annotate contrib/python-zstandard/zstd/decompress/zstd_decompress.c @ 35710:5cd60b0587a8

evolution: make reporting of new unstable changesets optional

This makes it possible to turn off the reporting of unstable
changesets (e.g. "1 new orphan changesets"), just in case it's too
slow for some users. Anyone who's been using the evolve extension has
already been accepting the cost of the reporting, so this is just for
the few users who have turned on obsmarkers but not been using the
evolve extension (as I believe Facebook has).

Differential Revision: https://phab.mercurial-scm.org/D1868

/**
 * Copyright (c) 2016-present, Yann Collet, Facebook, Inc.
 * All rights reserved.
 *
 * This source code is licensed under the BSD-style license found in the
 * LICENSE file in the root directory of this source tree. An additional grant
 * of patent rights can be found in the PATENTS file in the same directory.
 */


/* ***************************************************************
*  Tuning parameters
*****************************************************************/
/*!
 * HEAPMODE :
 * Select how default decompression function ZSTD_decompress() will allocate memory,
 * in memory stack (0), or in memory heap (1, requires malloc())
 */
#ifndef ZSTD_HEAPMODE
#  define ZSTD_HEAPMODE 1
#endif

/*!
*  LEGACY_SUPPORT :
*  if set to 1, ZSTD_decompress() can decode older formats (v0.1+)
*/
#ifndef ZSTD_LEGACY_SUPPORT
#  define ZSTD_LEGACY_SUPPORT 0
#endif

/*!
*  MAXWINDOWSIZE_DEFAULT :
*  maximum window size accepted by DStream, by default.
*  Frames requiring more memory will be rejected.
*/
#ifndef ZSTD_MAXWINDOWSIZE_DEFAULT
#  define ZSTD_MAXWINDOWSIZE_DEFAULT ((1 << ZSTD_WINDOWLOG_MAX) + 1)   /* defined within zstd.h */
#endif


/*-*******************************************************
*  Dependencies
*********************************************************/
#include <string.h>      /* memcpy, memmove, memset */
#include "mem.h"         /* low level memory routines */
#define XXH_STATIC_LINKING_ONLY   /* XXH64_state_t */
#include "xxhash.h"      /* XXH64_* */
#define FSE_STATIC_LINKING_ONLY
#include "fse.h"
#define HUF_STATIC_LINKING_ONLY
#include "huf.h"
#include "zstd_internal.h"

#if defined(ZSTD_LEGACY_SUPPORT) && (ZSTD_LEGACY_SUPPORT>=1)
#  include "zstd_legacy.h"
#endif


#if defined(_MSC_VER)
#  include <mmintrin.h>   /* https://msdn.microsoft.com/fr-fr/library/84szxsww(v=vs.90).aspx */
#  define ZSTD_PREFETCH(ptr)   _mm_prefetch((const char*)ptr, _MM_HINT_T0)
#elif defined(__GNUC__)
#  define ZSTD_PREFETCH(ptr)   __builtin_prefetch(ptr, 0, 0)
#else
#  define ZSTD_PREFETCH(ptr)   /* disabled */
#endif

/*-*************************************
*  Macros
***************************************/
#define ZSTD_isError ERR_isError   /* for inlining */
#define FSE_isError  ERR_isError
#define HUF_isError  ERR_isError


/*_*******************************************************
*  Memory operations
**********************************************************/
static void ZSTD_copy4(void* dst, const void* src) { memcpy(dst, src, 4); }


/*-*************************************************************
*   Context management
***************************************************************/
typedef enum { ZSTDds_getFrameHeaderSize, ZSTDds_decodeFrameHeader,
               ZSTDds_decodeBlockHeader, ZSTDds_decompressBlock,
               ZSTDds_decompressLastBlock, ZSTDds_checkChecksum,
               ZSTDds_decodeSkippableHeader, ZSTDds_skipFrame } ZSTD_dStage;

struct ZSTD_DCtx_s
{
    const FSE_DTable* LLTptr;
    const FSE_DTable* MLTptr;
    const FSE_DTable* OFTptr;
    const HUF_DTable* HUFptr;
    FSE_DTable LLTable[FSE_DTABLE_SIZE_U32(LLFSELog)];
    FSE_DTable OFTable[FSE_DTABLE_SIZE_U32(OffFSELog)];
    FSE_DTable MLTable[FSE_DTABLE_SIZE_U32(MLFSELog)];
    HUF_DTable hufTable[HUF_DTABLE_SIZE(HufLog)];  /* can accommodate HUF_decompress4X */
    const void* previousDstEnd;
    const void* base;
    const void* vBase;
    const void* dictEnd;
    size_t expected;
    U32 rep[ZSTD_REP_NUM];
    ZSTD_frameParams fParams;
    blockType_e bType;   /* used in ZSTD_decompressContinue(), to transfer blockType between header decoding and block decoding stages */
    ZSTD_dStage stage;
    U32 litEntropy;
    U32 fseEntropy;
    XXH64_state_t xxhState;
    size_t headerSize;
    U32 dictID;
    const BYTE* litPtr;
    ZSTD_customMem customMem;
    size_t litSize;
    size_t rleSize;
    BYTE litBuffer[ZSTD_BLOCKSIZE_ABSOLUTEMAX + WILDCOPY_OVERLENGTH];
    BYTE headerBuffer[ZSTD_FRAMEHEADERSIZE_MAX];
};  /* typedef'd to ZSTD_DCtx within "zstd.h" */

size_t ZSTD_sizeof_DCtx (const ZSTD_DCtx* dctx) { return (dctx==NULL) ? 0 : sizeof(ZSTD_DCtx); }

size_t ZSTD_estimateDCtxSize(void) { return sizeof(ZSTD_DCtx); }

size_t ZSTD_decompressBegin(ZSTD_DCtx* dctx)
{
    dctx->expected = ZSTD_frameHeaderSize_prefix;
    dctx->stage = ZSTDds_getFrameHeaderSize;
    dctx->previousDstEnd = NULL;
    dctx->base = NULL;
    dctx->vBase = NULL;
    dctx->dictEnd = NULL;
    dctx->hufTable[0] = (HUF_DTable)((HufLog)*0x1000001);  /* cover both little and big endian */
    dctx->litEntropy = dctx->fseEntropy = 0;
    dctx->dictID = 0;
    MEM_STATIC_ASSERT(sizeof(dctx->rep) == sizeof(repStartValue));
    memcpy(dctx->rep, repStartValue, sizeof(repStartValue));  /* initial repcodes */
    dctx->LLTptr = dctx->LLTable;
    dctx->MLTptr = dctx->MLTable;
    dctx->OFTptr = dctx->OFTable;
    dctx->HUFptr = dctx->hufTable;
    return 0;
}

ZSTD_DCtx* ZSTD_createDCtx_advanced(ZSTD_customMem customMem)
{
    ZSTD_DCtx* dctx;

    if (!customMem.customAlloc && !customMem.customFree) customMem = defaultCustomMem;
    if (!customMem.customAlloc || !customMem.customFree) return NULL;

    dctx = (ZSTD_DCtx*)ZSTD_malloc(sizeof(ZSTD_DCtx), customMem);
    if (!dctx) return NULL;
    memcpy(&dctx->customMem, &customMem, sizeof(customMem));
    ZSTD_decompressBegin(dctx);
    return dctx;
}

ZSTD_DCtx* ZSTD_createDCtx(void)
{
    return ZSTD_createDCtx_advanced(defaultCustomMem);
}

size_t ZSTD_freeDCtx(ZSTD_DCtx* dctx)
{
    if (dctx==NULL) return 0;   /* support free on NULL */
    ZSTD_free(dctx, dctx->customMem);
    return 0;   /* reserved as a potential error code in the future */
}

void ZSTD_copyDCtx(ZSTD_DCtx* dstDCtx, const ZSTD_DCtx* srcDCtx)
{
    size_t const workSpaceSize = (ZSTD_BLOCKSIZE_ABSOLUTEMAX+WILDCOPY_OVERLENGTH) + ZSTD_frameHeaderSize_max;
    memcpy(dstDCtx, srcDCtx, sizeof(ZSTD_DCtx) - workSpaceSize);  /* no need to copy workspace */
}

static void ZSTD_refDCtx(ZSTD_DCtx* dstDCtx, const ZSTD_DCtx* srcDCtx)
{
    ZSTD_decompressBegin(dstDCtx);  /* init */
    if (srcDCtx) {   /* support refDCtx on NULL */
        dstDCtx->dictEnd = srcDCtx->dictEnd;
        dstDCtx->vBase = srcDCtx->vBase;
        dstDCtx->base = srcDCtx->base;
        dstDCtx->previousDstEnd = srcDCtx->previousDstEnd;
        dstDCtx->dictID = srcDCtx->dictID;
        dstDCtx->litEntropy = srcDCtx->litEntropy;
        dstDCtx->fseEntropy = srcDCtx->fseEntropy;
        dstDCtx->LLTptr = srcDCtx->LLTable;
        dstDCtx->MLTptr = srcDCtx->MLTable;
        dstDCtx->OFTptr = srcDCtx->OFTable;
        dstDCtx->HUFptr = srcDCtx->hufTable;
        dstDCtx->rep[0] = srcDCtx->rep[0];
        dstDCtx->rep[1] = srcDCtx->rep[1];
        dstDCtx->rep[2] = srcDCtx->rep[2];
    }
}


/*-*************************************************************
*   Decompression section
***************************************************************/

/*! ZSTD_isFrame() :
 *  Tells if the content of `buffer` starts with a valid Frame Identifier.
 *  Note : Frame Identifier is 4 bytes. If `size < 4`, @return will always be 0.
 *  Note 2 : Legacy Frame Identifiers are considered valid only if Legacy Support is enabled.
 *  Note 3 : Skippable Frame Identifiers are considered valid. */
unsigned ZSTD_isFrame(const void* buffer, size_t size)
{
    if (size < 4) return 0;
    {   U32 const magic = MEM_readLE32(buffer);
        if (magic == ZSTD_MAGICNUMBER) return 1;
        if ((magic & 0xFFFFFFF0U) == ZSTD_MAGIC_SKIPPABLE_START) return 1;
    }
#if defined(ZSTD_LEGACY_SUPPORT) && (ZSTD_LEGACY_SUPPORT >= 1)
    if (ZSTD_isLegacy(buffer, size)) return 1;
#endif
    return 0;
}


/** ZSTD_frameHeaderSize() :
*   srcSize must be >= ZSTD_frameHeaderSize_prefix.
*   @return : size of the Frame Header */
static size_t ZSTD_frameHeaderSize(const void* src, size_t srcSize)
{
    if (srcSize < ZSTD_frameHeaderSize_prefix) return ERROR(srcSize_wrong);
    {   BYTE const fhd = ((const BYTE*)src)[4];
        U32 const dictID= fhd & 3;
        U32 const singleSegment = (fhd >> 5) & 1;
        U32 const fcsId = fhd >> 6;
        return ZSTD_frameHeaderSize_prefix + !singleSegment + ZSTD_did_fieldSize[dictID] + ZSTD_fcs_fieldSize[fcsId]
                + (singleSegment && !fcsId);
    }
}


/** ZSTD_getFrameParams() :
*   decode Frame Header, or require larger `srcSize`.
*   @return : 0, `fparamsPtr` is correctly filled,
*            >0, `srcSize` is too small, result is expected `srcSize`,
*             or an error code, which can be tested using ZSTD_isError() */
size_t ZSTD_getFrameParams(ZSTD_frameParams* fparamsPtr, const void* src, size_t srcSize)
{
    const BYTE* ip = (const BYTE*)src;

    if (srcSize < ZSTD_frameHeaderSize_prefix) return ZSTD_frameHeaderSize_prefix;
    if (MEM_readLE32(src) != ZSTD_MAGICNUMBER) {
        if ((MEM_readLE32(src) & 0xFFFFFFF0U) == ZSTD_MAGIC_SKIPPABLE_START) {
            if (srcSize < ZSTD_skippableHeaderSize) return ZSTD_skippableHeaderSize; /* magic number + skippable frame length */
            memset(fparamsPtr, 0, sizeof(*fparamsPtr));
            fparamsPtr->frameContentSize = MEM_readLE32((const char *)src + 4);
            fparamsPtr->windowSize = 0; /* windowSize==0 means a frame is skippable */
            return 0;
        }
        return ERROR(prefix_unknown);
    }

    /* ensure there is enough `srcSize` to fully read/decode frame header */
    { size_t const fhsize = ZSTD_frameHeaderSize(src, srcSize);
      if (srcSize < fhsize) return fhsize; }

    {   BYTE const fhdByte = ip[4];
        size_t pos = 5;
        U32 const dictIDSizeCode = fhdByte&3;
        U32 const checksumFlag = (fhdByte>>2)&1;
        U32 const singleSegment = (fhdByte>>5)&1;
        U32 const fcsID = fhdByte>>6;
        U32 const windowSizeMax = 1U << ZSTD_WINDOWLOG_MAX;
        U32 windowSize = 0;
        U32 dictID = 0;
        U64 frameContentSize = 0;
        if ((fhdByte & 0x08) != 0) return ERROR(frameParameter_unsupported);   /* reserved bits, which must be zero */
        if (!singleSegment) {
            BYTE const wlByte = ip[pos++];
            U32 const windowLog = (wlByte >> 3) + ZSTD_WINDOWLOG_ABSOLUTEMIN;
            if (windowLog > ZSTD_WINDOWLOG_MAX) return ERROR(frameParameter_windowTooLarge);  /* avoids issue with 1 << windowLog */
            windowSize = (1U << windowLog);
            windowSize += (windowSize >> 3) * (wlByte&7);
        }

        switch(dictIDSizeCode)
        {
            default:   /* impossible */
            case 0 : break;
            case 1 : dictID = ip[pos]; pos++; break;
            case 2 : dictID = MEM_readLE16(ip+pos); pos+=2; break;
            case 3 : dictID = MEM_readLE32(ip+pos); pos+=4; break;
        }
        switch(fcsID)
        {
            default:   /* impossible */
            case 0 : if (singleSegment) frameContentSize = ip[pos]; break;
            case 1 : frameContentSize = MEM_readLE16(ip+pos)+256; break;
            case 2 : frameContentSize = MEM_readLE32(ip+pos); break;
            case 3 : frameContentSize = MEM_readLE64(ip+pos); break;
        }
        if (!windowSize) windowSize = (U32)frameContentSize;
        if (windowSize > windowSizeMax) return ERROR(frameParameter_windowTooLarge);
        fparamsPtr->frameContentSize = frameContentSize;
        fparamsPtr->windowSize = windowSize;
        fparamsPtr->dictID = dictID;
        fparamsPtr->checksumFlag = checksumFlag;
    }
    return 0;
}


/** ZSTD_getDecompressedSize() :
*   compatible with legacy mode
*   @return : decompressed size if known, 0 otherwise
              note : 0 can mean any of the following :
                   - decompressed size is not present within frame header
                   - frame header unknown / not supported
                   - frame header not complete (`srcSize` too small) */
unsigned long long ZSTD_getDecompressedSize(const void* src, size_t srcSize)
{
#if defined(ZSTD_LEGACY_SUPPORT) && (ZSTD_LEGACY_SUPPORT==1)
    if (ZSTD_isLegacy(src, srcSize)) return ZSTD_getDecompressedSize_legacy(src, srcSize);
#endif
    {   ZSTD_frameParams fparams;
        size_t const frResult = ZSTD_getFrameParams(&fparams, src, srcSize);
        if (frResult!=0) return 0;
        return fparams.frameContentSize;
    }
}


/** ZSTD_decodeFrameHeader() :
*   `headerSize` must be the size provided by ZSTD_frameHeaderSize().
*   @return : 0 if success, or an error code, which can be tested using ZSTD_isError() */
static size_t ZSTD_decodeFrameHeader(ZSTD_DCtx* dctx, const void* src, size_t headerSize)
{
    size_t const result = ZSTD_getFrameParams(&(dctx->fParams), src, headerSize);
    if (ZSTD_isError(result)) return result;  /* invalid header */
    if (result>0) return ERROR(srcSize_wrong);   /* headerSize too small */
    if (dctx->fParams.dictID && (dctx->dictID != dctx->fParams.dictID)) return ERROR(dictionary_wrong);
    if (dctx->fParams.checksumFlag) XXH64_reset(&dctx->xxhState, 0);
    return 0;
}


typedef struct
{
    blockType_e blockType;
    U32 lastBlock;
    U32 origSize;
} blockProperties_t;

/*! ZSTD_getcBlockSize() :
*   Provides the size of compressed block from block header `src` */
size_t ZSTD_getcBlockSize(const void* src, size_t srcSize, blockProperties_t* bpPtr)
{
    if (srcSize < ZSTD_blockHeaderSize) return ERROR(srcSize_wrong);
    {   U32 const cBlockHeader = MEM_readLE24(src);
        U32 const cSize = cBlockHeader >> 3;
        bpPtr->lastBlock = cBlockHeader & 1;
        bpPtr->blockType = (blockType_e)((cBlockHeader >> 1) & 3);
        bpPtr->origSize = cSize;   /* only useful for RLE */
        if (bpPtr->blockType == bt_rle) return 1;
        if (bpPtr->blockType == bt_reserved) return ERROR(corruption_detected);
        return cSize;
    }
}


static size_t ZSTD_copyRawBlock(void* dst, size_t dstCapacity, const void* src, size_t srcSize)
{
    if (srcSize > dstCapacity) return ERROR(dstSize_tooSmall);
    memcpy(dst, src, srcSize);
    return srcSize;
}


static size_t ZSTD_setRleBlock(void* dst, size_t dstCapacity, const void* src, size_t srcSize, size_t regenSize)
{
    if (srcSize != 1) return ERROR(srcSize_wrong);
    if (regenSize > dstCapacity) return ERROR(dstSize_tooSmall);
    memset(dst, *(const BYTE*)src, regenSize);
    return regenSize;
}

/*! ZSTD_decodeLiteralsBlock() :
    @return : nb of bytes read from src (< srcSize ) */
size_t ZSTD_decodeLiteralsBlock(ZSTD_DCtx* dctx,
                          const void* src, size_t srcSize)   /* note : srcSize < BLOCKSIZE */
{
    if (srcSize < MIN_CBLOCK_SIZE) return ERROR(corruption_detected);

    {   const BYTE* const istart = (const BYTE*) src;
        symbolEncodingType_e const litEncType = (symbolEncodingType_e)(istart[0] & 3);

        switch(litEncType)
        {
        case set_repeat:
            if (dctx->litEntropy==0) return ERROR(dictionary_corrupted);
            /* fall-through */
        case set_compressed:
            if (srcSize < 5) return ERROR(corruption_detected);   /* srcSize >= MIN_CBLOCK_SIZE == 3; here we need up to 5 for case 3 */
            {   size_t lhSize, litSize, litCSize;
                U32 singleStream=0;
                U32 const lhlCode = (istart[0] >> 2) & 3;
                U32 const lhc = MEM_readLE32(istart);
                switch(lhlCode)
                {
                case 0: case 1: default:   /* note : default is impossible, since lhlCode into [0..3] */
                    /* 2 - 2 - 10 - 10 */
                    singleStream = !lhlCode;
                    lhSize = 3;
                    litSize  = (lhc >> 4) & 0x3FF;
                    litCSize = (lhc >> 14) & 0x3FF;
                    break;
                case 2:
                    /* 2 - 2 - 14 - 14 */
                    lhSize = 4;
                    litSize  = (lhc >> 4) & 0x3FFF;
                    litCSize = lhc >> 18;
                    break;
                case 3:
                    /* 2 - 2 - 18 - 18 */
                    lhSize = 5;
                    litSize  = (lhc >> 4) & 0x3FFFF;
                    litCSize = (lhc >> 22) + (istart[4] << 10);
                    break;
                }
                if (litSize > ZSTD_BLOCKSIZE_ABSOLUTEMAX) return ERROR(corruption_detected);
                if (litCSize + lhSize > srcSize) return ERROR(corruption_detected);

                if (HUF_isError((litEncType==set_repeat) ?
                                    ( singleStream ?
                                        HUF_decompress1X_usingDTable(dctx->litBuffer, litSize, istart+lhSize, litCSize, dctx->HUFptr) :
                                        HUF_decompress4X_usingDTable(dctx->litBuffer, litSize, istart+lhSize, litCSize, dctx->HUFptr) ) :
                                    ( singleStream ?
                                        HUF_decompress1X2_DCtx(dctx->hufTable, dctx->litBuffer, litSize, istart+lhSize, litCSize) :
                                        HUF_decompress4X_hufOnly (dctx->hufTable, dctx->litBuffer, litSize, istart+lhSize, litCSize)) ))
                    return ERROR(corruption_detected);

                dctx->litPtr = dctx->litBuffer;
                dctx->litSize = litSize;
                dctx->litEntropy = 1;
                if (litEncType==set_compressed) dctx->HUFptr = dctx->hufTable;
                memset(dctx->litBuffer + dctx->litSize, 0, WILDCOPY_OVERLENGTH);
                return litCSize + lhSize;
            }

        case set_basic:
            {   size_t litSize, lhSize;
                U32 const lhlCode = ((istart[0]) >> 2) & 3;
                switch(lhlCode)
                {
                case 0: case 2: default:   /* note : default is impossible, since lhlCode into [0..3] */
                    lhSize = 1;
                    litSize = istart[0] >> 3;
                    break;
                case 1:
                    lhSize = 2;
                    litSize = MEM_readLE16(istart) >> 4;
                    break;
                case 3:
                    lhSize = 3;
                    litSize = MEM_readLE24(istart) >> 4;
                    break;
                }

                if (lhSize+litSize+WILDCOPY_OVERLENGTH > srcSize) {  /* risk reading beyond src buffer with wildcopy */
                    if (litSize+lhSize > srcSize) return ERROR(corruption_detected);
                    memcpy(dctx->litBuffer, istart+lhSize, litSize);
                    dctx->litPtr = dctx->litBuffer;
                    dctx->litSize = litSize;
                    memset(dctx->litBuffer + dctx->litSize, 0, WILDCOPY_OVERLENGTH);
                    return lhSize+litSize;
                }
                /* direct reference into compressed stream */
                dctx->litPtr = istart+lhSize;
                dctx->litSize = litSize;
                return lhSize+litSize;
            }

        case set_rle:
            {   U32 const lhlCode = ((istart[0]) >> 2) & 3;
                size_t litSize, lhSize;
                switch(lhlCode)
                {
                case 0: case 2: default:   /* note : default is impossible, since lhlCode into [0..3] */
                    lhSize = 1;
                    litSize = istart[0] >> 3;
                    break;
                case 1:
                    lhSize = 2;
                    litSize = MEM_readLE16(istart) >> 4;
                    break;
                case 3:
                    lhSize = 3;
                    litSize = MEM_readLE24(istart) >> 4;
                    if (srcSize<4) return ERROR(corruption_detected);   /* srcSize >= MIN_CBLOCK_SIZE == 3; here we need lhSize+1 = 4 */
                    break;
                }
                if (litSize > ZSTD_BLOCKSIZE_ABSOLUTEMAX) return ERROR(corruption_detected);
                memset(dctx->litBuffer, istart[lhSize], litSize + WILDCOPY_OVERLENGTH);
                dctx->litPtr = dctx->litBuffer;
                dctx->litSize = litSize;
                return lhSize+1;
            }
        default:
            return ERROR(corruption_detected);   /* impossible */
        }
    }
}


typedef union {
    FSE_decode_t realData;
    U32 alignedBy4;
} FSE_decode_t4;

static const FSE_decode_t4 LL_defaultDTable[(1<<LL_DEFAULTNORMLOG)+1] = {
    { { LL_DEFAULTNORMLOG, 1, 1 } }, /* header : tableLog, fastMode, fastMode */
    { {  0,  0,  4 } },              /* 0 : base, symbol, bits */
    { { 16,  0,  4 } },
    { { 32,  1,  5 } },
    { {  0,  3,  5 } },
    { {  0,  4,  5 } },
    { {  0,  6,  5 } },
    { {  0,  7,  5 } },
    { {  0,  9,  5 } },
    { {  0, 10,  5 } },
    { {  0, 12,  5 } },
    { {  0, 14,  6 } },
    { {  0, 16,  5 } },
    { {  0, 18,  5 } },
    { {  0, 19,  5 } },
    { {  0, 21,  5 } },
    { {  0, 22,  5 } },
    { {  0, 24,  5 } },
    { { 32, 25,  5 } },
    { {  0, 26,  5 } },
    { {  0, 27,  6 } },
    { {  0, 29,  6 } },
    { {  0, 31,  6 } },
    { { 32,  0,  4 } },
    { {  0,  1,  4 } },
    { {  0,  2,  5 } },
    { { 32,  4,  5 } },
    { {  0,  5,  5 } },
    { { 32,  7,  5 } },
    { {  0,  8,  5 } },
    { { 32, 10,  5 } },
    { {  0, 11,  5 } },
    { {  0, 13,  6 } },
    { { 32, 16,  5 } },
    { {  0, 17,  5 } },
    { { 32, 19,  5 } },
    { {  0, 20,  5 } },
    { { 32, 22,  5 } },
    { {  0, 23,  5 } },
    { {  0, 25,  4 } },
    { { 16, 25,  4 } },
    { { 32, 26,  5 } },
    { {  0, 28,  6 } },
    { {  0, 30,  6 } },
    { { 48,  0,  4 } },
    { { 16,  1,  4 } },
    { { 32,  2,  5 } },
    { { 32,  3,  5 } },
    { { 32,  5,  5 } },
    { { 32,  6,  5 } },
    { { 32,  8,  5 } },
    { { 32,  9,  5 } },
    { { 32, 11,  5 } },
    { { 32, 12,  5 } },
    { {  0, 15,  6 } },
    { { 32, 17,  5 } },
    { { 32, 18,  5 } },
    { { 32, 20,  5 } },
    { { 32, 21,  5 } },
    { { 32, 23,  5 } },
    { { 32, 24,  5 } },
    { {  0, 35,  6 } },
    { {  0, 34,  6 } },
    { {  0, 33,  6 } },
    { {  0, 32,  6 } },
};   /* LL_defaultDTable */

static const FSE_decode_t4 ML_defaultDTable[(1<<ML_DEFAULTNORMLOG)+1] = {
    { { ML_DEFAULTNORMLOG, 1, 1 } }, /* header : tableLog, fastMode, fastMode */
    { {  0,  0,  6 } },              /* 0 : base, symbol, bits */
    { {  0,  1,  4 } },
    { { 32,  2,  5 } },
    { {  0,  3,  5 } },
    { {  0,  5,  5 } },
    { {  0,  6,  5 } },
    { {  0,  8,  5 } },
    { {  0, 10,  6 } },
    { {  0, 13,  6 } },
    { {  0, 16,  6 } },
    { {  0, 19,  6 } },
    { {  0, 22,  6 } },
    { {  0, 25,  6 } },
    { {  0, 28,  6 } },
    { {  0, 31,  6 } },
    { {  0, 33,  6 } },
    { {  0, 35,  6 } },
    { {  0, 37,  6 } },
    { {  0, 39,  6 } },
    { {  0, 41,  6 } },
    { {  0, 43,  6 } },
    { {  0, 45,  6 } },
    { { 16,  1,  4 } },
    { {  0,  2,  4 } },
    { { 32,  3,  5 } },
    { {  0,  4,  5 } },
    { { 32,  6,  5 } },
    { {  0,  7,  5 } },
    { {  0,  9,  6 } },
    { {  0, 12,  6 } },
    { {  0, 15,  6 } },
    { {  0, 18,  6 } },
    { {  0, 21,  6 } },
    { {  0, 24,  6 } },
    { {  0, 27,  6 } },
    { {  0, 30,  6 } },
    { {  0, 32,  6 } },
    { {  0, 34,  6 } },
    { {  0, 36,  6 } },
    { {  0, 38,  6 } },
    { {  0, 40,  6 } },
    { {  0, 42,  6 } },
    { {  0, 44,  6 } },
    { { 32,  1,  4 } },
    { { 48,  1,  4 } },
    { { 16,  2,  4 } },
    { { 32,  4,  5 } },
    { { 32,  5,  5 } },
    { { 32,  7,  5 } },
    { { 32,  8,  5 } },
    { {  0, 11,  6 } },
    { {  0, 14,  6 } },
    { {  0, 17,  6 } },
    { {  0, 20,  6 } },
    { {  0, 23,  6 } },
    { {  0, 26,  6 } },
    { {  0, 29,  6 } },
    { {  0, 52,  6 } },
    { {  0, 51,  6 } },
    { {  0, 50,  6 } },
    { {  0, 49,  6 } },
    { {  0, 48,  6 } },
    { {  0, 47,  6 } },
    { {  0, 46,  6 } },
};   /* ML_defaultDTable */

static const FSE_decode_t4 OF_defaultDTable[(1<<OF_DEFAULTNORMLOG)+1] = {
    { { OF_DEFAULTNORMLOG, 1, 1 } }, /* header : tableLog, fastMode, fastMode */
    { {  0,  0,  5 } },              /* 0 : base, symbol, bits */
    { {  0,  6,  4 } },
    { {  0,  9,  5 } },
    { {  0, 15,  5 } },
    { {  0, 21,  5 } },
    { {  0,  3,  5 } },
    { {  0,  7,  4 } },
    { {  0, 12,  5 } },
    { {  0, 18,  5 } },
    { {  0, 23,  5 } },
    { {  0,  5,  5 } },
    { {  0,  8,  4 } },
    { {  0, 14,  5 } },
    { {  0, 20,  5 } },
    { {  0,  2,  5 } },
    { { 16,  7,  4 } },
    { {  0, 11,  5 } },
    { {  0, 17,  5 } },
    { {  0, 22,  5 } },
    { {  0,  4,  5 } },
    { { 16,  8,  4 } },
    { {  0, 13,  5 } },
    { {  0, 19,  5 } },
    { {  0,  1,  5 } },
    { { 16,  6,  4 } },
    { {  0, 10,  5 } },
    { {  0, 16,  5 } },
    { {  0, 28,  5 } },
    { {  0, 27,  5 } },
    { {  0, 26,  5 } },
    { {  0, 25,  5 } },
    { {  0, 24,  5 } },
};   /* OF_defaultDTable */

/*! ZSTD_buildSeqTable() :
    @return : nb bytes read from src,
              or an error code if it fails, testable with ZSTD_isError()
*/
static size_t ZSTD_buildSeqTable(FSE_DTable* DTableSpace, const FSE_DTable** DTablePtr,
                                 symbolEncodingType_e type, U32 max, U32 maxLog,
                                 const void* src, size_t srcSize,
                                 const FSE_decode_t4* defaultTable, U32 flagRepeatTable)
{
    const void* const tmpPtr = defaultTable;   /* bypass strict aliasing */
    switch(type)
    {
    case set_rle :
        if (!srcSize) return ERROR(srcSize_wrong);
        if ( (*(const BYTE*)src) > max) return ERROR(corruption_detected);
        FSE_buildDTable_rle(DTableSpace, *(const BYTE*)src);
        *DTablePtr = DTableSpace;
        return 1;
    case set_basic :
        *DTablePtr = (const FSE_DTable*)tmpPtr;
        return 0;
    case set_repeat:
        if (!flagRepeatTable) return ERROR(corruption_detected);
        return 0;
    default :   /* impossible */
    case set_compressed :
        {   U32 tableLog;
            S16 norm[MaxSeq+1];
            size_t const headerSize = FSE_readNCount(norm, &max, &tableLog, src, srcSize);
            if (FSE_isError(headerSize)) return ERROR(corruption_detected);
            if (tableLog > maxLog) return ERROR(corruption_detected);
            FSE_buildDTable(DTableSpace, norm, max, tableLog);
            *DTablePtr = DTableSpace;
            return headerSize;
    }   }
}

size_t ZSTD_decodeSeqHeaders(ZSTD_DCtx* dctx, int* nbSeqPtr,
                             const void* src, size_t srcSize)
{
    const BYTE* const istart = (const BYTE* const)src;
    const BYTE* const iend = istart + srcSize;
    const BYTE* ip = istart;

    /* check */
    if (srcSize < MIN_SEQUENCES_SIZE) return ERROR(srcSize_wrong);

    /* SeqHead */
    {   int nbSeq = *ip++;
        if (!nbSeq) { *nbSeqPtr=0; return 1; }
        if (nbSeq > 0x7F) {
            if (nbSeq == 0xFF) {
                if (ip+2 > iend) return ERROR(srcSize_wrong);
                nbSeq = MEM_readLE16(ip) + LONGNBSEQ, ip+=2;
            } else {
                if (ip >= iend) return ERROR(srcSize_wrong);
                nbSeq = ((nbSeq-0x80)<<8) + *ip++;
            }
        }
        *nbSeqPtr = nbSeq;
    }

    /* FSE table descriptors */
    if (ip+4 > iend) return ERROR(srcSize_wrong); /* minimum possible size */
    {   symbolEncodingType_e const LLtype = (symbolEncodingType_e)(*ip >> 6);
        symbolEncodingType_e const OFtype = (symbolEncodingType_e)((*ip >> 4) & 3);
        symbolEncodingType_e const MLtype = (symbolEncodingType_e)((*ip >> 2) & 3);
        ip++;

        /* Build DTables */
        {   size_t const llhSize = ZSTD_buildSeqTable(dctx->LLTable, &dctx->LLTptr,
                                                      LLtype, MaxLL, LLFSELog,
                                                      ip, iend-ip, LL_defaultDTable, dctx->fseEntropy);
            if (ZSTD_isError(llhSize)) return ERROR(corruption_detected);
            ip += llhSize;
        }
        {   size_t const ofhSize = ZSTD_buildSeqTable(dctx->OFTable, &dctx->OFTptr,
                                                      OFtype, MaxOff, OffFSELog,
                                                      ip, iend-ip, OF_defaultDTable, dctx->fseEntropy);
            if (ZSTD_isError(ofhSize)) return ERROR(corruption_detected);
            ip += ofhSize;
        }
        {   size_t const mlhSize = ZSTD_buildSeqTable(dctx->MLTable, &dctx->MLTptr,
                                                      MLtype, MaxML, MLFSELog,
                                                      ip, iend-ip, ML_defaultDTable, dctx->fseEntropy);
            if (ZSTD_isError(mlhSize)) return ERROR(corruption_detected);
            ip += mlhSize;
        }
    }

    return ip-istart;
}


typedef struct {
    size_t litLength;
    size_t matchLength;
    size_t offset;
    const BYTE* match;
} seq_t;

typedef struct {
    BIT_DStream_t DStream;
    FSE_DState_t stateLL;
    FSE_DState_t stateOffb;
    FSE_DState_t stateML;
    size_t prevOffset[ZSTD_REP_NUM];
    const BYTE* base;
    size_t pos;
    iPtrDiff gotoDict;
} seqState_t;


FORCE_NOINLINE
size_t ZSTD_execSequenceLast7(BYTE* op,
                              BYTE* const oend, seq_t sequence,
                              const BYTE** litPtr, const BYTE* const litLimit,
                              const BYTE* const base, const BYTE* const vBase, const BYTE* const dictEnd)
{
    BYTE* const oLitEnd = op + sequence.litLength;
    size_t const sequenceLength = sequence.litLength + sequence.matchLength;
    BYTE* const oMatchEnd = op + sequenceLength;   /* risk : address space overflow (32-bits) */
    BYTE* const oend_w = oend - WILDCOPY_OVERLENGTH;
    const BYTE* const iLitEnd = *litPtr + sequence.litLength;
    const BYTE* match = oLitEnd - sequence.offset;

    /* check */
    if (oMatchEnd>oend) return ERROR(dstSize_tooSmall); /* last match must start at a minimum distance of WILDCOPY_OVERLENGTH from oend */
    if (iLitEnd > litLimit) return ERROR(corruption_detected);   /* over-read beyond lit buffer */
    if (oLitEnd <= oend_w) return ERROR(GENERIC);   /* Precondition */

    /* copy literals */
    if (op < oend_w) {
        ZSTD_wildcopy(op, *litPtr, oend_w - op);
        *litPtr += oend_w - op;
        op = oend_w;
    }
    while (op < oLitEnd) *op++ = *(*litPtr)++;

    /* copy Match */
    if (sequence.offset > (size_t)(oLitEnd - base)) {
        /* offset beyond prefix */
        if (sequence.offset > (size_t)(oLitEnd - vBase)) return ERROR(corruption_detected);
        match = dictEnd - (base-match);
        if (match + sequence.matchLength <= dictEnd) {
            memmove(oLitEnd, match, sequence.matchLength);
            return sequenceLength;
        }
        /* span extDict & currentPrefixSegment */
        {   size_t const length1 = dictEnd - match;
            memmove(oLitEnd, match, length1);
            op = oLitEnd + length1;
            sequence.matchLength -= length1;
            match = base;
    }   }
    while (op < oMatchEnd) *op++ = *match++;
    return sequenceLength;
}




static seq_t ZSTD_decodeSequence(seqState_t* seqState)
{
    seq_t seq;

    U32 const llCode = FSE_peekSymbol(&seqState->stateLL);
    U32 const mlCode = FSE_peekSymbol(&seqState->stateML);
    U32 const ofCode = FSE_peekSymbol(&seqState->stateOffb);   /* <= maxOff, by table construction */

    U32 const llBits = LL_bits[llCode];
    U32 const mlBits = ML_bits[mlCode];
    U32 const ofBits = ofCode;
    U32 const totalBits = llBits+mlBits+ofBits;

    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 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 };

    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 };

    /* sequence */
    {   size_t offset;
        if (!ofCode)
            offset = 0;
        else {
            offset = OF_base[ofCode] + BIT_readBitsFast(&seqState->DStream, ofBits);   /* <=  (ZSTD_WINDOWLOG_MAX-1) bits */
            if (MEM_32bits()) BIT_reloadDStream(&seqState->DStream);
        }

        if (ofCode <= 1) {
            offset += (llCode==0);
            if (offset) {
                size_t temp = (offset==3) ? seqState->prevOffset[0] - 1 : seqState->prevOffset[offset];
                temp += !temp;   /* 0 is not valid; input is corrupted; force offset to 1 */
                if (offset != 1) seqState->prevOffset[2] = seqState->prevOffset[1];
                seqState->prevOffset[1] = seqState->prevOffset[0];
                seqState->prevOffset[0] = offset = temp;
            } else {
                offset = seqState->prevOffset[0];
            }
        } else {
            seqState->prevOffset[2] = seqState->prevOffset[1];
            seqState->prevOffset[1] = seqState->prevOffset[0];
            seqState->prevOffset[0] = offset;
        }
        seq.offset = offset;
    }

    seq.matchLength = ML_base[mlCode] + ((mlCode>31) ? BIT_readBitsFast(&seqState->DStream, mlBits) : 0);  /* <=  16 bits */
    if (MEM_32bits() && (mlBits+llBits>24)) BIT_reloadDStream(&seqState->DStream);

    seq.litLength = LL_base[llCode] + ((llCode>15) ? BIT_readBitsFast(&seqState->DStream, llBits) : 0);    /* <=  16 bits */
    if (MEM_32bits() ||
       (totalBits > 64 - 7 - (LLFSELog+MLFSELog+OffFSELog)) ) BIT_reloadDStream(&seqState->DStream);

    /* ANS state update */
    FSE_updateState(&seqState->stateLL, &seqState->DStream);    /* <=  9 bits */
    FSE_updateState(&seqState->stateML, &seqState->DStream);    /* <=  9 bits */
    if (MEM_32bits()) BIT_reloadDStream(&seqState->DStream);    /* <= 18 bits */
    FSE_updateState(&seqState->stateOffb, &seqState->DStream);  /* <=  8 bits */

    return seq;
}


FORCE_INLINE
size_t ZSTD_execSequence(BYTE* op,
                                BYTE* const oend, seq_t sequence,
                                const BYTE** litPtr, const BYTE* const litLimit,
                                const BYTE* const base, const BYTE* const vBase, const BYTE* const dictEnd)
{
    BYTE* const oLitEnd = op + sequence.litLength;
    size_t const sequenceLength = sequence.litLength + sequence.matchLength;
    BYTE* const oMatchEnd = op + sequenceLength;   /* risk : address space overflow (32-bits) */
    BYTE* const oend_w = oend - WILDCOPY_OVERLENGTH;
    const BYTE* const iLitEnd = *litPtr + sequence.litLength;
    const BYTE* match = oLitEnd - sequence.offset;

    /* check */
    if (oMatchEnd>oend) return ERROR(dstSize_tooSmall); /* last match must start at a minimum distance of WILDCOPY_OVERLENGTH from oend */
    if (iLitEnd > litLimit) return ERROR(corruption_detected);   /* over-read beyond lit buffer */
    if (oLitEnd>oend_w) return ZSTD_execSequenceLast7(op, oend, sequence, litPtr, litLimit, base, vBase, dictEnd);

    /* copy Literals */
    ZSTD_copy8(op, *litPtr);
    if (sequence.litLength > 8)
        ZSTD_wildcopy(op+8, (*litPtr)+8, sequence.litLength - 8);   /* note : since oLitEnd <= oend-WILDCOPY_OVERLENGTH, no risk of overwrite beyond oend */
    op = oLitEnd;
    *litPtr = iLitEnd;   /* update for next sequence */

    /* copy Match */
    if (sequence.offset > (size_t)(oLitEnd - base)) {
        /* offset beyond prefix */
        if (sequence.offset > (size_t)(oLitEnd - vBase)) return ERROR(corruption_detected);
        match += (dictEnd-base);
        if (match + sequence.matchLength <= dictEnd) {
            memmove(oLitEnd, match, sequence.matchLength);
            return sequenceLength;
        }
        /* span extDict & currentPrefixSegment */
        {   size_t const length1 = dictEnd - match;
            memmove(oLitEnd, match, length1);
            op = oLitEnd + length1;
            sequence.matchLength -= length1;
            match = base;
            if (op > oend_w || sequence.matchLength < MINMATCH) {
              U32 i;
              for (i = 0; i < sequence.matchLength; ++i) op[i] = match[i];
              return sequenceLength;
            }
    }   }
    /* Requirement: op <= oend_w && sequence.matchLength >= MINMATCH */

    /* match within prefix */
    if (sequence.offset < 8) {
        /* close range match, overlap */
        static const U32 dec32table[] = { 0, 1, 2, 1, 4, 4, 4, 4 };   /* added */
        static const int dec64table[] = { 8, 8, 8, 7, 8, 9,10,11 };   /* substracted */
        int const sub2 = dec64table[sequence.offset];
        op[0] = match[0];
        op[1] = match[1];
        op[2] = match[2];
        op[3] = match[3];
        match += dec32table[sequence.offset];
        ZSTD_copy4(op+4, match);
        match -= sub2;
    } else {
        ZSTD_copy8(op, match);
    }
    op += 8; match += 8;

    if (oMatchEnd > oend-(16-MINMATCH)) {
        if (op < oend_w) {
            ZSTD_wildcopy(op, match, oend_w - op);
            match += oend_w - op;
            op = oend_w;
        }
        while (op < oMatchEnd) *op++ = *match++;
    } else {
        ZSTD_wildcopy(op, match, (ptrdiff_t)sequence.matchLength-8);   /* works even if matchLength < 8 */
    }
    return sequenceLength;
}


static size_t ZSTD_decompressSequences(
                               ZSTD_DCtx* dctx,
                               void* dst, size_t maxDstSize,
                         const void* seqStart, size_t seqSize)
{
    const BYTE* ip = (const BYTE*)seqStart;
    const BYTE* const iend = ip + seqSize;
    BYTE* const ostart = (BYTE* const)dst;
    BYTE* const oend = ostart + maxDstSize;
    BYTE* op = ostart;
    const BYTE* litPtr = dctx->litPtr;
    const BYTE* const litEnd = litPtr + dctx->litSize;
    const BYTE* const base = (const BYTE*) (dctx->base);
    const BYTE* const vBase = (const BYTE*) (dctx->vBase);
    const BYTE* const dictEnd = (const BYTE*) (dctx->dictEnd);
    int nbSeq;

    /* Build Decoding Tables */
    {   size_t const seqHSize = ZSTD_decodeSeqHeaders(dctx, &nbSeq, ip, seqSize);
        if (ZSTD_isError(seqHSize)) return seqHSize;
        ip += seqHSize;
    }

    /* Regen sequences */
    if (nbSeq) {
        seqState_t seqState;
        dctx->fseEntropy = 1;
        { U32 i; for (i=0; i<ZSTD_REP_NUM; i++) seqState.prevOffset[i] = dctx->rep[i]; }
        CHECK_E(BIT_initDStream(&seqState.DStream, ip, iend-ip), corruption_detected);
        FSE_initDState(&seqState.stateLL, &seqState.DStream, dctx->LLTptr);
        FSE_initDState(&seqState.stateOffb, &seqState.DStream, dctx->OFTptr);
        FSE_initDState(&seqState.stateML, &seqState.DStream, dctx->MLTptr);

        for ( ; (BIT_reloadDStream(&(seqState.DStream)) <= BIT_DStream_completed) && nbSeq ; ) {
            nbSeq--;
            {   seq_t const sequence = ZSTD_decodeSequence(&seqState);
                size_t const oneSeqSize = ZSTD_execSequence(op, oend, sequence, &litPtr, litEnd, base, vBase, dictEnd);
                if (ZSTD_isError(oneSeqSize)) return oneSeqSize;
                op += oneSeqSize;
        }   }

        /* check if reached exact end */
        if (nbSeq) return ERROR(corruption_detected);
        /* save reps for next block */
        { U32 i; for (i=0; i<ZSTD_REP_NUM; i++) dctx->rep[i] = (U32)(seqState.prevOffset[i]); }
    }

    /* last literal segment */
    {   size_t const lastLLSize = litEnd - litPtr;
        if (lastLLSize > (size_t)(oend-op)) return ERROR(dstSize_tooSmall);
        memcpy(op, litPtr, lastLLSize);
        op += lastLLSize;
    }

    return op-ostart;
}


static seq_t ZSTD_decodeSequenceLong(seqState_t* seqState)
{
    seq_t seq;

    U32 const llCode = FSE_peekSymbol(&seqState->stateLL);
    U32 const mlCode = FSE_peekSymbol(&seqState->stateML);
    U32 const ofCode = FSE_peekSymbol(&seqState->stateOffb);   /* <= maxOff, by table construction */

    U32 const llBits = LL_bits[llCode];
    U32 const mlBits = ML_bits[mlCode];
    U32 const ofBits = ofCode;
    U32 const totalBits = llBits+mlBits+ofBits;

    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 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 };

    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 };

    /* sequence */
    {   size_t offset;
        if (!ofCode)
            offset = 0;
        else {
            offset = OF_base[ofCode] + BIT_readBitsFast(&seqState->DStream, ofBits);   /* <=  (ZSTD_WINDOWLOG_MAX-1) bits */
            if (MEM_32bits()) BIT_reloadDStream(&seqState->DStream);
        }

        if (ofCode <= 1) {
            offset += (llCode==0);
            if (offset) {
                size_t temp = (offset==3) ? seqState->prevOffset[0] - 1 : seqState->prevOffset[offset];
                temp += !temp;   /* 0 is not valid; input is corrupted; force offset to 1 */
                if (offset != 1) seqState->prevOffset[2] = seqState->prevOffset[1];
                seqState->prevOffset[1] = seqState->prevOffset[0];
                seqState->prevOffset[0] = offset = temp;
            } else {
                offset = seqState->prevOffset[0];
            }
        } else {
            seqState->prevOffset[2] = seqState->prevOffset[1];
            seqState->prevOffset[1] = seqState->prevOffset[0];
            seqState->prevOffset[0] = offset;
        }
        seq.offset = offset;
    }

    seq.matchLength = ML_base[mlCode] + ((mlCode>31) ? BIT_readBitsFast(&seqState->DStream, mlBits) : 0);  /* <=  16 bits */
    if (MEM_32bits() && (mlBits+llBits>24)) BIT_reloadDStream(&seqState->DStream);

    seq.litLength = LL_base[llCode] + ((llCode>15) ? BIT_readBitsFast(&seqState->DStream, llBits) : 0);    /* <=  16 bits */
    if (MEM_32bits() ||
       (totalBits > 64 - 7 - (LLFSELog+MLFSELog+OffFSELog)) ) BIT_reloadDStream(&seqState->DStream);

    {   size_t const pos = seqState->pos + seq.litLength;
        seq.match = seqState->base + pos - seq.offset;    /* single memory segment */
        if (seq.offset > pos) seq.match += seqState->gotoDict;   /* separate memory segment */
        seqState->pos = pos + seq.matchLength;
    }

    /* ANS state update */
    FSE_updateState(&seqState->stateLL, &seqState->DStream);    /* <=  9 bits */
    FSE_updateState(&seqState->stateML, &seqState->DStream);    /* <=  9 bits */
    if (MEM_32bits()) BIT_reloadDStream(&seqState->DStream);    /* <= 18 bits */
    FSE_updateState(&seqState->stateOffb, &seqState->DStream);  /* <=  8 bits */

    return seq;
}

FORCE_INLINE
size_t ZSTD_execSequenceLong(BYTE* op,
                                BYTE* const oend, seq_t sequence,
                                const BYTE** litPtr, const BYTE* const litLimit,
                                const BYTE* const base, const BYTE* const vBase, const BYTE* const dictEnd)
{
    BYTE* const oLitEnd = op + sequence.litLength;
    size_t const sequenceLength = sequence.litLength + sequence.matchLength;
    BYTE* const oMatchEnd = op + sequenceLength;   /* risk : address space overflow (32-bits) */
    BYTE* const oend_w = oend - WILDCOPY_OVERLENGTH;
    const BYTE* const iLitEnd = *litPtr + sequence.litLength;
    const BYTE* match = sequence.match;

    /* check */
#if 1
    if (oMatchEnd>oend) return ERROR(dstSize_tooSmall); /* last match must start at a minimum distance of WILDCOPY_OVERLENGTH from oend */
    if (iLitEnd > litLimit) return ERROR(corruption_detected);   /* over-read beyond lit buffer */
    if (oLitEnd>oend_w) return ZSTD_execSequenceLast7(op, oend, sequence, litPtr, litLimit, base, vBase, dictEnd);
#endif

    /* copy Literals */
    ZSTD_copy8(op, *litPtr);
    if (sequence.litLength > 8)
        ZSTD_wildcopy(op+8, (*litPtr)+8, sequence.litLength - 8);   /* note : since oLitEnd <= oend-WILDCOPY_OVERLENGTH, no risk of overwrite beyond oend */
    op = oLitEnd;
    *litPtr = iLitEnd;   /* update for next sequence */

    /* copy Match */
#if 1
    if (sequence.offset > (size_t)(oLitEnd - base)) {
        /* offset beyond prefix */
        if (sequence.offset > (size_t)(oLitEnd - vBase)) return ERROR(corruption_detected);
        if (match + sequence.matchLength <= dictEnd) {
            memmove(oLitEnd, match, sequence.matchLength);
            return sequenceLength;
        }
        /* span extDict & currentPrefixSegment */
        {   size_t const length1 = dictEnd - match;
            memmove(oLitEnd, match, length1);
            op = oLitEnd + length1;
            sequence.matchLength -= length1;
            match = base;
            if (op > oend_w || sequence.matchLength < MINMATCH) {
              U32 i;
              for (i = 0; i < sequence.matchLength; ++i) op[i] = match[i];
              return sequenceLength;
            }
    }   }
    /* Requirement: op <= oend_w && sequence.matchLength >= MINMATCH */
#endif

    /* match within prefix */
    if (sequence.offset < 8) {
        /* close range match, overlap */
        static const U32 dec32table[] = { 0, 1, 2, 1, 4, 4, 4, 4 };   /* added */
        static const int dec64table[] = { 8, 8, 8, 7, 8, 9,10,11 };   /* substracted */
        int const sub2 = dec64table[sequence.offset];
        op[0] = match[0];
        op[1] = match[1];
        op[2] = match[2];
        op[3] = match[3];
        match += dec32table[sequence.offset];
        ZSTD_copy4(op+4, match);
        match -= sub2;
    } else {
        ZSTD_copy8(op, match);
    }
    op += 8; match += 8;

    if (oMatchEnd > oend-(16-MINMATCH)) {
        if (op < oend_w) {
            ZSTD_wildcopy(op, match, oend_w - op);
            match += oend_w - op;
            op = oend_w;
        }
        while (op < oMatchEnd) *op++ = *match++;
    } else {
        ZSTD_wildcopy(op, match, (ptrdiff_t)sequence.matchLength-8);   /* works even if matchLength < 8 */
    }
    return sequenceLength;
}

static size_t ZSTD_decompressSequencesLong(
                               ZSTD_DCtx* dctx,
                               void* dst, size_t maxDstSize,
                         const void* seqStart, size_t seqSize)
{
    const BYTE* ip = (const BYTE*)seqStart;
    const BYTE* const iend = ip + seqSize;
    BYTE* const ostart = (BYTE* const)dst;
    BYTE* const oend = ostart + maxDstSize;
    BYTE* op = ostart;
    const BYTE* litPtr = dctx->litPtr;
    const BYTE* const litEnd = litPtr + dctx->litSize;
    const BYTE* const base = (const BYTE*) (dctx->base);
    const BYTE* const vBase = (const BYTE*) (dctx->vBase);
    const BYTE* const dictEnd = (const BYTE*) (dctx->dictEnd);
    int nbSeq;

    /* Build Decoding Tables */
    {   size_t const seqHSize = ZSTD_decodeSeqHeaders(dctx, &nbSeq, ip, seqSize);
        if (ZSTD_isError(seqHSize)) return seqHSize;
        ip += seqHSize;
    }

    /* Regen sequences */
    if (nbSeq) {
#define STORED_SEQS 4
#define STOSEQ_MASK (STORED_SEQS-1)
#define ADVANCED_SEQS 4
        seq_t sequences[STORED_SEQS];
        int const seqAdvance = MIN(nbSeq, ADVANCED_SEQS);
        seqState_t seqState;
        int seqNb;
        dctx->fseEntropy = 1;
        { U32 i; for (i=0; i<ZSTD_REP_NUM; i++) seqState.prevOffset[i] = dctx->rep[i]; }
        seqState.base = base;
        seqState.pos = (size_t)(op-base);
        seqState.gotoDict = (iPtrDiff)(dictEnd - base);
        CHECK_E(BIT_initDStream(&seqState.DStream, ip, iend-ip), corruption_detected);
        FSE_initDState(&seqState.stateLL, &seqState.DStream, dctx->LLTptr);
        FSE_initDState(&seqState.stateOffb, &seqState.DStream, dctx->OFTptr);
        FSE_initDState(&seqState.stateML, &seqState.DStream, dctx->MLTptr);

        /* prepare in advance */
        for (seqNb=0; (BIT_reloadDStream(&seqState.DStream) <= BIT_DStream_completed) && seqNb<seqAdvance; seqNb++) {
            sequences[seqNb] = ZSTD_decodeSequenceLong(&seqState);
        }
        if (seqNb<seqAdvance) return ERROR(corruption_detected);

        /* decode and decompress */
        for ( ; (BIT_reloadDStream(&(seqState.DStream)) <= BIT_DStream_completed) && seqNb<nbSeq ; seqNb++) {
            seq_t const sequence = ZSTD_decodeSequenceLong(&seqState);
            size_t const oneSeqSize = ZSTD_execSequenceLong(op, oend, sequences[(seqNb-ADVANCED_SEQS) & STOSEQ_MASK], &litPtr, litEnd, base, vBase, dictEnd);
            if (ZSTD_isError(oneSeqSize)) return oneSeqSize;
            ZSTD_PREFETCH(sequence.match);
            sequences[seqNb&STOSEQ_MASK] = sequence;
            op += oneSeqSize;
        }
        if (seqNb<nbSeq) return ERROR(corruption_detected);

        /* finish queue */
        seqNb -= seqAdvance;
        for ( ; seqNb<nbSeq ; seqNb++) {
            size_t const oneSeqSize = ZSTD_execSequenceLong(op, oend, sequences[seqNb&STOSEQ_MASK], &litPtr, litEnd, base, vBase, dictEnd);
            if (ZSTD_isError(oneSeqSize)) return oneSeqSize;
            op += oneSeqSize;
        }

        /* save reps for next block */
        { U32 i; for (i=0; i<ZSTD_REP_NUM; i++) dctx->rep[i] = (U32)(seqState.prevOffset[i]); }
    }

    /* last literal segment */
    {   size_t const lastLLSize = litEnd - litPtr;
        if (lastLLSize > (size_t)(oend-op)) return ERROR(dstSize_tooSmall);
        memcpy(op, litPtr, lastLLSize);
        op += lastLLSize;
    }

    return op-ostart;
}


static size_t ZSTD_decompressBlock_internal(ZSTD_DCtx* dctx,
                            void* dst, size_t dstCapacity,
                      const void* src, size_t srcSize)
{   /* blockType == blockCompressed */
    const BYTE* ip = (const BYTE*)src;

    if (srcSize >= ZSTD_BLOCKSIZE_ABSOLUTEMAX) return ERROR(srcSize_wrong);

    /* Decode literals sub-block */
    {   size_t const litCSize = ZSTD_decodeLiteralsBlock(dctx, src, srcSize);
        if (ZSTD_isError(litCSize)) return litCSize;
        ip += litCSize;
        srcSize -= litCSize;
    }
    if (dctx->fParams.windowSize > (1<<23)) return ZSTD_decompressSequencesLong(dctx, dst, dstCapacity, ip, srcSize);
    return ZSTD_decompressSequences(dctx, dst, dstCapacity, ip, srcSize);
}


static void ZSTD_checkContinuity(ZSTD_DCtx* dctx, const void* dst)
{
    if (dst != dctx->previousDstEnd) {   /* not contiguous */
        dctx->dictEnd = dctx->previousDstEnd;
        dctx->vBase = (const char*)dst - ((const char*)(dctx->previousDstEnd) - (const char*)(dctx->base));
        dctx->base = dst;
        dctx->previousDstEnd = dst;
    }
}

size_t ZSTD_decompressBlock(ZSTD_DCtx* dctx,
                            void* dst, size_t dstCapacity,
                      const void* src, size_t srcSize)
{
    size_t dSize;
    ZSTD_checkContinuity(dctx, dst);
    dSize = ZSTD_decompressBlock_internal(dctx, dst, dstCapacity, src, srcSize);
    dctx->previousDstEnd = (char*)dst + dSize;
    return dSize;
}


/** ZSTD_insertBlock() :
    insert `src` block into `dctx` history. Useful to track uncompressed blocks. */
ZSTDLIB_API size_t ZSTD_insertBlock(ZSTD_DCtx* dctx, const void* blockStart, size_t blockSize)
{
    ZSTD_checkContinuity(dctx, blockStart);
    dctx->previousDstEnd = (const char*)blockStart + blockSize;
    return blockSize;
}


size_t ZSTD_generateNxBytes(void* dst, size_t dstCapacity, BYTE byte, size_t length)
{
    if (length > dstCapacity) return ERROR(dstSize_tooSmall);
    memset(dst, byte, length);
    return length;
}


/*! ZSTD_decompressFrame() :
*   `dctx` must be properly initialized */
static size_t ZSTD_decompressFrame(ZSTD_DCtx* dctx,
                                 void* dst, size_t dstCapacity,
                                 const void* src, size_t srcSize)
{
    const BYTE* ip = (const BYTE*)src;
    BYTE* const ostart = (BYTE* const)dst;
    BYTE* const oend = ostart + dstCapacity;
    BYTE* op = ostart;
    size_t remainingSize = srcSize;

    /* check */
    if (srcSize < ZSTD_frameHeaderSize_min+ZSTD_blockHeaderSize) return ERROR(srcSize_wrong);

    /* Frame Header */
    {   size_t const frameHeaderSize = ZSTD_frameHeaderSize(src, ZSTD_frameHeaderSize_prefix);
        if (ZSTD_isError(frameHeaderSize)) return frameHeaderSize;
        if (srcSize < frameHeaderSize+ZSTD_blockHeaderSize) return ERROR(srcSize_wrong);
        CHECK_F(ZSTD_decodeFrameHeader(dctx, src, frameHeaderSize));
        ip += frameHeaderSize; remainingSize -= frameHeaderSize;
    }

    /* Loop on each block */
    while (1) {
        size_t decodedSize;
        blockProperties_t blockProperties;
        size_t const cBlockSize = ZSTD_getcBlockSize(ip, remainingSize, &blockProperties);
        if (ZSTD_isError(cBlockSize)) return cBlockSize;

        ip += ZSTD_blockHeaderSize;
        remainingSize -= ZSTD_blockHeaderSize;
        if (cBlockSize > remainingSize) return ERROR(srcSize_wrong);

        switch(blockProperties.blockType)
        {
        case bt_compressed:
            decodedSize = ZSTD_decompressBlock_internal(dctx, op, oend-op, ip, cBlockSize);
            break;
        case bt_raw :
            decodedSize = ZSTD_copyRawBlock(op, oend-op, ip, cBlockSize);
            break;
        case bt_rle :
            decodedSize = ZSTD_generateNxBytes(op, oend-op, *ip, blockProperties.origSize);
            break;
        case bt_reserved :
        default:
            return ERROR(corruption_detected);
        }

        if (ZSTD_isError(decodedSize)) return decodedSize;
        if (dctx->fParams.checksumFlag) XXH64_update(&dctx->xxhState, op, decodedSize);
        op += decodedSize;
        ip += cBlockSize;
        remainingSize -= cBlockSize;
        if (blockProperties.lastBlock) break;
    }

    if (dctx->fParams.checksumFlag) {   /* Frame content checksum verification */
        U32 const checkCalc = (U32)XXH64_digest(&dctx->xxhState);
        U32 checkRead;
        if (remainingSize<4) return ERROR(checksum_wrong);
        checkRead = MEM_readLE32(ip);
        if (checkRead != checkCalc) return ERROR(checksum_wrong);
        remainingSize -= 4;
    }

    if (remainingSize) return ERROR(srcSize_wrong);
    return op-ostart;
}


size_t ZSTD_decompress_usingDict(ZSTD_DCtx* dctx,
                                 void* dst, size_t dstCapacity,
                           const void* src, size_t srcSize,
                           const void* dict, size_t dictSize)
{
#if defined(ZSTD_LEGACY_SUPPORT) && (ZSTD_LEGACY_SUPPORT==1)
    if (ZSTD_isLegacy(src, srcSize)) return ZSTD_decompressLegacy(dst, dstCapacity, src, srcSize, dict, dictSize);
#endif
    CHECK_F(ZSTD_decompressBegin_usingDict(dctx, dict, dictSize));
    ZSTD_checkContinuity(dctx, dst);
    return ZSTD_decompressFrame(dctx, dst, dstCapacity, src, srcSize);
}


size_t ZSTD_decompressDCtx(ZSTD_DCtx* dctx, void* dst, size_t dstCapacity, const void* src, size_t srcSize)
{
    return ZSTD_decompress_usingDict(dctx, dst, dstCapacity, src, srcSize, NULL, 0);
}


size_t ZSTD_decompress(void* dst, size_t dstCapacity, const void* src, size_t srcSize)
{
#if defined(ZSTD_HEAPMODE) && (ZSTD_HEAPMODE==1)
    size_t regenSize;
    ZSTD_DCtx* const dctx = ZSTD_createDCtx();
    if (dctx==NULL) return ERROR(memory_allocation);
    regenSize = ZSTD_decompressDCtx(dctx, dst, dstCapacity, src, srcSize);
    ZSTD_freeDCtx(dctx);
    return regenSize;
#else   /* stack mode */
    ZSTD_DCtx dctx;
    return ZSTD_decompressDCtx(&dctx, dst, dstCapacity, src, srcSize);
#endif
}


/*-**************************************
*   Advanced Streaming Decompression API
*   Bufferless and synchronous
****************************************/
size_t ZSTD_nextSrcSizeToDecompress(ZSTD_DCtx* dctx) { return dctx->expected; }

ZSTD_nextInputType_e ZSTD_nextInputType(ZSTD_DCtx* dctx) {
    switch(dctx->stage)
    {
    default:   /* should not happen */
    case ZSTDds_getFrameHeaderSize:
    case ZSTDds_decodeFrameHeader:
        return ZSTDnit_frameHeader;
    case ZSTDds_decodeBlockHeader:
        return ZSTDnit_blockHeader;
    case ZSTDds_decompressBlock:
        return ZSTDnit_block;
    case ZSTDds_decompressLastBlock:
        return ZSTDnit_lastBlock;
    case ZSTDds_checkChecksum:
        return ZSTDnit_checksum;
    case ZSTDds_decodeSkippableHeader:
    case ZSTDds_skipFrame:
        return ZSTDnit_skippableFrame;
    }
}

int ZSTD_isSkipFrame(ZSTD_DCtx* dctx) { return dctx->stage == ZSTDds_skipFrame; }   /* for zbuff */

/** ZSTD_decompressContinue() :
*   @return : nb of bytes generated into `dst` (necessarily <= `dstCapacity)
*             or an error code, which can be tested using ZSTD_isError() */
size_t ZSTD_decompressContinue(ZSTD_DCtx* dctx, void* dst, size_t dstCapacity, const void* src, size_t srcSize)
{
    /* Sanity check */
    if (srcSize != dctx->expected) return ERROR(srcSize_wrong);
    if (dstCapacity) ZSTD_checkContinuity(dctx, dst);

    switch (dctx->stage)
    {
    case ZSTDds_getFrameHeaderSize :
        if (srcSize != ZSTD_frameHeaderSize_prefix) return ERROR(srcSize_wrong);      /* impossible */
        if ((MEM_readLE32(src) & 0xFFFFFFF0U) == ZSTD_MAGIC_SKIPPABLE_START) {        /* skippable frame */
            memcpy(dctx->headerBuffer, src, ZSTD_frameHeaderSize_prefix);
            dctx->expected = ZSTD_skippableHeaderSize - ZSTD_frameHeaderSize_prefix;  /* magic number + skippable frame length */
            dctx->stage = ZSTDds_decodeSkippableHeader;
            return 0;
        }
        dctx->headerSize = ZSTD_frameHeaderSize(src, ZSTD_frameHeaderSize_prefix);
        if (ZSTD_isError(dctx->headerSize)) return dctx->headerSize;
        memcpy(dctx->headerBuffer, src, ZSTD_frameHeaderSize_prefix);
        if (dctx->headerSize > ZSTD_frameHeaderSize_prefix) {
            dctx->expected = dctx->headerSize - ZSTD_frameHeaderSize_prefix;
            dctx->stage = ZSTDds_decodeFrameHeader;
            return 0;
        }
        dctx->expected = 0;   /* not necessary to copy more */

    case ZSTDds_decodeFrameHeader:
        memcpy(dctx->headerBuffer + ZSTD_frameHeaderSize_prefix, src, dctx->expected);
        CHECK_F(ZSTD_decodeFrameHeader(dctx, dctx->headerBuffer, dctx->headerSize));
        dctx->expected = ZSTD_blockHeaderSize;
        dctx->stage = ZSTDds_decodeBlockHeader;
        return 0;

    case ZSTDds_decodeBlockHeader:
        {   blockProperties_t bp;
            size_t const cBlockSize = ZSTD_getcBlockSize(src, ZSTD_blockHeaderSize, &bp);
            if (ZSTD_isError(cBlockSize)) return cBlockSize;
            dctx->expected = cBlockSize;
            dctx->bType = bp.blockType;
            dctx->rleSize = bp.origSize;
            if (cBlockSize) {
                dctx->stage = bp.lastBlock ? ZSTDds_decompressLastBlock : ZSTDds_decompressBlock;
                return 0;
            }
            /* empty block */
            if (bp.lastBlock) {
                if (dctx->fParams.checksumFlag) {
                    dctx->expected = 4;
                    dctx->stage = ZSTDds_checkChecksum;
                } else {
                    dctx->expected = 0; /* end of frame */
                    dctx->stage = ZSTDds_getFrameHeaderSize;
                }
            } else {
                dctx->expected = 3;  /* go directly to next header */
                dctx->stage = ZSTDds_decodeBlockHeader;
            }
            return 0;
        }
    case ZSTDds_decompressLastBlock:
    case ZSTDds_decompressBlock:
        {   size_t rSize;
            switch(dctx->bType)
            {
            case bt_compressed:
                rSize = ZSTD_decompressBlock_internal(dctx, dst, dstCapacity, src, srcSize);
                break;
            case bt_raw :
                rSize = ZSTD_copyRawBlock(dst, dstCapacity, src, srcSize);
                break;
            case bt_rle :
                rSize = ZSTD_setRleBlock(dst, dstCapacity, src, srcSize, dctx->rleSize);
                break;
            case bt_reserved :   /* should never happen */
            default:
                return ERROR(corruption_detected);
            }
            if (ZSTD_isError(rSize)) return rSize;
            if (dctx->fParams.checksumFlag) XXH64_update(&dctx->xxhState, dst, rSize);

            if (dctx->stage == ZSTDds_decompressLastBlock) {   /* end of frame */
                if (dctx->fParams.checksumFlag) {  /* another round for frame checksum */
                    dctx->expected = 4;
                    dctx->stage = ZSTDds_checkChecksum;
                } else {
                    dctx->expected = 0;   /* ends here */
                    dctx->stage = ZSTDds_getFrameHeaderSize;
                }
            } else {
                dctx->stage = ZSTDds_decodeBlockHeader;
                dctx->expected = ZSTD_blockHeaderSize;
                dctx->previousDstEnd = (char*)dst + rSize;
            }
            return rSize;
        }
    case ZSTDds_checkChecksum:
        {   U32 const h32 = (U32)XXH64_digest(&dctx->xxhState);
            U32 const check32 = MEM_readLE32(src);   /* srcSize == 4, guaranteed by dctx->expected */
            if (check32 != h32) return ERROR(checksum_wrong);
            dctx->expected = 0;
            dctx->stage = ZSTDds_getFrameHeaderSize;
            return 0;
        }
    case ZSTDds_decodeSkippableHeader:
        {   memcpy(dctx->headerBuffer + ZSTD_frameHeaderSize_prefix, src, dctx->expected);
            dctx->expected = MEM_readLE32(dctx->headerBuffer + 4);
            dctx->stage = ZSTDds_skipFrame;
            return 0;
        }
    case ZSTDds_skipFrame:
        {   dctx->expected = 0;
            dctx->stage = ZSTDds_getFrameHeaderSize;
            return 0;
        }
    default:
        return ERROR(GENERIC);   /* impossible */
    }
}


static size_t ZSTD_refDictContent(ZSTD_DCtx* dctx, const void* dict, size_t dictSize)
{
    dctx->dictEnd = dctx->previousDstEnd;
    dctx->vBase = (const char*)dict - ((const char*)(dctx->previousDstEnd) - (const char*)(dctx->base));
    dctx->base = dict;
    dctx->previousDstEnd = (const char*)dict + dictSize;
    return 0;
}

static size_t ZSTD_loadEntropy(ZSTD_DCtx* dctx, const void* const dict, size_t const dictSize)
{
    const BYTE* dictPtr = (const BYTE*)dict;
    const BYTE* const dictEnd = dictPtr + dictSize;

    {   size_t const hSize = HUF_readDTableX4(dctx->hufTable, dict, dictSize);
        if (HUF_isError(hSize)) return ERROR(dictionary_corrupted);
        dictPtr += hSize;
    }

    {   short offcodeNCount[MaxOff+1];
        U32 offcodeMaxValue=MaxOff, offcodeLog;
        size_t const offcodeHeaderSize = FSE_readNCount(offcodeNCount, &offcodeMaxValue, &offcodeLog, dictPtr, dictEnd-dictPtr);
        if (FSE_isError(offcodeHeaderSize)) return ERROR(dictionary_corrupted);
        if (offcodeLog > OffFSELog) return ERROR(dictionary_corrupted);
        CHECK_E(FSE_buildDTable(dctx->OFTable, offcodeNCount, offcodeMaxValue, offcodeLog), dictionary_corrupted);
        dictPtr += offcodeHeaderSize;
    }

    {   short matchlengthNCount[MaxML+1];
        unsigned matchlengthMaxValue = MaxML, matchlengthLog;
        size_t const matchlengthHeaderSize = FSE_readNCount(matchlengthNCount, &matchlengthMaxValue, &matchlengthLog, dictPtr, dictEnd-dictPtr);
        if (FSE_isError(matchlengthHeaderSize)) return ERROR(dictionary_corrupted);
        if (matchlengthLog > MLFSELog) return ERROR(dictionary_corrupted);
        CHECK_E(FSE_buildDTable(dctx->MLTable, matchlengthNCount, matchlengthMaxValue, matchlengthLog), dictionary_corrupted);
        dictPtr += matchlengthHeaderSize;
    }

    {   short litlengthNCount[MaxLL+1];
        unsigned litlengthMaxValue = MaxLL, litlengthLog;
        size_t const litlengthHeaderSize = FSE_readNCount(litlengthNCount, &litlengthMaxValue, &litlengthLog, dictPtr, dictEnd-dictPtr);
        if (FSE_isError(litlengthHeaderSize)) return ERROR(dictionary_corrupted);
        if (litlengthLog > LLFSELog) return ERROR(dictionary_corrupted);
        CHECK_E(FSE_buildDTable(dctx->LLTable, litlengthNCount, litlengthMaxValue, litlengthLog), dictionary_corrupted);
        dictPtr += litlengthHeaderSize;
    }

    if (dictPtr+12 > dictEnd) return ERROR(dictionary_corrupted);
    dctx->rep[0] = MEM_readLE32(dictPtr+0); if (dctx->rep[0] == 0 || dctx->rep[0] >= dictSize) return ERROR(dictionary_corrupted);
    dctx->rep[1] = MEM_readLE32(dictPtr+4); if (dctx->rep[1] == 0 || dctx->rep[1] >= dictSize) return ERROR(dictionary_corrupted);
    dctx->rep[2] = MEM_readLE32(dictPtr+8); if (dctx->rep[2] == 0 || dctx->rep[2] >= dictSize) return ERROR(dictionary_corrupted);
    dictPtr += 12;

    dctx->litEntropy = dctx->fseEntropy = 1;
    return dictPtr - (const BYTE*)dict;
}

static size_t ZSTD_decompress_insertDictionary(ZSTD_DCtx* dctx, const void* dict, size_t dictSize)
{
    if (dictSize < 8) return ZSTD_refDictContent(dctx, dict, dictSize);
    {   U32 const magic = MEM_readLE32(dict);
        if (magic != ZSTD_DICT_MAGIC) {
            return ZSTD_refDictContent(dctx, dict, dictSize);   /* pure content mode */
    }   }
    dctx->dictID = MEM_readLE32((const char*)dict + 4);

    /* load entropy tables */
    dict = (const char*)dict + 8;
    dictSize -= 8;
    {   size_t const eSize = ZSTD_loadEntropy(dctx, dict, dictSize);
        if (ZSTD_isError(eSize)) return ERROR(dictionary_corrupted);
        dict = (const char*)dict + eSize;
        dictSize -= eSize;
    }

    /* reference dictionary content */
    return ZSTD_refDictContent(dctx, dict, dictSize);
}

size_t ZSTD_decompressBegin_usingDict(ZSTD_DCtx* dctx, const void* dict, size_t dictSize)
{
    CHECK_F(ZSTD_decompressBegin(dctx));
    if (dict && dictSize) CHECK_E(ZSTD_decompress_insertDictionary(dctx, dict, dictSize), dictionary_corrupted);
    return 0;
}


/* ======   ZSTD_DDict   ====== */

struct ZSTD_DDict_s {
    void* dictBuffer;
    const void* dictContent;
    size_t dictSize;
    ZSTD_DCtx* refContext;
};  /* typedef'd to ZSTD_DDict within "zstd.h" */

ZSTD_DDict* ZSTD_createDDict_advanced(const void* dict, size_t dictSize, unsigned byReference, ZSTD_customMem customMem)
{
    if (!customMem.customAlloc && !customMem.customFree) customMem = defaultCustomMem;
    if (!customMem.customAlloc || !customMem.customFree) return NULL;

    {   ZSTD_DDict* const ddict = (ZSTD_DDict*) ZSTD_malloc(sizeof(ZSTD_DDict), customMem);
        ZSTD_DCtx* const dctx = ZSTD_createDCtx_advanced(customMem);

        if (!ddict || !dctx) {
            ZSTD_free(ddict, customMem);
            ZSTD_free(dctx, customMem);
            return NULL;
        }

        if ((byReference) || (!dict) || (!dictSize)) {
            ddict->dictBuffer = NULL;
            ddict->dictContent = dict;
        } else {
            void* const internalBuffer = ZSTD_malloc(dictSize, customMem);
            if (!internalBuffer) { ZSTD_free(dctx, customMem); ZSTD_free(ddict, customMem); return NULL; }
            memcpy(internalBuffer, dict, dictSize);
            ddict->dictBuffer = internalBuffer;
            ddict->dictContent = internalBuffer;
        }
        {   size_t const errorCode = ZSTD_decompressBegin_usingDict(dctx, ddict->dictContent, dictSize);
            if (ZSTD_isError(errorCode)) {
                ZSTD_free(ddict->dictBuffer, customMem);
                ZSTD_free(ddict, customMem);
                ZSTD_free(dctx, customMem);
                return NULL;
        }   }

        ddict->dictSize = dictSize;
        ddict->refContext = dctx;
        return ddict;
    }
}

/*! ZSTD_createDDict() :
*   Create a digested dictionary, ready to start decompression without startup delay.
*   `dict` can be released after `ZSTD_DDict` creation */
ZSTD_DDict* ZSTD_createDDict(const void* dict, size_t dictSize)
{
    ZSTD_customMem const allocator = { NULL, NULL, NULL };
    return ZSTD_createDDict_advanced(dict, dictSize, 0, allocator);
}


/*! ZSTD_createDDict_byReference() :
 *  Create a digested dictionary, ready to start decompression operation without startup delay.
 *  Dictionary content is simply referenced, and therefore stays in dictBuffer.
 *  It is important that dictBuffer outlives DDict, it must remain read accessible throughout the lifetime of DDict */
ZSTD_DDict* ZSTD_createDDict_byReference(const void* dictBuffer, size_t dictSize)
{
    ZSTD_customMem const allocator = { NULL, NULL, NULL };
    return ZSTD_createDDict_advanced(dictBuffer, dictSize, 1, allocator);
}


size_t ZSTD_freeDDict(ZSTD_DDict* ddict)
{
    if (ddict==NULL) return 0;   /* support free on NULL */
    {   ZSTD_customMem const cMem = ddict->refContext->customMem;
        ZSTD_freeDCtx(ddict->refContext);
        ZSTD_free(ddict->dictBuffer, cMem);
        ZSTD_free(ddict, cMem);
        return 0;
    }
}

size_t ZSTD_sizeof_DDict(const ZSTD_DDict* ddict)
{
    if (ddict==NULL) return 0;   /* support sizeof on NULL */
    return sizeof(*ddict) + ZSTD_sizeof_DCtx(ddict->refContext) + (ddict->dictBuffer ? ddict->dictSize : 0) ;
}

/*! ZSTD_getDictID_fromDict() :
 *  Provides the dictID stored within dictionary.
 *  if @return == 0, the dictionary is not conformant with Zstandard specification.
 *  It can still be loaded, but as a content-only dictionary. */
unsigned ZSTD_getDictID_fromDict(const void* dict, size_t dictSize)
{
    if (dictSize < 8) return 0;
    if (MEM_readLE32(dict) != ZSTD_DICT_MAGIC) return 0;
    return MEM_readLE32((const char*)dict + 4);
}

/*! ZSTD_getDictID_fromDDict() :
 *  Provides the dictID of the dictionary loaded into `ddict`.
 *  If @return == 0, the dictionary is not conformant to Zstandard specification, or empty.
 *  Non-conformant dictionaries can still be loaded, but as content-only dictionaries. */
unsigned ZSTD_getDictID_fromDDict(const ZSTD_DDict* ddict)
{
    if (ddict==NULL) return 0;
    return ZSTD_getDictID_fromDict(ddict->dictContent, ddict->dictSize);
}

/*! ZSTD_getDictID_fromFrame() :
 *  Provides the dictID required to decompressed the frame stored within `src`.
 *  If @return == 0, the dictID could not be decoded.
 *  This could for one of the following reasons :
 *  - The frame does not require a dictionary to be decoded (most common case).
 *  - The frame was built with dictID intentionally removed. Whatever dictionary is necessary is a hidden information.
 *    Note : this use case also happens when using a non-conformant dictionary.
 *  - `srcSize` is too small, and as a result, the frame header could not be decoded (only possible if `srcSize < ZSTD_FRAMEHEADERSIZE_MAX`).
 *  - This is not a Zstandard frame.
 *  When identifying the exact failure cause, it's possible to used ZSTD_getFrameParams(), which will provide a more precise error code. */
unsigned ZSTD_getDictID_fromFrame(const void* src, size_t srcSize)
{
    ZSTD_frameParams zfp = { 0 , 0 , 0 , 0 };
    size_t const hError = ZSTD_getFrameParams(&zfp, src, srcSize);
    if (ZSTD_isError(hError)) return 0;
    return zfp.dictID;
}


/*! ZSTD_decompress_usingDDict() :
*   Decompression using a pre-digested Dictionary
*   Use dictionary without significant overhead. */
size_t ZSTD_decompress_usingDDict(ZSTD_DCtx* dctx,
                                  void* dst, size_t dstCapacity,
                            const void* src, size_t srcSize,
                            const ZSTD_DDict* ddict)
{
#if defined(ZSTD_LEGACY_SUPPORT) && (ZSTD_LEGACY_SUPPORT==1)
    if (ZSTD_isLegacy(src, srcSize)) return ZSTD_decompressLegacy(dst, dstCapacity, src, srcSize, ddict->dictContent, ddict->dictSize);
#endif
    ZSTD_refDCtx(dctx, ddict->refContext);
    ZSTD_checkContinuity(dctx, dst);
    return ZSTD_decompressFrame(dctx, dst, dstCapacity, src, srcSize);
}


/*=====================================
*   Streaming decompression
*====================================*/

typedef enum { zdss_init, zdss_loadHeader,
               zdss_read, zdss_load, zdss_flush } ZSTD_dStreamStage;

/* *** Resource management *** */
struct ZSTD_DStream_s {
    ZSTD_DCtx* dctx;
    ZSTD_DDict* ddictLocal;
    const ZSTD_DDict* ddict;
    ZSTD_frameParams fParams;
    ZSTD_dStreamStage stage;
    char*  inBuff;
    size_t inBuffSize;
    size_t inPos;
    size_t maxWindowSize;
    char*  outBuff;
    size_t outBuffSize;
    size_t outStart;
    size_t outEnd;
    size_t blockSize;
    BYTE headerBuffer[ZSTD_FRAMEHEADERSIZE_MAX];   /* tmp buffer to store frame header */
    size_t lhSize;
    ZSTD_customMem customMem;
    void* legacyContext;
    U32 previousLegacyVersion;
    U32 legacyVersion;
    U32 hostageByte;
};   /* typedef'd to ZSTD_DStream within "zstd.h" */


ZSTD_DStream* ZSTD_createDStream(void)
{
    return ZSTD_createDStream_advanced(defaultCustomMem);
}

ZSTD_DStream* ZSTD_createDStream_advanced(ZSTD_customMem customMem)
{
    ZSTD_DStream* zds;

    if (!customMem.customAlloc && !customMem.customFree) customMem = defaultCustomMem;
    if (!customMem.customAlloc || !customMem.customFree) return NULL;

    zds = (ZSTD_DStream*) ZSTD_malloc(sizeof(ZSTD_DStream), customMem);
    if (zds==NULL) return NULL;
    memset(zds, 0, sizeof(ZSTD_DStream));
    memcpy(&zds->customMem, &customMem, sizeof(ZSTD_customMem));
    zds->dctx = ZSTD_createDCtx_advanced(customMem);
    if (zds->dctx == NULL) { ZSTD_freeDStream(zds); return NULL; }
    zds->stage = zdss_init;
    zds->maxWindowSize = ZSTD_MAXWINDOWSIZE_DEFAULT;
    return zds;
}

size_t ZSTD_freeDStream(ZSTD_DStream* zds)
{
    if (zds==NULL) return 0;   /* support free on null */
    {   ZSTD_customMem const cMem = zds->customMem;
        ZSTD_freeDCtx(zds->dctx);
        ZSTD_freeDDict(zds->ddictLocal);
        ZSTD_free(zds->inBuff, cMem);
        ZSTD_free(zds->outBuff, cMem);
#if defined(ZSTD_LEGACY_SUPPORT) && (ZSTD_LEGACY_SUPPORT >= 1)
        if (zds->legacyContext)
            ZSTD_freeLegacyStreamContext(zds->legacyContext, zds->previousLegacyVersion);
#endif
        ZSTD_free(zds, cMem);
        return 0;
    }
}


/* *** Initialization *** */

size_t ZSTD_DStreamInSize(void)  { return ZSTD_BLOCKSIZE_ABSOLUTEMAX + ZSTD_blockHeaderSize; }
size_t ZSTD_DStreamOutSize(void) { return ZSTD_BLOCKSIZE_ABSOLUTEMAX; }

size_t ZSTD_initDStream_usingDict(ZSTD_DStream* zds, const void* dict, size_t dictSize)
{
    zds->stage = zdss_loadHeader;
    zds->lhSize = zds->inPos = zds->outStart = zds->outEnd = 0;
    ZSTD_freeDDict(zds->ddictLocal);
    if (dict && dictSize >= 8) {
        zds->ddictLocal = ZSTD_createDDict(dict, dictSize);
        if (zds->ddictLocal == NULL) return ERROR(memory_allocation);
    } else zds->ddictLocal = NULL;
    zds->ddict = zds->ddictLocal;
    zds->legacyVersion = 0;
    zds->hostageByte = 0;
    return ZSTD_frameHeaderSize_prefix;
}

size_t ZSTD_initDStream(ZSTD_DStream* zds)
{
    return ZSTD_initDStream_usingDict(zds, NULL, 0);
}

size_t ZSTD_initDStream_usingDDict(ZSTD_DStream* zds, const ZSTD_DDict* ddict)  /**< note : ddict will just be referenced, and must outlive decompression session */
{
    size_t const initResult = ZSTD_initDStream(zds);
    zds->ddict = ddict;
    return initResult;
}

size_t ZSTD_resetDStream(ZSTD_DStream* zds)
{
    zds->stage = zdss_loadHeader;
    zds->lhSize = zds->inPos = zds->outStart = zds->outEnd = 0;
    zds->legacyVersion = 0;
    zds->hostageByte = 0;
    return ZSTD_frameHeaderSize_prefix;
}

size_t ZSTD_setDStreamParameter(ZSTD_DStream* zds,
                                ZSTD_DStreamParameter_e paramType, unsigned paramValue)
{
    switch(paramType)
    {
        default : return ERROR(parameter_unknown);
        case DStream_p_maxWindowSize : zds->maxWindowSize = paramValue ? paramValue : (U32)(-1); break;
    }
    return 0;
}


size_t ZSTD_sizeof_DStream(const ZSTD_DStream* zds)
{
    if (zds==NULL) return 0;   /* support sizeof on NULL */
    return sizeof(*zds) + ZSTD_sizeof_DCtx(zds->dctx) + ZSTD_sizeof_DDict(zds->ddictLocal) + zds->inBuffSize + zds->outBuffSize;
}


/* *****   Decompression   ***** */

MEM_STATIC size_t ZSTD_limitCopy(void* dst, size_t dstCapacity, const void* src, size_t srcSize)
{
    size_t const length = MIN(dstCapacity, srcSize);
    memcpy(dst, src, length);
    return length;
}


size_t ZSTD_decompressStream(ZSTD_DStream* zds, ZSTD_outBuffer* output, ZSTD_inBuffer* input)
{
    const char* const istart = (const char*)(input->src) + input->pos;
    const char* const iend = (const char*)(input->src) + input->size;
    const char* ip = istart;
    char* const ostart = (char*)(output->dst) + output->pos;
    char* const oend = (char*)(output->dst) + output->size;
    char* op = ostart;
    U32 someMoreWork = 1;

#if defined(ZSTD_LEGACY_SUPPORT) && (ZSTD_LEGACY_SUPPORT>=1)
    if (zds->legacyVersion)
        return ZSTD_decompressLegacyStream(zds->legacyContext, zds->legacyVersion, output, input);
#endif

    while (someMoreWork) {
        switch(zds->stage)
        {
        case zdss_init :
            ZSTD_resetDStream(zds);   /* transparent reset on starting decoding a new frame */
            /* fall-through */

        case zdss_loadHeader :
            {   size_t const hSize = ZSTD_getFrameParams(&zds->fParams, zds->headerBuffer, zds->lhSize);
                if (ZSTD_isError(hSize))
#if defined(ZSTD_LEGACY_SUPPORT) && (ZSTD_LEGACY_SUPPORT>=1)
                {   U32 const legacyVersion = ZSTD_isLegacy(istart, iend-istart);
                    if (legacyVersion) {
                        const void* const dict = zds->ddict ? zds->ddict->dictContent : NULL;
                        size_t const dictSize = zds->ddict ? zds->ddict->dictSize : 0;
                        CHECK_F(ZSTD_initLegacyStream(&zds->legacyContext, zds->previousLegacyVersion, legacyVersion,
                                                       dict, dictSize));
                        zds->legacyVersion = zds->previousLegacyVersion = legacyVersion;
                        return ZSTD_decompressLegacyStream(zds->legacyContext, zds->legacyVersion, output, input);
                    } else {
                        return hSize; /* error */
                }   }
#else
                return hSize;
#endif
                if (hSize != 0) {   /* need more input */
                    size_t const toLoad = hSize - zds->lhSize;   /* if hSize!=0, hSize > zds->lhSize */
                    if (toLoad > (size_t)(iend-ip)) {   /* not enough input to load full header */
                        memcpy(zds->headerBuffer + zds->lhSize, ip, iend-ip);
                        zds->lhSize += iend-ip;
                        input->pos = input->size;
                        return (MAX(ZSTD_frameHeaderSize_min, hSize) - zds->lhSize) + ZSTD_blockHeaderSize;   /* remaining header bytes + next block header */
                    }
                    memcpy(zds->headerBuffer + zds->lhSize, ip, toLoad); zds->lhSize = hSize; ip += toLoad;
                    break;
            }   }

            /* Consume header */
            {   const ZSTD_DCtx* refContext = zds->ddict ? zds->ddict->refContext : NULL;
                ZSTD_refDCtx(zds->dctx, refContext);
            }
            {   size_t const h1Size = ZSTD_nextSrcSizeToDecompress(zds->dctx);  /* == ZSTD_frameHeaderSize_prefix */
                CHECK_F(ZSTD_decompressContinue(zds->dctx, NULL, 0, zds->headerBuffer, h1Size));
                {   size_t const h2Size = ZSTD_nextSrcSizeToDecompress(zds->dctx);
                    CHECK_F(ZSTD_decompressContinue(zds->dctx, NULL, 0, zds->headerBuffer+h1Size, h2Size));
            }   }

            zds->fParams.windowSize = MAX(zds->fParams.windowSize, 1U << ZSTD_WINDOWLOG_ABSOLUTEMIN);
            if (zds->fParams.windowSize > zds->maxWindowSize) return ERROR(frameParameter_windowTooLarge);

            /* Adapt buffer sizes to frame header instructions */
            {   size_t const blockSize = MIN(zds->fParams.windowSize, ZSTD_BLOCKSIZE_ABSOLUTEMAX);
                size_t const neededOutSize = zds->fParams.windowSize + blockSize;
                zds->blockSize = blockSize;
                if (zds->inBuffSize < blockSize) {
                    ZSTD_free(zds->inBuff, zds->customMem);
                    zds->inBuffSize = blockSize;
                    zds->inBuff = (char*)ZSTD_malloc(blockSize, zds->customMem);
                    if (zds->inBuff == NULL) return ERROR(memory_allocation);
                }
                if (zds->outBuffSize < neededOutSize) {
                    ZSTD_free(zds->outBuff, zds->customMem);
                    zds->outBuffSize = neededOutSize;
                    zds->outBuff = (char*)ZSTD_malloc(neededOutSize, zds->customMem);
                    if (zds->outBuff == NULL) return ERROR(memory_allocation);
            }   }
            zds->stage = zdss_read;
            /* pass-through */

        case zdss_read:
            {   size_t const neededInSize = ZSTD_nextSrcSizeToDecompress(zds->dctx);
                if (neededInSize==0) {  /* end of frame */
                    zds->stage = zdss_init;
                    someMoreWork = 0;
                    break;
                }
                if ((size_t)(iend-ip) >= neededInSize) {  /* decode directly from src */
                    const int isSkipFrame = ZSTD_isSkipFrame(zds->dctx);
                    size_t const decodedSize = ZSTD_decompressContinue(zds->dctx,
                        zds->outBuff + zds->outStart, (isSkipFrame ? 0 : zds->outBuffSize - zds->outStart),
                        ip, neededInSize);
                    if (ZSTD_isError(decodedSize)) return decodedSize;
                    ip += neededInSize;
                    if (!decodedSize && !isSkipFrame) break;   /* this was just a header */
                    zds->outEnd = zds->outStart + decodedSize;
                    zds->stage = zdss_flush;
                    break;
                }
                if (ip==iend) { someMoreWork = 0; break; }   /* no more input */
                zds->stage = zdss_load;
                /* pass-through */
            }

        case zdss_load:
            {   size_t const neededInSize = ZSTD_nextSrcSizeToDecompress(zds->dctx);
                size_t const toLoad = neededInSize - zds->inPos;   /* should always be <= remaining space within inBuff */
                size_t loadedSize;
                if (toLoad > zds->inBuffSize - zds->inPos) return ERROR(corruption_detected);   /* should never happen */
                loadedSize = ZSTD_limitCopy(zds->inBuff + zds->inPos, toLoad, ip, iend-ip);
                ip += loadedSize;
                zds->inPos += loadedSize;
                if (loadedSize < toLoad) { someMoreWork = 0; break; }   /* not enough input, wait for more */

                /* decode loaded input */
                {  const int isSkipFrame = ZSTD_isSkipFrame(zds->dctx);
                   size_t const decodedSize = ZSTD_decompressContinue(zds->dctx,
                        zds->outBuff + zds->outStart, zds->outBuffSize - zds->outStart,
                        zds->inBuff, neededInSize);
                    if (ZSTD_isError(decodedSize)) return decodedSize;
                    zds->inPos = 0;   /* input is consumed */
                    if (!decodedSize && !isSkipFrame) { zds->stage = zdss_read; break; }   /* this was just a header */
                    zds->outEnd = zds->outStart +  decodedSize;
                    zds->stage = zdss_flush;
                    /* pass-through */
            }   }

        case zdss_flush:
            {   size_t const toFlushSize = zds->outEnd - zds->outStart;
                size_t const flushedSize = ZSTD_limitCopy(op, oend-op, zds->outBuff + zds->outStart, toFlushSize);
                op += flushedSize;
                zds->outStart += flushedSize;
                if (flushedSize == toFlushSize) {  /* flush completed */
                    zds->stage = zdss_read;
                    if (zds->outStart + zds->blockSize > zds->outBuffSize)
                        zds->outStart = zds->outEnd = 0;
                    break;
                }
                /* cannot complete flush */
                someMoreWork = 0;
                break;
            }
        default: return ERROR(GENERIC);   /* impossible */
    }   }

    /* result */
    input->pos += (size_t)(ip-istart);
    output->pos += (size_t)(op-ostart);
    {   size_t nextSrcSizeHint = ZSTD_nextSrcSizeToDecompress(zds->dctx);
        if (!nextSrcSizeHint) {   /* frame fully decoded */
            if (zds->outEnd == zds->outStart) {  /* output fully flushed */
                if (zds->hostageByte) {
                    if (input->pos >= input->size) { zds->stage = zdss_read; return 1; }  /* can't release hostage (not present) */
                    input->pos++;  /* release hostage */
                }
                return 0;
            }
            if (!zds->hostageByte) { /* output not fully flushed; keep last byte as hostage; will be released when all output is flushed */
                input->pos--;   /* note : pos > 0, otherwise, impossible to finish reading last block */
                zds->hostageByte=1;
            }
            return 1;
        }
        nextSrcSizeHint += ZSTD_blockHeaderSize * (ZSTD_nextInputType(zds->dctx) == ZSTDnit_block);   /* preload header of next block */
        if (zds->inPos > nextSrcSizeHint) return ERROR(GENERIC);   /* should never happen */
        nextSrcSizeHint -= zds->inPos;   /* already loaded*/
        return nextSrcSizeHint;
    }
}