604	static void advanceBits(LodePNGBitReader* reader, size_t nbits) {
	605	reader->buffer >>= nbits;
	606	reader->bp += nbits;
	607	}
	608
	609	/* Must have enough bits available with ensureBits */
	610	static unsigned readBits(LodePNGBitReader* reader, size_t nbits) {
	611	unsigned result = peekBits(reader, nbits);
	612	advanceBits(reader, nbits);
	613	return result;
	614	}
	615	#endif /LODEPNG_COMPILE_DECODER/
	616
	617	static unsigned reverseBits(unsigned bits, unsigned num) {
	618	/TODO: implement faster lookup table based version when needed/
	619	unsigned i, result = 0;
	620	for(i = 0; i < num; i++) result \|= ((bits >> (num - i - 1u)) & 1u) << i;
	621	return result;
	622	}
	623
	624	/* ////////////////////////////////////////////////////////////////////////// */
	625	/* / Deflate - Huffman / */
	626	/* ////////////////////////////////////////////////////////////////////////// */
	627
	628	#define FIRST_LENGTH_CODE_INDEX 257
	629	#define LAST_LENGTH_CODE_INDEX 285
	630	/256 literals, the end code, some length codes, and 2 unused codes/
	631	#define NUM_DEFLATE_CODE_SYMBOLS 288
	632	/the distance codes have their own symbols, 30 used, 2 unused/
	633	#define NUM_DISTANCE_SYMBOLS 32
	634	/the code length codes. 0-15: code lengths, 16: copy previous 3-6 times, 17: 3-10 zeros, 18: 11-138 zeros/
	635	#define NUM_CODE_LENGTH_CODES 19
	636
	637	/the base lengths represented by codes 257-285/
	638	static const unsigned LENGTHBASE[29]
	639	= {3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 17, 19, 23, 27, 31, 35, 43, 51, 59,
	640	67, 83, 99, 115, 131, 163, 195, 227, 258};
	641
	642	/the extra bits used by codes 257-285 (added to base length)/
	643	static const unsigned LENGTHEXTRA[29]
	644	= {0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3,
	645	4, 4, 4, 4, 5, 5, 5, 5, 0};
	646
	647	/the base backwards distances (the bits of distance codes appear after length codes and use their own huffman tree)/
	648	static const unsigned DISTANCEBASE[30]
	649	= {1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49, 65, 97, 129, 193, 257, 385, 513,
	650	769, 1025, 1537, 2049, 3073, 4097, 6145, 8193, 12289, 16385, 24577};
	651
	652	/the extra bits of backwards distances (added to base)/
	653	static const unsigned DISTANCEEXTRA[30]
	654	= {0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8,
	655	8, 9, 9, 10, 10, 11, 11, 12, 12, 13, 13};
	656
	657	/*the order in which "code length alphabet code lengths" are stored, out of this
	658	the huffman tree of the dynamic huffman tree lengths is generated*/
	659	static const unsigned CLCL_ORDER[NUM_CODE_LENGTH_CODES]
	660	= {16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15};
	661
	662	/* ////////////////////////////////////////////////////////////////////////// */
	663
	664	/*
	665	Huffman tree struct, containing multiple representations of the tree
	666	*/
	667	typedef struct HuffmanTree {
	668	unsigned* codes; /the huffman codes (bit patterns representing the symbols)/
	669	unsigned* lengths; /the lengths of the huffman codes/
	670	unsigned maxbitlen; /maximum number of bits a single code can get/
	671	unsigned numcodes; /number of symbols in the alphabet = number of codes/
	672	/* for reading only */
	673	unsigned char* table_len; /length of symbol from lookup table, or max length if secondary lookup needed/
	674	unsigned short* table_value; /value of symbol from lookup table, or pointer to secondary table if needed/
	675	} HuffmanTree;
	676
	677	static void HuffmanTree_init(HuffmanTree* tree) {
	678	tree->codes = 0;
	679	tree->lengths = 0;
	680	tree->table_len = 0;
	681	tree->table_value = 0;
	682	}
	683
	684	static void HuffmanTree_cleanup(HuffmanTree* tree) {
	685	lodepng_free(tree->codes);
	686	lodepng_free(tree->lengths);
	687	lodepng_free(tree->table_len);
	688	lodepng_free(tree->table_value);
	689	}
	690
	691	/* amount of bits for first huffman table lookup (aka root bits), see HuffmanTree_makeTable and huffmanDecodeSymbol.*/
	692	/* values 8u and 9u work the fastest */
	693	#define FIRSTBITS 9u
	694
	695	/* make table for huffman decoding */
	696	static unsigned HuffmanTree_makeTable(HuffmanTree* tree) {
	697	static const unsigned headsize = 1u << FIRSTBITS; /size of the first table/
	698	static const unsigned mask = (1u << FIRSTBITS) /headsize/ - 1u;
	699	size_t i, pointer, size; /total table size/
	700	unsigned* maxlens = (unsigned)lodepng_malloc(headsize sizeof(unsigned));
	701	if(!maxlens) return 83; /alloc fail/
	702
	703	/* compute maxlens: max total bit length of symbols sharing prefix in the first table*/
	704	for(i = 0; i < headsize; ++i) maxlens[i] = 0;
	705	for(i = 0; i < tree->numcodes; i++) {
	706	unsigned symbol = tree->codes[i];
	707	unsigned l = tree->lengths[i];
	708	unsigned index;
	709	if(l <= FIRSTBITS) continue; /symbols that fit in first table don't increase secondary table size/
	710	/get the FIRSTBITS MSBs, the MSBs of the symbol are encoded first. See later comment about the reversing/
	711	index = reverseBits(symbol >> (l - FIRSTBITS), FIRSTBITS);
	712	maxlens[index] = LODEPNG_MAX(maxlens[index], l);
	713	}
	714	/* compute total table size: size of first table plus all secondary tables for symbols longer than FIRSTBITS */
	715	size = headsize;
	716	for(i = 0; i < headsize; ++i) {
	717	unsigned l = maxlens[i];
	718	if(l > FIRSTBITS) size += (1u << (l - FIRSTBITS));
	719	}
	720	tree->table_len = (unsigned char)lodepng_malloc(size sizeof(*tree->table_len));
	721	tree->table_value = (unsigned short)lodepng_malloc(size sizeof(*tree->table_value));
	722	if(!tree->table_len \|\| !tree->table_value) {
	723	lodepng_free(maxlens);
	724	/* freeing tree->table values is done at a higher scope */
	725	return 83; /alloc fail/
	726	}
	727	/initialize with an invalid length to indicate unused entries/
	728	for(i = 0; i < size; ++i) tree->table_len[i] = 16;
	729
	730	/fill in the first table for long symbols: max prefix size and pointer to secondary tables/
	731	pointer = headsize;
	732	for(i = 0; i < headsize; ++i) {
	733	unsigned l = maxlens[i];
	734	if(l <= FIRSTBITS) continue;
	735	tree->table_len[i] = l;
	736	tree->table_value[i] = pointer;
	737	pointer += (1u << (l - FIRSTBITS));
	738	}
	739	lodepng_free(maxlens);
	740
	741	/fill in the first table for short symbols, or secondary table for long symbols/
	742	for(i = 0; i < tree->numcodes; ++i) {
	743	unsigned l = tree->lengths[i];
	744	unsigned symbol = tree->codes[i]; /the huffman bit pattern. i itself is the value./
	745	/reverse bits, because the huffman bits are given in MSB first order but the bit reader reads LSB first/
	746	unsigned reverse = reverseBits(symbol, l);
	747	if(l == 0) {
	748	continue;
	749	} else if(l <= FIRSTBITS) {
	750	/short symbol, fully in first table, replicated num times if l < FIRSTBITS/
	751	unsigned num = 1u << (FIRSTBITS - l);
	752	unsigned j;
	753	for(j = 0; j < num; ++j) {
	754	/bit reader will read the l bits of symbol first, the remaining FIRSTBITS - l bits go to the MSB's/
	755	unsigned index = reverse \| (j << l);
	756	if(tree->table_len[index] != 16) return 55; /invalid tree: long symbol shares prefix with short symbol/
	757	tree->table_len[index] = l;
	758	tree->table_value[index] = i;
	759	}
	760	} else {
	761	/long symbol, shares prefix with other long symbols in first lookup table, needs second lookup/
	762	/the FIRSTBITS MSBs of the symbol are the first table index/
	763	unsigned index = reverse & mask;
	764	unsigned maxlen = tree->table_len[index];
	765	/log2 of secondary table length, should be >= l - FIRSTBITS/
	766	unsigned tablelen = maxlen - FIRSTBITS;
	767	unsigned start = tree->table_value[index]; /starting index in secondary table/
	768	unsigned num = 1u << (tablelen - (l - FIRSTBITS)); /amount of entries of this symbol in secondary table/
	769	unsigned j;
	770	if(maxlen < l) return 55; /invalid tree: long symbol shares prefix with short symbol/
	771	for(j = 0; j < num; ++j) {
	772	unsigned reverse2 = reverse >> FIRSTBITS; /* l - FIRSTBITS bits */
	773	unsigned index2 = start + (reverse2 \| (j << (l - FIRSTBITS)));
	774	tree->table_len[index2] = l;
	775	tree->table_value[index2] = i;
	776	}
	777	}
	778	}
	779
	780	/* A good huffman tree has N * 2 - 1 nodes, of which N - 1 are internal nodes.
	781	If that is not the case (due to too long length codes), the table will not
	782	have been fully used, and this is an error (not all bit combinations can be
	783	decoded): an oversubscribed huffman tree, indicated by error 55. */
	784	for(i = 0; i < size; ++i) {
	785	if(tree->table_len[i] == 16) return 55;
	786	}
	787
	788	return 0;
	789	}
	790
	791	/*
	792	Second step for the ...makeFromLengths and ...makeFromFrequencies functions.
	793	numcodes, lengths and maxbitlen must already be filled in correctly. return
	794	value is error.
	795	*/
	796	static unsigned HuffmanTree_makeFromLengths2(HuffmanTree* tree) {
	797	unsigned* blcount;
	798	unsigned* nextcode;
	799	unsigned error = 0;
	800	unsigned bits, n;
	801
	802	tree->codes = (unsigned)lodepng_malloc(tree->numcodes sizeof(unsigned));
	803	blcount = (unsigned)lodepng_malloc((tree->maxbitlen + 1) sizeof(unsigned));
	804	nextcode = (unsigned)lodepng_malloc((tree->maxbitlen + 1) sizeof(unsigned));
	805	if(!tree->codes \|\| !blcount \|\| !nextcode) error = 83; /alloc fail/
	806
	807	if(!error) {
	808	for(n = 0; n != tree->maxbitlen + 1; n++) blcount[n] = nextcode[n] = 0;
	809	/step 1: count number of instances of each code length/
	810	for(bits = 0; bits != tree->numcodes; ++bits) ++blcount[tree->lengths[bits]];
	811	/step 2: generate the nextcode values/
	812	for(bits = 1; bits <= tree->maxbitlen; ++bits) {
	813	nextcode[bits] = (nextcode[bits - 1] + blcount[bits - 1]) << 1;
	814	}
	815	/step 3: generate all the codes/
	816	for(n = 0; n != tree->numcodes; ++n) {
	817	if(tree->lengths[n] != 0) {
	818	tree->codes[n] = nextcode[tree->lengths[n]]++;
	819	/remove superfluous bits from the code/
	820	tree->codes[n] &= ((1u << tree->lengths[n]) - 1u);
	821	}
	822	}
	823	}
	824
	825	lodepng_free(blcount);
	826	lodepng_free(nextcode);
	827
	828	if(!error) error = HuffmanTree_makeTable(tree);
	829	return error;
	830	}
	831
	832	/*
	833	given the code lengths (as stored in the PNG file), generate the tree as defined
	834	by Deflate. maxbitlen is the maximum bits that a code in the tree can have.
	835	return value is error.
	836	*/
	837	static unsigned HuffmanTree_makeFromLengths(HuffmanTree* tree, const unsigned* bitlen,
	838	size_t numcodes, unsigned maxbitlen) {
	839	unsigned i;
	840	tree->lengths = (unsigned)lodepng_malloc(numcodes sizeof(unsigned));
	841	if(!tree->lengths) return 83; /alloc fail/
	842	for(i = 0; i != numcodes; ++i) tree->lengths[i] = bitlen[i];
	843	tree->numcodes = (unsigned)numcodes; /number of symbols/
	844	tree->maxbitlen = maxbitlen;
	845	return HuffmanTree_makeFromLengths2(tree);
	846	}
	847
	848	#ifdef LODEPNG_COMPILE_ENCODER
	849
	850	/*BPM: Boundary Package Merge, see "A Fast and Space-Economical Algorithm for Length-Limited Coding",
	851	Jyrki Katajainen, Alistair Moffat, Andrew Turpin, 1995.*/
	852
	853	/chain node for boundary package merge/
	854	typedef struct BPMNode {
	855	int weight; /the sum of all weights in this chain/
	856	unsigned index; /index of this leaf node (called "count" in the paper)/
	857	struct BPMNode* tail; /the next nodes in this chain (null if last)/
	858	int in_use;
	859	} BPMNode;
	860
	861	/lists of chains/
	862	typedef struct BPMLists {
	863	/memory pool/
	864	unsigned memsize;
	865	BPMNode* memory;
	866	unsigned numfree;
	867	unsigned nextfree;
	868	BPMNode** freelist;
	869	/two heads of lookahead chains per list/
	870	unsigned listsize;
	871	BPMNode** chains0;
	872	BPMNode** chains1;
	873	} BPMLists;
	874
	875	/creates a new chain node with the given parameters, from the memory in the lists /
	876	static BPMNode* bpmnode_create(BPMLists* lists, int weight, unsigned index, BPMNode* tail) {
	877	unsigned i;
	878	BPMNode* result;
	879
	880	/memory full, so garbage collect/
	881	if(lists->nextfree >= lists->numfree) {
	882	/mark only those that are in use/
	883	for(i = 0; i != lists->memsize; ++i) lists->memory[i].in_use = 0;
	884	for(i = 0; i != lists->listsize; ++i) {
	885	BPMNode* node;
	886	for(node = lists->chains0[i]; node != 0; node = node->tail) node->in_use = 1;
	887	for(node = lists->chains1[i]; node != 0; node = node->tail) node->in_use = 1;
	888	}
	889	/collect those that are free/
	890	lists->numfree = 0;
	891	for(i = 0; i != lists->memsize; ++i) {
	892	if(!lists->memory[i].in_use) lists->freelist[lists->numfree++] = &lists->memory[i];
	893	}
	894	lists->nextfree = 0;
	895	}
	896
	897	result = lists->freelist[lists->nextfree++];
	898	result->weight = weight;
	899	result->index = index;
	900	result->tail = tail;
	901	return result;
	902	}
	903
	904	/sort the leaves with stable mergesort/
	905	static void bpmnode_sort(BPMNode* leaves, size_t num) {
	906	BPMNode* mem = (BPMNode)lodepng_malloc(sizeof(leaves) * num);
	907	size_t width, counter = 0;
	908	for(width = 1; width < num; width *= 2) {
	909	BPMNode* a = (counter & 1) ? mem : leaves;
	910	BPMNode* b = (counter & 1) ? leaves : mem;
	911	size_t p;
	912	for(p = 0; p < num; p += 2 * width) {
	913	size_t q = (p + width > num) ? num : (p + width);
	914	size_t r = (p + 2 * width > num) ? num : (p + 2 * width);
	915	size_t i = p, j = q, k;
	916	for(k = p; k < r; k++) {
	917	if(i < q && (j >= r \|\| a[i].weight <= a[j].weight)) b[k] = a[i++];
	918	else b[k] = a[j++];
	919	}
	920	}
	921	counter++;
	922	}
	923	if(counter & 1) lodepng_memcpy(leaves, mem, sizeof(leaves) num);
	924	lodepng_free(mem);
	925	}
	926
	927	/Boundary Package Merge step, numpresent is the amount of leaves, and c is the current chain./
	928	static void boundaryPM(BPMLists* lists, BPMNode* leaves, size_t numpresent, int c, int num) {
	929	unsigned lastindex = lists->chains1[c]->index;
	930
	931	if(c == 0) {
	932	if(lastindex >= numpresent) return;
	933	lists->chains0[c] = lists->chains1[c];
	934	lists->chains1[c] = bpmnode_create(lists, leaves[lastindex].weight, lastindex + 1, 0);
	935	} else {
	936	/sum of the weights of the head nodes of the previous lookahead chains./
	937	int sum = lists->chains0[c - 1]->weight + lists->chains1[c - 1]->weight;
	938	lists->chains0[c] = lists->chains1[c];
	939	if(lastindex < numpresent && sum > leaves[lastindex].weight) {
	940	lists->chains1[c] = bpmnode_create(lists, leaves[lastindex].weight, lastindex + 1, lists->chains1[c]->tail);
	941	return;
	942	}
	943	lists->chains1[c] = bpmnode_create(lists, sum, lastindex, lists->chains1[c - 1]);
	944	/*in the end we are only interested in the chain of the last list, so no
	945	need to recurse if we're at the last one (this gives measurable speedup)*/
	946	if(num + 1 < (int)(2 * numpresent - 2)) {
	947	boundaryPM(lists, leaves, numpresent, c - 1, num);
	948	boundaryPM(lists, leaves, numpresent, c - 1, num);
	949	}
	950	}
	951	}
	952
	953	unsigned lodepng_huffman_code_lengths(unsigned* lengths, const unsigned* frequencies,
	954	size_t numcodes, unsigned maxbitlen) {
	955	unsigned error = 0;
	956	unsigned i;
	957	size_t numpresent = 0; /number of symbols with non-zero frequency/
	958	BPMNode* leaves; /the symbols, only those with > 0 frequency/
	959
	960	if(numcodes == 0) return 80; /error: a tree of 0 symbols is not supposed to be made/
	961	if((1u << maxbitlen) < (unsigned)numcodes) return 80; /error: represent all symbols/
	962
	963	leaves = (BPMNode)lodepng_malloc(numcodes sizeof(*leaves));
	964	if(!leaves) return 83; /alloc fail/
	965
	966	for(i = 0; i != numcodes; ++i) {
	967	if(frequencies[i] > 0) {
	968	leaves[numpresent].weight = (int)frequencies[i];
	969	leaves[numpresent].index = i;
	970	++numpresent;
	971	}
	972	}
	973
	974	for(i = 0; i != numcodes; ++i) lengths[i] = 0;
	975
	976	/*ensure at least two present symbols. There should be at least one symbol
	977	according to RFC 1951 section 3.2.7. Some decoders incorrectly require two. To
	978	make these work as well ensure there are at least two symbols. The
	979	Package-Merge code below also doesn't work correctly if there's only one
	980	symbol, it'd give it the theoretical 0 bits but in practice zlib wants 1 bit*/
	981	if(numpresent == 0) {
	982	lengths[0] = lengths[1] = 1; /note that for RFC 1951 section 3.2.7, only lengths[0] = 1 is needed/
	983	} else if(numpresent == 1) {
	984	lengths[leaves[0].index] = 1;
	985	lengths[leaves[0].index == 0 ? 1 : 0] = 1;
	986	} else {
	987	BPMLists lists;
	988	BPMNode* node;
	989
	990	bpmnode_sort(leaves, numpresent);
	991
	992	lists.listsize = maxbitlen;
	993	lists.memsize = 2 * maxbitlen * (maxbitlen + 1);
	994	lists.nextfree = 0;
	995	lists.numfree = lists.memsize;
	996	lists.memory = (BPMNode)lodepng_malloc(lists.memsize sizeof(*lists.memory));
	997	lists.freelist = (BPMNode*)lodepng_malloc(lists.memsize sizeof(BPMNode*));
	998	lists.chains0 = (BPMNode*)lodepng_malloc(lists.listsize sizeof(BPMNode*));
	999	lists.chains1 = (BPMNode*)lodepng_malloc(lists.listsize sizeof(BPMNode*));
	1000	if(!lists.memory \|\| !lists.freelist \|\| !lists.chains0 \|\| !lists.chains1) error = 83; /alloc fail/
	1001
	1002	if(!error) {
	1003	for(i = 0; i != lists.memsize; ++i) lists.freelist[i] = &lists.memory[i];
	1004
	1005	bpmnode_create(&lists, leaves[0].weight, 1, 0);
	1006	bpmnode_create(&lists, leaves[1].weight, 2, 0);
	1007
	1008	for(i = 0; i != lists.listsize; ++i) {
	1009	lists.chains0[i] = &lists.memory[0];
	1010	lists.chains1[i] = &lists.memory[1];
	1011	}
	1012
	1013	/each boundaryPM call adds one chain to the last list, and we need 2 numpresent - 2 chains.*/
	1014	for(i = 2; i != 2 * numpresent - 2; ++i) boundaryPM(&lists, leaves, numpresent, (int)maxbitlen - 1, (int)i);
	1015
	1016	for(node = lists.chains1[maxbitlen - 1]; node; node = node->tail) {
	1017	for(i = 0; i != node->index; ++i) ++lengths[leaves[i].index];
	1018	}
	1019	}
	1020
	1021	lodepng_free(lists.memory);
	1022	lodepng_free(lists.freelist);
	1023	lodepng_free(lists.chains0);
	1024	lodepng_free(lists.chains1);
	1025	}
	1026
	1027	lodepng_free(leaves);
	1028	return error;
	1029	}
	1030
	1031	/Create the Huffman tree given the symbol frequencies/
	1032	static unsigned HuffmanTree_makeFromFrequencies(HuffmanTree* tree, const unsigned* frequencies,
	1033	size_t mincodes, size_t numcodes, unsigned maxbitlen) {
	1034	size_t i;
	1035	unsigned error = 0;
	1036	while(!frequencies[numcodes - 1] && numcodes > mincodes) --numcodes; /trim zeroes/
	1037	tree->maxbitlen = maxbitlen;
	1038	tree->numcodes = (unsigned)numcodes; /number of symbols/
	1039	tree->lengths = (unsigned)lodepng_realloc(tree->lengths, numcodes sizeof(unsigned));
	1040	if(!tree->lengths) return 83; /alloc fail/
	1041	/initialize all lengths to 0/
	1042	for(i = 0; i < numcodes; i++) tree->lengths[i] = 0;
	1043
	1044	error = lodepng_huffman_code_lengths(tree->lengths, frequencies, numcodes, maxbitlen);
	1045	if(!error) error = HuffmanTree_makeFromLengths2(tree);
	1046	return error;
	1047	}
	1048
	1049	static unsigned HuffmanTree_getCode(const HuffmanTree* tree, unsigned index) {
	1050	return tree->codes[index];
	1051	}
	1052
	1053	static unsigned HuffmanTree_getLength(const HuffmanTree* tree, unsigned index) {
	1054	return tree->lengths[index];
	1055	}
	1056	#endif /LODEPNG_COMPILE_ENCODER/
	1057
	1058	/get the literal and length code tree of a deflated block with fixed tree, as per the deflate specification/
	1059	static unsigned generateFixedLitLenTree(HuffmanTree* tree) {
	1060	unsigned i, error = 0;
	1061	unsigned* bitlen = (unsigned)lodepng_malloc(NUM_DEFLATE_CODE_SYMBOLS sizeof(unsigned));
	1062	if(!bitlen) return 83; /alloc fail/
	1063
	1064	/288 possible codes: 0-255=literals, 256=endcode, 257-285=lengthcodes, 286-287=unused/
	1065	for(i = 0; i <= 143; ++i) bitlen[i] = 8;
	1066	for(i = 144; i <= 255; ++i) bitlen[i] = 9;
	1067	for(i = 256; i <= 279; ++i) bitlen[i] = 7;
	1068	for(i = 280; i <= 287; ++i) bitlen[i] = 8;
	1069
	1070	error = HuffmanTree_makeFromLengths(tree, bitlen, NUM_DEFLATE_CODE_SYMBOLS, 15);
	1071
	1072	lodepng_free(bitlen);
	1073	return error;
	1074	}
	1075
	1076	/get the distance code tree of a deflated block with fixed tree, as specified in the deflate specification/
	1077	static unsigned generateFixedDistanceTree(HuffmanTree* tree) {
	1078	unsigned i, error = 0;
	1079	unsigned* bitlen = (unsigned)lodepng_malloc(NUM_DISTANCE_SYMBOLS sizeof(unsigned));
	1080	if(!bitlen) return 83; /alloc fail/
	1081
	1082	/there are 32 distance codes, but 30-31 are unused/
	1083	for(i = 0; i != NUM_DISTANCE_SYMBOLS; ++i) bitlen[i] = 5;
	1084	error = HuffmanTree_makeFromLengths(tree, bitlen, NUM_DISTANCE_SYMBOLS, 15);
	1085
	1086	lodepng_free(bitlen);
	1087	return error;
	1088	}
	1089
	1090	#ifdef LODEPNG_COMPILE_DECODER
	1091
	1092	/*
	1093	returns the code. The bit reader must already have been ensured at least 15 bits
	1094	*/
	1095	static unsigned huffmanDecodeSymbol(LodePNGBitReader* reader, const HuffmanTree* codetree) {
	1096	unsigned short code = peekBits(reader, FIRSTBITS);
	1097	unsigned short l = codetree->table_len[code];
	1098	unsigned short value = codetree->table_value[code];
	1099	if(l <= FIRSTBITS) {
	1100	advanceBits(reader, l);
	1101	return value;
	1102	} else {
	1103	unsigned index2;
	1104	advanceBits(reader, FIRSTBITS);
	1105	index2 = value + peekBits(reader, l - FIRSTBITS);
	1106	advanceBits(reader, codetree->table_len[index2] - FIRSTBITS);
	1107	return codetree->table_value[index2];
	1108	}
	1109	}
	1110	#endif /LODEPNG_COMPILE_DECODER/
	1111
	1112	#ifdef LODEPNG_COMPILE_DECODER
	1113
	1114	/* ////////////////////////////////////////////////////////////////////////// */
	1115	/* / Inflator (Decompressor) / */
	1116	/* ////////////////////////////////////////////////////////////////////////// */
	1117
	1118	/get the tree of a deflated block with fixed tree, as specified in the deflate specification/
	1119	static void getTreeInflateFixed(HuffmanTree* tree_ll, HuffmanTree* tree_d) {
	1120	/TODO: check for out of memory errors/
	1121	generateFixedLitLenTree(tree_ll);
	1122	generateFixedDistanceTree(tree_d);
	1123	}
	1124
	1125	/get the tree of a deflated block with dynamic tree, the tree itself is also Huffman compressed with a known tree/
	1126	static unsigned getTreeInflateDynamic(HuffmanTree* tree_ll, HuffmanTree* tree_d,
	1127	LodePNGBitReader* reader) {
	1128	/make sure that length values that aren't filled in will be 0, or a wrong tree will be generated/
	1129	unsigned error = 0;
	1130	unsigned n, HLIT, HDIST, HCLEN, i;
	1131
	1132	/see comments in deflateDynamic for explanation of the context and these variables, it is analogous/
	1133	unsigned* bitlen_ll = 0; /lit,len code lengths/
	1134	unsigned* bitlen_d = 0; /dist code lengths/
	1135	/code length code lengths ("clcl"), the bit lengths of the huffman tree used to compress bitlen_ll and bitlen_d/
	1136	unsigned* bitlen_cl = 0;
	1137	HuffmanTree tree_cl; /the code tree for code length codes (the huffman tree for compressed huffman trees)/
	1138
	1139	if(!ensureBits17(reader, 14)) return 49; /error: the bit pointer is or will go past the memory/
	1140
	1141	/number of literal/length codes + 257. Unlike the spec, the value 257 is added to it here already/
	1142	HLIT = readBits(reader, 5) + 257;
	1143	/number of distance codes. Unlike the spec, the value 1 is added to it here already/
	1144	HDIST = readBits(reader, 5) + 1;
	1145	/number of code length codes. Unlike the spec, the value 4 is added to it here already/
	1146	HCLEN = readBits(reader, 4) + 4;
	1147
	1148	bitlen_cl = (unsigned)lodepng_malloc(NUM_CODE_LENGTH_CODES sizeof(unsigned));
	1149	if(!bitlen_cl) return 83 /alloc fail/;
	1150
	1151	HuffmanTree_init(&tree_cl);
	1152
	1153	while(!error) {
	1154	/read the code length codes out of 3 (amount of code length codes) bits*/
	1155	if(lodepng_gtofl(reader->bp, HCLEN * 3, reader->bitsize)) {
	1156	ERROR_BREAK(50); /error: the bit pointer is or will go past the memory/
	1157	}
	1158	for(i = 0; i != HCLEN; ++i) {
	1159	ensureBits9(reader, 3); /out of bounds already checked above /
	1160	bitlen_cl[CLCL_ORDER[i]] = readBits(reader, 3);
	1161	}
	1162	for(i = HCLEN; i != NUM_CODE_LENGTH_CODES; ++i) {
	1163	bitlen_cl[CLCL_ORDER[i]] = 0;
	1164	}
	1165
	1166	error = HuffmanTree_makeFromLengths(&tree_cl, bitlen_cl, NUM_CODE_LENGTH_CODES, 7);
	1167	if(error) break;
	1168
	1169	/now we can use this tree to read the lengths for the tree that this function will return/
	1170	bitlen_ll = (unsigned)lodepng_malloc(NUM_DEFLATE_CODE_SYMBOLS sizeof(unsigned));
	1171	bitlen_d = (unsigned)lodepng_malloc(NUM_DISTANCE_SYMBOLS sizeof(unsigned));
	1172	if(!bitlen_ll \|\| !bitlen_d) ERROR_BREAK(83 /alloc fail/);
	1173	for(i = 0; i != NUM_DEFLATE_CODE_SYMBOLS; ++i) bitlen_ll[i] = 0;
	1174	for(i = 0; i != NUM_DISTANCE_SYMBOLS; ++i) bitlen_d[i] = 0;
	1175
	1176	/i is the current symbol we're reading in the part that contains the code lengths of lit/len and dist codes/
	1177	i = 0;
	1178	while(i < HLIT + HDIST) {
	1179	unsigned code;
	1180	ensureBits25(reader, 22); /* up to 15 bits for huffman code, up to 7 extra bits below*/
	1181	code = huffmanDecodeSymbol(reader, &tree_cl);
	1182	if(code <= 15) /a length code/ {
	1183	if(i < HLIT) bitlen_ll[i] = code;
	1184	else bitlen_d[i - HLIT] = code;
	1185	++i;
	1186	} else if(code == 16) /repeat previous/ {
	1187	unsigned replength = 3; /read in the 2 bits that indicate repeat length (3-6)/
	1188	unsigned value; /set value to the previous code/
	1189
	1190	if(i == 0) ERROR_BREAK(54); /can't repeat previous if i is 0/
	1191
	1192	replength += readBits(reader, 2);
	1193
	1194	if(i < HLIT + 1) value = bitlen_ll[i - 1];
	1195	else value = bitlen_d[i - HLIT - 1];
	1196	/repeat this value in the next lengths/
	1197	for(n = 0; n < replength; ++n) {
	1198	if(i >= HLIT + HDIST) ERROR_BREAK(13); /error: i is larger than the amount of codes/
	1199	if(i < HLIT) bitlen_ll[i] = value;
	1200	else bitlen_d[i - HLIT] = value;
	1201	++i;
	1202	}
	1203	} else if(code == 17) /repeat "0" 3-10 times/ {
	1204	unsigned replength = 3; /read in the bits that indicate repeat length/
	1205	replength += readBits(reader, 3);
	1206
	1207	/repeat this value in the next lengths/
	1208	for(n = 0; n < replength; ++n) {
	1209	if(i >= HLIT + HDIST) ERROR_BREAK(14); /error: i is larger than the amount of codes/
	1210
	1211	if(i < HLIT) bitlen_ll[i] = 0;
	1212	else bitlen_d[i - HLIT] = 0;
	1213	++i;
	1214	}
	1215	} else if(code == 18) /repeat "0" 11-138 times/ {
	1216	unsigned replength = 11; /read in the bits that indicate repeat length/
	1217	replength += readBits(reader, 7);
	1218
	1219	/repeat this value in the next lengths/
	1220	for(n = 0; n < replength; ++n) {
	1221	if(i >= HLIT + HDIST) ERROR_BREAK(15); /error: i is larger than the amount of codes/
	1222
	1223	if(i < HLIT) bitlen_ll[i] = 0;
	1224	else bitlen_d[i - HLIT] = 0;
	1225	++i;
	1226	}
	1227	} else /if(code == (unsigned)(-1))/ /huffmanDecodeSymbol returns (unsigned)(-1) in case of error/ {
	1228	ERROR_BREAK(16); /nonexistent code, this can never happen/
	1229	}
	1230	/check if any of the ensureBits above went out of bounds/
	1231	if(reader->bp > reader->bitsize) {
	1232	/*return error code 10 or 11 depending on the situation that happened in huffmanDecodeSymbol
	1233	(10=no endcode, 11=wrong jump outside of tree)*/
	1234	/* TODO: revise error codes 10,11,50: the above comment is no longer valid */
	1235	ERROR_BREAK(50); /error, bit pointer jumps past memory/
	1236	}
	1237	}
	1238	if(error) break;
	1239
	1240	if(bitlen_ll[256] == 0) ERROR_BREAK(64); /the length of the end code 256 must be larger than 0/
	1241
	1242	/now we've finally got HLIT and HDIST, so generate the code trees, and the function is done/
	1243	error = HuffmanTree_makeFromLengths(tree_ll, bitlen_ll, NUM_DEFLATE_CODE_SYMBOLS, 15);
	1244	if(error) break;
	1245	error = HuffmanTree_makeFromLengths(tree_d, bitlen_d, NUM_DISTANCE_SYMBOLS, 15);
	1246
	1247	break; /end of error-while/
	1248	}
	1249
	1250	lodepng_free(bitlen_cl);
	1251	lodepng_free(bitlen_ll);
	1252	lodepng_free(bitlen_d);
	1253	HuffmanTree_cleanup(&tree_cl);
	1254
	1255	return error;
	1256	}
	1257
	1258	/inflate a block with dynamic of fixed Huffman tree. btype must be 1 or 2./
	1259	static unsigned inflateHuffmanBlock(ucvector* out, size_t* pos, LodePNGBitReader* reader,
	1260	unsigned btype) {
	1261	unsigned error = 0;
	1262	HuffmanTree tree_ll; /the huffman tree for literal and length codes/
	1263	HuffmanTree tree_d; /the huffman tree for distance codes/
	1264
	1265	HuffmanTree_init(&tree_ll);
	1266	HuffmanTree_init(&tree_d);
	1267
	1268	if(btype == 1) getTreeInflateFixed(&tree_ll, &tree_d);
	1269	else /if(btype == 2)/ error = getTreeInflateDynamic(&tree_ll, &tree_d, reader);
	1270
	1271	while(!error) /decode all symbols until end reached, breaks at end code/ {
	1272	/code_ll is literal, length or end code/
	1273	unsigned code_ll;
	1274	ensureBits25(reader, 20); /* up to 15 for the huffman symbol, up to 5 for the length extra bits */
	1275	code_ll = huffmanDecodeSymbol(reader, &tree_ll);
	1276	if(code_ll <= 255) /literal symbol/ {
	1277	/ucvector_push_back would do the same, but for some reason the two lines below run 10% faster/
	1278	if(!ucvector_resize(out, (pos) + 1)) ERROR_BREAK(83 /alloc fail*/);
	1279	out->data[*pos] = (unsigned char)code_ll;
	1280	++(*pos);
	1281	} else if(code_ll >= FIRST_LENGTH_CODE_INDEX && code_ll <= LAST_LENGTH_CODE_INDEX) /length code/ {
	1282	unsigned code_d, distance;
	1283	unsigned numextrabits_l, numextrabits_d; /extra bits for length and distance/
	1284	size_t start, backward, length;
	1285
	1286	/part 1: get length base/
	1287	length = LENGTHBASE[code_ll - FIRST_LENGTH_CODE_INDEX];
	1288
	1289	/part 2: get extra bits and add the value of that to length/
	1290	numextrabits_l = LENGTHEXTRA[code_ll - FIRST_LENGTH_CODE_INDEX];
	1291	if(numextrabits_l != 0) {
	1292	/* bits already ensured above */
	1293	length += readBits(reader, numextrabits_l);
	1294	}
	1295
	1296	/part 3: get distance code/
	1297	ensureBits32(reader, 28); /* up to 15 for the huffman symbol, up to 13 for the extra bits */
	1298	code_d = huffmanDecodeSymbol(reader, &tree_d);
	1299	if(code_d > 29) {
	1300	if(code_d == (unsigned)(-1)) /huffmanDecodeSymbol returns (unsigned)(-1) in case of error/ {
	1301	/*return error code 10 or 11 depending on the situation that happened in huffmanDecodeSymbol
	1302	(10=no endcode, 11=wrong jump outside of tree)*/
	1303	ERROR_BREAK((reader->bp > reader->bitsize) ? 10 : 11);
	1304	} else {
	1305	ERROR_BREAK(18); /error: invalid distance code (30-31 are never used)/
	1306	}
	1307	}
	1308	distance = DISTANCEBASE[code_d];
	1309
	1310	/part 4: get extra bits from distance/
	1311	numextrabits_d = DISTANCEEXTRA[code_d];
	1312	if(numextrabits_d != 0) {
	1313	/* bits already ensured above */
	1314	distance += readBits(reader, numextrabits_d);
	1315	}
	1316
	1317	/part 5: fill in all the out[n] values based on the length and dist/
	1318	start = (*pos);
	1319	if(distance > start) ERROR_BREAK(52); /too long backward distance/
	1320	backward = start - distance;
	1321
	1322	if(!ucvector_resize(out, (pos) + length)) ERROR_BREAK(83 /alloc fail*/);
	1323	if (distance < length) {
	1324	size_t forward;
	1325	lodepng_memcpy(out->data + *pos, out->data + backward, distance);
	1326	*pos += distance;
	1327	for(forward = distance; forward < length; ++forward) {
	1328	out->data[(*pos)++] = out->data[backward++];
	1329	}
	1330	} else {
	1331	lodepng_memcpy(out->data + *pos, out->data + backward, length);
	1332	*pos += length;
	1333	}
	1334	} else if(code_ll == 256) {
	1335	break; /end code, break the loop/
	1336	} else /if(code == (unsigned)(-1))/ /huffmanDecodeSymbol returns (unsigned)(-1) in case of error/ {
	1337	ERROR_BREAK(16) /* impossible */
	1338	}
	1339	/check if any of the ensureBits above went out of bounds/
	1340	if(reader->bp > reader->bitsize) {
	1341	/*return error code 10 or 11 depending on the situation that happened in huffmanDecodeSymbol
	1342	(10=no endcode, 11=wrong jump outside of tree)*/
	1343	/* TODO: revise error codes 10,11,50: the above comment is no longer valid */
	1344	ERROR_BREAK(51); /error, bit pointer jumps past memory/
	1345	}
	1346	}
	1347
	1348	HuffmanTree_cleanup(&tree_ll);
	1349	HuffmanTree_cleanup(&tree_d);
	1350
	1351	return error;
	1352	}
	1353
	1354	static unsigned inflateNoCompression(ucvector* out, size_t* pos,
	1355	LodePNGBitReader* reader, const LodePNGDecompressSettings* settings) {
	1356	size_t bytepos;
	1357	size_t size = reader->size;
	1358	unsigned LEN, NLEN, error = 0;
	1359
	1360	/go to first boundary of byte/
	1361	bytepos = (reader->bp + 7u) >> 3u;
	1362
	1363	/read LEN (2 bytes) and NLEN (2 bytes)/
	1364	if(bytepos + 4 >= size) return 52; /error, bit pointer will jump past memory/
	1365	LEN = (unsigned)reader->data[bytepos] + (unsigned)(reader->data[bytepos + 1] << 8u); bytepos += 2;
	1366	NLEN = (unsigned)reader->data[bytepos] + (unsigned)(reader->data[bytepos + 1] << 8u); bytepos += 2;
	1367
	1368	/check if 16-bit NLEN is really the one's complement of LEN/
	1369	if(!settings->ignore_nlen && LEN + NLEN != 65535) {
	1370	return 21; /error: NLEN is not one's complement of LEN/
	1371	}
	1372
	1373	if(!ucvector_resize(out, (pos) + LEN)) return 83; /alloc fail*/
	1374
	1375	/read the literal data: LEN bytes are now stored in the out buffer/
	1376	if(bytepos + LEN > size) return 23; /error: reading outside of in buffer/
	1377
	1378	lodepng_memcpy(out->data + *pos, reader->data + bytepos, LEN);
	1379	*pos += LEN;
	1380	bytepos += LEN;
	1381
	1382	reader->bp = bytepos << 3u;
	1383
	1384	return error;
	1385	}
	1386
	1387	static unsigned lodepng_inflatev(ucvector* out,
	1388	const unsigned char* in, size_t insize,
	1389	const LodePNGDecompressSettings* settings) {
	1390	unsigned BFINAL = 0;
	1391	size_t pos = 0; /byte position in the out buffer/
	1392	LodePNGBitReader reader;
	1393	unsigned error = LodePNGBitReader_init(&reader, in, insize);
	1394
	1395	if(error) return error;
	1396
	1397	while(!BFINAL) {
	1398	unsigned BTYPE;
	1399	if(!ensureBits9(&reader, 3)) return 52; /error, bit pointer will jump past memory/
	1400	BFINAL = readBits(&reader, 1);
	1401	BTYPE = readBits(&reader, 2);
	1402
	1403	if(BTYPE == 3) return 20; /error: invalid BTYPE/
	1404	else if(BTYPE == 0) error = inflateNoCompression(out, &pos, &reader, settings); /no compression/
	1405	else error = inflateHuffmanBlock(out, &pos, &reader, BTYPE); /compression, BTYPE 01 or 10/
	1406
	1407	if(error) return error;
	1408	}
	1409
	1410	return error;
	1411	}
	1412
	1413	unsigned lodepng_inflate(unsigned char** out, size_t* outsize,
	1414	const unsigned char* in, size_t insize,
	1415	const LodePNGDecompressSettings* settings) {
	1416	unsigned error;
	1417	ucvector v;
	1418	ucvector_init_buffer(&v, out, outsize);
	1419	error = lodepng_inflatev(&v, in, insize, settings);
	1420	*out = v.data;
	1421	*outsize = v.size;
	1422	return error;
	1423	}
	1424
	1425	static unsigned inflate(unsigned char** out, size_t* outsize,
	1426	const unsigned char* in, size_t insize,
	1427	const LodePNGDecompressSettings* settings) {
	1428	if(settings->custom_inflate) {
	1429	return settings->custom_inflate(out, outsize, in, insize, settings);
	1430	} else {
	1431	return lodepng_inflate(out, outsize, in, insize, settings);
	1432	}
	1433	}
	1434
	1435	#endif /LODEPNG_COMPILE_DECODER/
	1436
	1437	#ifdef LODEPNG_COMPILE_ENCODER
	1438
	1439	/* ////////////////////////////////////////////////////////////////////////// */
	1440	/* / Deflator (Compressor) / */
	1441	/* ////////////////////////////////////////////////////////////////////////// */
	1442
	1443	static const size_t MAX_SUPPORTED_DEFLATE_LENGTH = 258;
	1444
	1445	/*search the index in the array, that has the largest value smaller than or equal to the given value,
	1446	given array must be sorted (if no value is smaller, it returns the size of the given array)*/
	1447	static size_t searchCodeIndex(const unsigned* array, size_t array_size, size_t value) {
	1448	/binary search (only small gain over linear). TODO: use CPU log2 instruction for getting symbols instead/
	1449	size_t left = 1;
	1450	size_t right = array_size - 1;
	1451
	1452	while(left <= right) {
	1453	size_t mid = (left + right) >> 1;
	1454	if (array[mid] >= value) right = mid - 1;
	1455	else left = mid + 1;
	1456	}
	1457	if(left >= array_size \|\| array[left] > value) left--;
	1458	return left;
	1459	}
	1460
	1461	static void addLengthDistance(uivector* values, size_t length, size_t distance) {
	1462	/*values in encoded vector are those used by deflate:
	1463	0-255: literal bytes
	1464	256: end
	1465	257-285: length/distance pair (length code, followed by extra length bits, distance code, extra distance bits)
	1466	286-287: invalid*/
	1467
	1468	unsigned length_code = (unsigned)searchCodeIndex(LENGTHBASE, 29, length);
	1469	unsigned extra_length = (unsigned)(length - LENGTHBASE[length_code]);
	1470	unsigned dist_code = (unsigned)searchCodeIndex(DISTANCEBASE, 30, distance);
	1471	unsigned extra_distance = (unsigned)(distance - DISTANCEBASE[dist_code]);
	1472
	1473	uivector_push_back(values, length_code + FIRST_LENGTH_CODE_INDEX);
	1474	uivector_push_back(values, extra_length);
	1475	uivector_push_back(values, dist_code);
	1476	uivector_push_back(values, extra_distance);
	1477	}
	1478
	1479	/*3 bytes of data get encoded into two bytes. The hash cannot use more than 3
	1480	bytes as input because 3 is the minimum match length for deflate*/
	1481	static const unsigned HASH_NUM_VALUES = 65536;
	1482	static const unsigned HASH_BIT_MASK = 65535; /HASH_NUM_VALUES - 1, but C90 does not like that as initializer/
	1483
	1484	typedef struct Hash {
	1485	int* head; /hash value to head circular pos - can be outdated if went around window/
	1486	/circular pos to prev circular pos/
	1487	unsigned short* chain;
	1488	int* val; /circular pos to hash value/
	1489
	1490	/*TODO: do this not only for zeros but for any repeated byte. However for PNG
	1491	it's always going to be the zeros that dominate, so not important for PNG*/
	1492	int* headz; /similar to head, but for chainz/
	1493	unsigned short* chainz; /those with same amount of zeros/
	1494	unsigned short* zeros; /length of zeros streak, used as a second hash chain/
	1495	} Hash;
	1496
	1497	static unsigned hash_init(Hash* hash, unsigned windowsize) {
	1498	unsigned i;
	1499	hash->head = (int)lodepng_malloc(sizeof(int) HASH_NUM_VALUES);
	1500	hash->val = (int)lodepng_malloc(sizeof(int) windowsize);
	1501	hash->chain = (unsigned short)lodepng_malloc(sizeof(unsigned short) windowsize);
	1502
	1503	hash->zeros = (unsigned short)lodepng_malloc(sizeof(unsigned short) windowsize);
	1504	hash->headz = (int)lodepng_malloc(sizeof(int) (MAX_SUPPORTED_DEFLATE_LENGTH + 1));
	1505	hash->chainz = (unsigned short)lodepng_malloc(sizeof(unsigned short) windowsize);
	1506
	1507	if(!hash->head \|\| !hash->chain \|\| !hash->val \|\| !hash->headz\|\| !hash->chainz \|\| !hash->zeros) {
	1508	return 83; /alloc fail/
	1509	}
	1510
	1511	/initialize hash table/
	1512	for(i = 0; i != HASH_NUM_VALUES; ++i) hash->head[i] = -1;
	1513	for(i = 0; i != windowsize; ++i) hash->val[i] = -1;
	1514	for(i = 0; i != windowsize; ++i) hash->chain[i] = i; /same value as index indicates uninitialized/
	1515
	1516	for(i = 0; i <= MAX_SUPPORTED_DEFLATE_LENGTH; ++i) hash->headz[i] = -1;
	1517	for(i = 0; i != windowsize; ++i) hash->chainz[i] = i; /same value as index indicates uninitialized/
	1518
	1519	return 0;
	1520	}
	1521
	1522	static void hash_cleanup(Hash* hash) {
	1523	lodepng_free(hash->head);
	1524	lodepng_free(hash->val);
	1525	lodepng_free(hash->chain);
	1526
	1527	lodepng_free(hash->zeros);
	1528	lodepng_free(hash->headz);
	1529	lodepng_free(hash->chainz);
	1530	}
	1531
	1532
	1533
	1534	static unsigned getHash(const unsigned char* data, size_t size, size_t pos) {
	1535	unsigned result = 0;
	1536	if(pos + 2 < size) {
	1537	/*A simple shift and xor hash is used. Since the data of PNGs is dominated
	1538	by zeroes due to the filters, a better hash does not have a significant
	1539	effect on speed in traversing the chain, and causes more time spend on
	1540	calculating the hash.*/
	1541	result ^= (unsigned)(data[pos + 0] << 0u);
	1542	result ^= (unsigned)(data[pos + 1] << 4u);
	1543	result ^= (unsigned)(data[pos + 2] << 8u);
	1544	} else {
	1545	size_t amount, i;
	1546	if(pos >= size) return 0;
	1547	amount = size - pos;
	1548	for(i = 0; i != amount; ++i) result ^= (unsigned)(data[pos + i] << (i * 8u));
	1549	}
	1550	return result & HASH_BIT_MASK;
	1551	}
	1552
	1553	static unsigned countZeros(const unsigned char* data, size_t size, size_t pos) {
	1554	const unsigned char* start = data + pos;
	1555	const unsigned char* end = start + MAX_SUPPORTED_DEFLATE_LENGTH;
	1556	if(end > data + size) end = data + size;
	1557	data = start;
	1558	while(data != end && *data == 0) ++data;
	1559	/subtracting two addresses returned as 32-bit number (max value is MAX_SUPPORTED_DEFLATE_LENGTH)/
	1560	return (unsigned)(data - start);
	1561	}
	1562
	1563	/wpos = pos & (windowsize - 1)/
	1564	static void updateHashChain(Hash* hash, size_t wpos, unsigned hashval, unsigned short numzeros) {
	1565	hash->val[wpos] = (int)hashval;
	1566	if(hash->head[hashval] != -1) hash->chain[wpos] = hash->head[hashval];
	1567	hash->head[hashval] = (int)wpos;
	1568
	1569	hash->zeros[wpos] = numzeros;
	1570	if(hash->headz[numzeros] != -1) hash->chainz[wpos] = hash->headz[numzeros];
	1571	hash->headz[numzeros] = (int)wpos;
	1572	}
	1573
	1574	/*
	1575	LZ77-encode the data. Return value is error code. The input are raw bytes, the output
	1576	is in the form of unsigned integers with codes representing for example literal bytes, or
	1577	length/distance pairs.
	1578	It uses a hash table technique to let it encode faster. When doing LZ77 encoding, a
	1579	sliding window (of windowsize) is used, and all past bytes in that window can be used as
	1580	the "dictionary". A brute force search through all possible distances would be slow, and
	1581	this hash technique is one out of several ways to speed this up.
	1582	*/
	1583	static unsigned encodeLZ77(uivector* out, Hash* hash,
	1584	const unsigned char* in, size_t inpos, size_t insize, unsigned windowsize,
	1585	unsigned minmatch, unsigned nicematch, unsigned lazymatching) {
	1586	size_t pos;
	1587	unsigned i, error = 0;
	1588	/for large window lengths, assume the user wants no compression loss. Otherwise, max hash chain length speedup./
	1589	unsigned maxchainlength = windowsize >= 8192 ? windowsize : windowsize / 8u;
	1590	unsigned maxlazymatch = windowsize >= 8192 ? MAX_SUPPORTED_DEFLATE_LENGTH : 64;
	1591
	1592	unsigned usezeros = 1; /not sure if setting it to false for windowsize < 8192 is better or worse/
	1593	unsigned numzeros = 0;
	1594
	1595	unsigned offset; /the offset represents the distance in LZ77 terminology/
	1596	unsigned length;
	1597	unsigned lazy = 0;
	1598	unsigned lazylength = 0, lazyoffset = 0;
	1599	unsigned hashval;
	1600	unsigned current_offset, current_length;
	1601	unsigned prev_offset;
	1602	const unsigned char lastptr, foreptr, *backptr;
	1603	unsigned hashpos;
	1604
	1605	if(windowsize == 0 \|\| windowsize > 32768) return 60; /error: windowsize smaller/larger than allowed/
	1606	if((windowsize & (windowsize - 1)) != 0) return 90; /error: must be power of two/
	1607
	1608	if(nicematch > MAX_SUPPORTED_DEFLATE_LENGTH) nicematch = MAX_SUPPORTED_DEFLATE_LENGTH;
	1609
	1610	for(pos = inpos; pos < insize; ++pos) {
	1611	size_t wpos = pos & (windowsize - 1); /position for in 'circular' hash buffers/
	1612	unsigned chainlength = 0;
	1613
	1614	hashval = getHash(in, insize, pos);
	1615
	1616	if(usezeros && hashval == 0) {
	1617	if(numzeros == 0) numzeros = countZeros(in, insize, pos);
	1618	else if(pos + numzeros > insize \|\| in[pos + numzeros - 1] != 0) --numzeros;
	1619	} else {
	1620	numzeros = 0;
	1621	}
	1622
	1623	updateHashChain(hash, wpos, hashval, numzeros);
	1624
	1625	/the length and offset found for the current position/
	1626	length = 0;
	1627	offset = 0;
	1628
	1629	hashpos = hash->chain[wpos];
	1630
	1631	lastptr = &in[insize < pos + MAX_SUPPORTED_DEFLATE_LENGTH ? insize : pos + MAX_SUPPORTED_DEFLATE_LENGTH];
	1632
	1633	/search for the longest string/
	1634	prev_offset = 0;
	1635	for(;;) {
	1636	if(chainlength++ >= maxchainlength) break;
	1637	current_offset = (unsigned)(hashpos <= wpos ? wpos - hashpos : wpos - hashpos + windowsize);
	1638
	1639	if(current_offset < prev_offset) break; /stop when went completely around the circular buffer/
	1640	prev_offset = current_offset;
	1641	if(current_offset > 0) {
	1642	/test the next characters/
	1643	foreptr = &in[pos];
	1644	backptr = &in[pos - current_offset];
	1645
	1646	/common case in PNGs is lots of zeros. Quickly skip over them as a speedup/
	1647	if(numzeros >= 3) {
	1648	unsigned skip = hash->zeros[hashpos];
	1649	if(skip > numzeros) skip = numzeros;
	1650	backptr += skip;
	1651	foreptr += skip;
	1652	}
	1653
	1654	while(foreptr != lastptr && backptr == foreptr) /maximum supported length by deflate is max length/ {
	1655	++backptr;
	1656	++foreptr;
	1657	}
	1658	current_length = (unsigned)(foreptr - &in[pos]);
	1659
	1660	if(current_length > length) {
	1661	length = current_length; /the longest length/
	1662	offset = current_offset; /the offset that is related to this longest length/
	1663	/*jump out once a length of max length is found (speed gain). This also jumps
	1664	out if length is MAX_SUPPORTED_DEFLATE_LENGTH*/
	1665	if(current_length >= nicematch) break;
	1666	}
	1667	}
	1668
	1669	if(hashpos == hash->chain[hashpos]) break;
	1670
	1671	if(numzeros >= 3 && length > numzeros) {
	1672	hashpos = hash->chainz[hashpos];
	1673	if(hash->zeros[hashpos] != numzeros) break;
	1674	} else {
	1675	hashpos = hash->chain[hashpos];
	1676	/outdated hash value, happens if particular value was not encountered in whole last window/
	1677	if(hash->val[hashpos] != (int)hashval) break;
	1678	}
	1679	}
	1680
	1681	if(lazymatching) {
	1682	if(!lazy && length >= 3 && length <= maxlazymatch && length < MAX_SUPPORTED_DEFLATE_LENGTH) {
	1683	lazy = 1;
	1684	lazylength = length;
	1685	lazyoffset = offset;
	1686	continue; /try the next byte/
	1687	}
	1688	if(lazy) {
	1689	lazy = 0;
	1690	if(pos == 0) ERROR_BREAK(81);
	1691	if(length > lazylength + 1) {
	1692	/push the previous character as literal/
	1693	if(!uivector_push_back(out, in[pos - 1])) ERROR_BREAK(83 /alloc fail/);
	1694	} else {
	1695	length = lazylength;
	1696	offset = lazyoffset;
	1697	hash->head[hashval] = -1; /the same hashchain update will be done, this ensures no wrong alteration/
	1698	hash->headz[numzeros] = -1; /idem/
	1699	--pos;
	1700	}
	1701	}
	1702	}
	1703	if(length >= 3 && offset > windowsize) ERROR_BREAK(86 /too big (or overflown negative) offset/);
	1704
	1705	/encode it as length/distance pair or literal value/
	1706	if(length < 3) /only lengths of 3 or higher are supported as length/distance pair/ {
	1707	if(!uivector_push_back(out, in[pos])) ERROR_BREAK(83 /alloc fail/);
	1708	} else if(length < minmatch \|\| (length == 3 && offset > 4096)) {
	1709	/*compensate for the fact that longer offsets have more extra bits, a
	1710	length of only 3 may be not worth it then*/
	1711	if(!uivector_push_back(out, in[pos])) ERROR_BREAK(83 /alloc fail/);
	1712	} else {
	1713	addLengthDistance(out, length, offset);
	1714	for(i = 1; i < length; ++i) {
	1715	++pos;
	1716	wpos = pos & (windowsize - 1);
	1717	hashval = getHash(in, insize, pos);
	1718	if(usezeros && hashval == 0) {
	1719	if(numzeros == 0) numzeros = countZeros(in, insize, pos);
	1720	else if(pos + numzeros > insize \|\| in[pos + numzeros - 1] != 0) --numzeros;
	1721	} else {
	1722	numzeros = 0;
	1723	}
	1724	updateHashChain(hash, wpos, hashval, numzeros);
	1725	}
	1726	}
	1727	} /end of the loop through each character of input/
	1728
	1729	return error;
	1730	}
	1731
	1732	/* /////////////////////////////////////////////////////////////////////////// */
	1733
	1734	static unsigned deflateNoCompression(ucvector* out, const unsigned char* data, size_t datasize) {
	1735	/*non compressed deflate block data: 1 bit BFINAL,2 bits BTYPE,(5 bits): it jumps to start of next byte,
	1736	2 bytes LEN, 2 bytes NLEN, LEN bytes literal DATA*/
	1737
	1738	size_t i, j, numdeflateblocks = (datasize + 65534u) / 65535u;
	1739	unsigned datapos = 0;
	1740	for(i = 0; i != numdeflateblocks; ++i) {
	1741	unsigned BFINAL, BTYPE, LEN, NLEN;
	1742	unsigned char firstbyte;
	1743
	1744	BFINAL = (i == numdeflateblocks - 1);
	1745	BTYPE = 0;
	1746
	1747	firstbyte = (unsigned char)(BFINAL + ((BTYPE & 1) << 1) + ((BTYPE & 2) << 1));
	1748	ucvector_push_back(out, firstbyte);
	1749
	1750	LEN = 65535;
	1751	if(datasize - datapos < 65535u) LEN = (unsigned)datasize - datapos;
	1752	NLEN = 65535 - LEN;
	1753
	1754	ucvector_push_back(out, (unsigned char)(LEN & 255));
	1755	ucvector_push_back(out, (unsigned char)(LEN >> 8u));
	1756	ucvector_push_back(out, (unsigned char)(NLEN & 255));
	1757	ucvector_push_back(out, (unsigned char)(NLEN >> 8u));
	1758
	1759	/Decompressed data/
	1760	for(j = 0; j < 65535 && datapos < datasize; ++j) {
	1761	ucvector_push_back(out, data[datapos++]);
	1762	}
	1763	}
	1764
	1765	return 0;
	1766	}
	1767
	1768	/*
	1769	write the lz77-encoded data, which has lit, len and dist codes, to compressed stream using huffman trees.
	1770	tree_ll: the tree for lit and len codes.
	1771	tree_d: the tree for distance codes.
	1772	*/
	1773	static void writeLZ77data(LodePNGBitWriter* writer, const uivector* lz77_encoded,
	1774	const HuffmanTree* tree_ll, const HuffmanTree* tree_d) {
	1775	size_t i = 0;
	1776	for(i = 0; i != lz77_encoded->size; ++i) {
	1777	unsigned val = lz77_encoded->data[i];
	1778	writeBitsReversed(writer, HuffmanTree_getCode(tree_ll, val), HuffmanTree_getLength(tree_ll, val));
	1779	if(val > 256) /for a length code, 3 more things have to be added/ {
	1780	unsigned length_index = val - FIRST_LENGTH_CODE_INDEX;
	1781	unsigned n_length_extra_bits = LENGTHEXTRA[length_index];
	1782	unsigned length_extra_bits = lz77_encoded->data[++i];
	1783
	1784	unsigned distance_code = lz77_encoded->data[++i];
	1785
	1786	unsigned distance_index = distance_code;
	1787	unsigned n_distance_extra_bits = DISTANCEEXTRA[distance_index];
	1788	unsigned distance_extra_bits = lz77_encoded->data[++i];
	1789
	1790	writeBits(writer, length_extra_bits, n_length_extra_bits);
	1791	writeBitsReversed(writer, HuffmanTree_getCode(tree_d, distance_code),
	1792	HuffmanTree_getLength(tree_d, distance_code));
	1793	writeBits(writer, distance_extra_bits, n_distance_extra_bits);
	1794	}
	1795	}
	1796	}
	1797
	1798	/Deflate for a block of type "dynamic", that is, with freely, optimally, created huffman trees/
	1799	static unsigned deflateDynamic(LodePNGBitWriter* writer, Hash* hash,
	1800	const unsigned char* data, size_t datapos, size_t dataend,
	1801	const LodePNGCompressSettings* settings, unsigned final) {
	1802	unsigned error = 0;
	1803
	1804	/*
	1805	A block is compressed as follows: The PNG data is lz77 encoded, resulting in
	1806	literal bytes and length/distance pairs. This is then huffman compressed with
	1807	two huffman trees. One huffman tree is used for the lit and len values ("ll"),
	1808	another huffman tree is used for the dist values ("d"). These two trees are
	1809	stored using their code lengths, and to compress even more these code lengths
	1810	are also run-length encoded and huffman compressed. This gives a huffman tree
	1811	of code lengths "cl". The code lengths used to describe this third tree are
	1812	the code length code lengths ("clcl").
	1813	*/
	1814
	1815	/The lz77 encoded data, represented with integers since there will also be length and distance codes in it/
	1816	uivector lz77_encoded;
	1817	HuffmanTree tree_ll; /tree for lit,len values/
	1818	HuffmanTree tree_d; /tree for distance codes/
	1819	HuffmanTree tree_cl; /tree for encoding the code lengths representing tree_ll and tree_d/
	1820	uivector frequencies_ll; /frequency of lit,len codes/
	1821	uivector frequencies_d; /frequency of dist codes/
	1822	uivector frequencies_cl; /frequency of code length codes/
	1823	uivector bitlen_lld; /lit,len,dist code lengths (int bits), literally (without repeat codes)./
	1824	uivector bitlen_lld_e; /bitlen_lld encoded with repeat codes (this is a rudimentary run length compression)/
	1825	/*bitlen_cl is the code length code lengths ("clcl"). The bit lengths of codes to represent tree_cl
	1826	(these are written as is in the file, it would be crazy to compress these using yet another huffman
	1827	tree that needs to be represented by yet another set of code lengths)*/
	1828	uivector bitlen_cl;
	1829	size_t datasize = dataend - datapos;
	1830
	1831	/*
	1832	Due to the huffman compression of huffman tree representations ("two levels"), there are some analogies:
	1833	bitlen_lld is to tree_cl what data is to tree_ll and tree_d.
	1834	bitlen_lld_e is to bitlen_lld what lz77_encoded is to data.
	1835	bitlen_cl is to bitlen_lld_e what bitlen_lld is to lz77_encoded.
	1836	*/
	1837
	1838	unsigned BFINAL = final;
	1839	size_t numcodes_ll, numcodes_d, i;
	1840	unsigned HLIT, HDIST, HCLEN;
	1841
	1842	uivector_init(&lz77_encoded);
	1843	HuffmanTree_init(&tree_ll);
	1844	HuffmanTree_init(&tree_d);
	1845	HuffmanTree_init(&tree_cl);
	1846	uivector_init(&frequencies_ll);
	1847	uivector_init(&frequencies_d);
	1848	uivector_init(&frequencies_cl);
	1849	uivector_init(&bitlen_lld);
	1850	uivector_init(&bitlen_lld_e);
	1851	uivector_init(&bitlen_cl);
	1852
	1853	/*This while loop never loops due to a break at the end, it is here to
	1854	allow breaking out of it to the cleanup phase on error conditions.*/
	1855	while(!error) {
	1856	if(settings->use_lz77) {
	1857	error = encodeLZ77(&lz77_encoded, hash, data, datapos, dataend, settings->windowsize,
	1858	settings->minmatch, settings->nicematch, settings->lazymatching);
	1859	if(error) break;
	1860	} else {
	1861	if(!uivector_resize(&lz77_encoded, datasize)) ERROR_BREAK(83 /alloc fail/);
	1862	for(i = datapos; i < dataend; ++i) lz77_encoded.data[i - datapos] = data[i]; /no LZ77, but still will be Huffman compressed/
	1863	}
	1864
	1865	if(!uivector_resizev(&frequencies_ll, 286, 0)) ERROR_BREAK(83 /alloc fail/);
	1866	if(!uivector_resizev(&frequencies_d, 30, 0)) ERROR_BREAK(83 /alloc fail/);
	1867
	1868	/Count the frequencies of lit, len and dist codes/
	1869	for(i = 0; i != lz77_encoded.size; ++i) {
	1870	unsigned symbol = lz77_encoded.data[i];
	1871	++frequencies_ll.data[symbol];
	1872	if(symbol > 256) {
	1873	unsigned dist = lz77_encoded.data[i + 2];
	1874	++frequencies_d.data[dist];
	1875	i += 3;
	1876	}
	1877	}
	1878	frequencies_ll.data[256] = 1; /there will be exactly 1 end code, at the end of the block/
	1879
	1880	/Make both huffman trees, one for the lit and len codes, one for the dist codes/
	1881	error = HuffmanTree_makeFromFrequencies(&tree_ll, frequencies_ll.data, 257, frequencies_ll.size, 15);
	1882	if(error) break;
	1883	/2, not 1, is chosen for mincodes: some buggy PNG decoders require at least 2 symbols in the dist tree/
	1884	error = HuffmanTree_makeFromFrequencies(&tree_d, frequencies_d.data, 2, frequencies_d.size, 15);
	1885	if(error) break;
	1886
	1887	numcodes_ll = tree_ll.numcodes; if(numcodes_ll > 286) numcodes_ll = 286;
	1888	numcodes_d = tree_d.numcodes; if(numcodes_d > 30) numcodes_d = 30;
	1889	/store the code lengths of both generated trees in bitlen_lld/
	1890	for(i = 0; i != numcodes_ll; ++i) uivector_push_back(&bitlen_lld, HuffmanTree_getLength(&tree_ll, (unsigned)i));
	1891	for(i = 0; i != numcodes_d; ++i) uivector_push_back(&bitlen_lld, HuffmanTree_getLength(&tree_d, (unsigned)i));
	1892
	1893	/*run-length compress bitlen_ldd into bitlen_lld_e by using repeat codes 16 (copy length 3-6 times),
	1894	17 (3-10 zeroes), 18 (11-138 zeroes)*/
	1895	for(i = 0; i != (unsigned)bitlen_lld.size; ++i) {
	1896	unsigned j = 0; /amount of repetitions/
	1897	while(i + j + 1 < (unsigned)bitlen_lld.size && bitlen_lld.data[i + j + 1] == bitlen_lld.data[i]) ++j;
	1898
	1899	if(bitlen_lld.data[i] == 0 && j >= 2) /repeat code for zeroes/ {
	1900	++j; /include the first zero/
	1901	if(j <= 10) /repeat code 17 supports max 10 zeroes/ {
	1902	uivector_push_back(&bitlen_lld_e, 17);
	1903	uivector_push_back(&bitlen_lld_e, j - 3);
	1904	} else /repeat code 18 supports max 138 zeroes/ {
	1905	if(j > 138) j = 138;
	1906	uivector_push_back(&bitlen_lld_e, 18);
	1907	uivector_push_back(&bitlen_lld_e, j - 11);
	1908	}
	1909	i += (j - 1);
	1910	} else if(j >= 3) /repeat code for value other than zero/ {
	1911	size_t k;
	1912	unsigned num = j / 6u, rest = j % 6u;
	1913	uivector_push_back(&bitlen_lld_e, bitlen_lld.data[i]);
	1914	for(k = 0; k < num; ++k) {
	1915	uivector_push_back(&bitlen_lld_e, 16);
	1916	uivector_push_back(&bitlen_lld_e, 6 - 3);
	1917	}
	1918	if(rest >= 3) {
	1919	uivector_push_back(&bitlen_lld_e, 16);
	1920	uivector_push_back(&bitlen_lld_e, rest - 3);
	1921	}
	1922	else j -= rest;
	1923	i += j;
	1924	} else /too short to benefit from repeat code/ {
	1925	uivector_push_back(&bitlen_lld_e, bitlen_lld.data[i]);
	1926	}
	1927	}
	1928
	1929	/generate tree_cl, the huffmantree of huffmantrees/
	1930
	1931	if(!uivector_resizev(&frequencies_cl, NUM_CODE_LENGTH_CODES, 0)) ERROR_BREAK(83 /alloc fail/);
	1932	for(i = 0; i != bitlen_lld_e.size; ++i) {
	1933	++frequencies_cl.data[bitlen_lld_e.data[i]];
	1934	/*after a repeat code come the bits that specify the number of repetitions,
	1935	those don't need to be in the frequencies_cl calculation*/
	1936	if(bitlen_lld_e.data[i] >= 16) ++i;
	1937	}
	1938
	1939	error = HuffmanTree_makeFromFrequencies(&tree_cl, frequencies_cl.data,
	1940	frequencies_cl.size, frequencies_cl.size, 7);
	1941	if(error) break;
	1942
	1943	if(!uivector_resize(&bitlen_cl, tree_cl.numcodes)) ERROR_BREAK(83 /alloc fail/);
	1944	for(i = 0; i != tree_cl.numcodes; ++i) {
	1945	/lengths of code length tree is in the order as specified by deflate/
	1946	bitlen_cl.data[i] = HuffmanTree_getLength(&tree_cl, CLCL_ORDER[i]);
	1947	}
	1948	while(bitlen_cl.data[bitlen_cl.size - 1] == 0 && bitlen_cl.size > 4) {
	1949	/remove zeros at the end, but minimum size must be 4/
	1950	if(!uivector_resize(&bitlen_cl, bitlen_cl.size - 1)) ERROR_BREAK(83 /alloc fail/);
	1951	}
	1952	if(error) break;
	1953
	1954	/*
	1955	Write everything into the output
	1956
	1957	After the BFINAL and BTYPE, the dynamic block consists out of the following:
	1958	- 5 bits HLIT, 5 bits HDIST, 4 bits HCLEN
	1959	- (HCLEN+4)*3 bits code lengths of code length alphabet
	1960	- HLIT + 257 code lengths of lit/length alphabet (encoded using the code length
	1961	alphabet, + possible repetition codes 16, 17, 18)
	1962	- HDIST + 1 code lengths of distance alphabet (encoded using the code length
	1963	alphabet, + possible repetition codes 16, 17, 18)
	1964	- compressed data
	1965	- 256 (end code)
	1966	*/
	1967
	1968	/Write block type/
	1969	writeBits(writer, BFINAL, 1);
	1970	writeBits(writer, 0, 1); /first bit of BTYPE "dynamic"/
	1971	writeBits(writer, 1, 1); /second bit of BTYPE "dynamic"/
	1972
	1973	/write the HLIT, HDIST and HCLEN values/
	1974	HLIT = (unsigned)(numcodes_ll - 257);
	1975	HDIST = (unsigned)(numcodes_d - 1);
	1976	HCLEN = (unsigned)bitlen_cl.size - 4;
	1977	/trim zeroes for HCLEN. HLIT and HDIST were already trimmed at tree creation/
	1978	while(!bitlen_cl.data[HCLEN + 4 - 1] && HCLEN > 0) --HCLEN;
	1979	writeBits(writer, HLIT, 5);
	1980	writeBits(writer, HDIST, 5);
	1981	writeBits(writer, HCLEN, 4);
	1982
	1983	/write the code lengths of the code length alphabet/
	1984	for(i = 0; i != HCLEN + 4; ++i) writeBits(writer, bitlen_cl.data[i], 3);
	1985
	1986	/write the lengths of the lit/len AND the dist alphabet/
	1987	for(i = 0; i != bitlen_lld_e.size; ++i) {
	1988	writeBitsReversed(writer, HuffmanTree_getCode(&tree_cl, bitlen_lld_e.data[i]),
	1989	HuffmanTree_getLength(&tree_cl, bitlen_lld_e.data[i]));
	1990	/extra bits of repeat codes/
	1991	if(bitlen_lld_e.data[i] == 16) writeBits(writer, bitlen_lld_e.data[++i], 2);
	1992	else if(bitlen_lld_e.data[i] == 17) writeBits(writer, bitlen_lld_e.data[++i], 3);
	1993	else if(bitlen_lld_e.data[i] == 18) writeBits(writer, bitlen_lld_e.data[++i], 7);
	1994	}
	1995
	1996	/write the compressed data symbols/
	1997	writeLZ77data(writer, &lz77_encoded, &tree_ll, &tree_d);
	1998	/error: the length of the end code 256 must be larger than 0/
	1999	if(HuffmanTree_getLength(&tree_ll, 256) == 0) ERROR_BREAK(64);
	2000
	2001	/write the end code/
	2002	writeBitsReversed(writer, HuffmanTree_getCode(&tree_ll, 256), HuffmanTree_getLength(&tree_ll, 256));
	2003
	2004	break; /end of error-while/
	2005	}
	2006
	2007	/cleanup/
	2008	uivector_cleanup(&lz77_encoded);
	2009	HuffmanTree_cleanup(&tree_ll);
	2010	HuffmanTree_cleanup(&tree_d);
	2011	HuffmanTree_cleanup(&tree_cl);
	2012	uivector_cleanup(&frequencies_ll);
	2013	uivector_cleanup(&frequencies_d);
	2014	uivector_cleanup(&frequencies_cl);
	2015	uivector_cleanup(&bitlen_lld_e);
	2016	uivector_cleanup(&bitlen_lld);
	2017	uivector_cleanup(&bitlen_cl);
	2018
	2019	return error;
	2020	}
	2021
	2022	static unsigned deflateFixed(LodePNGBitWriter* writer, Hash* hash,
	2023	const unsigned char* data,
	2024	size_t datapos, size_t dataend,
	2025	const LodePNGCompressSettings* settings, unsigned final) {
	2026	HuffmanTree tree_ll; /tree for literal values and length codes/
	2027	HuffmanTree tree_d; /tree for distance codes/
	2028
	2029	unsigned BFINAL = final;
	2030	unsigned error = 0;
	2031	size_t i;
	2032
	2033	HuffmanTree_init(&tree_ll);
	2034	HuffmanTree_init(&tree_d);
	2035
	2036	generateFixedLitLenTree(&tree_ll);
	2037	generateFixedDistanceTree(&tree_d);
	2038
	2039	writeBits(writer, BFINAL, 1);
	2040	writeBits(writer, 1, 1); /first bit of BTYPE/
	2041	writeBits(writer, 0, 1); /second bit of BTYPE/
	2042
	2043	if(settings->use_lz77) /LZ77 encoded/ {
	2044	uivector lz77_encoded;
	2045	uivector_init(&lz77_encoded);
	2046	error = encodeLZ77(&lz77_encoded, hash, data, datapos, dataend, settings->windowsize,
	2047	settings->minmatch, settings->nicematch, settings->lazymatching);
	2048	if(!error) writeLZ77data(writer, &lz77_encoded, &tree_ll, &tree_d);
	2049	uivector_cleanup(&lz77_encoded);
	2050	} else /no LZ77, but still will be Huffman compressed/ {
	2051	for(i = datapos; i < dataend; ++i) {
	2052	writeBitsReversed(writer, HuffmanTree_getCode(&tree_ll, data[i]), HuffmanTree_getLength(&tree_ll, data[i]));
	2053	}
	2054	}
	2055	/add END code/
	2056	if(!error) writeBitsReversed(writer, HuffmanTree_getCode(&tree_ll, 256), HuffmanTree_getLength(&tree_ll, 256));
	2057
	2058	/cleanup/
	2059	HuffmanTree_cleanup(&tree_ll);
	2060	HuffmanTree_cleanup(&tree_d);
	2061
	2062	return error;
	2063	}
	2064
	2065	static unsigned lodepng_deflatev(ucvector* out, const unsigned char* in, size_t insize,
	2066	const LodePNGCompressSettings* settings) {
	2067	unsigned error = 0;
	2068	size_t i, blocksize, numdeflateblocks;
	2069	Hash hash;
	2070	LodePNGBitWriter writer;
	2071
	2072	LodePNGBitWriter_init(&writer, out);
	2073
	2074	if(settings->btype > 2) return 61;
	2075	else if(settings->btype == 0) return deflateNoCompression(out, in, insize);
	2076	else if(settings->btype == 1) blocksize = insize;
	2077	else /if(settings->btype == 2)/ {
	2078	/on PNGs, deflate blocks of 65-262k seem to give most dense encoding/
	2079	blocksize = insize / 8u + 8;
	2080	if(blocksize < 65536) blocksize = 65536;
	2081	if(blocksize > 262144) blocksize = 262144;
	2082	}
	2083
	2084	numdeflateblocks = (insize + blocksize - 1) / blocksize;
	2085	if(numdeflateblocks == 0) numdeflateblocks = 1;
	2086
	2087	error = hash_init(&hash, settings->windowsize);
	2088	if(error) return error;
	2089
	2090	for(i = 0; i != numdeflateblocks && !error; ++i) {
	2091	unsigned final = (i == numdeflateblocks - 1);
	2092	size_t start = i * blocksize;
	2093	size_t end = start + blocksize;
	2094	if(end > insize) end = insize;
	2095
	2096	if(settings->btype == 1) error = deflateFixed(&writer, &hash, in, start, end, settings, final);
	2097	else if(settings->btype == 2) error = deflateDynamic(&writer, &hash, in, start, end, settings, final);
	2098	}
	2099
	2100	hash_cleanup(&hash);
	2101
	2102	return error;
	2103	}
	2104
	2105	unsigned lodepng_deflate(unsigned char** out, size_t* outsize,
	2106	const unsigned char* in, size_t insize,
	2107	const LodePNGCompressSettings* settings) {
	2108	unsigned error;
	2109	ucvector v;
	2110	ucvector_init_buffer(&v, out, outsize);
	2111	error = lodepng_deflatev(&v, in, insize, settings);
	2112	*out = v.data;
	2113	*outsize = v.size;
	2114	return error;
	2115	}
	2116
	2117	static unsigned deflate(unsigned char** out, size_t* outsize,
	2118	const unsigned char* in, size_t insize,
	2119	const LodePNGCompressSettings* settings) {
	2120	if(settings->custom_deflate) {
	2121	return settings->custom_deflate(out, outsize, in, insize, settings);
	2122	} else {
	2123	return lodepng_deflate(out, outsize, in, insize, settings);
	2124	}
	2125	}
	2126
	2127	#endif /LODEPNG_COMPILE_DECODER/
	2128
	2129	/* ////////////////////////////////////////////////////////////////////////// */
	2130	/* / Adler32 / */
	2131	/* ////////////////////////////////////////////////////////////////////////// */
	2132
	2133	static unsigned update_adler32(unsigned adler, const unsigned char* data, unsigned len) {
	2134	unsigned s1 = adler & 0xffffu;
	2135	unsigned s2 = (adler >> 16u) & 0xffffu;
	2136
	2137	while(len != 0u) {
	2138	unsigned i;
	2139	/at least 5552 sums can be done before the sums overflow, saving a lot of module divisions/
	2140	unsigned amount = len > 5552u ? 5552u : len;
	2141	len -= amount;
	2142	for(i = 0; i != amount; ++i) {
	2143	s1 += (*data++);
	2144	s2 += s1;
	2145	}
	2146	s1 %= 65521u;
	2147	s2 %= 65521u;
	2148	}
	2149
	2150	return (s2 << 16u) \| s1;
	2151	}
	2152
	2153	/Return the adler32 of the bytes data[0..len-1]/
	2154	static unsigned adler32(const unsigned char* data, unsigned len) {
	2155	return update_adler32(1u, data, len);
	2156	}
	2157
	2158	/* ////////////////////////////////////////////////////////////////////////// */
	2159	/* / Zlib / */
	2160	/* ////////////////////////////////////////////////////////////////////////// */
	2161
	2162	#ifdef LODEPNG_COMPILE_DECODER
	2163
	2164	unsigned lodepng_zlib_decompress(unsigned char** out, size_t* outsize, const unsigned char* in,
	2165	size_t insize, const LodePNGDecompressSettings* settings) {
	2166	unsigned error = 0;
	2167	unsigned CM, CINFO, FDICT;
	2168
	2169	if(insize < 2) return 53; /error, size of zlib data too small/
	2170	/read information from zlib header/
	2171	if((in[0] * 256 + in[1]) % 31 != 0) {
	2172	/error: 256 in[0] + in[1] must be a multiple of 31, the FCHECK value is supposed to be made that way*/
	2173	return 24;
	2174	}
	2175
	2176	CM = in[0] & 15;
	2177	CINFO = (in[0] >> 4) & 15;
	2178	/FCHECK = in[1] & 31;/ /FCHECK is already tested above/
	2179	FDICT = (in[1] >> 5) & 1;
	2180	/FLEVEL = (in[1] >> 6) & 3;/ /FLEVEL is not used here/
	2181
	2182	if(CM != 8 \|\| CINFO > 7) {
	2183	/error: only compression method 8: inflate with sliding window of 32k is supported by the PNG spec/
	2184	return 25;
	2185	}
	2186	if(FDICT != 0) {
	2187	/*error: the specification of PNG says about the zlib stream:
	2188	"The additional flags shall not specify a preset dictionary."*/
	2189	return 26;
	2190	}
	2191
	2192	error = inflate(out, outsize, in + 2, insize - 2, settings);
	2193	if(error) return error;
	2194
	2195	if(!settings->ignore_adler32) {
	2196	unsigned ADLER32 = lodepng_read32bitInt(&in[insize - 4]);
	2197	unsigned checksum = adler32(out, (unsigned)(outsize));
	2198	if(checksum != ADLER32) return 58; /error, adler checksum not correct, data must be corrupted/
	2199	}
	2200
	2201	return 0; /no error/
	2202	}
	2203
	2204	static unsigned zlib_decompress(unsigned char** out, size_t* outsize, const unsigned char* in,
	2205	size_t insize, const LodePNGDecompressSettings* settings) {
	2206	if(settings->custom_zlib) {
	2207	return settings->custom_zlib(out, outsize, in, insize, settings);
	2208	} else {
	2209	return lodepng_zlib_decompress(out, outsize, in, insize, settings);
	2210	}
	2211	}
	2212
	2213	#endif /LODEPNG_COMPILE_DECODER/
	2214
	2215	#ifdef LODEPNG_COMPILE_ENCODER
	2216
	2217	unsigned lodepng_zlib_compress(unsigned char** out, size_t* outsize, const unsigned char* in,
	2218	size_t insize, const LodePNGCompressSettings* settings) {
	2219	size_t i;
	2220	unsigned error;
	2221	unsigned char* deflatedata = 0;
	2222	size_t deflatesize = 0;
	2223
	2224	error = deflate(&deflatedata, &deflatesize, in, insize, settings);
	2225
	2226	*out = NULL;
	2227	*outsize = 0;
	2228	if(!error) {
	2229	*outsize = deflatesize + 6;
	2230	out = (unsigned char)lodepng_malloc(*outsize);
	2231	if(!out) error = 83; /alloc fail/
	2232	}
	2233
	2234	if(!error) {
	2235	unsigned ADLER32 = adler32(in, (unsigned)insize);
	2236	/zlib data: 1 byte CMF (CM+CINFO), 1 byte FLG, deflate data, 4 byte ADLER32 checksum of the Decompressed data/
	2237	unsigned CMF = 120; /0b01111000: CM 8, CINFO 7. With CINFO 7, any window size up to 32768 can be used./
	2238	unsigned FLEVEL = 0;
	2239	unsigned FDICT = 0;
	2240	unsigned CMFFLG = 256 * CMF + FDICT * 32 + FLEVEL * 64;
	2241	unsigned FCHECK = 31 - CMFFLG % 31;
	2242	CMFFLG += FCHECK;
	2243
	2244	(*out)[0] = (unsigned char)(CMFFLG >> 8);
	2245	(*out)[1] = (unsigned char)(CMFFLG & 255);
	2246	for(i = 0; i != deflatesize; ++i) (*out)[i + 2] = deflatedata[i];
	2247	lodepng_set32bitInt(&(out)[outsize - 4], ADLER32);
	2248	}
	2249
	2250	lodepng_free(deflatedata);
	2251	return error;
	2252	}
	2253
	2254	/* compress using the default or custom zlib function */
	2255	static unsigned zlib_compress(unsigned char** out, size_t* outsize, const unsigned char* in,
	2256	size_t insize, const LodePNGCompressSettings* settings) {
	2257	if(settings->custom_zlib) {
	2258	return settings->custom_zlib(out, outsize, in, insize, settings);
	2259	} else {
	2260	return lodepng_zlib_compress(out, outsize, in, insize, settings);
	2261	}
	2262	}
	2263
	2264	#endif /LODEPNG_COMPILE_ENCODER/
	2265
	2266	#else /no LODEPNG_COMPILE_ZLIB/
	2267
	2268	#ifdef LODEPNG_COMPILE_DECODER
	2269	static unsigned zlib_decompress(unsigned char** out, size_t* outsize, const unsigned char* in,
	2270	size_t insize, const LodePNGDecompressSettings* settings) {
	2271	if(!settings->custom_zlib) return 87; /no custom zlib function provided /
	2272	return settings->custom_zlib(out, outsize, in, insize, settings);
	2273	}
	2274	#endif /LODEPNG_COMPILE_DECODER/
	2275	#ifdef LODEPNG_COMPILE_ENCODER
	2276	static unsigned zlib_compress(unsigned char** out, size_t* outsize, const unsigned char* in,
	2277	size_t insize, const LodePNGCompressSettings* settings) {
	2278	if(!settings->custom_zlib) return 87; /no custom zlib function provided /
	2279	return settings->custom_zlib(out, outsize, in, insize, settings);
	2280	}
	2281	#endif /LODEPNG_COMPILE_ENCODER/
	2282
	2283	#endif /LODEPNG_COMPILE_ZLIB/
	2284
	2285	/* ////////////////////////////////////////////////////////////////////////// */
	2286
	2287	#ifdef LODEPNG_COMPILE_ENCODER
	2288
	2289	/this is a good tradeoff between speed and compression ratio/
	2290	#define DEFAULT_WINDOWSIZE 2048
	2291
	2292	void lodepng_compress_settings_init(LodePNGCompressSettings* settings) {
	2293	/compress with dynamic huffman tree (not in the mathematical sense, just not the predefined one)/
	2294	settings->btype = 2;
	2295	settings->use_lz77 = 1;
	2296	settings->windowsize = DEFAULT_WINDOWSIZE;
	2297	settings->minmatch = 3;
	2298	settings->nicematch = 128;
	2299	settings->lazymatching = 1;
	2300
	2301	settings->custom_zlib = 0;
	2302	settings->custom_deflate = 0;
	2303	settings->custom_context = 0;
	2304	}
	2305
	2306	const LodePNGCompressSettings lodepng_default_compress_settings = {2, 1, DEFAULT_WINDOWSIZE, 3, 128, 1, 0, 0, 0};
	2307
	2308
	2309	#endif /LODEPNG_COMPILE_ENCODER/
	2310
	2311	#ifdef LODEPNG_COMPILE_DECODER
	2312
	2313	void lodepng_decompress_settings_init(LodePNGDecompressSettings* settings) {
	2314	settings->ignore_adler32 = 0;
	2315	settings->ignore_nlen = 0;
	2316
	2317	settings->custom_zlib = 0;
	2318	settings->custom_inflate = 0;
	2319	settings->custom_context = 0;
	2320	}
	2321
	2322	const LodePNGDecompressSettings lodepng_default_decompress_settings = {0, 0, 0, 0, 0};
	2323
	2324	#endif /LODEPNG_COMPILE_DECODER/
	2325
	2326	/* ////////////////////////////////////////////////////////////////////////// */
	2327	/* ////////////////////////////////////////////////////////////////////////// */
	2328	/* // End of Zlib related code. Begin of PNG related code. // */
	2329	/* ////////////////////////////////////////////////////////////////////////// */
	2330	/* ////////////////////////////////////////////////////////////////////////// */
	2331
	2332	#ifdef LODEPNG_COMPILE_PNG
	2333
	2334	/* ////////////////////////////////////////////////////////////////////////// */
	2335	/* / CRC32 / */
	2336	/* ////////////////////////////////////////////////////////////////////////// */
	2337
	2338
	2339	#ifndef LODEPNG_NO_COMPILE_CRC
	2340	/* CRC polynomial: 0xedb88320 */
	2341	static unsigned lodepng_crc32_table[256] = {
	2342	0u, 1996959894u, 3993919788u, 2567524794u, 124634137u, 1886057615u, 3915621685u, 2657392035u,
	2343	249268274u, 2044508324u, 3772115230u, 2547177864u, 162941995u, 2125561021u, 3887607047u, 2428444049u,
	2344	498536548u, 1789927666u, 4089016648u, 2227061214u, 450548861u, 1843258603u, 4107580753u, 2211677639u,
	2345	325883990u, 1684777152u, 4251122042u, 2321926636u, 335633487u, 1661365465u, 4195302755u, 2366115317u,
	2346	997073096u, 1281953886u, 3579855332u, 2724688242u, 1006888145u, 1258607687u, 3524101629u, 2768942443u,
	2347	901097722u, 1119000684u, 3686517206u, 2898065728u, 853044451u, 1172266101u, 3705015759u, 2882616665u,
	2348	651767980u, 1373503546u, 3369554304u, 3218104598u, 565507253u, 1454621731u, 3485111705u, 3099436303u,
	2349	671266974u, 1594198024u, 3322730930u, 2970347812u, 795835527u, 1483230225u, 3244367275u, 3060149565u,
	2350	1994146192u, 31158534u, 2563907772u, 4023717930u, 1907459465u, 112637215u, 2680153253u, 3904427059u,
	2351	2013776290u, 251722036u, 2517215374u, 3775830040u, 2137656763u, 141376813u, 2439277719u, 3865271297u,
	2352	1802195444u, 476864866u, 2238001368u, 4066508878u, 1812370925u, 453092731u, 2181625025u, 4111451223u,
	2353	1706088902u, 314042704u, 2344532202u, 4240017532u, 1658658271u, 366619977u, 2362670323u, 4224994405u,
	2354	1303535960u, 984961486u, 2747007092u, 3569037538u, 1256170817u, 1037604311u, 2765210733u, 3554079995u,
	2355	1131014506u, 879679996u, 2909243462u, 3663771856u, 1141124467u, 855842277u, 2852801631u, 3708648649u,
	2356	1342533948u, 654459306u, 3188396048u, 3373015174u, 1466479909u, 544179635u, 3110523913u, 3462522015u,
	2357	1591671054u, 702138776u, 2966460450u, 3352799412u, 1504918807u, 783551873u, 3082640443u, 3233442989u,
	2358	3988292384u, 2596254646u, 62317068u, 1957810842u, 3939845945u, 2647816111u, 81470997u, 1943803523u,
	2359	3814918930u, 2489596804u, 225274430u, 2053790376u, 3826175755u, 2466906013u, 167816743u, 2097651377u,
	2360	4027552580u, 2265490386u, 503444072u, 1762050814u, 4150417245u, 2154129355u, 426522225u, 1852507879u,
	2361	4275313526u, 2312317920u, 282753626u, 1742555852u, 4189708143u, 2394877945u, 397917763u, 1622183637u,
	2362	3604390888u, 2714866558u, 953729732u, 1340076626u, 3518719985u, 2797360999u, 1068828381u, 1219638859u,
	2363	3624741850u, 2936675148u, 906185462u, 1090812512u, 3747672003u, 2825379669u, 829329135u, 1181335161u,
	2364	3412177804u, 3160834842u, 628085408u, 1382605366u, 3423369109u, 3138078467u, 570562233u, 1426400815u,
	2365	3317316542u, 2998733608u, 733239954u, 1555261956u, 3268935591u, 3050360625u, 752459403u, 1541320221u,
	2366	2607071920u, 3965973030u, 1969922972u, 40735498u, 2617837225u, 3943577151u, 1913087877u, 83908371u,
	2367	2512341634u, 3803740692u, 2075208622u, 213261112u, 2463272603u, 3855990285u, 2094854071u, 198958881u,
	2368	2262029012u, 4057260610u, 1759359992u, 534414190u, 2176718541u, 4139329115u, 1873836001u, 414664567u,
	2369	2282248934u, 4279200368u, 1711684554u, 285281116u, 2405801727u, 4167216745u, 1634467795u, 376229701u,
	2370	2685067896u, 3608007406u, 1308918612u, 956543938u, 2808555105u, 3495958263u, 1231636301u, 1047427035u,
	2371	2932959818u, 3654703836u, 1088359270u, 936918000u, 2847714899u, 3736837829u, 1202900863u, 817233897u,
	2372	3183342108u, 3401237130u, 1404277552u, 615818150u, 3134207493u, 3453421203u, 1423857449u, 601450431u,
	2373	3009837614u, 3294710456u, 1567103746u, 711928724u, 3020668471u, 3272380065u, 1510334235u, 755167117u
	2374	};
	2375
	2376	/Return the CRC of the bytes buf[0..len-1]./
	2377	unsigned lodepng_crc32(const unsigned char* data, size_t length) {
	2378	unsigned r = 0xffffffffu;
	2379	size_t i;
	2380	for(i = 0; i < length; ++i) {
	2381	r = lodepng_crc32_table[(r ^ data[i]) & 0xffu] ^ (r >> 8u);
	2382	}
	2383	return r ^ 0xffffffffu;
	2384	}
	2385	#else /* !LODEPNG_NO_COMPILE_CRC */
	2386	unsigned lodepng_crc32(const unsigned char* data, size_t length);
	2387	#endif /* !LODEPNG_NO_COMPILE_CRC */
	2388
	2389	/* ////////////////////////////////////////////////////////////////////////// */
	2390	/* / Reading and writing PNG color channel bits / */
	2391	/* ////////////////////////////////////////////////////////////////////////// */
	2392
	2393	/* The color channel bits of less-than-8-bit pixels are read with the MSB of bytes first,
	2394	so LodePNGBitWriter and LodePNGBitReader can't be used for those. */
	2395
	2396	static unsigned char readBitFromReversedStream(size_t* bitpointer, const unsigned char* bitstream) {
	2397	unsigned char result = (unsigned char)((bitstream[(bitpointer) >> 3] >> (7 - ((bitpointer) & 0x7))) & 1);
	2398	++(*bitpointer);
	2399	return result;
	2400	}
	2401
	2402	/* TODO: make this faster */
	2403	static unsigned readBitsFromReversedStream(size_t* bitpointer, const unsigned char* bitstream, size_t nbits) {
	2404	unsigned result = 0;
	2405	size_t i;
	2406	for(i = 0 ; i < nbits; ++i) {
	2407	result <<= 1;
	2408	result \|= (unsigned)readBitFromReversedStream(bitpointer, bitstream);
	2409	}
	2410	return result;
	2411	}
	2412
	2413	static void setBitOfReversedStream(size_t* bitpointer, unsigned char* bitstream, unsigned char bit) {
	2414	/the current bit in bitstream may be 0 or 1 for this to work/
	2415	if(bit == 0) bitstream[(bitpointer) >> 3] &= (unsigned char)(~(1 << (7 - ((bitpointer) & 0x7))));
	2416	else bitstream[(bitpointer) >> 3] \|= (1 << (7 - ((bitpointer) & 0x7)));
	2417	++(*bitpointer);
	2418	}
	2419
	2420	/* ////////////////////////////////////////////////////////////////////////// */
	2421	/* / PNG chunks / */
	2422	/* ////////////////////////////////////////////////////////////////////////// */
	2423
	2424	unsigned lodepng_chunk_length(const unsigned char* chunk) {
	2425	return lodepng_read32bitInt(&chunk[0]);
	2426	}
	2427
	2428	void lodepng_chunk_type(char type[5], const unsigned char* chunk) {
	2429	unsigned i;
	2430	for(i = 0; i != 4; ++i) type[i] = (char)chunk[4 + i];
	2431	type[4] = 0; /null termination char/
	2432	}
	2433
	2434	unsigned char lodepng_chunk_type_equals(const unsigned char* chunk, const char* type) {
	2435	if(lodepng_strlen(type) != 4) return 0;
	2436	return (chunk[4] == type[0] && chunk[5] == type[1] && chunk[6] == type[2] && chunk[7] == type[3]);
	2437	}
	2438
	2439	unsigned char lodepng_chunk_ancillary(const unsigned char* chunk) {
	2440	return((chunk[4] & 32) != 0);
	2441	}
	2442
	2443	unsigned char lodepng_chunk_private(const unsigned char* chunk) {
	2444	return((chunk[6] & 32) != 0);
	2445	}
	2446
	2447	unsigned char lodepng_chunk_safetocopy(const unsigned char* chunk) {
	2448	return((chunk[7] & 32) != 0);
	2449	}
	2450
	2451	unsigned char* lodepng_chunk_data(unsigned char* chunk) {
	2452	return &chunk[8];
	2453	}
	2454
	2455	const unsigned char* lodepng_chunk_data_const(const unsigned char* chunk) {
	2456	return &chunk[8];
	2457	}
	2458
	2459	unsigned lodepng_chunk_check_crc(const unsigned char* chunk) {
	2460	unsigned length = lodepng_chunk_length(chunk);
	2461	unsigned CRC = lodepng_read32bitInt(&chunk[length + 8]);
	2462	/the CRC is taken of the data and the 4 chunk type letters, not the length/
	2463	unsigned checksum = lodepng_crc32(&chunk[4], length + 4);
	2464	if(CRC != checksum) return 1;
	2465	else return 0;
	2466	}
	2467
	2468	void lodepng_chunk_generate_crc(unsigned char* chunk) {
	2469	unsigned length = lodepng_chunk_length(chunk);
	2470	unsigned CRC = lodepng_crc32(&chunk[4], length + 4);
	2471	lodepng_set32bitInt(chunk + 8 + length, CRC);
	2472	}
	2473
	2474	unsigned char* lodepng_chunk_next(unsigned char* chunk) {
	2475	if(chunk[0] == 0x89 && chunk[1] == 0x50 && chunk[2] == 0x4e && chunk[3] == 0x47
	2476	&& chunk[4] == 0x0d && chunk[5] == 0x0a && chunk[6] == 0x1a && chunk[7] == 0x0a) {
	2477	/* Is PNG magic header at start of PNG file. Jump to first actual chunk. */
	2478	return chunk + 8;
	2479	} else {
	2480	unsigned total_chunk_length = lodepng_chunk_length(chunk) + 12;
	2481	return chunk + total_chunk_length;
	2482	}
	2483	}
	2484
	2485	const unsigned char* lodepng_chunk_next_const(const unsigned char* chunk) {
	2486	if(chunk[0] == 0x89 && chunk[1] == 0x50 && chunk[2] == 0x4e && chunk[3] == 0x47
	2487	&& chunk[4] == 0x0d && chunk[5] == 0x0a && chunk[6] == 0x1a && chunk[7] == 0x0a) {
	2488	/* Is PNG magic header at start of PNG file. Jump to first actual chunk. */
	2489	return chunk + 8;
	2490	} else {
	2491	unsigned total_chunk_length = lodepng_chunk_length(chunk) + 12;
	2492	return chunk + total_chunk_length;
	2493	}
	2494	}
	2495
	2496	unsigned char* lodepng_chunk_find(unsigned char* chunk, const unsigned char* end, const char type[5]) {
	2497	for(;;) {
	2498	if(chunk + 12 >= end) return 0;
	2499	if(lodepng_chunk_type_equals(chunk, type)) return chunk;
	2500	chunk = lodepng_chunk_next(chunk);
	2501	}
	2502	}
	2503
	2504	const unsigned char* lodepng_chunk_find_const(const unsigned char* chunk, const unsigned char* end, const char type[5]) {
	2505	for(;;) {
	2506	if(chunk + 12 >= end) return 0;
	2507	if(lodepng_chunk_type_equals(chunk, type)) return chunk;
	2508	chunk = lodepng_chunk_next_const(chunk);
	2509	}
	2510	}
	2511
	2512	unsigned lodepng_chunk_append(unsigned char** out, size_t* outlength, const unsigned char* chunk) {
	2513	unsigned i;
	2514	unsigned total_chunk_length = lodepng_chunk_length(chunk) + 12;
	2515	unsigned char chunk_start, new_buffer;
	2516	size_t new_length = (*outlength) + total_chunk_length;
	2517	if(new_length < total_chunk_length \|\| new_length < (outlength)) return 77; /integer overflow happened*/
	2518
	2519	new_buffer = (unsigned char)lodepng_realloc(out, new_length);
	2520	if(!new_buffer) return 83; /alloc fail/
	2521	(*out) = new_buffer;
	2522	(*outlength) = new_length;
	2523	chunk_start = &(*out)[new_length - total_chunk_length];
	2524
	2525	for(i = 0; i != total_chunk_length; ++i) chunk_start[i] = chunk[i];
	2526
	2527	return 0;
	2528	}
	2529
	2530	unsigned lodepng_chunk_create(unsigned char** out, size_t* outlength, unsigned length,
	2531	const char* type, const unsigned char* data) {
	2532	unsigned i;
	2533	unsigned char chunk, new_buffer;
	2534	size_t new_length = (*outlength) + length + 12;
	2535	if(new_length < length + 12 \|\| new_length < (outlength)) return 77; /integer overflow happened*/
	2536	new_buffer = (unsigned char)lodepng_realloc(out, new_length);
	2537	if(!new_buffer) return 83; /alloc fail/
	2538	(*out) = new_buffer;
	2539	(*outlength) = new_length;
	2540	chunk = &(out)[(outlength) - length - 12];
	2541
	2542	/1: length/
	2543	lodepng_set32bitInt(chunk, (unsigned)length);
	2544
	2545	/2: chunk name (4 letters)/
	2546	chunk[4] = (unsigned char)type[0];
	2547	chunk[5] = (unsigned char)type[1];
	2548	chunk[6] = (unsigned char)type[2];
	2549	chunk[7] = (unsigned char)type[3];
	2550
	2551	/3: the data/
	2552	for(i = 0; i != length; ++i) chunk[8 + i] = data[i];
	2553
	2554	/4: CRC (of the chunkname characters and the data)/
	2555	lodepng_chunk_generate_crc(chunk);
	2556
	2557	return 0;
	2558	}
	2559
	2560	/* ////////////////////////////////////////////////////////////////////////// */
	2561	/* / Color types, channels, bits / */
	2562	/* ////////////////////////////////////////////////////////////////////////// */
	2563
	2564	/*checks if the colortype is valid and the bitdepth bd is allowed for this colortype.
	2565	Return value is a LodePNG error code.*/
	2566	static unsigned checkColorValidity(LodePNGColorType colortype, unsigned bd) {
	2567	switch(colortype) {
	2568	case LCT_GREY: if(!(bd == 1 \|\| bd == 2 \|\| bd == 4 \|\| bd == 8 \|\| bd == 16)) return 37; break;
	2569	case LCT_RGB: if(!( bd == 8 \|\| bd == 16)) return 37; break;
	2570	case LCT_PALETTE: if(!(bd == 1 \|\| bd == 2 \|\| bd == 4 \|\| bd == 8 )) return 37; break;
	2571	case LCT_GREY_ALPHA: if(!( bd == 8 \|\| bd == 16)) return 37; break;
	2572	case LCT_RGBA: if(!( bd == 8 \|\| bd == 16)) return 37; break;
	2573	default: return 31; /* invalid color type */
	2574	}
	2575	return 0; /allowed color type / bits combination/
	2576	}
	2577
	2578	static unsigned getNumColorChannels(LodePNGColorType colortype) {
	2579	switch(colortype) {
	2580	case LCT_GREY: return 1;
	2581	case LCT_RGB: return 3;
	2582	case LCT_PALETTE: return 1;
	2583	case LCT_GREY_ALPHA: return 2;
	2584	case LCT_RGBA: return 4;
	2585	default: return 0; /invalid color type/
	2586	}
	2587	}
	2588
	2589	static unsigned lodepng_get_bpp_lct(LodePNGColorType colortype, unsigned bitdepth) {
	2590	/bits per pixel is amount of channels bits per channel*/
	2591	return getNumColorChannels(colortype) * bitdepth;
	2592	}
	2593
	2594	/* ////////////////////////////////////////////////////////////////////////// */
	2595
	2596	void lodepng_color_mode_init(LodePNGColorMode* info) {
	2597	info->key_defined = 0;
	2598	info->key_r = info->key_g = info->key_b = 0;
	2599	info->colortype = LCT_RGBA;
	2600	info->bitdepth = 8;
	2601	info->palette = 0;
	2602	info->palettesize = 0;
	2603	}
	2604
	2605	void lodepng_color_mode_alloc_palette(LodePNGColorMode* info) {
	2606	size_t i;
	2607	/room for 256 colors with 4 bytes each. Using realloc to avoid leak if it is being overwritten/
	2608	info->palette = (unsigned char*)lodepng_realloc(info->palette, 1024);
	2609	if(!info->palette) return; /alloc fail/
	2610	for(i = 0; i != 256; ++i) {
	2611	/*Initialize all unused colors with black, the value used for invalid palette indices.
	2612	This is an error according to the PNG spec, but common PNG decoders make it black instead.
	2613	That makes color conversion slightly faster due to no error handling needed.*/
	2614	info->palette[i * 4 + 0] = 0;
	2615	info->palette[i * 4 + 1] = 0;
	2616	info->palette[i * 4 + 2] = 0;
	2617	info->palette[i * 4 + 3] = 255;
	2618	}
	2619	}
	2620
	2621	void lodepng_color_mode_cleanup(LodePNGColorMode* info) {
	2622	lodepng_palette_clear(info);
	2623	}
	2624
	2625	unsigned lodepng_color_mode_copy(LodePNGColorMode* dest, const LodePNGColorMode* source) {
	2626	size_t i;
	2627	lodepng_color_mode_cleanup(dest);
	2628	dest = source;
	2629	if(source->palette) {
	2630	dest->palette = (unsigned char*)lodepng_malloc(1024);
	2631	if(!dest->palette && source->palettesize) return 83; /alloc fail/
	2632	for(i = 0; i != source->palettesize * 4; ++i) dest->palette[i] = source->palette[i];
	2633	}
	2634	return 0;
	2635	}
	2636
	2637	LodePNGColorMode lodepng_color_mode_make(LodePNGColorType colortype, unsigned bitdepth) {
	2638	LodePNGColorMode result;
	2639	lodepng_color_mode_init(&result);
	2640	result.colortype = colortype;
	2641	result.bitdepth = bitdepth;
	2642	return result;
	2643	}
	2644
	2645	static int lodepng_color_mode_equal(const LodePNGColorMode* a, const LodePNGColorMode* b) {
	2646	size_t i;
	2647	if(a->colortype != b->colortype) return 0;
	2648	if(a->bitdepth != b->bitdepth) return 0;
	2649	if(a->key_defined != b->key_defined) return 0;
	2650	if(a->key_defined) {
	2651	if(a->key_r != b->key_r) return 0;
	2652	if(a->key_g != b->key_g) return 0;
	2653	if(a->key_b != b->key_b) return 0;
	2654	}
	2655	if(a->palettesize != b->palettesize) return 0;
	2656	for(i = 0; i != a->palettesize * 4; ++i) {
	2657	if(a->palette[i] != b->palette[i]) return 0;
	2658	}
	2659	return 1;
	2660	}
	2661
	2662	void lodepng_palette_clear(LodePNGColorMode* info) {
	2663	if(info->palette) lodepng_free(info->palette);
	2664	info->palette = 0;
	2665	info->palettesize = 0;
	2666	}
	2667
	2668	unsigned lodepng_palette_add(LodePNGColorMode* info,
	2669	unsigned char r, unsigned char g, unsigned char b, unsigned char a) {
	2670	if(!info->palette) /allocate palette if empty/ {
	2671	lodepng_color_mode_alloc_palette(info);
	2672	if(!info->palette) return 83; /alloc fail/
	2673	}
	2674	if(info->palettesize >= 256) {
	2675	return 108; /too many palette values/
	2676	}
	2677	info->palette[4 * info->palettesize + 0] = r;
	2678	info->palette[4 * info->palettesize + 1] = g;
	2679	info->palette[4 * info->palettesize + 2] = b;
	2680	info->palette[4 * info->palettesize + 3] = a;
	2681	++info->palettesize;
	2682	return 0;
	2683	}
	2684
	2685	/calculate bits per pixel out of colortype and bitdepth/
	2686	unsigned lodepng_get_bpp(const LodePNGColorMode* info) {
	2687	return lodepng_get_bpp_lct(info->colortype, info->bitdepth);
	2688	}
	2689
	2690	unsigned lodepng_get_channels(const LodePNGColorMode* info) {
	2691	return getNumColorChannels(info->colortype);
	2692	}
	2693
	2694	unsigned lodepng_is_greyscale_type(const LodePNGColorMode* info) {
	2695	return info->colortype == LCT_GREY \|\| info->colortype == LCT_GREY_ALPHA;
	2696	}
	2697
	2698	unsigned lodepng_is_alpha_type(const LodePNGColorMode* info) {
	2699	return (info->colortype & 4) != 0; /4 or 6/
	2700	}
	2701
	2702	unsigned lodepng_is_palette_type(const LodePNGColorMode* info) {
	2703	return info->colortype == LCT_PALETTE;
	2704	}
	2705
	2706	unsigned lodepng_has_palette_alpha(const LodePNGColorMode* info) {
	2707	size_t i;
	2708	for(i = 0; i != info->palettesize; ++i) {
	2709	if(info->palette[i * 4 + 3] < 255) return 1;
	2710	}
	2711	return 0;
	2712	}
	2713
	2714	unsigned lodepng_can_have_alpha(const LodePNGColorMode* info) {
	2715	return info->key_defined
	2716	\|\| lodepng_is_alpha_type(info)
	2717	\|\| lodepng_has_palette_alpha(info);
	2718	}
	2719
	2720	static size_t lodepng_get_raw_size_lct(unsigned w, unsigned h, LodePNGColorType colortype, unsigned bitdepth) {
	2721	size_t bpp = lodepng_get_bpp_lct(colortype, bitdepth);
	2722	size_t n = (size_t)w * (size_t)h;
	2723	return ((n / 8u) * bpp) + ((n & 7u) * bpp + 7u) / 8u;
	2724	}
	2725
	2726	size_t lodepng_get_raw_size(unsigned w, unsigned h, const LodePNGColorMode* color) {
	2727	return lodepng_get_raw_size_lct(w, h, color->colortype, color->bitdepth);
	2728	}
	2729
	2730
	2731	#ifdef LODEPNG_COMPILE_PNG
	2732	#ifdef LODEPNG_COMPILE_DECODER
	2733
	2734	/*in an idat chunk, each scanline is a multiple of 8 bits, unlike the lodepng output buffer,
	2735	and in addition has one extra byte per line: the filter byte. So this gives a larger
	2736	result than lodepng_get_raw_size. */
	2737	static size_t lodepng_get_raw_size_idat(unsigned w, unsigned h, const LodePNGColorMode* color) {
	2738	size_t bpp = lodepng_get_bpp(color);
	2739	/* + 1 for the filter byte, and possibly plus padding bits per line */
	2740	size_t line = ((size_t)(w / 8u) * bpp) + 1u + ((w & 7u) * bpp + 7u) / 8u;
	2741	return (size_t)h * line;
	2742	}
	2743
	2744	/*Safely checks whether size_t overflow can be caused due to amount of pixels.
	2745	This check is overcautious rather than precise. If this check indicates no overflow,
	2746	you can safely compute in a size_t (but not an unsigned):
	2747	-(size_t)w * (size_t)h * 8
	2748	-amount of bytes in IDAT (including filter, padding and Adam7 bytes)
	2749	-amount of bytes in raw color model
	2750	Returns 1 if overflow possible, 0 if not.
	2751	*/
	2752	static int lodepng_pixel_overflow(unsigned w, unsigned h,
	2753	const LodePNGColorMode* pngcolor, const LodePNGColorMode* rawcolor) {
	2754	size_t bpp = LODEPNG_MAX(lodepng_get_bpp(pngcolor), lodepng_get_bpp(rawcolor));
	2755	size_t numpixels, total;
	2756	size_t line; /* bytes per line in worst case */
	2757
	2758	if(lodepng_mulofl((size_t)w, (size_t)h, &numpixels)) return 1;
	2759	if(lodepng_mulofl(numpixels, 8, &total)) return 1; /* bit pointer with 8-bit color, or 8 bytes per channel color */
	2760
	2761	/* Bytes per scanline with the expression "(w / 8u) * bpp) + ((w & 7u) * bpp + 7u) / 8u" */
	2762	if(lodepng_mulofl((size_t)(w / 8u), bpp, &line)) return 1;
	2763	if(lodepng_addofl(line, ((w & 7u) * bpp + 7u) / 8u, &line)) return 1;
	2764
	2765	if(lodepng_addofl(line, 5, &line)) return 1; /* 5 bytes overhead per line: 1 filterbyte, 4 for Adam7 worst case */
	2766	if(lodepng_mulofl(line, h, &total)) return 1; /* Total bytes in worst case */
	2767
	2768	return 0; /* no overflow */
	2769	}
	2770	#endif /LODEPNG_COMPILE_DECODER/
	2771	#endif /LODEPNG_COMPILE_PNG/
	2772
	2773	#ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
	2774
	2775	static void LodePNGUnknownChunks_init(LodePNGInfo* info) {
	2776	unsigned i;
	2777	for(i = 0; i != 3; ++i) info->unknown_chunks_data[i] = 0;
	2778	for(i = 0; i != 3; ++i) info->unknown_chunks_size[i] = 0;
	2779	}
	2780
	2781	static void LodePNGUnknownChunks_cleanup(LodePNGInfo* info) {
	2782	unsigned i;
	2783	for(i = 0; i != 3; ++i) lodepng_free(info->unknown_chunks_data[i]);
	2784	}
	2785
	2786	static unsigned LodePNGUnknownChunks_copy(LodePNGInfo* dest, const LodePNGInfo* src) {
	2787	unsigned i;
	2788
	2789	LodePNGUnknownChunks_cleanup(dest);
	2790
	2791	for(i = 0; i != 3; ++i) {
	2792	size_t j;
	2793	dest->unknown_chunks_size[i] = src->unknown_chunks_size[i];
	2794	dest->unknown_chunks_data[i] = (unsigned char*)lodepng_malloc(src->unknown_chunks_size[i]);
	2795	if(!dest->unknown_chunks_data[i] && dest->unknown_chunks_size[i]) return 83; /alloc fail/
	2796	for(j = 0; j < src->unknown_chunks_size[i]; ++j) {
	2797	dest->unknown_chunks_data[i][j] = src->unknown_chunks_data[i][j];
	2798	}
	2799	}
	2800
	2801	return 0;
	2802	}
	2803
	2804	/******************************************************************************/
	2805
	2806	static void LodePNGText_init(LodePNGInfo* info) {
	2807	info->text_num = 0;
	2808	info->text_keys = NULL;
	2809	info->text_strings = NULL;
	2810	}
	2811
	2812	static void LodePNGText_cleanup(LodePNGInfo* info) {
	2813	size_t i;
	2814	for(i = 0; i != info->text_num; ++i) {
	2815	string_cleanup(&info->text_keys[i]);
	2816	string_cleanup(&info->text_strings[i]);
	2817	}
	2818	lodepng_free(info->text_keys);
	2819	lodepng_free(info->text_strings);
	2820	}
	2821
	2822	static unsigned LodePNGText_copy(LodePNGInfo* dest, const LodePNGInfo* source) {
	2823	size_t i = 0;
	2824	dest->text_keys = 0;
	2825	dest->text_strings = 0;
	2826	dest->text_num = 0;
	2827	for(i = 0; i != source->text_num; ++i) {
	2828	CERROR_TRY_RETURN(lodepng_add_text(dest, source->text_keys[i], source->text_strings[i]));
	2829	}
	2830	return 0;
	2831	}
	2832
	2833	void lodepng_clear_text(LodePNGInfo* info) {
	2834	LodePNGText_cleanup(info);
	2835	}
	2836
	2837	unsigned lodepng_add_text(LodePNGInfo* info, const char* key, const char* str) {
	2838	char new_keys = (char)(lodepng_realloc(info->text_keys, sizeof(char) (info->text_num + 1)));
	2839	char new_strings = (char)(lodepng_realloc(info->text_strings, sizeof(char) (info->text_num + 1)));
	2840	if(!new_keys \|\| !new_strings) {
	2841	lodepng_free(new_keys);
	2842	lodepng_free(new_strings);
	2843	return 83; /alloc fail/
	2844	}
	2845
	2846	++info->text_num;
	2847	info->text_keys = new_keys;
	2848	info->text_strings = new_strings;
	2849
	2850	info->text_keys[info->text_num - 1] = alloc_string(key);
	2851	info->text_strings[info->text_num - 1] = alloc_string(str);
	2852
	2853	return 0;
	2854	}
	2855
	2856	/******************************************************************************/
	2857
	2858	static void LodePNGIText_init(LodePNGInfo* info) {
	2859	info->itext_num = 0;
	2860	info->itext_keys = NULL;
	2861	info->itext_langtags = NULL;
	2862	info->itext_transkeys = NULL;
	2863	info->itext_strings = NULL;
	2864	}
	2865
	2866	static void LodePNGIText_cleanup(LodePNGInfo* info) {
	2867	size_t i;
	2868	for(i = 0; i != info->itext_num; ++i) {
	2869	string_cleanup(&info->itext_keys[i]);
	2870	string_cleanup(&info->itext_langtags[i]);
	2871	string_cleanup(&info->itext_transkeys[i]);
	2872	string_cleanup(&info->itext_strings[i]);
	2873	}
	2874	lodepng_free(info->itext_keys);
	2875	lodepng_free(info->itext_langtags);
	2876	lodepng_free(info->itext_transkeys);
	2877	lodepng_free(info->itext_strings);
	2878	}
	2879
	2880	static unsigned LodePNGIText_copy(LodePNGInfo* dest, const LodePNGInfo* source) {
	2881	size_t i = 0;
	2882	dest->itext_keys = 0;
	2883	dest->itext_langtags = 0;
	2884	dest->itext_transkeys = 0;
	2885	dest->itext_strings = 0;
	2886	dest->itext_num = 0;
	2887	for(i = 0; i != source->itext_num; ++i) {
	2888	CERROR_TRY_RETURN(lodepng_add_itext(dest, source->itext_keys[i], source->itext_langtags[i],
	2889	source->itext_transkeys[i], source->itext_strings[i]));
	2890	}
	2891	return 0;
	2892	}
	2893
	2894	void lodepng_clear_itext(LodePNGInfo* info) {
	2895	LodePNGIText_cleanup(info);
	2896	}
	2897
	2898	unsigned lodepng_add_itext(LodePNGInfo* info, const char* key, const char* langtag,
	2899	const char* transkey, const char* str) {
	2900	char new_keys = (char)(lodepng_realloc(info->itext_keys, sizeof(char) (info->itext_num + 1)));
	2901	char new_langtags = (char)(lodepng_realloc(info->itext_langtags, sizeof(char) (info->itext_num + 1)));
	2902	char new_transkeys = (char)(lodepng_realloc(info->itext_transkeys, sizeof(char) (info->itext_num + 1)));
	2903	char new_strings = (char)(lodepng_realloc(info->itext_strings, sizeof(char) (info->itext_num + 1)));
	2904	if(!new_keys \|\| !new_langtags \|\| !new_transkeys \|\| !new_strings) {
	2905	lodepng_free(new_keys);
	2906	lodepng_free(new_langtags);
	2907	lodepng_free(new_transkeys);
	2908	lodepng_free(new_strings);
	2909	return 83; /alloc fail/
	2910	}
	2911
	2912	++info->itext_num;
	2913	info->itext_keys = new_keys;
	2914	info->itext_langtags = new_langtags;
	2915	info->itext_transkeys = new_transkeys;
	2916	info->itext_strings = new_strings;
	2917
	2918	info->itext_keys[info->itext_num - 1] = alloc_string(key);
	2919	info->itext_langtags[info->itext_num - 1] = alloc_string(langtag);
	2920	info->itext_transkeys[info->itext_num - 1] = alloc_string(transkey);
	2921	info->itext_strings[info->itext_num - 1] = alloc_string(str);
	2922
	2923	return 0;
	2924	}
	2925
	2926	/* same as set but does not delete */
	2927	static unsigned lodepng_assign_icc(LodePNGInfo* info, const char* name, const unsigned char* profile, unsigned profile_size) {
	2928	if(profile_size == 0) return 100; /invalid ICC profile size/
	2929
	2930	info->iccp_name = alloc_string(name);
	2931	info->iccp_profile = (unsigned char*)lodepng_malloc(profile_size);
	2932
	2933	if(!info->iccp_name \|\| !info->iccp_profile) return 83; /alloc fail/
	2934
	2935	lodepng_memcpy(info->iccp_profile, profile, profile_size);
	2936	info->iccp_profile_size = profile_size;
	2937
	2938	return 0; /ok/
	2939	}
	2940
	2941	unsigned lodepng_set_icc(LodePNGInfo* info, const char* name, const unsigned char* profile, unsigned profile_size) {
	2942	if(info->iccp_name) lodepng_clear_icc(info);
	2943	info->iccp_defined = 1;
	2944
	2945	return lodepng_assign_icc(info, name, profile, profile_size);
	2946	}
	2947
	2948	void lodepng_clear_icc(LodePNGInfo* info) {
	2949	string_cleanup(&info->iccp_name);
	2950	lodepng_free(info->iccp_profile);
	2951	info->iccp_profile = NULL;
	2952	info->iccp_profile_size = 0;
	2953	info->iccp_defined = 0;
	2954	}
	2955	#endif /LODEPNG_COMPILE_ANCILLARY_CHUNKS/
	2956
	2957	void lodepng_info_init(LodePNGInfo* info) {
	2958	lodepng_color_mode_init(&info->color);
	2959	info->interlace_method = 0;
	2960	info->compression_method = 0;
	2961	info->filter_method = 0;
	2962	#ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
	2963	info->background_defined = 0;
	2964	info->background_r = info->background_g = info->background_b = 0;
	2965
	2966	LodePNGText_init(info);
	2967	LodePNGIText_init(info);
	2968
	2969	info->time_defined = 0;
	2970	info->phys_defined = 0;
	2971
	2972	info->gama_defined = 0;
	2973	info->chrm_defined = 0;
	2974	info->srgb_defined = 0;
	2975	info->iccp_defined = 0;
	2976	info->iccp_name = NULL;
	2977	info->iccp_profile = NULL;
	2978
	2979	LodePNGUnknownChunks_init(info);
	2980	#endif /LODEPNG_COMPILE_ANCILLARY_CHUNKS/
	2981	}
	2982
	2983	void lodepng_info_cleanup(LodePNGInfo* info) {
	2984	lodepng_color_mode_cleanup(&info->color);
	2985	#ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
	2986	LodePNGText_cleanup(info);
	2987	LodePNGIText_cleanup(info);
	2988
	2989	lodepng_clear_icc(info);
	2990
	2991	LodePNGUnknownChunks_cleanup(info);
	2992	#endif /LODEPNG_COMPILE_ANCILLARY_CHUNKS/
	2993	}
	2994
	2995	unsigned lodepng_info_copy(LodePNGInfo* dest, const LodePNGInfo* source) {
	2996	lodepng_info_cleanup(dest);
	2997	dest = source;
	2998	lodepng_color_mode_init(&dest->color);
	2999	CERROR_TRY_RETURN(lodepng_color_mode_copy(&dest->color, &source->color));
	3000
	3001	#ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
	3002	CERROR_TRY_RETURN(LodePNGText_copy(dest, source));
	3003	CERROR_TRY_RETURN(LodePNGIText_copy(dest, source));
	3004	if(source->iccp_defined) {
	3005	CERROR_TRY_RETURN(lodepng_assign_icc(dest, source->iccp_name, source->iccp_profile, source->iccp_profile_size));
	3006	}
	3007
	3008	LodePNGUnknownChunks_init(dest);
	3009	CERROR_TRY_RETURN(LodePNGUnknownChunks_copy(dest, source));
	3010	#endif /LODEPNG_COMPILE_ANCILLARY_CHUNKS/
	3011	return 0;
	3012	}
	3013
	3014	/* ////////////////////////////////////////////////////////////////////////// */
	3015
	3016	/index: bitgroup index, bits: bitgroup size(1, 2 or 4), in: bitgroup value, out: octet array to add bits to/
	3017	static void addColorBits(unsigned char* out, size_t index, unsigned bits, unsigned in) {
	3018	unsigned m = bits == 1 ? 7 : bits == 2 ? 3 : 1; /8 / bits - 1/
	3019	/p = the partial index in the byte, e.g. with 4 palettebits it is 0 for first half or 1 for second half/
	3020	unsigned p = index & m;
	3021	in &= (1u << bits) - 1u; /filter out any other bits of the input value/
	3022	in = in << (bits * (m - p));
	3023	if(p == 0) out[index * bits / 8u] = in;
	3024	else out[index * bits / 8u] \|= in;
	3025	}
	3026
	3027	typedef struct ColorTree ColorTree;
	3028
	3029	/*
	3030	One node of a color tree
	3031	This is the data structure used to count the number of unique colors and to get a palette
	3032	index for a color. It's like an octree, but because the alpha channel is used too, each
	3033	node has 16 instead of 8 children.
	3034	*/
	3035	struct ColorTree {
	3036	ColorTree* children[16]; /up to 16 pointers to ColorTree of next level/
	3037	int index; /the payload. Only has a meaningful value if this is in the last level/
	3038	};
	3039
	3040	static void color_tree_init(ColorTree* tree) {
	3041	int i;
	3042	for(i = 0; i != 16; ++i) tree->children[i] = 0;
	3043	tree->index = -1;