GRASS 8 Programmer's Manual
8.5.0dev(2025)-52a061bce6
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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 |
#define | LZ4_STATIC_LINKING_ONLY |
#define | LZ4_FORCE_INLINE static |
#define | LZ4_FORCE_O2 |
#define | expect(expr, value) (expr) |
#define | likely(expr) expect((expr) != 0, 1) |
#define | unlikely(expr) expect((expr) != 0, 0) |
#define | LZ4_ALIGN_TEST 1 |
#define | ALLOC(s) malloc(s) |
#define | ALLOC_AND_ZERO(s) calloc(1, s) |
#define | FREEMEM(p) free(p) |
#define | LZ4_memset(p, v, s) memset((p), (v), (s)) |
#define | MEM_INIT(p, v, s) LZ4_memset((p), (v), (s)) |
#define | MINMATCH 4 |
#define | WILDCOPYLENGTH 8 |
#define | LASTLITERALS |
#define | MFLIMIT 12 /* see ../doc/lz4_Block_format.md#parsing-restrictions */ |
#define | MATCH_SAFEGUARD_DISTANCE |
#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) ((void)0) |
#define | LZ4_STATIC_ASSERT(c) |
#define | DEBUGLOG(l, ...) |
#define | LZ4_memcpy(dst, src, size) 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) ((a) < (b) ? (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 | |
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) |
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) |
#define ALLOC | ( | s | ) | 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.
#define LASTLITERALS |
#define LZ4_DISABLE_DEPRECATE_WARNINGS |
#define LZ4_memcpy | ( | dst, | |
src, | |||
size | |||
) | 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.
#define LZ4_STATIC_ASSERT | ( | c | ) |
#define MATCH_SAFEGUARD_DISTANCE |
#define MEM_INIT | ( | p, | |
v, | |||
s | |||
) | LZ4_memset((p), (v), (s)) |
#define MFLIMIT 12 /* see ../doc/lz4_Block_format.md#parsing-restrictions */ |
enum dict_directive |
This enum distinguishes several different modes of accessing previous content in the stream.
Enumerator | |
---|---|
noDict | |
withPrefix64k | |
usingExtDict | |
usingDictCtx |
enum dictIssue_directive |
enum earlyEnd_directive |
enum LoadDict_mode_e |
enum tableType_t |
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.
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) |
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".
[in,out] | srcSizePtr | 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. |
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
int LZ4_compress_destSize_extState | ( | void * | state, |
const char * | src, | ||
char * | dst, | ||
int * | srcSizePtr, | ||
int | targetDstSize, | ||
int | acceleration | ||
) |
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).
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.
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.
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 | ||
) |
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").
int LZ4_compress_forceExtDict | ( | LZ4_stream_t * | LZ4_dict, |
const char * | source, | ||
char * | dest, | ||
int | srcSize | ||
) |
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 |
Definition at line 879 of file lz4.c.
References LZ4_VERSION_STRING.
Referenced by G_lz4_compress_bound().
LZ4_stream_t* LZ4_createStream | ( | void | ) |
Note about RC_INVOKED
Definition at line 1892 of file lz4.c.
References ALLOC, DEBUGLOG, LZ4_initStream(), LZ4_STATIC_ASSERT, and NULL.
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 | ||
) |
int LZ4_freeStream | ( | LZ4_stream_t * | LZ4_stream | ) |
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
Note : initialization fails if size and alignment conditions are not respected. In which case, the function will
Definition at line 1917 of file lz4.c.
Referenced by LZ4_createStream().
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.
int LZ4_loadDict_internal | ( | LZ4_stream_t * | LZ4_dict, |
const char * | dictionary, | ||
int | dictSize, | ||
LoadDict_mode_e | _ld | ||
) |
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.
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.
Definition at line 1934 of file lz4.c.
References DEBUGLOG.
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.
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.
Definition at line 2238 of file lz4.c.
References assert, DEBUGLOG, LZ4_stream_t_internal::dictionary, LZ4_stream_t_internal::dictSize, LZ4_stream_u::internal_donotuse, KB, LZ4_memmove, and NULL.
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.
Definition at line 883 of file lz4.c.
References LZ4_COMPRESSBOUND.
int LZ4_versionNumber | ( | void | ) |
const char* LZ4_versionString | ( | void | ) |
library version string; useful to check dll version; requires v1.7.5+
Definition at line 875 of file lz4.c.
References LZ4_VERSION_NUMBER.