/*

 * Copyright (c) 2016-present, 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 "mem.h"             /* BYTE, U16, U32 */

#include "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;

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;

    /* workspace */

    BYTE litBuffer[ZSTD_BLOCKSIZE_MAX + WILDCOPY_OVERLENGTH];

    BYTE headerBuffer[ZSTD_FRAMEHEADERSIZE_MAX];

};  /* 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 entropy tables read */

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 */