comparison contrib/python-zstandard/zstd/common/fse.h @ 30822:b54a2984cdd4

zstd: vendor python-zstandard 0.6.0

Commit 63c68d6f5fc8de4afd9bde81b13b537beb4e47e8 from
https://github.com/indygreg/python-zstandard is imported without
modifications (other than removing unwanted files).

This includes minor performance and feature improvements. It also
changes the vendored zstd library from 1.1.1 to 1.1.2.

# no-check-commit

30821:7005c03f7387

/* FSE buffer bounds */
#define FSE_NCOUNTBOUND 512
#define FSE_BLOCKBOUND(size) (size + (size>>7))
#define FSE_COMPRESSBOUND(size) (FSE_NCOUNTBOUND + FSE_BLOCKBOUND(size))   /* Macro version, useful for static allocation */

/* It is possible to statically allocate FSE CTable/DTable as a table of unsigned using below macros */
#define FSE_CTABLE_SIZE_U32(maxTableLog, maxSymbolValue)   (1 + (1<<(maxTableLog-1)) + ((maxSymbolValue+1)*2))
#define FSE_DTABLE_SIZE_U32(maxTableLog)                   (1 + (1<<maxTableLog))


/* *****************************************
*  FSE advanced API
*******************************************/
size_t FSE_countFast(unsigned* count, unsigned* maxSymbolValuePtr, const void* src, size_t srcSize);
/**< same as FSE_count(), but blindly trusts that all byte values within src are <= *maxSymbolValuePtr  */

unsigned FSE_optimalTableLog_internal(unsigned maxTableLog, size_t srcSize, unsigned maxSymbolValue, unsigned minus);
/**< same as FSE_optimalTableLog(), which used `minus==2` */

size_t FSE_buildCTable_raw (FSE_CTable* ct, unsigned nbBits);
/**< build a fake FSE_CTable, designed to not compress an input, where each symbol uses nbBits */

size_t FSE_buildCTable_rle (FSE_CTable* ct, unsigned char symbolValue);
/**< build a fake FSE_CTable, designed to compress always the same symbolValue */

size_t FSE_buildDTable_raw (FSE_DTable* dt, unsigned nbBits);
/**< build a fake FSE_DTable, designed to read an uncompressed bitstream where each symbol uses nbBits */

size_t FSE_buildDTable_rle (FSE_DTable* dt, unsigned char symbolValue);
/**< build a fake FSE_DTable, designed to always generate the same symbolValue */


/* *****************************************
*  FSE symbol compression API
*******************************************/
/*!
   This API consists of small unitary functions, which highly benefit from being inlined.
   You will want to enable link-time-optimization to ensure these functions are properly inlined in your binary.
   Visual seems to do it automatically.
   For gcc or clang, you'll need to add -flto flag at compilation and linking stages.
   If none of these solutions is applicable, include "fse.c" directly.
*/
typedef struct
{
    ptrdiff_t   value;
    const void* stateTable;
    const void* symbolTT;
    unsigned    stateLog;
} FSE_CState_t;

/* *****************************************
*  FSE symbol decompression API
*******************************************/
typedef struct
{
    size_t      state;
    const void* table;   /* precise table may vary, depending on U16 */
} FSE_DState_t;

30822:b54a2984cdd4

/* FSE buffer bounds */
#define FSE_NCOUNTBOUND 512
#define FSE_BLOCKBOUND(size) (size + (size>>7))
#define FSE_COMPRESSBOUND(size) (FSE_NCOUNTBOUND + FSE_BLOCKBOUND(size))   /* Macro version, useful for static allocation */

/* It is possible to statically allocate FSE CTable/DTable as a table of FSE_CTable/FSE_DTable using below macros */
#define FSE_CTABLE_SIZE_U32(maxTableLog, maxSymbolValue)   (1 + (1<<(maxTableLog-1)) + ((maxSymbolValue+1)*2))
#define FSE_DTABLE_SIZE_U32(maxTableLog)                   (1 + (1<<maxTableLog))


/* *****************************************
*  FSE advanced API
*******************************************/
/* FSE_count_wksp() :
 * Same as FSE_count(), but using an externally provided scratch buffer.
 * `workSpace` size must be table of >= `1024` unsigned
 */
size_t FSE_count_wksp(unsigned* count, unsigned* maxSymbolValuePtr,
                 const void* source, size_t sourceSize, unsigned* workSpace);

/** FSE_countFast() :
 *  same as FSE_count(), but blindly trusts that all byte values within src are <= *maxSymbolValuePtr
 */
size_t FSE_countFast(unsigned* count, unsigned* maxSymbolValuePtr, const void* src, size_t srcSize);

/* FSE_countFast_wksp() :
 * Same as FSE_countFast(), but using an externally provided scratch buffer.
 * `workSpace` must be a table of minimum `1024` unsigned
 */
size_t FSE_countFast_wksp(unsigned* count, unsigned* maxSymbolValuePtr, const void* src, size_t srcSize, unsigned* workSpace);

/*! FSE_count_simple
 * Same as FSE_countFast(), but does not use any additional memory (not even on stack).
 * This function is unsafe, and will segfault if any value within `src` is `> *maxSymbolValuePtr` (presuming it's also the size of `count`).
*/
size_t FSE_count_simple(unsigned* count, unsigned* maxSymbolValuePtr, const void* src, size_t srcSize);



unsigned FSE_optimalTableLog_internal(unsigned maxTableLog, size_t srcSize, unsigned maxSymbolValue, unsigned minus);
/**< same as FSE_optimalTableLog(), which used `minus==2` */

/* FSE_compress_wksp() :
 * Same as FSE_compress2(), but using an externally allocated scratch buffer (`workSpace`).
 * FSE_WKSP_SIZE_U32() provides the minimum size required for `workSpace` as a table of FSE_CTable.
 */
#define FSE_WKSP_SIZE_U32(maxTableLog, maxSymbolValue)   ( FSE_CTABLE_SIZE_U32(maxTableLog, maxSymbolValue) + (1<<((maxTableLog>2)?(maxTableLog-2):0)) )
size_t FSE_compress_wksp (void* dst, size_t dstSize, const void* src, size_t srcSize, unsigned maxSymbolValue, unsigned tableLog, void* workSpace, size_t wkspSize);

size_t FSE_buildCTable_raw (FSE_CTable* ct, unsigned nbBits);
/**< build a fake FSE_CTable, designed for a flat distribution, where each symbol uses nbBits */

size_t FSE_buildCTable_rle (FSE_CTable* ct, unsigned char symbolValue);
/**< build a fake FSE_CTable, designed to compress always the same symbolValue */

/* FSE_buildCTable_wksp() :
 * Same as FSE_buildCTable(), but using an externally allocated scratch buffer (`workSpace`).
 * `wkspSize` must be >= `(1<<tableLog)`.
 */
size_t FSE_buildCTable_wksp(FSE_CTable* ct, const short* normalizedCounter, unsigned maxSymbolValue, unsigned tableLog, void* workSpace, size_t wkspSize);

size_t FSE_buildDTable_raw (FSE_DTable* dt, unsigned nbBits);
/**< build a fake FSE_DTable, designed to read a flat distribution where each symbol uses nbBits */

size_t FSE_buildDTable_rle (FSE_DTable* dt, unsigned char symbolValue);
/**< build a fake FSE_DTable, designed to always generate the same symbolValue */

size_t FSE_decompress_wksp(void* dst, size_t dstCapacity, const void* cSrc, size_t cSrcSize, FSE_DTable* workSpace, unsigned maxLog);
/**< same as FSE_decompress(), using an externally allocated `workSpace` produced with `FSE_DTABLE_SIZE_U32(maxLog)` */


/* *****************************************
*  FSE symbol compression API
*******************************************/
/*!
   This API consists of small unitary functions, which highly benefit from being inlined.
   Hence their body are included in next section.
*/
typedef struct {
    ptrdiff_t   value;
    const void* stateTable;
    const void* symbolTT;
    unsigned    stateLog;
} FSE_CState_t;

/* *****************************************
*  FSE symbol decompression API
*******************************************/
typedef struct {
    size_t      state;
    const void* table;   /* precise table may vary, depending on U16 */
} FSE_DState_t;