/* SPDX-License-Identifier: GPL-2.0+ OR BSD-3-Clause *//* ****************************************************************** * huff0 huffman codec, * part of Finite State Entropy library * Copyright (c) Meta Platforms, Inc. and affiliates. * * You can contact the author at : * - Source repository : https://github.com/Cyan4973/FiniteStateEntropy * * This source code is licensed under both the BSD-style license (found in the * LICENSE file in the root directory of this source tree) and the GPLv2 (found * in the COPYING file in the root directory of this source tree). * You may select, at your option, one of the above-listed licenses.****************************************************************** */ #ifndef HUF_H_298734234#define HUF_H_298734234 /* *** Dependencies *** */#include "zstd_deps.h"    /* size_t */#include "mem.h"          /* U32 */#define FSE_STATIC_LINKING_ONLY#include "fse.h" /* ***   Tool functions *** */#define HUF_BLOCKSIZE_MAX (128 * 1024)   /*< maximum input size for a single block compressed with HUF_compress */size_t HUF_compressBound(size_t size);   /*< maximum compressed size (worst case) */ /* Error Management */unsigned    HUF_isError(size_t code);       /*< tells if a return value is an error code */const char* HUF_getErrorName(size_t code);  /*< provides error code string (useful for debugging) */  #define HUF_WORKSPACE_SIZE ((8 << 10) + 512 /* sorting scratch space */)#define HUF_WORKSPACE_SIZE_U64 (HUF_WORKSPACE_SIZE / sizeof(U64)) /* *** Constants *** */#define HUF_TABLELOG_MAX      12      /* max runtime value of tableLog (due to static allocation); can be modified up to HUF_TABLELOG_ABSOLUTEMAX */#define HUF_TABLELOG_DEFAULT  11      /* default tableLog value when none specified */#define HUF_SYMBOLVALUE_MAX  255 #define HUF_TABLELOG_ABSOLUTEMAX  12  /* absolute limit of HUF_MAX_TABLELOG. Beyond that value, code does not work */#if (HUF_TABLELOG_MAX > HUF_TABLELOG_ABSOLUTEMAX)#  error "HUF_TABLELOG_MAX is too large !"#endif  /* *****************************************  Static allocation******************************************//* HUF buffer bounds */#define HUF_CTABLEBOUND 129#define HUF_BLOCKBOUND(size) (size + (size>>8) + 8)   /* only true when incompressible is pre-filtered with fast heuristic */#define HUF_COMPRESSBOUND(size) (HUF_CTABLEBOUND + HUF_BLOCKBOUND(size))   /* Macro version, useful for static allocation */ /* static allocation of HUF's Compression Table *//* this is a private definition, just exposed for allocation and strict aliasing purpose. never EVER access its members directly */typedef size_t HUF_CElt;   /* consider it an incomplete type */#define HUF_CTABLE_SIZE_ST(maxSymbolValue)   ((maxSymbolValue)+2)   /* Use tables of size_t, for proper alignment */#define HUF_CTABLE_SIZE(maxSymbolValue)       (HUF_CTABLE_SIZE_ST(maxSymbolValue) * sizeof(size_t))#define HUF_CREATE_STATIC_CTABLE(name, maxSymbolValue) \    HUF_CElt name[HUF_CTABLE_SIZE_ST(maxSymbolValue)] /* no final ; */ /* static allocation of HUF's DTable */typedef U32 HUF_DTable;#define HUF_DTABLE_SIZE(maxTableLog)   (1 + (1<<(maxTableLog)))#define HUF_CREATE_STATIC_DTABLEX1(DTable, maxTableLog) \        HUF_DTable DTable[HUF_DTABLE_SIZE((maxTableLog)-1)] = { ((U32)((maxTableLog)-1) * 0x01000001) }#define HUF_CREATE_STATIC_DTABLEX2(DTable, maxTableLog) \        HUF_DTable DTable[HUF_DTABLE_SIZE(maxTableLog)] = { ((U32)(maxTableLog) * 0x01000001) }  /* *****************************************  Advanced decompression functions******************************************/ /* * Huffman flags bitset. * For all flags, 0 is the default value. */typedef enum {    /*     * If compiled with DYNAMIC_BMI2: Set flag only if the CPU supports BMI2 at runtime.     * Otherwise: Ignored.     */    HUF_flags_bmi2 = (1 << 0),    /*     * If set: Test possible table depths to find the one that produces the smallest header + encoded size.     * If unset: Use heuristic to find the table depth.     */    HUF_flags_optimalDepth = (1 << 1),    /*     * If set: If the previous table can encode the input, always reuse the previous table.     * If unset: If the previous table can encode the input, reuse the previous table if it results in a smaller output.     */    HUF_flags_preferRepeat = (1 << 2),    /*     * If set: Sample the input and check if the sample is uncompressible, if it is then don't attempt to compress.     * If unset: Always histogram the entire input.     */    HUF_flags_suspectUncompressible = (1 << 3),    /*     * If set: Don't use assembly implementations     * If unset: Allow using assembly implementations     */    HUF_flags_disableAsm = (1 << 4),    /*     * If set: Don't use the fast decoding loop, always use the fallback decoding loop.     * If unset: Use the fast decoding loop when possible.     */    HUF_flags_disableFast = (1 << 5)} HUF_flags_e;  /* **************************************** *  HUF detailed API * ****************************************/#define HUF_OPTIMAL_DEPTH_THRESHOLD ZSTD_btultra /*! HUF_compress() does the following: *  1. count symbol occurrence from source[] into table count[] using FSE_count() (exposed within "fse.h") *  2. (optional) refine tableLog using HUF_optimalTableLog() *  3. build Huffman table from count using HUF_buildCTable() *  4. save Huffman table to memory buffer using HUF_writeCTable() *  5. encode the data stream using HUF_compress4X_usingCTable() * *  The following API allows targeting specific sub-functions for advanced tasks. *  For example, it's possible to compress several blocks using the same 'CTable', *  or to save and regenerate 'CTable' using external methods. */unsigned HUF_minTableLog(unsigned symbolCardinality);unsigned HUF_cardinality(const unsigned* count, unsigned maxSymbolValue);unsigned HUF_optimalTableLog(unsigned maxTableLog, size_t srcSize, unsigned maxSymbolValue, void* workSpace, size_t wkspSize, HUF_CElt* table, const unsigned* count, int flags); /* table is used as scratch space for building and testing tables, not a return value */size_t HUF_writeCTable_wksp(void* dst, size_t maxDstSize, const HUF_CElt* CTable, unsigned maxSymbolValue, unsigned huffLog, void* workspace, size_t workspaceSize);size_t HUF_compress4X_usingCTable(void* dst, size_t dstSize, const void* src, size_t srcSize, const HUF_CElt* CTable, int flags);size_t HUF_estimateCompressedSize(const HUF_CElt* CTable, const unsigned* count, unsigned maxSymbolValue);int HUF_validateCTable(const HUF_CElt* CTable, const unsigned* count, unsigned maxSymbolValue); typedef enum {   HUF_repeat_none,  /*< Cannot use the previous table */   HUF_repeat_check, /*< Can use the previous table but it must be checked. Note : The previous table must have been constructed by HUF_compress{1, 4}X_repeat */   HUF_repeat_valid  /*< Can use the previous table and it is assumed to be valid */ } HUF_repeat; /* HUF_compress4X_repeat() : *  Same as HUF_compress4X_wksp(), but considers using hufTable if *repeat != HUF_repeat_none. *  If it uses hufTable it does not modify hufTable or repeat. *  If it doesn't, it sets *repeat = HUF_repeat_none, and it sets hufTable to the table used. *  If preferRepeat then the old table will always be used if valid. *  If suspectUncompressible then some sampling checks will be run to potentially skip huffman coding */size_t HUF_compress4X_repeat(void* dst, size_t dstSize,                       const void* src, size_t srcSize,                       unsigned maxSymbolValue, unsigned tableLog,                       void* workSpace, size_t wkspSize,    /*< `workSpace` must be aligned on 4-bytes boundaries, `wkspSize` must be >= HUF_WORKSPACE_SIZE */                       HUF_CElt* hufTable, HUF_repeat* repeat, int flags); /* HUF_buildCTable_wksp() : *  Same as HUF_buildCTable(), but using externally allocated scratch buffer. * `workSpace` must be aligned on 4-bytes boundaries, and its size must be >= HUF_CTABLE_WORKSPACE_SIZE. */#define HUF_CTABLE_WORKSPACE_SIZE_U32 ((4 * (HUF_SYMBOLVALUE_MAX + 1)) + 192)#define HUF_CTABLE_WORKSPACE_SIZE (HUF_CTABLE_WORKSPACE_SIZE_U32 * sizeof(unsigned))size_t HUF_buildCTable_wksp (HUF_CElt* tree,                       const unsigned* count, U32 maxSymbolValue, U32 maxNbBits,                             void* workSpace, size_t wkspSize); /*! HUF_readStats() : *  Read compact Huffman tree, saved by HUF_writeCTable(). * `huffWeight` is destination buffer. * @return : size read from `src` , or an error Code . *  Note : Needed by HUF_readCTable() and HUF_readDTableXn() . */size_t HUF_readStats(BYTE* huffWeight, size_t hwSize,                     U32* rankStats, U32* nbSymbolsPtr, U32* tableLogPtr,                     const void* src, size_t srcSize); /*! HUF_readStats_wksp() : * Same as HUF_readStats() but takes an external workspace which must be * 4-byte aligned and its size must be >= HUF_READ_STATS_WORKSPACE_SIZE. * If the CPU has BMI2 support, pass bmi2=1, otherwise pass bmi2=0. */#define HUF_READ_STATS_WORKSPACE_SIZE_U32 FSE_DECOMPRESS_WKSP_SIZE_U32(6, HUF_TABLELOG_MAX-1)#define HUF_READ_STATS_WORKSPACE_SIZE (HUF_READ_STATS_WORKSPACE_SIZE_U32 * sizeof(unsigned))size_t HUF_readStats_wksp(BYTE* huffWeight, size_t hwSize,                          U32* rankStats, U32* nbSymbolsPtr, U32* tableLogPtr,                          const void* src, size_t srcSize,                          void* workspace, size_t wkspSize,                          int flags); /* HUF_readCTable() : *  Loading a CTable saved with HUF_writeCTable() */size_t HUF_readCTable (HUF_CElt* CTable, unsigned* maxSymbolValuePtr, const void* src, size_t srcSize, unsigned *hasZeroWeights); /* HUF_getNbBitsFromCTable() : *  Read nbBits from CTable symbolTable, for symbol `symbolValue` presumed <= HUF_SYMBOLVALUE_MAX *  Note 1 : If symbolValue > HUF_readCTableHeader(symbolTable).maxSymbolValue, returns 0 *  Note 2 : is not inlined, as HUF_CElt definition is private */U32 HUF_getNbBitsFromCTable(const HUF_CElt* symbolTable, U32 symbolValue); typedef struct {    BYTE tableLog;    BYTE maxSymbolValue;    BYTE unused[sizeof(size_t) - 2];} HUF_CTableHeader; /* HUF_readCTableHeader() : *  @returns The header from the CTable specifying the tableLog and the maxSymbolValue. */HUF_CTableHeader HUF_readCTableHeader(HUF_CElt const* ctable); /* * HUF_decompress() does the following: * 1. select the decompression algorithm (X1, X2) based on pre-computed heuristics * 2. build Huffman table from save, using HUF_readDTableX?() * 3. decode 1 or 4 segments in parallel using HUF_decompress?X?_usingDTable() */ /* HUF_selectDecoder() : *  Tells which decoder is likely to decode faster, *  based on a set of pre-computed metrics. * @return : 0==HUF_decompress4X1, 1==HUF_decompress4X2 . *  Assumption : 0 < dstSize <= 128 KB */U32 HUF_selectDecoder (size_t dstSize, size_t cSrcSize); /* *  The minimum workspace size for the `workSpace` used in *  HUF_readDTableX1_wksp() and HUF_readDTableX2_wksp(). * *  The space used depends on HUF_TABLELOG_MAX, ranging from ~1500 bytes when *  HUF_TABLE_LOG_MAX=12 to ~1850 bytes when HUF_TABLE_LOG_MAX=15. *  Buffer overflow errors may potentially occur if code modifications result in *  a required workspace size greater than that specified in the following *  macro. */#define HUF_DECOMPRESS_WORKSPACE_SIZE ((2 << 10) + (1 << 9))#define HUF_DECOMPRESS_WORKSPACE_SIZE_U32 (HUF_DECOMPRESS_WORKSPACE_SIZE / sizeof(U32))  /* ====================== *//* single stream variants *//* ====================== */ size_t HUF_compress1X_usingCTable(void* dst, size_t dstSize, const void* src, size_t srcSize, const HUF_CElt* CTable, int flags);/* HUF_compress1X_repeat() : *  Same as HUF_compress1X_wksp(), but considers using hufTable if *repeat != HUF_repeat_none. *  If it uses hufTable it does not modify hufTable or repeat. *  If it doesn't, it sets *repeat = HUF_repeat_none, and it sets hufTable to the table used. *  If preferRepeat then the old table will always be used if valid. *  If suspectUncompressible then some sampling checks will be run to potentially skip huffman coding */size_t HUF_compress1X_repeat(void* dst, size_t dstSize,                       const void* src, size_t srcSize,                       unsigned maxSymbolValue, unsigned tableLog,                       void* workSpace, size_t wkspSize,   /*< `workSpace` must be aligned on 4-bytes boundaries, `wkspSize` must be >= HUF_WORKSPACE_SIZE */                       HUF_CElt* hufTable, HUF_repeat* repeat, int flags); size_t HUF_decompress1X_DCtx_wksp(HUF_DTable* dctx, void* dst, size_t dstSize, const void* cSrc, size_t cSrcSize, void* workSpace, size_t wkspSize, int flags);#ifndef HUF_FORCE_DECOMPRESS_X1size_t HUF_decompress1X2_DCtx_wksp(HUF_DTable* dctx, void* dst, size_t dstSize, const void* cSrc, size_t cSrcSize, void* workSpace, size_t wkspSize, int flags);   /*< double-symbols decoder */#endif /* BMI2 variants. * If the CPU has BMI2 support, pass bmi2=1, otherwise pass bmi2=0. */size_t HUF_decompress1X_usingDTable(void* dst, size_t maxDstSize, const void* cSrc, size_t cSrcSize, const HUF_DTable* DTable, int flags);#ifndef HUF_FORCE_DECOMPRESS_X2size_t HUF_decompress1X1_DCtx_wksp(HUF_DTable* dctx, void* dst, size_t dstSize, const void* cSrc, size_t cSrcSize, void* workSpace, size_t wkspSize, int flags);#endifsize_t HUF_decompress4X_usingDTable(void* dst, size_t maxDstSize, const void* cSrc, size_t cSrcSize, const HUF_DTable* DTable, int flags);size_t HUF_decompress4X_hufOnly_wksp(HUF_DTable* dctx, void* dst, size_t dstSize, const void* cSrc, size_t cSrcSize, void* workSpace, size_t wkspSize, int flags);#ifndef HUF_FORCE_DECOMPRESS_X2size_t HUF_readDTableX1_wksp(HUF_DTable* DTable, const void* src, size_t srcSize, void* workSpace, size_t wkspSize, int flags);#endif#ifndef HUF_FORCE_DECOMPRESS_X1size_t HUF_readDTableX2_wksp(HUF_DTable* DTable, const void* src, size_t srcSize, void* workSpace, size_t wkspSize, int flags);#endif #endif   /* HUF_H_298734234 */