FreeBSD/Linux Kernel Cross Reference
sys/contrib/openzfs/module/zstd/lib/decompress/zstd_decompress_internal.h

     /*
      * Copyright (c) 2016-2020, Yann Collet, Facebook, Inc.
      * All rights reserved.
      *
      * 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.
      */
    
    
    /* zstd_decompress_internal:
     * objects and definitions shared within lib/decompress modules */
    
     #ifndef ZSTD_DECOMPRESS_INTERNAL_H
     #define ZSTD_DECOMPRESS_INTERNAL_H
    
    
    /*-*******************************************************
     *  Dependencies
     *********************************************************/
    #include "../common/mem.h"             /* BYTE, U16, U32 */
    #include "../common/zstd_internal.h"   /* ZSTD_seqSymbol */
    
    
    
    /*-*******************************************************
     *  Constants
     *********************************************************/
    static const U32 LL_base[MaxLL+1] = {
                     0,    1,    2,     3,     4,     5,     6,      7,
                     8,    9,   10,    11,    12,    13,    14,     15,
                    16,   18,   20,    22,    24,    28,    32,     40,
                    48,   64, 0x80, 0x100, 0x200, 0x400, 0x800, 0x1000,
                    0x2000, 0x4000, 0x8000, 0x10000 };
    
    static const U32 OF_base[MaxOff+1] = {
                     0,        1,       1,       5,     0xD,     0x1D,     0x3D,     0x7D,
                     0xFD,   0x1FD,   0x3FD,   0x7FD,   0xFFD,   0x1FFD,   0x3FFD,   0x7FFD,
                     0xFFFD, 0x1FFFD, 0x3FFFD, 0x7FFFD, 0xFFFFD, 0x1FFFFD, 0x3FFFFD, 0x7FFFFD,
                     0xFFFFFD, 0x1FFFFFD, 0x3FFFFFD, 0x7FFFFFD, 0xFFFFFFD, 0x1FFFFFFD, 0x3FFFFFFD, 0x7FFFFFFD };
    
    static const U32 OF_bits[MaxOff+1] = {
                         0,  1,  2,  3,  4,  5,  6,  7,
                         8,  9, 10, 11, 12, 13, 14, 15,
                        16, 17, 18, 19, 20, 21, 22, 23,
                        24, 25, 26, 27, 28, 29, 30, 31 };
    
    static const U32 ML_base[MaxML+1] = {
                         3,  4,  5,    6,     7,     8,     9,    10,
                        11, 12, 13,   14,    15,    16,    17,    18,
                        19, 20, 21,   22,    23,    24,    25,    26,
                        27, 28, 29,   30,    31,    32,    33,    34,
                        35, 37, 39,   41,    43,    47,    51,    59,
                        67, 83, 99, 0x83, 0x103, 0x203, 0x403, 0x803,
                        0x1003, 0x2003, 0x4003, 0x8003, 0x10003 };
    
    
    /*-*******************************************************
     *  Decompression types
     *********************************************************/
     typedef struct {
         U32 fastMode;
         U32 tableLog;
     } ZSTD_seqSymbol_header;
    
     typedef struct {
         U16  nextState;
         BYTE nbAdditionalBits;
         BYTE nbBits;
         U32  baseValue;
     } ZSTD_seqSymbol;
    
     #define SEQSYMBOL_TABLE_SIZE(log)   (1 + (1 << (log)))
    
    typedef struct {
        ZSTD_seqSymbol LLTable[SEQSYMBOL_TABLE_SIZE(LLFSELog)];    /* Note : Space reserved for FSE Tables */
        ZSTD_seqSymbol OFTable[SEQSYMBOL_TABLE_SIZE(OffFSELog)];   /* is also used as temporary workspace while building hufTable during DDict creation */
        ZSTD_seqSymbol MLTable[SEQSYMBOL_TABLE_SIZE(MLFSELog)];    /* and therefore must be at least HUF_DECOMPRESS_WORKSPACE_SIZE large */
        HUF_DTable hufTable[HUF_DTABLE_SIZE(HufLog)];  /* can accommodate HUF_decompress4X */
        U32 rep[ZSTD_REP_NUM];
    } ZSTD_entropyDTables_t;
    
    typedef enum { ZSTDds_getFrameHeaderSize, ZSTDds_decodeFrameHeader,
                   ZSTDds_decodeBlockHeader, ZSTDds_decompressBlock,
                   ZSTDds_decompressLastBlock, ZSTDds_checkChecksum,
                   ZSTDds_decodeSkippableHeader, ZSTDds_skipFrame } ZSTD_dStage;
    
    typedef enum { zdss_init=0, zdss_loadHeader,
                   zdss_read, zdss_load, zdss_flush } ZSTD_dStreamStage;
    
    typedef enum {
        ZSTD_use_indefinitely = -1,  /* Use the dictionary indefinitely */
        ZSTD_dont_use = 0,           /* Do not use the dictionary (if one exists free it) */
        ZSTD_use_once = 1            /* Use the dictionary once and set to ZSTD_dont_use */
    } ZSTD_dictUses_e;
    
    typedef enum {
        ZSTD_obm_buffered = 0,  /* Buffer the output */
       ZSTD_obm_stable = 1     /* ZSTD_outBuffer is stable */
   } ZSTD_outBufferMode_e;
   
   struct ZSTD_DCtx_s
   {
       const ZSTD_seqSymbol* LLTptr;
       const ZSTD_seqSymbol* MLTptr;
       const ZSTD_seqSymbol* OFTptr;
       const HUF_DTable* HUFptr;
       ZSTD_entropyDTables_t entropy;
       U32 workspace[HUF_DECOMPRESS_WORKSPACE_SIZE_U32];   /* space needed when building huffman tables */
       const void* previousDstEnd;   /* detect continuity */
       const void* prefixStart;      /* start of current segment */
       const void* virtualStart;     /* virtual start of previous segment if it was just before current one */
       const void* dictEnd;          /* end of previous segment */
       size_t expected;
       ZSTD_frameHeader fParams;
       U64 decodedSize;
       blockType_e bType;            /* used in ZSTD_decompressContinue(), store blockType between block header decoding and block decompression stages */
       ZSTD_dStage stage;
       U32 litEntropy;
       U32 fseEntropy;
       XXH64_state_t xxhState;
       size_t headerSize;
       ZSTD_format_e format;
       const BYTE* litPtr;
       ZSTD_customMem customMem;
       size_t litSize;
       size_t rleSize;
       size_t staticSize;
       int bmi2;                     /* == 1 if the CPU supports BMI2 and 0 otherwise. CPU support is determined dynamically once per context lifetime. */
   
       /* dictionary */
       ZSTD_DDict* ddictLocal;
       const ZSTD_DDict* ddict;     /* set by ZSTD_initDStream_usingDDict(), or ZSTD_DCtx_refDDict() */
       U32 dictID;
       int ddictIsCold;             /* if == 1 : dictionary is "new" for working context, and presumed "cold" (not in cpu cache) */
       ZSTD_dictUses_e dictUses;
   
       /* streaming */
       ZSTD_dStreamStage streamStage;
       char*  inBuff;
       size_t inBuffSize;
       size_t inPos;
       size_t maxWindowSize;
       char*  outBuff;
       size_t outBuffSize;
       size_t outStart;
       size_t outEnd;
       size_t lhSize;
       void* legacyContext;
       U32 previousLegacyVersion;
       U32 legacyVersion;
       U32 hostageByte;
       int noForwardProgress;
       ZSTD_outBufferMode_e outBufferMode;
       ZSTD_outBuffer expectedOutBuffer;
   
       /* workspace */
       BYTE litBuffer[ZSTD_BLOCKSIZE_MAX + WILDCOPY_OVERLENGTH];
       BYTE headerBuffer[ZSTD_FRAMEHEADERSIZE_MAX];
   
       size_t oversizedDuration;
   
   #ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
       void const* dictContentBeginForFuzzing;
       void const* dictContentEndForFuzzing;
   #endif
   };  /* typedef'd to ZSTD_DCtx within "zstd.h" */
   
   
   /*-*******************************************************
    *  Shared internal functions
    *********************************************************/
   
   /*! ZSTD_loadDEntropy() :
    *  dict : must point at beginning of a valid zstd dictionary.
    * @return : size of dictionary header (size of magic number + dict ID + entropy tables) */
   size_t ZSTD_loadDEntropy(ZSTD_entropyDTables_t* entropy,
                      const void* const dict, size_t const dictSize);
   
   /*! ZSTD_checkContinuity() :
    *  check if next `dst` follows previous position, where decompression ended.
    *  If yes, do nothing (continue on current segment).
    *  If not, classify previous segment as "external dictionary", and start a new segment.
    *  This function cannot fail. */
   void ZSTD_checkContinuity(ZSTD_DCtx* dctx, const void* dst);
   
   
   #endif /* ZSTD_DECOMPRESS_INTERNAL_H */

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