lz4.c File Reference

#include "lz4.h"
#include <stdlib.h>
#include <string.h>
#include <limits.h>

Macros
#define	LZ4_HEAPMODE   0
#define	LZ4_ACCELERATION_DEFAULT   1
#define	LZ4_ACCELERATION_MAX   65537
#define	LZ4_SRC_INCLUDED   1
#define	LZ4_DISABLE_DEPRECATE_WARNINGS   /* due to LZ4_decompress_safe_withPrefix64k */
#define	LZ4_STATIC_LINKING_ONLY
#define	LZ4_FORCE_INLINE   static
#define	LZ4_FORCE_O2
#define	expect(expr, value)
#define	likely(expr)
#define	unlikely(expr)
#define	LZ4_ALIGN_TEST   1
#define	ALLOC(s)
#define	ALLOC_AND_ZERO(s)
#define	FREEMEM(p)
#define	LZ4_memset(p, v, s)
#define	MEM_INIT(p, v, s)
#define	MINMATCH   4
#define	WILDCOPYLENGTH   8
#define	LASTLITERALS   5 /* see ../doc/lz4_Block_format.md#parsing-restrictions */
#define	MFLIMIT   12 /* see ../doc/lz4_Block_format.md#parsing-restrictions */
#define	MATCH_SAFEGUARD_DISTANCE   ((2*WILDCOPYLENGTH) - MINMATCH) /* ensure it's possible to write 2 x wildcopyLength without overflowing output buffer */
#define	FASTLOOP_SAFE_DISTANCE   64
#define	KB   *(1 <<10)
#define	MB   *(1 <<20)
#define	GB   *(1U<<30)
#define	LZ4_DISTANCE_ABSOLUTE_MAX   65535
#define	ML_BITS   4
#define	ML_MASK   ((1U<<ML_BITS)-1)
#define	RUN_BITS   (8-ML_BITS)
#define	RUN_MASK   ((1U<<RUN_BITS)-1)
#define	assert(condition)
#define	LZ4_STATIC_ASSERT(c)
#define	DEBUGLOG(l, ...)
#define	LZ4_memcpy(dst, src, size)
#define	LZ4_memmove   memmove
#define	LZ4_FAST_DEC_LOOP   0
#define	STEPSIZE   sizeof(reg_t)
#define	HASH_UNIT   sizeof(reg_t)
#define	MIN(a, b)

Typedefs
typedef unsigned char	BYTE
typedef unsigned short	U16
typedef unsigned int	U32
typedef signed int	S32
typedef unsigned long long	U64
typedef size_t	uptrval
typedef size_t	reg_t
typedef size_t	Rvl_t

Enumerations
enum	limitedOutput_directive { notLimited = 0 , limitedOutput = 1 , fillOutput = 2 }
enum	tableType_t { clearedTable = 0 , byPtr , byU32 , byU16 }
enum	dict_directive { noDict = 0 , withPrefix64k , usingExtDict , usingDictCtx }
enum	dictIssue_directive { noDictIssue = 0 , dictSmall }
enum	LoadDict_mode_e { _ld_fast , _ld_slow }
enum	earlyEnd_directive { decode_full_block = 0 , partial_decode = 1 }

Functions
LZ4_FORCE_INLINE void	LZ4_wildCopy8 (void *dstPtr, const void *srcPtr, void *dstEnd)
LZ4_FORCE_INLINE unsigned	LZ4_count (const BYTE *pIn, const BYTE *pMatch, const BYTE *pInLimit)
int	LZ4_versionNumber (void)
const char *	LZ4_versionString (void)
int	LZ4_compressBound (int isize)
int	LZ4_sizeofState (void)
int	LZ4_compress_forceExtDict (LZ4_stream_t *LZ4_dict, const char *source, char *dest, int srcSize)
int	LZ4_decompress_safe_forceExtDict (const char *source, char *dest, int compressedSize, int maxOutputSize, const void *dictStart, size_t dictSize)
int	LZ4_decompress_safe_partial_forceExtDict (const char *source, char *dest, int compressedSize, int targetOutputSize, int dstCapacity, const void *dictStart, size_t dictSize)
LZ4_FORCE_INLINE U32	LZ4_hash4 (U32 sequence, tableType_t const tableType)
LZ4_FORCE_INLINE U32	LZ4_hash5 (U64 sequence, tableType_t const tableType)
LZ4_FORCE_INLINE U32	LZ4_hashPosition (const void *const p, tableType_t const tableType)
LZ4_FORCE_INLINE void	LZ4_clearHash (U32 h, void *tableBase, tableType_t const tableType)
LZ4_FORCE_INLINE void	LZ4_putIndexOnHash (U32 idx, U32 h, void *tableBase, tableType_t const tableType)
LZ4_FORCE_INLINE void	LZ4_putPositionOnHash (const BYTE *p, U32 h, void *tableBase, tableType_t const tableType)
LZ4_FORCE_INLINE void	LZ4_putPosition (const BYTE *p, void *tableBase, tableType_t tableType)
LZ4_FORCE_INLINE U32	LZ4_getIndexOnHash (U32 h, const void *tableBase, tableType_t tableType)
LZ4_FORCE_INLINE const BYTE *	LZ4_getPosition (const BYTE *p, const void *tableBase, tableType_t tableType)
LZ4_FORCE_INLINE void	LZ4_prepareTable (LZ4_stream_t_internal *const cctx, const int inputSize, const tableType_t tableType)
LZ4_FORCE_INLINE int	LZ4_compress_generic_validated (LZ4_stream_t_internal *const cctx, const char *const source, char *const dest, const int inputSize, int *inputConsumed, const int maxOutputSize, const limitedOutput_directive outputDirective, const tableType_t tableType, const dict_directive dictDirective, const dictIssue_directive dictIssue, const int acceleration)
LZ4_FORCE_INLINE int	LZ4_compress_generic (LZ4_stream_t_internal *const cctx, const char *const src, char *const dst, const int srcSize, int *inputConsumed, const int dstCapacity, const limitedOutput_directive outputDirective, const tableType_t tableType, const dict_directive dictDirective, const dictIssue_directive dictIssue, const int acceleration)
int	LZ4_compress_fast_extState (void *state, const char *source, char *dest, int inputSize, int maxOutputSize, int acceleration)
int	LZ4_compress_fast_extState_fastReset (void *state, const char *src, char *dst, int srcSize, int dstCapacity, int acceleration)
int	LZ4_compress_fast (const char *src, char *dest, int srcSize, int dstCapacity, int acceleration)
int	LZ4_compress_default (const char *src, char *dst, int srcSize, int dstCapacity)
int	LZ4_compress_destSize_extState (void *state, const char *src, char *dst, int *srcSizePtr, int targetDstSize, int acceleration)
int	LZ4_compress_destSize (const char *src, char *dst, int *srcSizePtr, int targetDstSize)
LZ4_stream_t *	LZ4_createStream (void)
LZ4_stream_t *	LZ4_initStream (void *buffer, size_t size)
void	LZ4_resetStream (LZ4_stream_t *LZ4_stream)
void	LZ4_resetStream_fast (LZ4_stream_t *ctx)
int	LZ4_freeStream (LZ4_stream_t *LZ4_stream)
int	LZ4_loadDict_internal (LZ4_stream_t *LZ4_dict, const char *dictionary, int dictSize, LoadDict_mode_e _ld)
int	LZ4_loadDict (LZ4_stream_t *LZ4_dict, const char *dictionary, int dictSize)
int	LZ4_loadDictSlow (LZ4_stream_t *LZ4_dict, const char *dictionary, int dictSize)
void	LZ4_attach_dictionary (LZ4_stream_t *workingStream, const LZ4_stream_t *dictionaryStream)
int	LZ4_compress_fast_continue (LZ4_stream_t *LZ4_stream, const char *source, char *dest, int inputSize, int maxOutputSize, int acceleration)
int	LZ4_saveDict (LZ4_stream_t *LZ4_dict, char *safeBuffer, int dictSize)
LZ4_FORCE_INLINE int	LZ4_decompress_unsafe_generic (const BYTE *const istart, BYTE *const ostart, int decompressedSize, size_t prefixSize, const BYTE *const dictStart, const size_t dictSize)
LZ4_FORCE_INLINE Rvl_t	read_variable_length (const BYTE **ip, const BYTE *ilimit, int initial_check)
LZ4_FORCE_INLINE int	LZ4_decompress_generic (const char *const src, char *const dst, int srcSize, int outputSize, earlyEnd_directive partialDecoding, dict_directive dict, const BYTE *const lowPrefix, const BYTE *const dictStart, const size_t dictSize)
LZ4_FORCE_O2 int	LZ4_decompress_safe (const char *source, char *dest, int compressedSize, int maxDecompressedSize)
LZ4_FORCE_O2 int	LZ4_decompress_safe_partial (const char *src, char *dst, int compressedSize, int targetOutputSize, int dstCapacity)
LZ4_FORCE_O2 int	LZ4_decompress_fast (const char *source, char *dest, int originalSize)
LZ4_FORCE_O2 int	LZ4_decompress_safe_withPrefix64k (const char *source, char *dest, int compressedSize, int maxOutputSize)
int	LZ4_decompress_fast_withPrefix64k (const char *source, char *dest, int originalSize)
LZ4_FORCE_INLINE int	LZ4_decompress_safe_doubleDict (const char *source, char *dest, int compressedSize, int maxOutputSize, size_t prefixSize, const void *dictStart, size_t dictSize)
LZ4_streamDecode_t *	LZ4_createStreamDecode (void)
int	LZ4_freeStreamDecode (LZ4_streamDecode_t *LZ4_stream)
int	LZ4_setStreamDecode (LZ4_streamDecode_t *LZ4_streamDecode, const char *dictionary, int dictSize)
int	LZ4_decoderRingBufferSize (int maxBlockSize)
LZ4_FORCE_O2 int	LZ4_decompress_safe_continue (LZ4_streamDecode_t *LZ4_streamDecode, const char *source, char *dest, int compressedSize, int maxOutputSize)
LZ4_FORCE_O2 int	LZ4_decompress_fast_continue (LZ4_streamDecode_t *LZ4_streamDecode, const char *source, char *dest, int originalSize)
int	LZ4_decompress_safe_usingDict (const char *source, char *dest, int compressedSize, int maxOutputSize, const char *dictStart, int dictSize)
int	LZ4_decompress_safe_partial_usingDict (const char *source, char *dest, int compressedSize, int targetOutputSize, int dstCapacity, const char *dictStart, int dictSize)
int	LZ4_decompress_fast_usingDict (const char *source, char *dest, int originalSize, const char *dictStart, int dictSize)
int	LZ4_compress_limitedOutput (const char *source, char *dest, int inputSize, int maxOutputSize)
int	LZ4_compress (const char *src, char *dest, int srcSize)
int	LZ4_compress_limitedOutput_withState (void *state, const char *src, char *dst, int srcSize, int dstSize)
int	LZ4_compress_withState (void *state, const char *src, char *dst, int srcSize)
int	LZ4_compress_limitedOutput_continue (LZ4_stream_t *LZ4_stream, const char *src, char *dst, int srcSize, int dstCapacity)
int	LZ4_compress_continue (LZ4_stream_t *LZ4_stream, const char *source, char *dest, int inputSize)
int	LZ4_uncompress (const char *source, char *dest, int outputSize)
int	LZ4_uncompress_unknownOutputSize (const char *source, char *dest, int isize, int maxOutputSize)
int	LZ4_sizeofStreamState (void)
int	LZ4_resetStreamState (void *state, char *inputBuffer)
void *	LZ4_create (char *inputBuffer)
char *	LZ4_slideInputBuffer (void *state)

Macro Definition Documentation

ALLOC

#define ALLOC

(

s

)

Value:

malloc(s)

LZ4_STATIC_LINKING_ONLY_DISABLE_MEMORY_ALLOCATION : Disable relatively high-level LZ4/HC functions that use dynamic memory allocation functions (malloc(), calloc(), free()).

Note that this is a compile-time switch. And since it disables public/stable LZ4 v1 API functions, we don't recommend using this symbol to generate a library for distribution.

The following public functions are removed when this symbol is defined.

• lz4 : LZ4_createStream, LZ4_freeStream, LZ4_createStreamDecode, LZ4_freeStreamDecode, LZ4_create (deprecated)
• lz4hc : LZ4_createStreamHC, LZ4_freeStreamHC, LZ4_createHC (deprecated), LZ4_freeHC (deprecated)
• lz4frame, lz4file : All LZ4F_* functions

ALLOC_AND_ZERO

#define ALLOC_AND_ZERO

(

s

)

Value:

calloc(1,s)

assert

#define assert

(

condition

)

Value:

((void)0)

DEBUGLOG

#define DEBUGLOG	(		l,
			... )

Value:

{}    /* disabled */

expect

#define expect	(		expr,
			value )

Value:

(expr)

FASTLOOP_SAFE_DISTANCE

#define FASTLOOP_SAFE_DISTANCE   64

FREEMEM

#define FREEMEM

(

p

)

Value:

free(p)

GB

#define GB   *(1U<<30)

HASH_UNIT

#define HASH_UNIT   sizeof(reg_t)

KB

#define KB   *(1 <<10)

LASTLITERALS

#define LASTLITERALS   5 /* see ../doc/lz4_Block_format.md#parsing-restrictions */

likely

#define likely

(

expr

)

Value:

expect((expr) != 0, 1)

LZ4_ACCELERATION_DEFAULT

#define LZ4_ACCELERATION_DEFAULT   1

LZ4_ACCELERATION_MAX

#define LZ4_ACCELERATION_MAX   65537

LZ4_ALIGN_TEST

#define LZ4_ALIGN_TEST   1

LZ4_DISABLE_DEPRECATE_WARNINGS

#define LZ4_DISABLE_DEPRECATE_WARNINGS   /* due to LZ4_decompress_safe_withPrefix64k */

LZ4_DISTANCE_ABSOLUTE_MAX

#define LZ4_DISTANCE_ABSOLUTE_MAX   65535

LZ4_FAST_DEC_LOOP

#define LZ4_FAST_DEC_LOOP   0

LZ4_FORCE_INLINE

#define LZ4_FORCE_INLINE   static

LZ4_FORCE_O2

#define LZ4_FORCE_O2

LZ4_HEAPMODE

#define LZ4_HEAPMODE   0

LZ4_memcpy

#define LZ4_memcpy	(		dst,
			src,
			size )

Value:

memcpy(dst, src, size)

LZ4 relies on memcpy with a constant size being inlined. In freestanding environments, the compiler can't assume the implementation of memcpy() is standard compliant, so it can't apply its specialized memcpy() inlining logic. When possible, use __builtin_memcpy() to tell the compiler to analyze memcpy() as if it were standard compliant, so it can inline it in freestanding environments. This is needed when decompressing the Linux Kernel, for example.

LZ4_memmove

#define LZ4_memmove   memmove

LZ4_memset

#define LZ4_memset	(		p,
			v,
			s )

Value:

memset((p),(v),(s))

LZ4_SRC_INCLUDED

#define LZ4_SRC_INCLUDED   1

LZ4_STATIC_ASSERT

#define LZ4_STATIC_ASSERT

(

c

)

Value:

{ enum { LZ4_static_assert = 1/(int)(!!(c)) }; }   /* use after variable declarations */

LZ4_STATIC_LINKING_ONLY

#define LZ4_STATIC_LINKING_ONLY

MATCH_SAFEGUARD_DISTANCE

#define MATCH_SAFEGUARD_DISTANCE   ((2*WILDCOPYLENGTH) - MINMATCH) /* ensure it's possible to write 2 x wildcopyLength without overflowing output buffer */

MB

#define MB   *(1 <<20)

MEM_INIT

#define MEM_INIT	(		p,
			v,
			s )

Value:

LZ4_memset((p),(v),(s))

MFLIMIT

#define MFLIMIT   12 /* see ../doc/lz4_Block_format.md#parsing-restrictions */

MIN

#define MIN	(		a,
			b )

Value:

( (a) < (b) ? (a) : (b) )

MINMATCH

#define MINMATCH   4

ML_BITS

#define ML_BITS   4

ML_MASK

#define ML_MASK   ((1U<<ML_BITS)-1)

RUN_BITS

#define RUN_BITS   (8-ML_BITS)

RUN_MASK

#define RUN_MASK   ((1U<<RUN_BITS)-1)

STEPSIZE

#define STEPSIZE   sizeof(reg_t)

unlikely

#define unlikely

(

expr

)

Value:

expect((expr) != 0, 0)

WILDCOPYLENGTH

#define WILDCOPYLENGTH   8

Typedef Documentation

BYTE

typedef unsigned char BYTE

reg_t

typedef size_t reg_t

Rvl_t

typedef size_t Rvl_t

S32

typedef signed int S32

U16

typedef unsigned short U16

U32

typedef unsigned int U32

U64

typedef unsigned long long U64

uptrval

typedef size_t uptrval

Enumeration Type Documentation

dict_directive

enum dict_directive

This enum distinguishes several different modes of accessing previous content in the stream.

• noDict : There is no preceding content.
• withPrefix64k : Table entries up to ctx->dictSize before the current blob blob being compressed are valid and refer to the preceding content (of length ctx->dictSize), which is available contiguously preceding in memory the content currently being compressed.
• usingExtDict : Like withPrefix64k, but the preceding content is somewhere else in memory, starting at ctx->dictionary with length ctx->dictSize.
• usingDictCtx : Everything concerning the preceding content is in a separate context, pointed to by ctx->dictCtx. ctx->dictionary, ctx->dictSize, and table entries in the current context that refer to positions preceding the beginning of the current compression are ignored. Instead, ctx->dictCtx->dictionary and ctx->dictCtx ->dictSize describe the location and size of the preceding content, and matches are found by looking in the ctx ->dictCtx->hashTable.

Enumerator
noDict
withPrefix64k
usingExtDict
usingDictCtx

dictIssue_directive

enum dictIssue_directive

Enumerator
noDictIssue
dictSmall

earlyEnd_directive

enum earlyEnd_directive

Enumerator
decode_full_block
partial_decode

limitedOutput_directive

enum limitedOutput_directive

Enumerator
notLimited
limitedOutput
fillOutput

LoadDict_mode_e

enum LoadDict_mode_e

Enumerator
_ld_fast
_ld_slow

tableType_t

enum tableType_t

Enumerator
clearedTable
byPtr
byU32
byU16

Function Documentation

LZ4_attach_dictionary()

void LZ4_attach_dictionary	(	LZ4_stream_t *	workingStream,
		const LZ4_stream_t *	dictionaryStream )

LZ4_attach_dictionary() : stable since v1.10.0

This allows efficient re-use of a static dictionary multiple times.

Rather than re-loading the dictionary buffer into a working context before each compression, or copying a pre-loaded dictionary's LZ4_stream_t into a working LZ4_stream_t, this function introduces a no-copy setup mechanism, in which the working stream references @dictionaryStream in-place.

Several assumptions are made about the state of @dictionaryStream. Currently, only states which have been prepared by LZ4_loadDict() or LZ4_loadDictSlow() should be expected to work.

Alternatively, the provided @dictionaryStream may be NULL, in which case any existing dictionary stream is unset.

If a dictionary is provided, it replaces any pre-existing stream history. The dictionary contents are the only history that can be referenced and logically immediately precede the data compressed in the first subsequent compression call.

The dictionary will only remain attached to the working stream through the first compression call, at the end of which it is cleared. @dictionaryStream stream (and source buffer) must remain in-place / accessible / unchanged through the completion of the compression session.

Note: there is no equivalent LZ4_attach_*() method on the decompression side because there is no initialization cost, hence no need to share the cost across multiple sessions. To decompress LZ4 blocks using dictionary, attached or not, just employ the regular LZ4_setStreamDecode() for streaming, or the stateless LZ4_decompress_safe_usingDict() for one-shot decompression.

LZ4_clearHash()

LZ4_FORCE_INLINE void LZ4_clearHash	(	U32	h,
		void *	tableBase,
		tableType_t const	tableType )

LZ4_compress()

int LZ4_compress	(	const char *	src,
		char *	dest,
		int	srcSize )

LZ4_compress_continue()

int LZ4_compress_continue	(	LZ4_stream_t *	LZ4_stream,
		const char *	source,
		char *	dest,
		int	inputSize )

LZ4_compress_default()

int LZ4_compress_default	(	const char *	src,
		char *	dst,
		int	srcSize,
		int	dstCapacity )

LZ4_compress_default() : Compresses 'srcSize' bytes from buffer 'src' into already allocated 'dst' buffer of size 'dstCapacity'. Compression is guaranteed to succeed if 'dstCapacity' >= LZ4_compressBound(srcSize). It also runs faster, so it's a recommended setting. If the function cannot compress 'src' into a more limited 'dst' budget, compression stops immediately, and the function result is zero. In which case, 'dst' content is undefined (invalid). srcSize : max supported value is LZ4_MAX_INPUT_SIZE. dstCapacity : size of buffer 'dst' (which must be already allocated)

Returns

: the number of bytes written into buffer 'dst' (necessarily <= dstCapacity) or 0 if compression fails Note : This function is protected against buffer overflow scenarios (never writes outside 'dst' buffer, nor read outside 'source' buffer).

LZ4_compress_destSize()

int LZ4_compress_destSize	(	const char *	src,
		char *	dst,
		int *	srcSizePtr,
		int	targetDstSize )

LZ4_compress_destSize() : Reverse the logic : compresses as much data as possible from 'src' buffer into already allocated buffer 'dst', of size >= 'dstCapacity'. This function either compresses the entire 'src' content into 'dst' if it's large enough, or fill 'dst' buffer completely with as much data as possible from 'src'. note: acceleration parameter is fixed to "default".

*srcSizePtr : in+out parameter. Initially contains size of input. Will be modified to indicate how many bytes where read from 'src' to fill 'dst'. New value is necessarily <= input value.

Returns

: Nb bytes written into 'dst' (necessarily <= dstCapacity) or 0 if compression fails.

Note : from v1.8.2 to v1.9.1, this function had a bug (fixed in v1.9.2+): the produced compressed content could, in specific circumstances, require to be decompressed into a destination buffer larger by at least 1 byte than the content to decompress. If an application uses LZ4_compress_destSize(), it's highly recommended to update liblz4 to v1.9.2 or better. If this can't be done or ensured, the receiving decompression function should provide a dstCapacity which is > decompressedSize, by at least 1 byte. See https://github.com/lz4/lz4/issues/859 for details

LZ4_compress_destSize_extState()

int LZ4_compress_destSize_extState	(	void *	state,
		const char *	src,
		char *	dst,
		int *	srcSizePtr,
		int	targetDstSize,
		int	acceleration )

LZ4_compress_fast()

int LZ4_compress_fast	(	const char *	src,
		char *	dst,
		int	srcSize,
		int	dstCapacity,
		int	acceleration )

LZ4_compress_fast() : Same as LZ4_compress_default(), but allows selection of "acceleration" factor. The larger the acceleration value, the faster the algorithm, but also the lesser the compression. It's a trade-off. It can be fine tuned, with each successive value providing roughly +~3% to speed. An acceleration value of "1" is the same as regular LZ4_compress_default() Values <= 0 will be replaced by LZ4_ACCELERATION_DEFAULT (currently == 1, see lz4.c). Values > LZ4_ACCELERATION_MAX will be replaced by LZ4_ACCELERATION_MAX (currently == 65537, see lz4.c).

LZ4_compress_fast_continue()

int LZ4_compress_fast_continue	(	LZ4_stream_t *	streamPtr,
		const char *	src,
		char *	dst,
		int	srcSize,
		int	dstCapacity,
		int	acceleration )

LZ4_compress_fast_continue() : Compress 'src' content using data from previously compressed blocks, for better compression ratio. 'dst' buffer must be already allocated. If dstCapacity >= LZ4_compressBound(srcSize), compression is guaranteed to succeed, and runs faster.

Returns

: size of compressed block or 0 if there is an error (typically, cannot fit into 'dst').

Note 1 : Each invocation to LZ4_compress_fast_continue() generates a new block. Each block has precise boundaries. Each block must be decompressed separately, calling LZ4_decompress_*() with relevant metadata. It's not possible to append blocks together and expect a single invocation of LZ4_decompress_*() to decompress them together.

Note 2 : The previous 64KB of source data is assumed to remain present, unmodified, at same address in memory !

Note 3 : When input is structured as a double-buffer, each buffer can have any size, including < 64 KB. Make sure that buffers are separated, by at least one byte. This construction ensures that each block only depends on previous block.

Note 4 : If input buffer is a ring-buffer, it can have any size, including < 64 KB.

Note 5 : After an error, the stream status is undefined (invalid), it can only be reset or freed.

LZ4_compress_fast_extState()

int LZ4_compress_fast_extState	(	void *	state,
		const char *	source,
		char *	dest,
		int	inputSize,
		int	maxOutputSize,
		int	acceleration )

LZ4_compress_fast_extState_fastReset()

int LZ4_compress_fast_extState_fastReset	(	void *	state,
		const char *	src,
		char *	dst,
		int	srcSize,
		int	dstCapacity,
		int	acceleration )

LZ4_compress_fast_extState_fastReset() : A variant of LZ4_compress_fast_extState().

Using this variant avoids an expensive initialization step. It is only safe to call if the state buffer is known to be correctly initialized already (see comment in lz4.h on LZ4_resetStream_fast() for a definition of "correctly initialized").

LZ4_compress_forceExtDict()

int LZ4_compress_forceExtDict	(	LZ4_stream_t *	LZ4_dict,
		const char *	source,
		char *	dest,
		int	srcSize )

LZ4_compress_generic()

LZ4_FORCE_INLINE int LZ4_compress_generic	(	LZ4_stream_t_internal *const	cctx,
		const char *const	src,
		char *const	dst,
		const int	srcSize,
		int *	inputConsumed,
		const int	dstCapacity,
		const limitedOutput_directive	outputDirective,
		const tableType_t	tableType,
		const dict_directive	dictDirective,
		const dictIssue_directive	dictIssue,
		const int	acceleration )

LZ4_compress_generic() : inlined, to ensure branches are decided at compilation time; takes care of src == (NULL, 0) and forward the rest to LZ4_compress_generic_validated

LZ4_compress_generic_validated()

LZ4_FORCE_INLINE int LZ4_compress_generic_validated	(	LZ4_stream_t_internal *const	cctx,
		const char *const	source,
		char *const	dest,
		const int	inputSize,
		int *	inputConsumed,
		const int	maxOutputSize,
		const limitedOutput_directive	outputDirective,
		const tableType_t	tableType,
		const dict_directive	dictDirective,
		const dictIssue_directive	dictIssue,
		const int	acceleration )

LZ4_compress_generic_validated() : inlined, to ensure branches are decided at compilation time. The following conditions are presumed already validated:

• source != NULL
• inputSize > 0

LZ4_compress_limitedOutput()

int LZ4_compress_limitedOutput	(	const char *	source,
		char *	dest,
		int	inputSize,
		int	maxOutputSize )

LZ4_compress_limitedOutput_continue()

int LZ4_compress_limitedOutput_continue	(	LZ4_stream_t *	LZ4_stream,
		const char *	src,
		char *	dst,
		int	srcSize,
		int	dstCapacity )

LZ4_compress_limitedOutput_withState()

int LZ4_compress_limitedOutput_withState	(	void *	state,
		const char *	src,
		char *	dst,
		int	srcSize,
		int	dstSize )

LZ4_compress_withState()

int LZ4_compress_withState	(	void *	state,
		const char *	src,
		char *	dst,
		int	srcSize )

LZ4_compressBound()

int LZ4_compressBound

(

int

inputSize

)

LZ4_compressBound() : Provides the maximum size that LZ4 compression may output in a "worst case" scenario (input data not compressible) This function is primarily useful for memory allocation purposes (destination buffer size). Macro LZ4_COMPRESSBOUND() is also provided for compilation-time evaluation (stack memory allocation for example). Note that LZ4_compress_default() compresses faster when dstCapacity is >= LZ4_compressBound(srcSize) inputSize : max supported value is LZ4_MAX_INPUT_SIZE return : maximum output size in a "worst case" scenario or 0, if input size is incorrect (too large or negative)

LZ4_count()

LZ4_FORCE_INLINE unsigned LZ4_count	(	const BYTE *	pIn,
		const BYTE *	pMatch,
		const BYTE *	pInLimit )

LZ4_create()

void * LZ4_create

(

char *

inputBuffer

)

LZ4_createStream()

LZ4_stream_t * LZ4_createStream

(

void

)

Note about RC_INVOKED

• RC_INVOKED is predefined symbol of rc.exe (the resource compiler which is part of MSVC/Visual Studio). https://docs.microsoft.com/en-us/windows/win32/menurc/predefined-macros
• Since rc.exe is a legacy compiler, it truncates long symbol (> 30 chars) and reports warning "RC4011: identifier truncated".
• To eliminate the warning, we surround long preprocessor symbol with "#if !defined(RC_INVOKED) ... #endif" block that means "skip this block when rc.exe is trying to read it".

LZ4_createStreamDecode()

LZ4_streamDecode_t * LZ4_createStreamDecode

(

void

)

LZ4_createStreamDecode() and LZ4_freeStreamDecode() : creation / destruction of streaming decompression tracking context. A tracking context can be re-used multiple times.

LZ4_decoderRingBufferSize()

int LZ4_decoderRingBufferSize

(

int

maxBlockSize

)

LZ4_decoderRingBufferSize() : when setting a ring buffer for streaming decompression (optional scenario), provides the minimum size of this ring buffer to be compatible with any source respecting maxBlockSize condition. Note : in a ring buffer scenario, blocks are presumed decompressed next to each other. When not enough space remains for next block (remainingSize < maxBlockSize), decoding resumes from beginning of ring buffer.

Returns

: minimum ring buffer size, or 0 if there is an error (invalid maxBlockSize).

LZ4_decompress_fast()

LZ4_FORCE_O2 int LZ4_decompress_fast	(	const char *	src,
		char *	dst,
		int	originalSize )

Obsolete LZ4_decompress_fast variants (since v1.9.0) : These functions used to be faster than LZ4_decompress_safe(), but this is no longer the case. They are now slower. This is because LZ4_decompress_fast() doesn't know the input size, and therefore must progress more cautiously into the input buffer to not read beyond the end of block. On top of that LZ4_decompress_fast() is not protected vs malformed or malicious inputs, making it a security liability. As a consequence, LZ4_decompress_fast() is strongly discouraged, and deprecated.

The last remaining LZ4_decompress_fast() specificity is that it can decompress a block without knowing its compressed size. Such functionality can be achieved in a more secure manner by employing LZ4_decompress_safe_partial().

Parameters: originalSize : is the uncompressed size to regenerate. dst must be already allocated, its size must be >= 'originalSize' bytes.

Returns

: number of bytes read from source buffer (== compressed size). The function expects to finish at block's end exactly. If the source stream is detected malformed, the function stops decoding and returns a negative result. note : LZ4_decompress_fast*() requires originalSize. Thanks to this information, it never writes past the output buffer. However, since it doesn't know its 'src' size, it may read an unknown amount of input, past input buffer bounds. Also, since match offsets are not validated, match reads from 'src' may underflow too. These issues never happen if input (compressed) data is correct. But they may happen if input data is invalid (error or intentional tampering). As a consequence, use these functions in trusted environments with trusted data only.

LZ4_decompress_fast_continue()

LZ4_FORCE_O2 int LZ4_decompress_fast_continue	(	LZ4_streamDecode_t *	LZ4_streamDecode,
		const char *	source,
		char *	dest,
		int	originalSize )

LZ4_decompress_fast_usingDict()

int LZ4_decompress_fast_usingDict	(	const char *	source,
		char *	dest,
		int	originalSize,
		const char *	dictStart,
		int	dictSize )

LZ4_decompress_fast_withPrefix64k()

int LZ4_decompress_fast_withPrefix64k	(	const char *	source,
		char *	dest,
		int	originalSize )

LZ4_decompress_generic()

LZ4_FORCE_INLINE int LZ4_decompress_generic	(	const char *const	src,
		char *const	dst,
		int	srcSize,
		int	outputSize,
		earlyEnd_directive	partialDecoding,
		dict_directive	dict,
		const BYTE *const	lowPrefix,
		const BYTE *const	dictStart,
		const size_t	dictSize )

LZ4_decompress_generic() : This generic decompression function covers all use cases. It shall be instantiated several times, using different sets of directives. Note that it is important for performance that this function really get inlined, in order to remove useless branches during compilation optimization.

LZ4_decompress_safe()

LZ4_FORCE_O2 int LZ4_decompress_safe	(	const char *	src,
		char *	dst,
		int	compressedSize,
		int	dstCapacity )

LZ4_decompress_safe() : @compressedSize : is the exact complete size of the compressed block. @dstCapacity : is the size of destination buffer (which must be already allocated), presumed an upper bound of decompressed size.

Returns

: the number of bytes decompressed into destination buffer (necessarily <= dstCapacity) If destination buffer is not large enough, decoding will stop and output an error code (negative value). If the source stream is detected malformed, the function will stop decoding and return a negative result. Note 1 : This function is protected against malicious data packets : it will never writes outside 'dst' buffer, nor read outside 'source' buffer, even if the compressed block is maliciously modified to order the decoder to do these actions. In such case, the decoder stops immediately, and considers the compressed block malformed. Note 2 : compressedSize and dstCapacity must be provided to the function, the compressed block does not contain them. The implementation is free to send / store / derive this information in whichever way is most beneficial. If there is a need for a different format which bundles together both compressed data and its metadata, consider looking at lz4frame.h instead.

LZ4_decompress_safe_continue()

LZ4_FORCE_O2 int LZ4_decompress_safe_continue	(	LZ4_streamDecode_t *	LZ4_streamDecode,
		const char *	src,
		char *	dst,
		int	srcSize,
		int	dstCapacity )

LZ4_decompress_safe_continue() : This decoding function allows decompression of consecutive blocks in "streaming" mode. The difference with the usual independent blocks is that new blocks are allowed to find references into former blocks. A block is an unsplittable entity, and must be presented entirely to the decompression function. LZ4_decompress_safe_continue() only accepts one block at a time. It's modeled after LZ4_decompress_safe() and behaves similarly.

@LZ4_streamDecode : decompression state, tracking the position in memory of past data @compressedSize : exact complete size of one compressed block. @dstCapacity : size of destination buffer (which must be already allocated), must be an upper bound of decompressed size.

Returns

: number of bytes decompressed into destination buffer (necessarily <= dstCapacity) If destination buffer is not large enough, decoding will stop and output an error code (negative value). If the source stream is detected malformed, the function will stop decoding and return a negative result.

The last 64KB of previously decoded data must remain available and unmodified at the memory position where they were previously decoded. If less than 64KB of data has been decoded, all the data must be present.

Special : if decompression side sets a ring buffer, it must respect one of the following conditions :

• Decompression buffer size is at least LZ4_decoderRingBufferSize(maxBlockSize). maxBlockSize is the maximum size of any single block. It can have any value > 16 bytes. In which case, encoding and decoding buffers do not need to be synchronized. Actually, data can be produced by any source compliant with LZ4 format specification, and respecting maxBlockSize.
• Synchronized mode : Decompression buffer size is exactly the same as compression buffer size, and follows exactly same update rule (block boundaries at same positions), and decoding function is provided with exact decompressed size of each block (exception for last block of the stream), then decoding & encoding ring buffer can have any size, including small ones ( < 64 KB).
• Decompression buffer is larger than encoding buffer, by a minimum of maxBlockSize more bytes. In which case, encoding and decoding buffers do not need to be synchronized, and encoding ring buffer can have any size, including small ones ( < 64 KB).

Whenever these conditions are not possible, save the last 64KB of decoded data into a safe buffer where it can't be modified during decompression, then indicate where this data is saved using LZ4_setStreamDecode(), before decompressing next block.

LZ4_decompress_safe_doubleDict()

LZ4_FORCE_INLINE int LZ4_decompress_safe_doubleDict	(	const char *	source,
		char *	dest,
		int	compressedSize,
		int	maxOutputSize,
		size_t	prefixSize,
		const void *	dictStart,
		size_t	dictSize )

LZ4_decompress_safe_forceExtDict()

LZ4_FORCE_O2 int LZ4_decompress_safe_forceExtDict	(	const char *	source,
		char *	dest,
		int	compressedSize,
		int	maxOutputSize,
		const void *	dictStart,
		size_t	dictSize )

LZ4_decompress_safe_partial()

LZ4_FORCE_O2 int LZ4_decompress_safe_partial	(	const char *	src,
		char *	dst,
		int	srcSize,
		int	targetOutputSize,
		int	dstCapacity )

LZ4_decompress_safe_partial() : Decompress an LZ4 compressed block, of size 'srcSize' at position 'src', into destination buffer 'dst' of size 'dstCapacity'. Up to 'targetOutputSize' bytes will be decoded. The function stops decoding on reaching this objective. This can be useful to boost performance whenever only the beginning of a block is required.

Returns

: the number of bytes decoded in dst (necessarily <= targetOutputSize) If source stream is detected malformed, function returns a negative result.

Note 1 :

Returns

can be < targetOutputSize, if compressed block contains less data.

Note 2 : targetOutputSize must be <= dstCapacity

Note 3 : this function effectively stops decoding on reaching targetOutputSize, so dstCapacity is kind of redundant. This is because in older versions of this function, decoding operation would still write complete sequences. Therefore, there was no guarantee that it would stop writing at exactly targetOutputSize, it could write more bytes, though only up to dstCapacity. Some "margin" used to be required for this operation to work properly. Thankfully, this is no longer necessary. The function nonetheless keeps the same signature, in an effort to preserve API compatibility.

Note 4 : If srcSize is the exact size of the block, then targetOutputSize can be any value, including larger than the block's decompressed size. The function will, at most, generate block's decompressed size.

Note 5 : If srcSize is larger than block's compressed size, then targetOutputSize MUST be <= block's decompressed size. Otherwise, silent corruption will occur.

LZ4_decompress_safe_partial_forceExtDict()

LZ4_FORCE_O2 int LZ4_decompress_safe_partial_forceExtDict	(	const char *	source,
		char *	dest,
		int	compressedSize,
		int	targetOutputSize,
		int	dstCapacity,
		const void *	dictStart,
		size_t	dictSize )

LZ4_decompress_safe_partial_usingDict()

int LZ4_decompress_safe_partial_usingDict	(	const char *	src,
		char *	dst,
		int	compressedSize,
		int	targetOutputSize,
		int	maxOutputSize,
		const char *	dictStart,
		int	dictSize )

LZ4_decompress_safe_partial_usingDict() : Behaves the same as LZ4_decompress_safe_partial() with the added ability to specify a memory segment for past data. Performance tip : Decompression speed can be substantially increased when dst == dictStart + dictSize.

LZ4_decompress_safe_usingDict()

int LZ4_decompress_safe_usingDict	(	const char *	src,
		char *	dst,
		int	srcSize,
		int	dstCapacity,
		const char *	dictStart,
		int	dictSize )

LZ4_decompress_safe_usingDict() : Works the same as a combination of LZ4_setStreamDecode() followed by LZ4_decompress_safe_continue() However, it's stateless: it doesn't need any LZ4_streamDecode_t state. Dictionary is presumed stable : it must remain accessible and unmodified during decompression. Performance tip : Decompression speed can be substantially increased when dst == dictStart + dictSize.

LZ4_decompress_safe_withPrefix64k()

LZ4_FORCE_O2 int LZ4_decompress_safe_withPrefix64k	(	const char *	source,
		char *	dest,
		int	compressedSize,
		int	maxOutputSize )

LZ4_decompress_unsafe_generic()

LZ4_FORCE_INLINE int LZ4_decompress_unsafe_generic	(	const BYTE *const	istart,
		BYTE *const	ostart,
		int	decompressedSize,
		size_t	prefixSize,
		const BYTE *const	dictStart,
		const size_t	dictSize )

LZ4_freeStream()

int LZ4_freeStream

(

LZ4_stream_t *

LZ4_stream

)

LZ4_freeStreamDecode()

int LZ4_freeStreamDecode

(

LZ4_streamDecode_t *

LZ4_stream

)

LZ4_getIndexOnHash()

LZ4_FORCE_INLINE U32 LZ4_getIndexOnHash	(	U32	h,
		const void *	tableBase,
		tableType_t	tableType )

LZ4_getPosition()

LZ4_FORCE_INLINE const BYTE * LZ4_getPosition	(	const BYTE *	p,
		const void *	tableBase,
		tableType_t	tableType )

LZ4_hash4()

LZ4_FORCE_INLINE U32 LZ4_hash4	(	U32	sequence,
		tableType_t const	tableType )

LZ4_hash5()

LZ4_FORCE_INLINE U32 LZ4_hash5	(	U64	sequence,
		tableType_t const	tableType )

LZ4_hashPosition()

LZ4_FORCE_INLINE U32 LZ4_hashPosition	(	const void *const	p,
		tableType_t const	tableType )

LZ4_initStream()

LZ4_stream_t * LZ4_initStream	(	void *	stateBuffer,
		size_t	size )

LZ4_initStream() : v1.9.0+ An LZ4_stream_t structure must be initialized at least once. This is automatically done when invoking LZ4_createStream(), but it's not when the structure is simply declared on stack (for example).

Use LZ4_initStream() to properly initialize a newly declared LZ4_stream_t. It can also initialize any arbitrary buffer of sufficient size, and will

Returns

a pointer of proper type upon initialization.

Note : initialization fails if size and alignment conditions are not respected. In which case, the function will

Returns

NULL. Note2: An LZ4_stream_t structure guarantees correct alignment and size. Note3: Before v1.9.0, use LZ4_resetStream() instead

LZ4_loadDict()

int LZ4_loadDict	(	LZ4_stream_t *	streamPtr,
		const char *	dictionary,
		int	dictSize )

LZ4_loadDict() : Use this function to reference a static dictionary into LZ4_stream_t. The dictionary must remain available during compression. LZ4_loadDict() triggers a reset, so any previous data will be forgotten. The same dictionary will have to be loaded on decompression side for successful decoding. Dictionary are useful for better compression of small data (KB range). While LZ4 itself accepts any input as dictionary, dictionary efficiency is also a topic. When in doubt, employ the Zstandard's Dictionary Builder. Loading a size of 0 is allowed, and is the same as reset.

Returns

: loaded dictionary size, in bytes (note: only the last 64 KB are loaded)

LZ4_loadDict_internal()

int LZ4_loadDict_internal	(	LZ4_stream_t *	LZ4_dict,
		const char *	dictionary,
		int	dictSize,
		LoadDict_mode_e	_ld )

LZ4_loadDictSlow()

int LZ4_loadDictSlow	(	LZ4_stream_t *	streamPtr,
		const char *	dictionary,
		int	dictSize )

LZ4_loadDictSlow() : v1.10.0+ Same as LZ4_loadDict(), but uses a bit more cpu to reference the dictionary content more thoroughly. This is expected to slightly improve compression ratio. The extra-cpu cost is likely worth it if the dictionary is re-used across multiple sessions.

Returns

: loaded dictionary size, in bytes (note: only the last 64 KB are loaded)

LZ4_prepareTable()

LZ4_FORCE_INLINE void LZ4_prepareTable	(	LZ4_stream_t_internal *const	cctx,
		const int	inputSize,
		const tableType_t	tableType )

LZ4_putIndexOnHash()

LZ4_FORCE_INLINE void LZ4_putIndexOnHash	(	U32	idx,
		U32	h,
		void *	tableBase,
		tableType_t const	tableType )

LZ4_putPosition()

LZ4_FORCE_INLINE void LZ4_putPosition	(	const BYTE *	p,
		void *	tableBase,
		tableType_t	tableType )

LZ4_putPositionOnHash()

LZ4_FORCE_INLINE void LZ4_putPositionOnHash	(	const BYTE *	p,
		U32	h,
		void *	tableBase,
		tableType_t const	tableType )

LZ4_resetStream()

void LZ4_resetStream

(

LZ4_stream_t *

streamPtr

)

LZ4_resetStream() : An LZ4_stream_t structure must be initialized at least once. This is done with LZ4_initStream(), or LZ4_resetStream(). Consider switching to LZ4_initStream(), invoking LZ4_resetStream() will trigger deprecation warnings in the future.

LZ4_resetStream_fast()

void LZ4_resetStream_fast

(

LZ4_stream_t *

streamPtr

)

LZ4_resetStream_fast() : v1.9.0+ Use this to prepare an LZ4_stream_t for a new chain of dependent blocks (e.g., LZ4_compress_fast_continue()).

An LZ4_stream_t must be initialized once before usage. This is automatically done when created by LZ4_createStream(). However, should the LZ4_stream_t be simply declared on stack (for example), it's necessary to initialize it first, using LZ4_initStream().

After init, start any new stream with LZ4_resetStream_fast(). A same LZ4_stream_t can be re-used multiple times consecutively and compress multiple streams, provided that it starts each new stream with LZ4_resetStream_fast().

LZ4_resetStream_fast() is much faster than LZ4_initStream(), but is not compatible with memory regions containing garbage data.

Note: it's only useful to call LZ4_resetStream_fast() in the context of streaming compression. The extState functions perform their own resets. Invoking LZ4_resetStream_fast() before is redundant, and even counterproductive.

LZ4_resetStreamState()

int LZ4_resetStreamState	(	void *	state,
		char *	inputBuffer )

LZ4_saveDict()

int LZ4_saveDict	(	LZ4_stream_t *	LZ4_dict,
		char *	safeBuffer,
		int	dictSize )

LZ4_saveDict() : If previously compressed data block is not guaranteed to remain available at its memory location, save it into a safer place (char* safeBuffer). Note : no need to call LZ4_loadDict() afterwards, dictionary is immediately usable, one can therefore call LZ4_compress_fast_continue() right after.

Returns

: saved dictionary size in bytes (necessarily <= dictSize), or 0 if error.

LZ4_setStreamDecode()

int LZ4_setStreamDecode	(	LZ4_streamDecode_t *	LZ4_streamDecode,
		const char *	dictionary,
		int	dictSize )

LZ4_setStreamDecode() : Use this function to instruct where to find the dictionary. This function is not necessary if previous data is still available where it was decoded. Loading a size of 0 is allowed (same effect as no dictionary).

Returns

: 1 if OK, 0 if error

LZ4_sizeofState()

int LZ4_sizeofState

(

void

)

LZ4_compress_fast_extState() : Same as LZ4_compress_fast(), using an externally allocated memory space for its state. Use LZ4_sizeofState() to know how much memory must be allocated, and allocate it on 8-bytes boundaries (using malloc() typically). Then, provide this buffer as void* state to compression function.

LZ4_sizeofStreamState()

int LZ4_sizeofStreamState

(

void

)

LZ4_slideInputBuffer()

char * LZ4_slideInputBuffer

(

void *

state

)

LZ4_uncompress()

int LZ4_uncompress	(	const char *	source,
		char *	dest,
		int	outputSize )

LZ4_uncompress_unknownOutputSize()

int LZ4_uncompress_unknownOutputSize	(	const char *	source,
		char *	dest,
		int	isize,
		int	maxOutputSize )

LZ4_versionNumber()

int LZ4_versionNumber

(

void

)

library version number; useful to check dll version; requires v1.3.0+

LZ4_versionString()

const char * LZ4_versionString

(

void

)

library version string; useful to check dll version; requires v1.7.5+

LZ4_wildCopy8()

LZ4_FORCE_INLINE void LZ4_wildCopy8	(	void *	dstPtr,
		const void *	srcPtr,
		void *	dstEnd )

read_variable_length()

LZ4_FORCE_INLINE Rvl_t read_variable_length	(	const BYTE **	ip,
		const BYTE *	ilimit,
		int	initial_check )