annotate contrib/python-zstandard/zstd/compress/zstd_compress.c @ 30434:2e484bdea8c4

zstd: vendor zstd 1.1.1

zstd is a new compression format and it is awesome, yielding
higher compression ratios and significantly faster compression
and decompression operations compared to zlib (our current
compression engine of choice) across the board.

We want zstd to be a 1st class citizen in Mercurial and to eventually
be the preferred compression format for various operations.

This patch starts the formal process of supporting zstd by vendoring
a copy of zstd. Why do we need to vendor zstd? Good question.

First, zstd is relatively new and not widely available yet. If we
didn't vendor zstd or distribute it with Mercurial, most users likely
wouldn't have zstd installed or even available to install. What good
is a feature if you can't use it? Vendoring and distributing the zstd
sources gives us the highest liklihood that zstd will be available to
Mercurial installs.

Second, the Python bindings to zstd (which will be vendored in a
separate changeset) make use of zstd APIs that are only available
via static linking. One reason they are only available via static
linking is that they are unstable and could change at any time.
While it might be possible for the Python bindings to attempt to
talk to different versions of the zstd C library, the safest thing to
do is link against a specific, known-working version of zstd. This
is why the Python zstd bindings themselves vendor zstd and why we
must as well. This also explains why the added files are in a
"python-zstandard" directory.

The added files are from the 1.1.1 release of zstd (Git commit
4c0b44f8ced84c4c8edfa07b564d31e4fa3e8885 from
https://github.com/facebook/zstd) and are added without modifications.
Not all files from the zstd "distribution" have been added. Notably
missing are files to support interacting with "legacy," pre-1.0
versions of zstd. The decision of which files to include is made by
the upstream python-zstandard project (which I'm the author of). The
files in this commit are a snapshot of the files from the 0.5.0
release of that project, Git commit
e637c1b214d5f869cf8116c550dcae23ec13b677 from
https://github.com/indygreg/python-zstandard.

/**
 * 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.
 */


/*-*************************************
*  Dependencies
***************************************/
#include <string.h>         /* memset */
#include "mem.h"
#define XXH_STATIC_LINKING_ONLY   /* XXH64_state_t */
#include "xxhash.h"               /* XXH_reset, update, digest */
#define FSE_STATIC_LINKING_ONLY   /* FSE_encodeSymbol */
#include "fse.h"
#define HUF_STATIC_LINKING_ONLY
#include "huf.h"
#include "zstd_internal.h"  /* includes zstd.h */


/*-*************************************
*  Constants
***************************************/
static const U32 g_searchStrength = 8;   /* control skip over incompressible data */
#define HASH_READ_SIZE 8
typedef enum { ZSTDcs_created=0, ZSTDcs_init, ZSTDcs_ongoing, ZSTDcs_ending } ZSTD_compressionStage_e;


/*-*************************************
*  Helper functions
***************************************/
size_t ZSTD_compressBound(size_t srcSize) { return FSE_compressBound(srcSize) + 12; }


/*-*************************************
*  Sequence storage
***************************************/
static void ZSTD_resetSeqStore(seqStore_t* ssPtr)
{
    ssPtr->lit = ssPtr->litStart;
    ssPtr->sequences = ssPtr->sequencesStart;
    ssPtr->longLengthID = 0;
}


/*-*************************************
*  Context memory management
***************************************/
struct ZSTD_CCtx_s
{
    const BYTE* nextSrc;    /* next block here to continue on current prefix */
    const BYTE* base;       /* All regular indexes relative to this position */
    const BYTE* dictBase;   /* extDict indexes relative to this position */
    U32   dictLimit;        /* below that point, need extDict */
    U32   lowLimit;         /* below that point, no more data */
    U32   nextToUpdate;     /* index from which to continue dictionary update */
    U32   nextToUpdate3;    /* index from which to continue dictionary update */
    U32   hashLog3;         /* dispatch table : larger == faster, more memory */
    U32   loadedDictEnd;
    ZSTD_compressionStage_e stage;
    U32   rep[ZSTD_REP_NUM];
    U32   savedRep[ZSTD_REP_NUM];
    U32   dictID;
    ZSTD_parameters params;
    void* workSpace;
    size_t workSpaceSize;
    size_t blockSize;
    U64 frameContentSize;
    XXH64_state_t xxhState;
    ZSTD_customMem customMem;

    seqStore_t seqStore;    /* sequences storage ptrs */
    U32* hashTable;
    U32* hashTable3;
    U32* chainTable;
    HUF_CElt* hufTable;
    U32 flagStaticTables;
    FSE_CTable offcodeCTable  [FSE_CTABLE_SIZE_U32(OffFSELog, MaxOff)];
    FSE_CTable matchlengthCTable[FSE_CTABLE_SIZE_U32(MLFSELog, MaxML)];
    FSE_CTable litlengthCTable  [FSE_CTABLE_SIZE_U32(LLFSELog, MaxLL)];
};

ZSTD_CCtx* ZSTD_createCCtx(void)
{
    return ZSTD_createCCtx_advanced(defaultCustomMem);
}

ZSTD_CCtx* ZSTD_createCCtx_advanced(ZSTD_customMem customMem)
{
    ZSTD_CCtx* cctx;

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

    cctx = (ZSTD_CCtx*) ZSTD_malloc(sizeof(ZSTD_CCtx), customMem);
    if (!cctx) return NULL;
    memset(cctx, 0, sizeof(ZSTD_CCtx));
    memcpy(&(cctx->customMem), &customMem, sizeof(customMem));
    return cctx;
}

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

size_t ZSTD_sizeof_CCtx(const ZSTD_CCtx* cctx)
{
    if (cctx==NULL) return 0;   /* support sizeof on NULL */
    return sizeof(*cctx) + cctx->workSpaceSize;
}

const seqStore_t* ZSTD_getSeqStore(const ZSTD_CCtx* ctx)   /* hidden interface */
{
    return &(ctx->seqStore);
}

static ZSTD_parameters ZSTD_getParamsFromCCtx(const ZSTD_CCtx* cctx)
{
    return cctx->params;
}


/** ZSTD_checkParams() :
    ensure param values remain within authorized range.
    @return : 0, or an error code if one value is beyond authorized range */
size_t ZSTD_checkCParams(ZSTD_compressionParameters cParams)
{
#   define CLAMPCHECK(val,min,max) { if ((val<min) | (val>max)) return ERROR(compressionParameter_unsupported); }
    CLAMPCHECK(cParams.windowLog, ZSTD_WINDOWLOG_MIN, ZSTD_WINDOWLOG_MAX);
    CLAMPCHECK(cParams.chainLog, ZSTD_CHAINLOG_MIN, ZSTD_CHAINLOG_MAX);
    CLAMPCHECK(cParams.hashLog, ZSTD_HASHLOG_MIN, ZSTD_HASHLOG_MAX);
    CLAMPCHECK(cParams.searchLog, ZSTD_SEARCHLOG_MIN, ZSTD_SEARCHLOG_MAX);
    { U32 const searchLengthMin = ((cParams.strategy == ZSTD_fast) | (cParams.strategy == ZSTD_greedy)) ? ZSTD_SEARCHLENGTH_MIN+1 : ZSTD_SEARCHLENGTH_MIN;
      U32 const searchLengthMax = (cParams.strategy == ZSTD_fast) ? ZSTD_SEARCHLENGTH_MAX : ZSTD_SEARCHLENGTH_MAX-1;
      CLAMPCHECK(cParams.searchLength, searchLengthMin, searchLengthMax); }
    CLAMPCHECK(cParams.targetLength, ZSTD_TARGETLENGTH_MIN, ZSTD_TARGETLENGTH_MAX);
    if ((U32)(cParams.strategy) > (U32)ZSTD_btopt2) return ERROR(compressionParameter_unsupported);
    return 0;
}


/** ZSTD_adjustCParams() :
    optimize `cPar` for a given input (`srcSize` and `dictSize`).
    mostly downsizing to reduce memory consumption and initialization.
    Both `srcSize` and `dictSize` are optional (use 0 if unknown),
    but if both are 0, no optimization can be done.
    Note : cPar is considered validated at this stage. Use ZSTD_checkParams() to ensure that. */
ZSTD_compressionParameters ZSTD_adjustCParams(ZSTD_compressionParameters cPar, unsigned long long srcSize, size_t dictSize)
{
    if (srcSize+dictSize == 0) return cPar;   /* no size information available : no adjustment */

    /* resize params, to use less memory when necessary */
    {   U32 const minSrcSize = (srcSize==0) ? 500 : 0;
        U64 const rSize = srcSize + dictSize + minSrcSize;
        if (rSize < ((U64)1<<ZSTD_WINDOWLOG_MAX)) {
            U32 const srcLog = MAX(ZSTD_HASHLOG_MIN, ZSTD_highbit32((U32)(rSize)-1) + 1);
            if (cPar.windowLog > srcLog) cPar.windowLog = srcLog;
    }   }
    if (cPar.hashLog > cPar.windowLog) cPar.hashLog = cPar.windowLog;
    {   U32 const btPlus = (cPar.strategy == ZSTD_btlazy2) | (cPar.strategy == ZSTD_btopt) | (cPar.strategy == ZSTD_btopt2);
        U32 const maxChainLog = cPar.windowLog+btPlus;
        if (cPar.chainLog > maxChainLog) cPar.chainLog = maxChainLog; }   /* <= ZSTD_CHAINLOG_MAX */

    if (cPar.windowLog < ZSTD_WINDOWLOG_ABSOLUTEMIN) cPar.windowLog = ZSTD_WINDOWLOG_ABSOLUTEMIN;  /* required for frame header */

    return cPar;
}


size_t ZSTD_estimateCCtxSize(ZSTD_compressionParameters cParams)
{
    size_t const blockSize = MIN(ZSTD_BLOCKSIZE_ABSOLUTEMAX, (size_t)1 << cParams.windowLog);
    U32    const divider = (cParams.searchLength==3) ? 3 : 4;
    size_t const maxNbSeq = blockSize / divider;
    size_t const tokenSpace = blockSize + 11*maxNbSeq;

    size_t const chainSize = (cParams.strategy == ZSTD_fast) ? 0 : (1 << cParams.chainLog);
    size_t const hSize = ((size_t)1) << cParams.hashLog;
    U32    const hashLog3 = (cParams.searchLength>3) ? 0 : MIN(ZSTD_HASHLOG3_MAX, cParams.windowLog);
    size_t const h3Size = ((size_t)1) << hashLog3;
    size_t const tableSpace = (chainSize + hSize + h3Size) * sizeof(U32);

    size_t const optSpace = ((MaxML+1) + (MaxLL+1) + (MaxOff+1) + (1<<Litbits))*sizeof(U32)
                          + (ZSTD_OPT_NUM+1)*(sizeof(ZSTD_match_t) + sizeof(ZSTD_optimal_t));
    size_t const neededSpace = tableSpace + (256*sizeof(U32)) /* huffTable */ + tokenSpace
                             + (((cParams.strategy == ZSTD_btopt) || (cParams.strategy == ZSTD_btopt2)) ? optSpace : 0);

    return sizeof(ZSTD_CCtx) + neededSpace;
}


static U32 ZSTD_equivalentParams(ZSTD_parameters param1, ZSTD_parameters param2)
{
    return (param1.cParams.hashLog  == param2.cParams.hashLog)
         & (param1.cParams.chainLog == param2.cParams.chainLog)
         & (param1.cParams.strategy == param2.cParams.strategy)
         & ((param1.cParams.searchLength==3) == (param2.cParams.searchLength==3));
}

/*! ZSTD_continueCCtx() :
    reuse CCtx without reset (note : requires no dictionary) */
static size_t ZSTD_continueCCtx(ZSTD_CCtx* cctx, ZSTD_parameters params, U64 frameContentSize)
{
    U32 const end = (U32)(cctx->nextSrc - cctx->base);
    cctx->params = params;
    cctx->frameContentSize = frameContentSize;
    cctx->lowLimit = end;
    cctx->dictLimit = end;
    cctx->nextToUpdate = end+1;
    cctx->stage = ZSTDcs_init;
    cctx->dictID = 0;
    cctx->loadedDictEnd = 0;
    { int i; for (i=0; i<ZSTD_REP_NUM; i++) cctx->rep[i] = repStartValue[i]; }
    cctx->seqStore.litLengthSum = 0;  /* force reset of btopt stats */
    XXH64_reset(&cctx->xxhState, 0);
    return 0;
}

typedef enum { ZSTDcrp_continue, ZSTDcrp_noMemset, ZSTDcrp_fullReset } ZSTD_compResetPolicy_e;

/*! ZSTD_resetCCtx_advanced() :
    note : 'params' must be validated */
static size_t ZSTD_resetCCtx_advanced (ZSTD_CCtx* zc,
                                       ZSTD_parameters params, U64 frameContentSize,
                                       ZSTD_compResetPolicy_e const crp)
{
    if (crp == ZSTDcrp_continue)
        if (ZSTD_equivalentParams(params, zc->params))
            return ZSTD_continueCCtx(zc, params, frameContentSize);

    {   size_t const blockSize = MIN(ZSTD_BLOCKSIZE_ABSOLUTEMAX, (size_t)1 << params.cParams.windowLog);
        U32    const divider = (params.cParams.searchLength==3) ? 3 : 4;
        size_t const maxNbSeq = blockSize / divider;
        size_t const tokenSpace = blockSize + 11*maxNbSeq;
        size_t const chainSize = (params.cParams.strategy == ZSTD_fast) ? 0 : (1 << params.cParams.chainLog);
        size_t const hSize = ((size_t)1) << params.cParams.hashLog;
        U32    const hashLog3 = (params.cParams.searchLength>3) ? 0 : MIN(ZSTD_HASHLOG3_MAX, params.cParams.windowLog);
        size_t const h3Size = ((size_t)1) << hashLog3;
        size_t const tableSpace = (chainSize + hSize + h3Size) * sizeof(U32);
        void* ptr;

        /* Check if workSpace is large enough, alloc a new one if needed */
        {   size_t const optSpace = ((MaxML+1) + (MaxLL+1) + (MaxOff+1) + (1<<Litbits))*sizeof(U32)
                                  + (ZSTD_OPT_NUM+1)*(sizeof(ZSTD_match_t) + sizeof(ZSTD_optimal_t));
            size_t const neededSpace = tableSpace + (256*sizeof(U32)) /* huffTable */ + tokenSpace
                                  + (((params.cParams.strategy == ZSTD_btopt) || (params.cParams.strategy == ZSTD_btopt2)) ? optSpace : 0);
            if (zc->workSpaceSize < neededSpace) {
                ZSTD_free(zc->workSpace, zc->customMem);
                zc->workSpace = ZSTD_malloc(neededSpace, zc->customMem);
                if (zc->workSpace == NULL) return ERROR(memory_allocation);
                zc->workSpaceSize = neededSpace;
        }   }

        if (crp!=ZSTDcrp_noMemset) memset(zc->workSpace, 0, tableSpace);   /* reset tables only */
        XXH64_reset(&zc->xxhState, 0);
        zc->hashLog3 = hashLog3;
        zc->hashTable = (U32*)(zc->workSpace);
        zc->chainTable = zc->hashTable + hSize;
        zc->hashTable3 = zc->chainTable + chainSize;
        ptr = zc->hashTable3 + h3Size;
        zc->hufTable = (HUF_CElt*)ptr;
        zc->flagStaticTables = 0;
        ptr = ((U32*)ptr) + 256;  /* note : HUF_CElt* is incomplete type, size is simulated using U32 */

        zc->nextToUpdate = 1;
        zc->nextSrc = NULL;
        zc->base = NULL;
        zc->dictBase = NULL;
        zc->dictLimit = 0;
        zc->lowLimit = 0;
        zc->params = params;
        zc->blockSize = blockSize;
        zc->frameContentSize = frameContentSize;
        { int i; for (i=0; i<ZSTD_REP_NUM; i++) zc->rep[i] = repStartValue[i]; }

        if ((params.cParams.strategy == ZSTD_btopt) || (params.cParams.strategy == ZSTD_btopt2)) {
            zc->seqStore.litFreq = (U32*)ptr;
            zc->seqStore.litLengthFreq = zc->seqStore.litFreq + (1<<Litbits);
            zc->seqStore.matchLengthFreq = zc->seqStore.litLengthFreq + (MaxLL+1);
            zc->seqStore.offCodeFreq = zc->seqStore.matchLengthFreq + (MaxML+1);
            ptr = zc->seqStore.offCodeFreq + (MaxOff+1);
            zc->seqStore.matchTable = (ZSTD_match_t*)ptr;
            ptr = zc->seqStore.matchTable + ZSTD_OPT_NUM+1;
            zc->seqStore.priceTable = (ZSTD_optimal_t*)ptr;
            ptr = zc->seqStore.priceTable + ZSTD_OPT_NUM+1;
            zc->seqStore.litLengthSum = 0;
        }
        zc->seqStore.sequencesStart = (seqDef*)ptr;
        ptr = zc->seqStore.sequencesStart + maxNbSeq;
        zc->seqStore.llCode = (BYTE*) ptr;
        zc->seqStore.mlCode = zc->seqStore.llCode + maxNbSeq;
        zc->seqStore.ofCode = zc->seqStore.mlCode + maxNbSeq;
        zc->seqStore.litStart = zc->seqStore.ofCode + maxNbSeq;

        zc->stage = ZSTDcs_init;
        zc->dictID = 0;
        zc->loadedDictEnd = 0;

        return 0;
    }
}


/*! ZSTD_copyCCtx() :
*   Duplicate an existing context `srcCCtx` into another one `dstCCtx`.
*   Only works during stage ZSTDcs_init (i.e. after creation, but before first call to ZSTD_compressContinue()).
*   @return : 0, or an error code */
size_t ZSTD_copyCCtx(ZSTD_CCtx* dstCCtx, const ZSTD_CCtx* srcCCtx, unsigned long long pledgedSrcSize)
{
    if (srcCCtx->stage!=ZSTDcs_init) return ERROR(stage_wrong);

    memcpy(&dstCCtx->customMem, &srcCCtx->customMem, sizeof(ZSTD_customMem));
    ZSTD_resetCCtx_advanced(dstCCtx, srcCCtx->params, pledgedSrcSize, ZSTDcrp_noMemset);

    /* copy tables */
    {   size_t const chainSize = (srcCCtx->params.cParams.strategy == ZSTD_fast) ? 0 : (1 << srcCCtx->params.cParams.chainLog);
        size_t const hSize = ((size_t)1) << srcCCtx->params.cParams.hashLog;
        size_t const h3Size = (size_t)1 << srcCCtx->hashLog3;
        size_t const tableSpace = (chainSize + hSize + h3Size) * sizeof(U32);
        memcpy(dstCCtx->workSpace, srcCCtx->workSpace, tableSpace);
    }

    /* copy dictionary offsets */
    dstCCtx->nextToUpdate = srcCCtx->nextToUpdate;
    dstCCtx->nextToUpdate3= srcCCtx->nextToUpdate3;
    dstCCtx->nextSrc      = srcCCtx->nextSrc;
    dstCCtx->base         = srcCCtx->base;
    dstCCtx->dictBase     = srcCCtx->dictBase;
    dstCCtx->dictLimit    = srcCCtx->dictLimit;
    dstCCtx->lowLimit     = srcCCtx->lowLimit;
    dstCCtx->loadedDictEnd= srcCCtx->loadedDictEnd;
    dstCCtx->dictID       = srcCCtx->dictID;

    /* copy entropy tables */
    dstCCtx->flagStaticTables = srcCCtx->flagStaticTables;
    if (srcCCtx->flagStaticTables) {
        memcpy(dstCCtx->hufTable, srcCCtx->hufTable, 256*4);
        memcpy(dstCCtx->litlengthCTable, srcCCtx->litlengthCTable, sizeof(dstCCtx->litlengthCTable));
        memcpy(dstCCtx->matchlengthCTable, srcCCtx->matchlengthCTable, sizeof(dstCCtx->matchlengthCTable));
        memcpy(dstCCtx->offcodeCTable, srcCCtx->offcodeCTable, sizeof(dstCCtx->offcodeCTable));
    }

    return 0;
}


/*! ZSTD_reduceTable() :
*   reduce table indexes by `reducerValue` */
static void ZSTD_reduceTable (U32* const table, U32 const size, U32 const reducerValue)
{
    U32 u;
    for (u=0 ; u < size ; u++) {
        if (table[u] < reducerValue) table[u] = 0;
        else table[u] -= reducerValue;
    }
}

/*! ZSTD_reduceIndex() :
*   rescale all indexes to avoid future overflow (indexes are U32) */
static void ZSTD_reduceIndex (ZSTD_CCtx* zc, const U32 reducerValue)
{
    { U32 const hSize = 1 << zc->params.cParams.hashLog;
      ZSTD_reduceTable(zc->hashTable, hSize, reducerValue); }

    { U32 const chainSize = (zc->params.cParams.strategy == ZSTD_fast) ? 0 : (1 << zc->params.cParams.chainLog);
      ZSTD_reduceTable(zc->chainTable, chainSize, reducerValue); }

    { U32 const h3Size = (zc->hashLog3) ? 1 << zc->hashLog3 : 0;
      ZSTD_reduceTable(zc->hashTable3, h3Size, reducerValue); }
}


/*-*******************************************************
*  Block entropic compression
*********************************************************/

/* See doc/zstd_compression_format.md for detailed format description */

size_t ZSTD_noCompressBlock (void* dst, size_t dstCapacity, const void* src, size_t srcSize)
{
    if (srcSize + ZSTD_blockHeaderSize > dstCapacity) return ERROR(dstSize_tooSmall);
    memcpy((BYTE*)dst + ZSTD_blockHeaderSize, src, srcSize);
    MEM_writeLE24(dst, (U32)(srcSize << 2) + (U32)bt_raw);
    return ZSTD_blockHeaderSize+srcSize;
}


static size_t ZSTD_noCompressLiterals (void* dst, size_t dstCapacity, const void* src, size_t srcSize)
{
    BYTE* const ostart = (BYTE* const)dst;
    U32   const flSize = 1 + (srcSize>31) + (srcSize>4095);

    if (srcSize + flSize > dstCapacity) return ERROR(dstSize_tooSmall);

    switch(flSize)
    {
        case 1: /* 2 - 1 - 5 */
            ostart[0] = (BYTE)((U32)set_basic + (srcSize<<3));
            break;
        case 2: /* 2 - 2 - 12 */
            MEM_writeLE16(ostart, (U16)((U32)set_basic + (1<<2) + (srcSize<<4)));
            break;
        default:   /*note : should not be necessary : flSize is within {1,2,3} */
        case 3: /* 2 - 2 - 20 */
            MEM_writeLE32(ostart, (U32)((U32)set_basic + (3<<2) + (srcSize<<4)));
            break;
    }

    memcpy(ostart + flSize, src, srcSize);
    return srcSize + flSize;
}

static size_t ZSTD_compressRleLiteralsBlock (void* dst, size_t dstCapacity, const void* src, size_t srcSize)
{
    BYTE* const ostart = (BYTE* const)dst;
    U32   const flSize = 1 + (srcSize>31) + (srcSize>4095);

    (void)dstCapacity;  /* dstCapacity already guaranteed to be >=4, hence large enough */

    switch(flSize)
    {
        case 1: /* 2 - 1 - 5 */
            ostart[0] = (BYTE)((U32)set_rle + (srcSize<<3));
            break;
        case 2: /* 2 - 2 - 12 */
            MEM_writeLE16(ostart, (U16)((U32)set_rle + (1<<2) + (srcSize<<4)));
            break;
        default:   /*note : should not be necessary : flSize is necessarily within {1,2,3} */
        case 3: /* 2 - 2 - 20 */
            MEM_writeLE32(ostart, (U32)((U32)set_rle + (3<<2) + (srcSize<<4)));
            break;
    }

    ostart[flSize] = *(const BYTE*)src;
    return flSize+1;
}


static size_t ZSTD_minGain(size_t srcSize) { return (srcSize >> 6) + 2; }

static size_t ZSTD_compressLiterals (ZSTD_CCtx* zc,
                                     void* dst, size_t dstCapacity,
                               const void* src, size_t srcSize)
{
    size_t const minGain = ZSTD_minGain(srcSize);
    size_t const lhSize = 3 + (srcSize >= 1 KB) + (srcSize >= 16 KB);
    BYTE*  const ostart = (BYTE*)dst;
    U32 singleStream = srcSize < 256;
    symbolEncodingType_e hType = set_compressed;
    size_t cLitSize;


    /* small ? don't even attempt compression (speed opt) */
#   define LITERAL_NOENTROPY 63
    {   size_t const minLitSize = zc->flagStaticTables ? 6 : LITERAL_NOENTROPY;
        if (srcSize <= minLitSize) return ZSTD_noCompressLiterals(dst, dstCapacity, src, srcSize);
    }

    if (dstCapacity < lhSize+1) return ERROR(dstSize_tooSmall);   /* not enough space for compression */
    if (zc->flagStaticTables && (lhSize==3)) {
        hType = set_repeat;
        singleStream = 1;
        cLitSize = HUF_compress1X_usingCTable(ostart+lhSize, dstCapacity-lhSize, src, srcSize, zc->hufTable);
    } else {
        cLitSize = singleStream ? HUF_compress1X(ostart+lhSize, dstCapacity-lhSize, src, srcSize, 255, 11)
                                : HUF_compress2 (ostart+lhSize, dstCapacity-lhSize, src, srcSize, 255, 11);
    }

    if ((cLitSize==0) | (cLitSize >= srcSize - minGain))
        return ZSTD_noCompressLiterals(dst, dstCapacity, src, srcSize);
    if (cLitSize==1)
        return ZSTD_compressRleLiteralsBlock(dst, dstCapacity, src, srcSize);

    /* Build header */
    switch(lhSize)
    {
    case 3: /* 2 - 2 - 10 - 10 */
        {   U32 const lhc = hType + ((!singleStream) << 2) + ((U32)srcSize<<4) + ((U32)cLitSize<<14);
            MEM_writeLE24(ostart, lhc);
            break;
        }
    case 4: /* 2 - 2 - 14 - 14 */
        {   U32 const lhc = hType + (2 << 2) + ((U32)srcSize<<4) + ((U32)cLitSize<<18);
            MEM_writeLE32(ostart, lhc);
            break;
        }
    default:   /* should not be necessary, lhSize is only {3,4,5} */
    case 5: /* 2 - 2 - 18 - 18 */
        {   U32 const lhc = hType + (3 << 2) + ((U32)srcSize<<4) + ((U32)cLitSize<<22);
            MEM_writeLE32(ostart, lhc);
            ostart[4] = (BYTE)(cLitSize >> 10);
            break;
        }
    }
    return lhSize+cLitSize;
}

static const BYTE LL_Code[64] = {  0,  1,  2,  3,  4,  5,  6,  7,
                                   8,  9, 10, 11, 12, 13, 14, 15,
                                  16, 16, 17, 17, 18, 18, 19, 19,
                                  20, 20, 20, 20, 21, 21, 21, 21,
                                  22, 22, 22, 22, 22, 22, 22, 22,
                                  23, 23, 23, 23, 23, 23, 23, 23,
                                  24, 24, 24, 24, 24, 24, 24, 24,
                                  24, 24, 24, 24, 24, 24, 24, 24 };

static const BYTE ML_Code[128] = { 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,
                                  32, 32, 33, 33, 34, 34, 35, 35, 36, 36, 36, 36, 37, 37, 37, 37,
                                  38, 38, 38, 38, 38, 38, 38, 38, 39, 39, 39, 39, 39, 39, 39, 39,
                                  40, 40, 40, 40, 40, 40, 40, 40, 40, 40, 40, 40, 40, 40, 40, 40,
                                  41, 41, 41, 41, 41, 41, 41, 41, 41, 41, 41, 41, 41, 41, 41, 41,
                                  42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42,
                                  42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42 };


void ZSTD_seqToCodes(const seqStore_t* seqStorePtr)
{
    BYTE const LL_deltaCode = 19;
    BYTE const ML_deltaCode = 36;
    const seqDef* const sequences = seqStorePtr->sequencesStart;
    BYTE* const llCodeTable = seqStorePtr->llCode;
    BYTE* const ofCodeTable = seqStorePtr->ofCode;
    BYTE* const mlCodeTable = seqStorePtr->mlCode;
    U32 const nbSeq = (U32)(seqStorePtr->sequences - seqStorePtr->sequencesStart);
    U32 u;
    for (u=0; u<nbSeq; u++) {
        U32 const llv = sequences[u].litLength;
        U32 const mlv = sequences[u].matchLength;
        llCodeTable[u] = (llv> 63) ? (BYTE)ZSTD_highbit32(llv) + LL_deltaCode : LL_Code[llv];
        ofCodeTable[u] = (BYTE)ZSTD_highbit32(sequences[u].offset);
        mlCodeTable[u] = (mlv>127) ? (BYTE)ZSTD_highbit32(mlv) + ML_deltaCode : ML_Code[mlv];
    }
    if (seqStorePtr->longLengthID==1)
        llCodeTable[seqStorePtr->longLengthPos] = MaxLL;
    if (seqStorePtr->longLengthID==2)
        mlCodeTable[seqStorePtr->longLengthPos] = MaxML;
}


size_t ZSTD_compressSequences(ZSTD_CCtx* zc,
                              void* dst, size_t dstCapacity,
                              size_t srcSize)
{
    const seqStore_t* seqStorePtr = &(zc->seqStore);
    U32 count[MaxSeq+1];
    S16 norm[MaxSeq+1];
    FSE_CTable* CTable_LitLength = zc->litlengthCTable;
    FSE_CTable* CTable_OffsetBits = zc->offcodeCTable;
    FSE_CTable* CTable_MatchLength = zc->matchlengthCTable;
    U32 LLtype, Offtype, MLtype;   /* compressed, raw or rle */
    const seqDef* const sequences = seqStorePtr->sequencesStart;
    const BYTE* const ofCodeTable = seqStorePtr->ofCode;
    const BYTE* const llCodeTable = seqStorePtr->llCode;
    const BYTE* const mlCodeTable = seqStorePtr->mlCode;
    BYTE* const ostart = (BYTE*)dst;
    BYTE* const oend = ostart + dstCapacity;
    BYTE* op = ostart;
    size_t const nbSeq = seqStorePtr->sequences - seqStorePtr->sequencesStart;
    BYTE* seqHead;

    /* Compress literals */
    {   const BYTE* const literals = seqStorePtr->litStart;
        size_t const litSize = seqStorePtr->lit - literals;
        size_t const cSize = ZSTD_compressLiterals(zc, op, dstCapacity, literals, litSize);
        if (ZSTD_isError(cSize)) return cSize;
        op += cSize;
    }

    /* Sequences Header */
    if ((oend-op) < 3 /*max nbSeq Size*/ + 1 /*seqHead */) return ERROR(dstSize_tooSmall);
    if (nbSeq < 0x7F) *op++ = (BYTE)nbSeq;
    else if (nbSeq < LONGNBSEQ) op[0] = (BYTE)((nbSeq>>8) + 0x80), op[1] = (BYTE)nbSeq, op+=2;
    else op[0]=0xFF, MEM_writeLE16(op+1, (U16)(nbSeq - LONGNBSEQ)), op+=3;
    if (nbSeq==0) goto _check_compressibility;

    /* seqHead : flags for FSE encoding type */
    seqHead = op++;

#define MIN_SEQ_FOR_DYNAMIC_FSE   64
#define MAX_SEQ_FOR_STATIC_FSE  1000

    /* convert length/distances into codes */
    ZSTD_seqToCodes(seqStorePtr);

    /* CTable for Literal Lengths */
    {   U32 max = MaxLL;
        size_t const mostFrequent = FSE_countFast(count, &max, llCodeTable, nbSeq);
        if ((mostFrequent == nbSeq) && (nbSeq > 2)) {
            *op++ = llCodeTable[0];
            FSE_buildCTable_rle(CTable_LitLength, (BYTE)max);
            LLtype = set_rle;
        } else if ((zc->flagStaticTables) && (nbSeq < MAX_SEQ_FOR_STATIC_FSE)) {
            LLtype = set_repeat;
        } else if ((nbSeq < MIN_SEQ_FOR_DYNAMIC_FSE) || (mostFrequent < (nbSeq >> (LL_defaultNormLog-1)))) {
            FSE_buildCTable(CTable_LitLength, LL_defaultNorm, MaxLL, LL_defaultNormLog);
            LLtype = set_basic;
        } else {
            size_t nbSeq_1 = nbSeq;
            const U32 tableLog = FSE_optimalTableLog(LLFSELog, nbSeq, max);
            if (count[llCodeTable[nbSeq-1]]>1) { count[llCodeTable[nbSeq-1]]--; nbSeq_1--; }
            FSE_normalizeCount(norm, tableLog, count, nbSeq_1, max);
            { size_t const NCountSize = FSE_writeNCount(op, oend-op, norm, max, tableLog);   /* overflow protected */
              if (FSE_isError(NCountSize)) return ERROR(GENERIC);
              op += NCountSize; }
            FSE_buildCTable(CTable_LitLength, norm, max, tableLog);
            LLtype = set_compressed;
    }   }

    /* CTable for Offsets */
    {   U32 max = MaxOff;
        size_t const mostFrequent = FSE_countFast(count, &max, ofCodeTable, nbSeq);
        if ((mostFrequent == nbSeq) && (nbSeq > 2)) {
            *op++ = ofCodeTable[0];
            FSE_buildCTable_rle(CTable_OffsetBits, (BYTE)max);
            Offtype = set_rle;
        } else if ((zc->flagStaticTables) && (nbSeq < MAX_SEQ_FOR_STATIC_FSE)) {
            Offtype = set_repeat;
        } else if ((nbSeq < MIN_SEQ_FOR_DYNAMIC_FSE) || (mostFrequent < (nbSeq >> (OF_defaultNormLog-1)))) {
            FSE_buildCTable(CTable_OffsetBits, OF_defaultNorm, MaxOff, OF_defaultNormLog);
            Offtype = set_basic;
        } else {
            size_t nbSeq_1 = nbSeq;
            const U32 tableLog = FSE_optimalTableLog(OffFSELog, nbSeq, max);
            if (count[ofCodeTable[nbSeq-1]]>1) { count[ofCodeTable[nbSeq-1]]--; nbSeq_1--; }
            FSE_normalizeCount(norm, tableLog, count, nbSeq_1, max);
            { size_t const NCountSize = FSE_writeNCount(op, oend-op, norm, max, tableLog);   /* overflow protected */
              if (FSE_isError(NCountSize)) return ERROR(GENERIC);
              op += NCountSize; }
            FSE_buildCTable(CTable_OffsetBits, norm, max, tableLog);
            Offtype = set_compressed;
    }   }

    /* CTable for MatchLengths */
    {   U32 max = MaxML;
        size_t const mostFrequent = FSE_countFast(count, &max, mlCodeTable, nbSeq);
        if ((mostFrequent == nbSeq) && (nbSeq > 2)) {
            *op++ = *mlCodeTable;
            FSE_buildCTable_rle(CTable_MatchLength, (BYTE)max);
            MLtype = set_rle;
        } else if ((zc->flagStaticTables) && (nbSeq < MAX_SEQ_FOR_STATIC_FSE)) {
            MLtype = set_repeat;
        } else if ((nbSeq < MIN_SEQ_FOR_DYNAMIC_FSE) || (mostFrequent < (nbSeq >> (ML_defaultNormLog-1)))) {
            FSE_buildCTable(CTable_MatchLength, ML_defaultNorm, MaxML, ML_defaultNormLog);
            MLtype = set_basic;
        } else {
            size_t nbSeq_1 = nbSeq;
            const U32 tableLog = FSE_optimalTableLog(MLFSELog, nbSeq, max);
            if (count[mlCodeTable[nbSeq-1]]>1) { count[mlCodeTable[nbSeq-1]]--; nbSeq_1--; }
            FSE_normalizeCount(norm, tableLog, count, nbSeq_1, max);
            { size_t const NCountSize = FSE_writeNCount(op, oend-op, norm, max, tableLog);   /* overflow protected */
              if (FSE_isError(NCountSize)) return ERROR(GENERIC);
              op += NCountSize; }
            FSE_buildCTable(CTable_MatchLength, norm, max, tableLog);
            MLtype = set_compressed;
    }   }

    *seqHead = (BYTE)((LLtype<<6) + (Offtype<<4) + (MLtype<<2));
    zc->flagStaticTables = 0;

    /* Encoding Sequences */
    {   BIT_CStream_t blockStream;
        FSE_CState_t  stateMatchLength;
        FSE_CState_t  stateOffsetBits;
        FSE_CState_t  stateLitLength;

        CHECK_E(BIT_initCStream(&blockStream, op, oend-op), dstSize_tooSmall); /* not enough space remaining */

        /* first symbols */
        FSE_initCState2(&stateMatchLength, CTable_MatchLength, mlCodeTable[nbSeq-1]);
        FSE_initCState2(&stateOffsetBits,  CTable_OffsetBits,  ofCodeTable[nbSeq-1]);
        FSE_initCState2(&stateLitLength,   CTable_LitLength,   llCodeTable[nbSeq-1]);
        BIT_addBits(&blockStream, sequences[nbSeq-1].litLength, LL_bits[llCodeTable[nbSeq-1]]);
        if (MEM_32bits()) BIT_flushBits(&blockStream);
        BIT_addBits(&blockStream, sequences[nbSeq-1].matchLength, ML_bits[mlCodeTable[nbSeq-1]]);
        if (MEM_32bits()) BIT_flushBits(&blockStream);
        BIT_addBits(&blockStream, sequences[nbSeq-1].offset, ofCodeTable[nbSeq-1]);
        BIT_flushBits(&blockStream);

        {   size_t n;
            for (n=nbSeq-2 ; n<nbSeq ; n--) {      /* intentional underflow */
                BYTE const llCode = llCodeTable[n];
                BYTE const ofCode = ofCodeTable[n];
                BYTE const mlCode = mlCodeTable[n];
                U32  const llBits = LL_bits[llCode];
                U32  const ofBits = ofCode;                                     /* 32b*/  /* 64b*/
                U32  const mlBits = ML_bits[mlCode];
                                                                                /* (7)*/  /* (7)*/
                FSE_encodeSymbol(&blockStream, &stateOffsetBits, ofCode);       /* 15 */  /* 15 */
                FSE_encodeSymbol(&blockStream, &stateMatchLength, mlCode);      /* 24 */  /* 24 */
                if (MEM_32bits()) BIT_flushBits(&blockStream);                  /* (7)*/
                FSE_encodeSymbol(&blockStream, &stateLitLength, llCode);        /* 16 */  /* 33 */
                if (MEM_32bits() || (ofBits+mlBits+llBits >= 64-7-(LLFSELog+MLFSELog+OffFSELog)))
                    BIT_flushBits(&blockStream);                                /* (7)*/
                BIT_addBits(&blockStream, sequences[n].litLength, llBits);
                if (MEM_32bits() && ((llBits+mlBits)>24)) BIT_flushBits(&blockStream);
                BIT_addBits(&blockStream, sequences[n].matchLength, mlBits);
                if (MEM_32bits()) BIT_flushBits(&blockStream);                  /* (7)*/
                BIT_addBits(&blockStream, sequences[n].offset, ofBits);         /* 31 */
                BIT_flushBits(&blockStream);                                    /* (7)*/
        }   }

        FSE_flushCState(&blockStream, &stateMatchLength);
        FSE_flushCState(&blockStream, &stateOffsetBits);
        FSE_flushCState(&blockStream, &stateLitLength);

        {   size_t const streamSize = BIT_closeCStream(&blockStream);
            if (streamSize==0) return ERROR(dstSize_tooSmall);   /* not enough space */
            op += streamSize;
    }   }

    /* check compressibility */
_check_compressibility:
    { size_t const minGain = ZSTD_minGain(srcSize);
      size_t const maxCSize = srcSize - minGain;
      if ((size_t)(op-ostart) >= maxCSize) return 0; }

    /* confirm repcodes */
    { int i; for (i=0; i<ZSTD_REP_NUM; i++) zc->rep[i] = zc->savedRep[i]; }

    return op - ostart;
}


/*! ZSTD_storeSeq() :
    Store a sequence (literal length, literals, offset code and match length code) into seqStore_t.
    `offsetCode` : distance to match, or 0 == repCode.
    `matchCode` : matchLength - MINMATCH
*/
MEM_STATIC void ZSTD_storeSeq(seqStore_t* seqStorePtr, size_t litLength, const void* literals, U32 offsetCode, size_t matchCode)
{
#if 0  /* for debug */
    static const BYTE* g_start = NULL;
    const U32 pos = (U32)(literals - g_start);
    if (g_start==NULL) g_start = literals;
    //if ((pos > 1) && (pos < 50000))
        printf("Cpos %6u :%5u literals & match %3u bytes at distance %6u \n",
               pos, (U32)litLength, (U32)matchCode+MINMATCH, (U32)offsetCode);
#endif
    /* copy Literals */
    ZSTD_wildcopy(seqStorePtr->lit, literals, litLength);
    seqStorePtr->lit += litLength;

    /* literal Length */
    if (litLength>0xFFFF) { seqStorePtr->longLengthID = 1; seqStorePtr->longLengthPos = (U32)(seqStorePtr->sequences - seqStorePtr->sequencesStart); }
    seqStorePtr->sequences[0].litLength = (U16)litLength;

    /* match offset */
    seqStorePtr->sequences[0].offset = offsetCode + 1;

    /* match Length */
    if (matchCode>0xFFFF) { seqStorePtr->longLengthID = 2; seqStorePtr->longLengthPos = (U32)(seqStorePtr->sequences - seqStorePtr->sequencesStart); }
    seqStorePtr->sequences[0].matchLength = (U16)matchCode;

    seqStorePtr->sequences++;
}


/*-*************************************
*  Match length counter
***************************************/
static unsigned ZSTD_NbCommonBytes (register size_t val)
{
    if (MEM_isLittleEndian()) {
        if (MEM_64bits()) {
#       if defined(_MSC_VER) && defined(_WIN64)
            unsigned long r = 0;
            _BitScanForward64( &r, (U64)val );
            return (unsigned)(r>>3);
#       elif defined(__GNUC__) && (__GNUC__ >= 3)
            return (__builtin_ctzll((U64)val) >> 3);
#       else
            static const int DeBruijnBytePos[64] = { 0, 0, 0, 0, 0, 1, 1, 2, 0, 3, 1, 3, 1, 4, 2, 7, 0, 2, 3, 6, 1, 5, 3, 5, 1, 3, 4, 4, 2, 5, 6, 7, 7, 0, 1, 2, 3, 3, 4, 6, 2, 6, 5, 5, 3, 4, 5, 6, 7, 1, 2, 4, 6, 4, 4, 5, 7, 2, 6, 5, 7, 6, 7, 7 };
            return DeBruijnBytePos[((U64)((val & -(long long)val) * 0x0218A392CDABBD3FULL)) >> 58];
#       endif
        } else { /* 32 bits */
#       if defined(_MSC_VER)
            unsigned long r=0;
            _BitScanForward( &r, (U32)val );
            return (unsigned)(r>>3);
#       elif defined(__GNUC__) && (__GNUC__ >= 3)
            return (__builtin_ctz((U32)val) >> 3);
#       else
            static const int DeBruijnBytePos[32] = { 0, 0, 3, 0, 3, 1, 3, 0, 3, 2, 2, 1, 3, 2, 0, 1, 3, 3, 1, 2, 2, 2, 2, 0, 3, 1, 2, 0, 1, 0, 1, 1 };
            return DeBruijnBytePos[((U32)((val & -(S32)val) * 0x077CB531U)) >> 27];
#       endif
        }
    } else {  /* Big Endian CPU */
        if (MEM_64bits()) {
#       if defined(_MSC_VER) && defined(_WIN64)
            unsigned long r = 0;
            _BitScanReverse64( &r, val );
            return (unsigned)(r>>3);
#       elif defined(__GNUC__) && (__GNUC__ >= 3)
            return (__builtin_clzll(val) >> 3);
#       else
            unsigned r;
            const unsigned n32 = sizeof(size_t)*4;   /* calculate this way due to compiler complaining in 32-bits mode */
            if (!(val>>n32)) { r=4; } else { r=0; val>>=n32; }
            if (!(val>>16)) { r+=2; val>>=8; } else { val>>=24; }
            r += (!val);
            return r;
#       endif
        } else { /* 32 bits */
#       if defined(_MSC_VER)
            unsigned long r = 0;
            _BitScanReverse( &r, (unsigned long)val );
            return (unsigned)(r>>3);
#       elif defined(__GNUC__) && (__GNUC__ >= 3)
            return (__builtin_clz((U32)val) >> 3);
#       else
            unsigned r;
            if (!(val>>16)) { r=2; val>>=8; } else { r=0; val>>=24; }
            r += (!val);
            return r;
#       endif
    }   }
}


static size_t ZSTD_count(const BYTE* pIn, const BYTE* pMatch, const BYTE* const pInLimit)
{
    const BYTE* const pStart = pIn;
    const BYTE* const pInLoopLimit = pInLimit - (sizeof(size_t)-1);

    while (pIn < pInLoopLimit) {
        size_t const diff = MEM_readST(pMatch) ^ MEM_readST(pIn);
        if (!diff) { pIn+=sizeof(size_t); pMatch+=sizeof(size_t); continue; }
        pIn += ZSTD_NbCommonBytes(diff);
        return (size_t)(pIn - pStart);
    }
    if (MEM_64bits()) if ((pIn<(pInLimit-3)) && (MEM_read32(pMatch) == MEM_read32(pIn))) { pIn+=4; pMatch+=4; }
    if ((pIn<(pInLimit-1)) && (MEM_read16(pMatch) == MEM_read16(pIn))) { pIn+=2; pMatch+=2; }
    if ((pIn<pInLimit) && (*pMatch == *pIn)) pIn++;
    return (size_t)(pIn - pStart);
}

/** ZSTD_count_2segments() :
*   can count match length with `ip` & `match` in 2 different segments.
*   convention : on reaching mEnd, match count continue starting from iStart
*/
static size_t ZSTD_count_2segments(const BYTE* ip, const BYTE* match, const BYTE* iEnd, const BYTE* mEnd, const BYTE* iStart)
{
    const BYTE* const vEnd = MIN( ip + (mEnd - match), iEnd);
    size_t const matchLength = ZSTD_count(ip, match, vEnd);
    if (match + matchLength != mEnd) return matchLength;
    return matchLength + ZSTD_count(ip+matchLength, iStart, iEnd);
}


/*-*************************************
*  Hashes
***************************************/
static const U32 prime3bytes = 506832829U;
static U32    ZSTD_hash3(U32 u, U32 h) { return ((u << (32-24)) * prime3bytes)  >> (32-h) ; }
MEM_STATIC size_t ZSTD_hash3Ptr(const void* ptr, U32 h) { return ZSTD_hash3(MEM_readLE32(ptr), h); }   /* only in zstd_opt.h */

static const U32 prime4bytes = 2654435761U;
static U32    ZSTD_hash4(U32 u, U32 h) { return (u * prime4bytes) >> (32-h) ; }
static size_t ZSTD_hash4Ptr(const void* ptr, U32 h) { return ZSTD_hash4(MEM_read32(ptr), h); }

static const U64 prime5bytes = 889523592379ULL;
static size_t ZSTD_hash5(U64 u, U32 h) { return (size_t)(((u  << (64-40)) * prime5bytes) >> (64-h)) ; }
static size_t ZSTD_hash5Ptr(const void* p, U32 h) { return ZSTD_hash5(MEM_readLE64(p), h); }

static const U64 prime6bytes = 227718039650203ULL;
static size_t ZSTD_hash6(U64 u, U32 h) { return (size_t)(((u  << (64-48)) * prime6bytes) >> (64-h)) ; }
static size_t ZSTD_hash6Ptr(const void* p, U32 h) { return ZSTD_hash6(MEM_readLE64(p), h); }

static const U64 prime7bytes = 58295818150454627ULL;
static size_t ZSTD_hash7(U64 u, U32 h) { return (size_t)(((u  << (64-56)) * prime7bytes) >> (64-h)) ; }
static size_t ZSTD_hash7Ptr(const void* p, U32 h) { return ZSTD_hash7(MEM_readLE64(p), h); }

static const U64 prime8bytes = 0xCF1BBCDCB7A56463ULL;
static size_t ZSTD_hash8(U64 u, U32 h) { return (size_t)(((u) * prime8bytes) >> (64-h)) ; }
static size_t ZSTD_hash8Ptr(const void* p, U32 h) { return ZSTD_hash8(MEM_readLE64(p), h); }

static size_t ZSTD_hashPtr(const void* p, U32 hBits, U32 mls)
{
    switch(mls)
    {
    default:
    case 4: return ZSTD_hash4Ptr(p, hBits);
    case 5: return ZSTD_hash5Ptr(p, hBits);
    case 6: return ZSTD_hash6Ptr(p, hBits);
    case 7: return ZSTD_hash7Ptr(p, hBits);
    case 8: return ZSTD_hash8Ptr(p, hBits);
    }
}


/*-*************************************
*  Fast Scan
***************************************/
static void ZSTD_fillHashTable (ZSTD_CCtx* zc, const void* end, const U32 mls)
{
    U32* const hashTable = zc->hashTable;
    U32  const hBits = zc->params.cParams.hashLog;
    const BYTE* const base = zc->base;
    const BYTE* ip = base + zc->nextToUpdate;
    const BYTE* const iend = ((const BYTE*)end) - HASH_READ_SIZE;
    const size_t fastHashFillStep = 3;

    while(ip <= iend) {
        hashTable[ZSTD_hashPtr(ip, hBits, mls)] = (U32)(ip - base);
        ip += fastHashFillStep;
    }
}


FORCE_INLINE
void ZSTD_compressBlock_fast_generic(ZSTD_CCtx* cctx,
                               const void* src, size_t srcSize,
                               const U32 mls)
{
    U32* const hashTable = cctx->hashTable;
    U32  const hBits = cctx->params.cParams.hashLog;
    seqStore_t* seqStorePtr = &(cctx->seqStore);
    const BYTE* const base = cctx->base;
    const BYTE* const istart = (const BYTE*)src;
    const BYTE* ip = istart;
    const BYTE* anchor = istart;
    const U32   lowestIndex = cctx->dictLimit;
    const BYTE* const lowest = base + lowestIndex;
    const BYTE* const iend = istart + srcSize;
    const BYTE* const ilimit = iend - HASH_READ_SIZE;
    U32 offset_1=cctx->rep[0], offset_2=cctx->rep[1];
    U32 offsetSaved = 0;

    /* init */
    ip += (ip==lowest);
    {   U32 const maxRep = (U32)(ip-lowest);
        if (offset_2 > maxRep) offsetSaved = offset_2, offset_2 = 0;
        if (offset_1 > maxRep) offsetSaved = offset_1, offset_1 = 0;
    }

    /* Main Search Loop */
    while (ip < ilimit) {   /* < instead of <=, because repcode check at (ip+1) */
        size_t mLength;
        size_t const h = ZSTD_hashPtr(ip, hBits, mls);
        U32 const current = (U32)(ip-base);
        U32 const matchIndex = hashTable[h];
        const BYTE* match = base + matchIndex;
        hashTable[h] = current;   /* update hash table */

        if ((offset_1 > 0) & (MEM_read32(ip+1-offset_1) == MEM_read32(ip+1))) {
            mLength = ZSTD_count(ip+1+4, ip+1+4-offset_1, iend) + 4;
            ip++;
            ZSTD_storeSeq(seqStorePtr, ip-anchor, anchor, 0, mLength-MINMATCH);
        } else {
            U32 offset;
            if ( (matchIndex <= lowestIndex) || (MEM_read32(match) != MEM_read32(ip)) ) {
                ip += ((ip-anchor) >> g_searchStrength) + 1;
                continue;
            }
            mLength = ZSTD_count(ip+4, match+4, iend) + 4;
            offset = (U32)(ip-match);
            while (((ip>anchor) & (match>lowest)) && (ip[-1] == match[-1])) { ip--; match--; mLength++; } /* catch up */
            offset_2 = offset_1;
            offset_1 = offset;

            ZSTD_storeSeq(seqStorePtr, ip-anchor, anchor, offset + ZSTD_REP_MOVE, mLength-MINMATCH);
        }

        /* match found */
        ip += mLength;
        anchor = ip;

        if (ip <= ilimit) {
            /* Fill Table */
            hashTable[ZSTD_hashPtr(base+current+2, hBits, mls)] = current+2;  /* here because current+2 could be > iend-8 */
            hashTable[ZSTD_hashPtr(ip-2, hBits, mls)] = (U32)(ip-2-base);
            /* check immediate repcode */
            while ( (ip <= ilimit)
                 && ( (offset_2>0)
                 & (MEM_read32(ip) == MEM_read32(ip - offset_2)) )) {
                /* store sequence */
                size_t const rLength = ZSTD_count(ip+4, ip+4-offset_2, iend) + 4;
                { U32 const tmpOff = offset_2; offset_2 = offset_1; offset_1 = tmpOff; }  /* swap offset_2 <=> offset_1 */
                hashTable[ZSTD_hashPtr(ip, hBits, mls)] = (U32)(ip-base);
                ZSTD_storeSeq(seqStorePtr, 0, anchor, 0, rLength-MINMATCH);
                ip += rLength;
                anchor = ip;
                continue;   /* faster when present ... (?) */
    }   }   }

    /* save reps for next block */
    cctx->savedRep[0] = offset_1 ? offset_1 : offsetSaved;
    cctx->savedRep[1] = offset_2 ? offset_2 : offsetSaved;

    /* Last Literals */
    {   size_t const lastLLSize = iend - anchor;
        memcpy(seqStorePtr->lit, anchor, lastLLSize);
        seqStorePtr->lit += lastLLSize;
    }
}


static void ZSTD_compressBlock_fast(ZSTD_CCtx* ctx,
                       const void* src, size_t srcSize)
{
    const U32 mls = ctx->params.cParams.searchLength;
    switch(mls)
    {
    default:
    case 4 :
        ZSTD_compressBlock_fast_generic(ctx, src, srcSize, 4); return;
    case 5 :
        ZSTD_compressBlock_fast_generic(ctx, src, srcSize, 5); return;
    case 6 :
        ZSTD_compressBlock_fast_generic(ctx, src, srcSize, 6); return;
    case 7 :
        ZSTD_compressBlock_fast_generic(ctx, src, srcSize, 7); return;
    }
}


static void ZSTD_compressBlock_fast_extDict_generic(ZSTD_CCtx* ctx,
                                 const void* src, size_t srcSize,
                                 const U32 mls)
{
    U32* hashTable = ctx->hashTable;
    const U32 hBits = ctx->params.cParams.hashLog;
    seqStore_t* seqStorePtr = &(ctx->seqStore);
    const BYTE* const base = ctx->base;
    const BYTE* const dictBase = ctx->dictBase;
    const BYTE* const istart = (const BYTE*)src;
    const BYTE* ip = istart;
    const BYTE* anchor = istart;
    const U32   lowestIndex = ctx->lowLimit;
    const BYTE* const dictStart = dictBase + lowestIndex;
    const U32   dictLimit = ctx->dictLimit;
    const BYTE* const lowPrefixPtr = base + dictLimit;
    const BYTE* const dictEnd = dictBase + dictLimit;
    const BYTE* const iend = istart + srcSize;
    const BYTE* const ilimit = iend - 8;
    U32 offset_1=ctx->rep[0], offset_2=ctx->rep[1];

    /* Search Loop */
    while (ip < ilimit) {  /* < instead of <=, because (ip+1) */
        const size_t h = ZSTD_hashPtr(ip, hBits, mls);
        const U32 matchIndex = hashTable[h];
        const BYTE* matchBase = matchIndex < dictLimit ? dictBase : base;
        const BYTE* match = matchBase + matchIndex;
        const U32 current = (U32)(ip-base);
        const U32 repIndex = current + 1 - offset_1;   /* offset_1 expected <= current +1 */
        const BYTE* repBase = repIndex < dictLimit ? dictBase : base;
        const BYTE* repMatch = repBase + repIndex;
        size_t mLength;
        hashTable[h] = current;   /* update hash table */

        if ( (((U32)((dictLimit-1) - repIndex) >= 3) /* intentional underflow */ & (repIndex > lowestIndex))
           && (MEM_read32(repMatch) == MEM_read32(ip+1)) ) {
            const BYTE* repMatchEnd = repIndex < dictLimit ? dictEnd : iend;
            mLength = ZSTD_count_2segments(ip+1+EQUAL_READ32, repMatch+EQUAL_READ32, iend, repMatchEnd, lowPrefixPtr) + EQUAL_READ32;
            ip++;
            ZSTD_storeSeq(seqStorePtr, ip-anchor, anchor, 0, mLength-MINMATCH);
        } else {
            if ( (matchIndex < lowestIndex) ||
                 (MEM_read32(match) != MEM_read32(ip)) ) {
                ip += ((ip-anchor) >> g_searchStrength) + 1;
                continue;
            }
            {   const BYTE* matchEnd = matchIndex < dictLimit ? dictEnd : iend;
                const BYTE* lowMatchPtr = matchIndex < dictLimit ? dictStart : lowPrefixPtr;
                U32 offset;
                mLength = ZSTD_count_2segments(ip+EQUAL_READ32, match+EQUAL_READ32, iend, matchEnd, lowPrefixPtr) + EQUAL_READ32;
                while (((ip>anchor) & (match>lowMatchPtr)) && (ip[-1] == match[-1])) { ip--; match--; mLength++; }   /* catch up */
                offset = current - matchIndex;
                offset_2 = offset_1;
                offset_1 = offset;
                ZSTD_storeSeq(seqStorePtr, ip-anchor, anchor, offset + ZSTD_REP_MOVE, mLength-MINMATCH);
        }   }

        /* found a match : store it */
        ip += mLength;
        anchor = ip;

        if (ip <= ilimit) {
            /* Fill Table */
            hashTable[ZSTD_hashPtr(base+current+2, hBits, mls)] = current+2;
            hashTable[ZSTD_hashPtr(ip-2, hBits, mls)] = (U32)(ip-2-base);
            /* check immediate repcode */
            while (ip <= ilimit) {
                U32 const current2 = (U32)(ip-base);
                U32 const repIndex2 = current2 - offset_2;
                const BYTE* repMatch2 = repIndex2 < dictLimit ? dictBase + repIndex2 : base + repIndex2;
                if ( (((U32)((dictLimit-1) - repIndex2) >= 3) & (repIndex2 > lowestIndex))  /* intentional overflow */
                   && (MEM_read32(repMatch2) == MEM_read32(ip)) ) {
                    const BYTE* const repEnd2 = repIndex2 < dictLimit ? dictEnd : iend;
                    size_t repLength2 = ZSTD_count_2segments(ip+EQUAL_READ32, repMatch2+EQUAL_READ32, iend, repEnd2, lowPrefixPtr) + EQUAL_READ32;
                    U32 tmpOffset = offset_2; offset_2 = offset_1; offset_1 = tmpOffset;   /* swap offset_2 <=> offset_1 */
                    ZSTD_storeSeq(seqStorePtr, 0, anchor, 0, repLength2-MINMATCH);
                    hashTable[ZSTD_hashPtr(ip, hBits, mls)] = current2;
                    ip += repLength2;
                    anchor = ip;
                    continue;
                }
                break;
    }   }   }

    /* save reps for next block */
    ctx->savedRep[0] = offset_1; ctx->savedRep[1] = offset_2;

    /* Last Literals */
    {   size_t const lastLLSize = iend - anchor;
        memcpy(seqStorePtr->lit, anchor, lastLLSize);
        seqStorePtr->lit += lastLLSize;
    }
}


static void ZSTD_compressBlock_fast_extDict(ZSTD_CCtx* ctx,
                         const void* src, size_t srcSize)
{
    U32 const mls = ctx->params.cParams.searchLength;
    switch(mls)
    {
    default:
    case 4 :
        ZSTD_compressBlock_fast_extDict_generic(ctx, src, srcSize, 4); return;
    case 5 :
        ZSTD_compressBlock_fast_extDict_generic(ctx, src, srcSize, 5); return;
    case 6 :
        ZSTD_compressBlock_fast_extDict_generic(ctx, src, srcSize, 6); return;
    case 7 :
        ZSTD_compressBlock_fast_extDict_generic(ctx, src, srcSize, 7); return;
    }
}


/*-*************************************
*  Double Fast
***************************************/
static void ZSTD_fillDoubleHashTable (ZSTD_CCtx* cctx, const void* end, const U32 mls)
{
    U32* const hashLarge = cctx->hashTable;
    U32  const hBitsL = cctx->params.cParams.hashLog;
    U32* const hashSmall = cctx->chainTable;
    U32  const hBitsS = cctx->params.cParams.chainLog;
    const BYTE* const base = cctx->base;
    const BYTE* ip = base + cctx->nextToUpdate;
    const BYTE* const iend = ((const BYTE*)end) - HASH_READ_SIZE;
    const size_t fastHashFillStep = 3;

    while(ip <= iend) {
        hashSmall[ZSTD_hashPtr(ip, hBitsS, mls)] = (U32)(ip - base);
        hashLarge[ZSTD_hashPtr(ip, hBitsL, 8)] = (U32)(ip - base);
        ip += fastHashFillStep;
    }
}


FORCE_INLINE
void ZSTD_compressBlock_doubleFast_generic(ZSTD_CCtx* cctx,
                                 const void* src, size_t srcSize,
                                 const U32 mls)
{
    U32* const hashLong = cctx->hashTable;
    const U32 hBitsL = cctx->params.cParams.hashLog;
    U32* const hashSmall = cctx->chainTable;
    const U32 hBitsS = cctx->params.cParams.chainLog;
    seqStore_t* seqStorePtr = &(cctx->seqStore);
    const BYTE* const base = cctx->base;
    const BYTE* const istart = (const BYTE*)src;
    const BYTE* ip = istart;
    const BYTE* anchor = istart;
    const U32 lowestIndex = cctx->dictLimit;
    const BYTE* const lowest = base + lowestIndex;
    const BYTE* const iend = istart + srcSize;
    const BYTE* const ilimit = iend - HASH_READ_SIZE;
    U32 offset_1=cctx->rep[0], offset_2=cctx->rep[1];
    U32 offsetSaved = 0;

    /* init */
    ip += (ip==lowest);
    {   U32 const maxRep = (U32)(ip-lowest);
        if (offset_2 > maxRep) offsetSaved = offset_2, offset_2 = 0;
        if (offset_1 > maxRep) offsetSaved = offset_1, offset_1 = 0;
    }

    /* Main Search Loop */
    while (ip < ilimit) {   /* < instead of <=, because repcode check at (ip+1) */
        size_t mLength;
        size_t const h2 = ZSTD_hashPtr(ip, hBitsL, 8);
        size_t const h = ZSTD_hashPtr(ip, hBitsS, mls);
        U32 const current = (U32)(ip-base);
        U32 const matchIndexL = hashLong[h2];
        U32 const matchIndexS = hashSmall[h];
        const BYTE* matchLong = base + matchIndexL;
        const BYTE* match = base + matchIndexS;
        hashLong[h2] = hashSmall[h] = current;   /* update hash tables */

        if ((offset_1 > 0) & (MEM_read32(ip+1-offset_1) == MEM_read32(ip+1))) { /* note : by construction, offset_1 <= current */
            mLength = ZSTD_count(ip+1+4, ip+1+4-offset_1, iend) + 4;
            ip++;
            ZSTD_storeSeq(seqStorePtr, ip-anchor, anchor, 0, mLength-MINMATCH);
        } else {
            U32 offset;
            if ( (matchIndexL > lowestIndex) && (MEM_read64(matchLong) == MEM_read64(ip)) ) {
                mLength = ZSTD_count(ip+8, matchLong+8, iend) + 8;
                offset = (U32)(ip-matchLong);
                while (((ip>anchor) & (matchLong>lowest)) && (ip[-1] == matchLong[-1])) { ip--; matchLong--; mLength++; } /* catch up */
            } else if ( (matchIndexS > lowestIndex) && (MEM_read32(match) == MEM_read32(ip)) ) {
                size_t const h3 = ZSTD_hashPtr(ip+1, hBitsL, 8);
                U32 const matchIndex3 = hashLong[h3];
                const BYTE* match3 = base + matchIndex3;
                hashLong[h3] = current + 1;
                if ( (matchIndex3 > lowestIndex) && (MEM_read64(match3) == MEM_read64(ip+1)) ) {
                    mLength = ZSTD_count(ip+9, match3+8, iend) + 8;
                    ip++;
                    offset = (U32)(ip-match3);
                    while (((ip>anchor) & (match3>lowest)) && (ip[-1] == match3[-1])) { ip--; match3--; mLength++; } /* catch up */
                } else {
                    mLength = ZSTD_count(ip+4, match+4, iend) + 4;
                    offset = (U32)(ip-match);
                    while (((ip>anchor) & (match>lowest)) && (ip[-1] == match[-1])) { ip--; match--; mLength++; } /* catch up */
                }
            } else {
                ip += ((ip-anchor) >> g_searchStrength) + 1;
                continue;
            }

            offset_2 = offset_1;
            offset_1 = offset;

            ZSTD_storeSeq(seqStorePtr, ip-anchor, anchor, offset + ZSTD_REP_MOVE, mLength-MINMATCH);
        }

        /* match found */
        ip += mLength;
        anchor = ip;

        if (ip <= ilimit) {
            /* Fill Table */
            hashLong[ZSTD_hashPtr(base+current+2, hBitsL, 8)] =
                hashSmall[ZSTD_hashPtr(base+current+2, hBitsS, mls)] = current+2;  /* here because current+2 could be > iend-8 */
            hashLong[ZSTD_hashPtr(ip-2, hBitsL, 8)] =
                hashSmall[ZSTD_hashPtr(ip-2, hBitsS, mls)] = (U32)(ip-2-base);

            /* check immediate repcode */
            while ( (ip <= ilimit)
                 && ( (offset_2>0)
                 & (MEM_read32(ip) == MEM_read32(ip - offset_2)) )) {
                /* store sequence */
                size_t const rLength = ZSTD_count(ip+4, ip+4-offset_2, iend) + 4;
                { U32 const tmpOff = offset_2; offset_2 = offset_1; offset_1 = tmpOff; } /* swap offset_2 <=> offset_1 */
                hashSmall[ZSTD_hashPtr(ip, hBitsS, mls)] = (U32)(ip-base);
                hashLong[ZSTD_hashPtr(ip, hBitsL, 8)] = (U32)(ip-base);
                ZSTD_storeSeq(seqStorePtr, 0, anchor, 0, rLength-MINMATCH);
                ip += rLength;
                anchor = ip;
                continue;   /* faster when present ... (?) */
    }   }   }

    /* save reps for next block */
    cctx->savedRep[0] = offset_1 ? offset_1 : offsetSaved;
    cctx->savedRep[1] = offset_2 ? offset_2 : offsetSaved;

    /* Last Literals */
    {   size_t const lastLLSize = iend - anchor;
        memcpy(seqStorePtr->lit, anchor, lastLLSize);
        seqStorePtr->lit += lastLLSize;
    }
}


static void ZSTD_compressBlock_doubleFast(ZSTD_CCtx* ctx, const void* src, size_t srcSize)
{
    const U32 mls = ctx->params.cParams.searchLength;
    switch(mls)
    {
    default:
    case 4 :
        ZSTD_compressBlock_doubleFast_generic(ctx, src, srcSize, 4); return;
    case 5 :
        ZSTD_compressBlock_doubleFast_generic(ctx, src, srcSize, 5); return;
    case 6 :
        ZSTD_compressBlock_doubleFast_generic(ctx, src, srcSize, 6); return;
    case 7 :
        ZSTD_compressBlock_doubleFast_generic(ctx, src, srcSize, 7); return;
    }
}


static void ZSTD_compressBlock_doubleFast_extDict_generic(ZSTD_CCtx* ctx,
                                 const void* src, size_t srcSize,
                                 const U32 mls)
{
    U32* const hashLong = ctx->hashTable;
    U32  const hBitsL = ctx->params.cParams.hashLog;
    U32* const hashSmall = ctx->chainTable;
    U32  const hBitsS = ctx->params.cParams.chainLog;
    seqStore_t* seqStorePtr = &(ctx->seqStore);
    const BYTE* const base = ctx->base;
    const BYTE* const dictBase = ctx->dictBase;
    const BYTE* const istart = (const BYTE*)src;
    const BYTE* ip = istart;
    const BYTE* anchor = istart;
    const U32   lowestIndex = ctx->lowLimit;
    const BYTE* const dictStart = dictBase + lowestIndex;
    const U32   dictLimit = ctx->dictLimit;
    const BYTE* const lowPrefixPtr = base + dictLimit;
    const BYTE* const dictEnd = dictBase + dictLimit;
    const BYTE* const iend = istart + srcSize;
    const BYTE* const ilimit = iend - 8;
    U32 offset_1=ctx->rep[0], offset_2=ctx->rep[1];

    /* Search Loop */
    while (ip < ilimit) {  /* < instead of <=, because (ip+1) */
        const size_t hSmall = ZSTD_hashPtr(ip, hBitsS, mls);
        const U32 matchIndex = hashSmall[hSmall];
        const BYTE* matchBase = matchIndex < dictLimit ? dictBase : base;
        const BYTE* match = matchBase + matchIndex;

        const size_t hLong = ZSTD_hashPtr(ip, hBitsL, 8);
        const U32 matchLongIndex = hashLong[hLong];
        const BYTE* matchLongBase = matchLongIndex < dictLimit ? dictBase : base;
        const BYTE* matchLong = matchLongBase + matchLongIndex;

        const U32 current = (U32)(ip-base);
        const U32 repIndex = current + 1 - offset_1;   /* offset_1 expected <= current +1 */
        const BYTE* repBase = repIndex < dictLimit ? dictBase : base;
        const BYTE* repMatch = repBase + repIndex;
        size_t mLength;
        hashSmall[hSmall] = hashLong[hLong] = current;   /* update hash table */

        if ( (((U32)((dictLimit-1) - repIndex) >= 3) /* intentional underflow */ & (repIndex > lowestIndex))
           && (MEM_read32(repMatch) == MEM_read32(ip+1)) ) {
            const BYTE* repMatchEnd = repIndex < dictLimit ? dictEnd : iend;
            mLength = ZSTD_count_2segments(ip+1+4, repMatch+4, iend, repMatchEnd, lowPrefixPtr) + 4;
            ip++;
            ZSTD_storeSeq(seqStorePtr, ip-anchor, anchor, 0, mLength-MINMATCH);
        } else {
            if ((matchLongIndex > lowestIndex) && (MEM_read64(matchLong) == MEM_read64(ip))) {
                const BYTE* matchEnd = matchLongIndex < dictLimit ? dictEnd : iend;
                const BYTE* lowMatchPtr = matchLongIndex < dictLimit ? dictStart : lowPrefixPtr;
                U32 offset;
                mLength = ZSTD_count_2segments(ip+8, matchLong+8, iend, matchEnd, lowPrefixPtr) + 8;
                offset = current - matchLongIndex;
                while (((ip>anchor) & (matchLong>lowMatchPtr)) && (ip[-1] == matchLong[-1])) { ip--; matchLong--; mLength++; }   /* catch up */
                offset_2 = offset_1;
                offset_1 = offset;
                ZSTD_storeSeq(seqStorePtr, ip-anchor, anchor, offset + ZSTD_REP_MOVE, mLength-MINMATCH);

            } else if ((matchIndex > lowestIndex) && (MEM_read32(match) == MEM_read32(ip))) {
                size_t const h3 = ZSTD_hashPtr(ip+1, hBitsL, 8);
                U32 const matchIndex3 = hashLong[h3];
                const BYTE* const match3Base = matchIndex3 < dictLimit ? dictBase : base;
                const BYTE* match3 = match3Base + matchIndex3;
                U32 offset;
                hashLong[h3] = current + 1;
                if ( (matchIndex3 > lowestIndex) && (MEM_read64(match3) == MEM_read64(ip+1)) ) {
                    const BYTE* matchEnd = matchIndex3 < dictLimit ? dictEnd : iend;
                    const BYTE* lowMatchPtr = matchIndex3 < dictLimit ? dictStart : lowPrefixPtr;
                    mLength = ZSTD_count_2segments(ip+9, match3+8, iend, matchEnd, lowPrefixPtr) + 8;
                    ip++;
                    offset = current+1 - matchIndex3;
                    while (((ip>anchor) & (match3>lowMatchPtr)) && (ip[-1] == match3[-1])) { ip--; match3--; mLength++; } /* catch up */
                } else {
                    const BYTE* matchEnd = matchIndex < dictLimit ? dictEnd : iend;
                    const BYTE* lowMatchPtr = matchIndex < dictLimit ? dictStart : lowPrefixPtr;
                    mLength = ZSTD_count_2segments(ip+4, match+4, iend, matchEnd, lowPrefixPtr) + 4;
                    offset = current - matchIndex;
                    while (((ip>anchor) & (match>lowMatchPtr)) && (ip[-1] == match[-1])) { ip--; match--; mLength++; }   /* catch up */
                }
                offset_2 = offset_1;
                offset_1 = offset;
                ZSTD_storeSeq(seqStorePtr, ip-anchor, anchor, offset + ZSTD_REP_MOVE, mLength-MINMATCH);

            } else {
                ip += ((ip-anchor) >> g_searchStrength) + 1;
                continue;
        }   }

        /* found a match : store it */
        ip += mLength;
        anchor = ip;

        if (ip <= ilimit) {
            /* Fill Table */
			hashSmall[ZSTD_hashPtr(base+current+2, hBitsS, mls)] = current+2;
			hashLong[ZSTD_hashPtr(base+current+2, hBitsL, 8)] = current+2;
            hashSmall[ZSTD_hashPtr(ip-2, hBitsS, mls)] = (U32)(ip-2-base);
            hashLong[ZSTD_hashPtr(ip-2, hBitsL, 8)] = (U32)(ip-2-base);
            /* check immediate repcode */
            while (ip <= ilimit) {
                U32 const current2 = (U32)(ip-base);
                U32 const repIndex2 = current2 - offset_2;
                const BYTE* repMatch2 = repIndex2 < dictLimit ? dictBase + repIndex2 : base + repIndex2;
                if ( (((U32)((dictLimit-1) - repIndex2) >= 3) & (repIndex2 > lowestIndex))  /* intentional overflow */
                   && (MEM_read32(repMatch2) == MEM_read32(ip)) ) {
                    const BYTE* const repEnd2 = repIndex2 < dictLimit ? dictEnd : iend;
                    size_t const repLength2 = ZSTD_count_2segments(ip+EQUAL_READ32, repMatch2+EQUAL_READ32, iend, repEnd2, lowPrefixPtr) + EQUAL_READ32;
                    U32 tmpOffset = offset_2; offset_2 = offset_1; offset_1 = tmpOffset;   /* swap offset_2 <=> offset_1 */
                    ZSTD_storeSeq(seqStorePtr, 0, anchor, 0, repLength2-MINMATCH);
                    hashSmall[ZSTD_hashPtr(ip, hBitsS, mls)] = current2;
                    hashLong[ZSTD_hashPtr(ip, hBitsL, 8)] = current2;
                    ip += repLength2;
                    anchor = ip;
                    continue;
                }
                break;
    }   }   }

    /* save reps for next block */
    ctx->savedRep[0] = offset_1; ctx->savedRep[1] = offset_2;

    /* Last Literals */
    {   size_t const lastLLSize = iend - anchor;
        memcpy(seqStorePtr->lit, anchor, lastLLSize);
        seqStorePtr->lit += lastLLSize;
    }
}


static void ZSTD_compressBlock_doubleFast_extDict(ZSTD_CCtx* ctx,
                         const void* src, size_t srcSize)
{
    U32 const mls = ctx->params.cParams.searchLength;
    switch(mls)
    {
    default:
    case 4 :
        ZSTD_compressBlock_doubleFast_extDict_generic(ctx, src, srcSize, 4); return;
    case 5 :
        ZSTD_compressBlock_doubleFast_extDict_generic(ctx, src, srcSize, 5); return;
    case 6 :
        ZSTD_compressBlock_doubleFast_extDict_generic(ctx, src, srcSize, 6); return;
    case 7 :
        ZSTD_compressBlock_doubleFast_extDict_generic(ctx, src, srcSize, 7); return;
    }
}


/*-*************************************
*  Binary Tree search
***************************************/
/** ZSTD_insertBt1() : add one or multiple positions to tree.
*   ip : assumed <= iend-8 .
*   @return : nb of positions added */
static U32 ZSTD_insertBt1(ZSTD_CCtx* zc, const BYTE* const ip, const U32 mls, const BYTE* const iend, U32 nbCompares,
                          U32 extDict)
{
    U32*   const hashTable = zc->hashTable;
    U32    const hashLog = zc->params.cParams.hashLog;
    size_t const h  = ZSTD_hashPtr(ip, hashLog, mls);
    U32*   const bt = zc->chainTable;
    U32    const btLog  = zc->params.cParams.chainLog - 1;
    U32    const btMask = (1 << btLog) - 1;
    U32 matchIndex = hashTable[h];
    size_t commonLengthSmaller=0, commonLengthLarger=0;
    const BYTE* const base = zc->base;
    const BYTE* const dictBase = zc->dictBase;
    const U32 dictLimit = zc->dictLimit;
    const BYTE* const dictEnd = dictBase + dictLimit;
    const BYTE* const prefixStart = base + dictLimit;
    const BYTE* match;
    const U32 current = (U32)(ip-base);
    const U32 btLow = btMask >= current ? 0 : current - btMask;
    U32* smallerPtr = bt + 2*(current&btMask);
    U32* largerPtr  = smallerPtr + 1;
    U32 dummy32;   /* to be nullified at the end */
    U32 const windowLow = zc->lowLimit;
    U32 matchEndIdx = current+8;
    size_t bestLength = 8;
#ifdef ZSTD_C_PREDICT
    U32 predictedSmall = *(bt + 2*((current-1)&btMask) + 0);
    U32 predictedLarge = *(bt + 2*((current-1)&btMask) + 1);
    predictedSmall += (predictedSmall>0);
    predictedLarge += (predictedLarge>0);
#endif /* ZSTD_C_PREDICT */

    hashTable[h] = current;   /* Update Hash Table */

    while (nbCompares-- && (matchIndex > windowLow)) {
        U32* nextPtr = bt + 2*(matchIndex & btMask);
        size_t matchLength = MIN(commonLengthSmaller, commonLengthLarger);   /* guaranteed minimum nb of common bytes */
#ifdef ZSTD_C_PREDICT   /* note : can create issues when hlog small <= 11 */
        const U32* predictPtr = bt + 2*((matchIndex-1) & btMask);   /* written this way, as bt is a roll buffer */
        if (matchIndex == predictedSmall) {
            /* no need to check length, result known */
            *smallerPtr = matchIndex;
            if (matchIndex <= btLow) { smallerPtr=&dummy32; break; }   /* beyond tree size, stop the search */
            smallerPtr = nextPtr+1;               /* new "smaller" => larger of match */
            matchIndex = nextPtr[1];              /* new matchIndex larger than previous (closer to current) */
            predictedSmall = predictPtr[1] + (predictPtr[1]>0);
            continue;
        }
        if (matchIndex == predictedLarge) {
            *largerPtr = matchIndex;
            if (matchIndex <= btLow) { largerPtr=&dummy32; break; }   /* beyond tree size, stop the search */
            largerPtr = nextPtr;
            matchIndex = nextPtr[0];
            predictedLarge = predictPtr[0] + (predictPtr[0]>0);
            continue;
        }
#endif
        if ((!extDict) || (matchIndex+matchLength >= dictLimit)) {
            match = base + matchIndex;
            if (match[matchLength] == ip[matchLength])
                matchLength += ZSTD_count(ip+matchLength+1, match+matchLength+1, iend) +1;
        } else {
            match = dictBase + matchIndex;
            matchLength += ZSTD_count_2segments(ip+matchLength, match+matchLength, iend, dictEnd, prefixStart);
            if (matchIndex+matchLength >= dictLimit)
				match = base + matchIndex;   /* to prepare for next usage of match[matchLength] */
        }

        if (matchLength > bestLength) {
            bestLength = matchLength;
            if (matchLength > matchEndIdx - matchIndex)
                matchEndIdx = matchIndex + (U32)matchLength;
        }

        if (ip+matchLength == iend)   /* equal : no way to know if inf or sup */
            break;   /* drop , to guarantee consistency ; miss a bit of compression, but other solutions can corrupt the tree */

        if (match[matchLength] < ip[matchLength]) {  /* necessarily within correct buffer */
            /* match is smaller than current */
            *smallerPtr = matchIndex;             /* update smaller idx */
            commonLengthSmaller = matchLength;    /* all smaller will now have at least this guaranteed common length */
            if (matchIndex <= btLow) { smallerPtr=&dummy32; break; }   /* beyond tree size, stop the search */
            smallerPtr = nextPtr+1;               /* new "smaller" => larger of match */
            matchIndex = nextPtr[1];              /* new matchIndex larger than previous (closer to current) */
        } else {
            /* match is larger than current */
            *largerPtr = matchIndex;
            commonLengthLarger = matchLength;
            if (matchIndex <= btLow) { largerPtr=&dummy32; break; }   /* beyond tree size, stop the search */
            largerPtr = nextPtr;
            matchIndex = nextPtr[0];
    }   }

    *smallerPtr = *largerPtr = 0;
    if (bestLength > 384) return MIN(192, (U32)(bestLength - 384));   /* speed optimization */
    if (matchEndIdx > current + 8) return matchEndIdx - current - 8;
    return 1;
}


static size_t ZSTD_insertBtAndFindBestMatch (
                        ZSTD_CCtx* zc,
                        const BYTE* const ip, const BYTE* const iend,
                        size_t* offsetPtr,
                        U32 nbCompares, const U32 mls,
                        U32 extDict)
{
    U32*   const hashTable = zc->hashTable;
    U32    const hashLog = zc->params.cParams.hashLog;
    size_t const h  = ZSTD_hashPtr(ip, hashLog, mls);
    U32*   const bt = zc->chainTable;
    U32    const btLog  = zc->params.cParams.chainLog - 1;
    U32    const btMask = (1 << btLog) - 1;
    U32 matchIndex  = hashTable[h];
    size_t commonLengthSmaller=0, commonLengthLarger=0;
    const BYTE* const base = zc->base;
    const BYTE* const dictBase = zc->dictBase;
    const U32 dictLimit = zc->dictLimit;
    const BYTE* const dictEnd = dictBase + dictLimit;
    const BYTE* const prefixStart = base + dictLimit;
    const U32 current = (U32)(ip-base);
    const U32 btLow = btMask >= current ? 0 : current - btMask;
    const U32 windowLow = zc->lowLimit;
    U32* smallerPtr = bt + 2*(current&btMask);
    U32* largerPtr  = bt + 2*(current&btMask) + 1;
    U32 matchEndIdx = current+8;
    U32 dummy32;   /* to be nullified at the end */
    size_t bestLength = 0;

    hashTable[h] = current;   /* Update Hash Table */

    while (nbCompares-- && (matchIndex > windowLow)) {
        U32* nextPtr = bt + 2*(matchIndex & btMask);
        size_t matchLength = MIN(commonLengthSmaller, commonLengthLarger);   /* guaranteed minimum nb of common bytes */
        const BYTE* match;

        if ((!extDict) || (matchIndex+matchLength >= dictLimit)) {
            match = base + matchIndex;
            if (match[matchLength] == ip[matchLength])
                matchLength += ZSTD_count(ip+matchLength+1, match+matchLength+1, iend) +1;
        } else {
            match = dictBase + matchIndex;
            matchLength += ZSTD_count_2segments(ip+matchLength, match+matchLength, iend, dictEnd, prefixStart);
            if (matchIndex+matchLength >= dictLimit)
				match = base + matchIndex;   /* to prepare for next usage of match[matchLength] */
        }

        if (matchLength > bestLength) {
            if (matchLength > matchEndIdx - matchIndex)
                matchEndIdx = matchIndex + (U32)matchLength;
            if ( (4*(int)(matchLength-bestLength)) > (int)(ZSTD_highbit32(current-matchIndex+1) - ZSTD_highbit32((U32)offsetPtr[0]+1)) )
                bestLength = matchLength, *offsetPtr = ZSTD_REP_MOVE + current - matchIndex;
            if (ip+matchLength == iend)   /* equal : no way to know if inf or sup */
                break;   /* drop, to guarantee consistency (miss a little bit of compression) */
        }

        if (match[matchLength] < ip[matchLength]) {
            /* match is smaller than current */
            *smallerPtr = matchIndex;             /* update smaller idx */
            commonLengthSmaller = matchLength;    /* all smaller will now have at least this guaranteed common length */
            if (matchIndex <= btLow) { smallerPtr=&dummy32; break; }   /* beyond tree size, stop the search */
            smallerPtr = nextPtr+1;               /* new "smaller" => larger of match */
            matchIndex = nextPtr[1];              /* new matchIndex larger than previous (closer to current) */
        } else {
            /* match is larger than current */
            *largerPtr = matchIndex;
            commonLengthLarger = matchLength;
            if (matchIndex <= btLow) { largerPtr=&dummy32; break; }   /* beyond tree size, stop the search */
            largerPtr = nextPtr;
            matchIndex = nextPtr[0];
    }   }

    *smallerPtr = *largerPtr = 0;

    zc->nextToUpdate = (matchEndIdx > current + 8) ? matchEndIdx - 8 : current+1;
    return bestLength;
}


static void ZSTD_updateTree(ZSTD_CCtx* zc, const BYTE* const ip, const BYTE* const iend, const U32 nbCompares, const U32 mls)
{
    const BYTE* const base = zc->base;
    const U32 target = (U32)(ip - base);
    U32 idx = zc->nextToUpdate;

    while(idx < target)
        idx += ZSTD_insertBt1(zc, base+idx, mls, iend, nbCompares, 0);
}

/** ZSTD_BtFindBestMatch() : Tree updater, providing best match */
static size_t ZSTD_BtFindBestMatch (
                        ZSTD_CCtx* zc,
                        const BYTE* const ip, const BYTE* const iLimit,
                        size_t* offsetPtr,
                        const U32 maxNbAttempts, const U32 mls)
{
    if (ip < zc->base + zc->nextToUpdate) return 0;   /* skipped area */
    ZSTD_updateTree(zc, ip, iLimit, maxNbAttempts, mls);
    return ZSTD_insertBtAndFindBestMatch(zc, ip, iLimit, offsetPtr, maxNbAttempts, mls, 0);
}


static size_t ZSTD_BtFindBestMatch_selectMLS (
                        ZSTD_CCtx* zc,   /* Index table will be updated */
                        const BYTE* ip, const BYTE* const iLimit,
                        size_t* offsetPtr,
                        const U32 maxNbAttempts, const U32 matchLengthSearch)
{
    switch(matchLengthSearch)
    {
    default :
    case 4 : return ZSTD_BtFindBestMatch(zc, ip, iLimit, offsetPtr, maxNbAttempts, 4);
    case 5 : return ZSTD_BtFindBestMatch(zc, ip, iLimit, offsetPtr, maxNbAttempts, 5);
    case 6 : return ZSTD_BtFindBestMatch(zc, ip, iLimit, offsetPtr, maxNbAttempts, 6);
    }
}


static void ZSTD_updateTree_extDict(ZSTD_CCtx* zc, const BYTE* const ip, const BYTE* const iend, const U32 nbCompares, const U32 mls)
{
    const BYTE* const base = zc->base;
    const U32 target = (U32)(ip - base);
    U32 idx = zc->nextToUpdate;

    while (idx < target) idx += ZSTD_insertBt1(zc, base+idx, mls, iend, nbCompares, 1);
}


/** Tree updater, providing best match */
static size_t ZSTD_BtFindBestMatch_extDict (
                        ZSTD_CCtx* zc,
                        const BYTE* const ip, const BYTE* const iLimit,
                        size_t* offsetPtr,
                        const U32 maxNbAttempts, const U32 mls)
{
    if (ip < zc->base + zc->nextToUpdate) return 0;   /* skipped area */
    ZSTD_updateTree_extDict(zc, ip, iLimit, maxNbAttempts, mls);
    return ZSTD_insertBtAndFindBestMatch(zc, ip, iLimit, offsetPtr, maxNbAttempts, mls, 1);
}


static size_t ZSTD_BtFindBestMatch_selectMLS_extDict (
                        ZSTD_CCtx* zc,   /* Index table will be updated */
                        const BYTE* ip, const BYTE* const iLimit,
                        size_t* offsetPtr,
                        const U32 maxNbAttempts, const U32 matchLengthSearch)
{
    switch(matchLengthSearch)
    {
    default :
    case 4 : return ZSTD_BtFindBestMatch_extDict(zc, ip, iLimit, offsetPtr, maxNbAttempts, 4);
    case 5 : return ZSTD_BtFindBestMatch_extDict(zc, ip, iLimit, offsetPtr, maxNbAttempts, 5);
    case 6 : return ZSTD_BtFindBestMatch_extDict(zc, ip, iLimit, offsetPtr, maxNbAttempts, 6);
    }
}



/* *********************************
*  Hash Chain
***********************************/
#define NEXT_IN_CHAIN(d, mask)   chainTable[(d) & mask]

/* Update chains up to ip (excluded)
   Assumption : always within prefix (ie. not within extDict) */
FORCE_INLINE
U32 ZSTD_insertAndFindFirstIndex (ZSTD_CCtx* zc, const BYTE* ip, U32 mls)
{
    U32* const hashTable  = zc->hashTable;
    const U32 hashLog = zc->params.cParams.hashLog;
    U32* const chainTable = zc->chainTable;
    const U32 chainMask = (1 << zc->params.cParams.chainLog) - 1;
    const BYTE* const base = zc->base;
    const U32 target = (U32)(ip - base);
    U32 idx = zc->nextToUpdate;

    while(idx < target) { /* catch up */
        size_t const h = ZSTD_hashPtr(base+idx, hashLog, mls);
        NEXT_IN_CHAIN(idx, chainMask) = hashTable[h];
        hashTable[h] = idx;
        idx++;
    }

    zc->nextToUpdate = target;
    return hashTable[ZSTD_hashPtr(ip, hashLog, mls)];
}



FORCE_INLINE /* inlining is important to hardwire a hot branch (template emulation) */
size_t ZSTD_HcFindBestMatch_generic (
                        ZSTD_CCtx* zc,   /* Index table will be updated */
                        const BYTE* const ip, const BYTE* const iLimit,
                        size_t* offsetPtr,
                        const U32 maxNbAttempts, const U32 mls, const U32 extDict)
{
    U32* const chainTable = zc->chainTable;
    const U32 chainSize = (1 << zc->params.cParams.chainLog);
    const U32 chainMask = chainSize-1;
    const BYTE* const base = zc->base;
    const BYTE* const dictBase = zc->dictBase;
    const U32 dictLimit = zc->dictLimit;
    const BYTE* const prefixStart = base + dictLimit;
    const BYTE* const dictEnd = dictBase + dictLimit;
    const U32 lowLimit = zc->lowLimit;
    const U32 current = (U32)(ip-base);
    const U32 minChain = current > chainSize ? current - chainSize : 0;
    int nbAttempts=maxNbAttempts;
    size_t ml=EQUAL_READ32-1;

    /* HC4 match finder */
    U32 matchIndex = ZSTD_insertAndFindFirstIndex (zc, ip, mls);

    for ( ; (matchIndex>lowLimit) & (nbAttempts>0) ; nbAttempts--) {
        const BYTE* match;
        size_t currentMl=0;
        if ((!extDict) || matchIndex >= dictLimit) {
            match = base + matchIndex;
            if (match[ml] == ip[ml])   /* potentially better */
                currentMl = ZSTD_count(ip, match, iLimit);
        } else {
            match = dictBase + matchIndex;
            if (MEM_read32(match) == MEM_read32(ip))   /* assumption : matchIndex <= dictLimit-4 (by table construction) */
                currentMl = ZSTD_count_2segments(ip+EQUAL_READ32, match+EQUAL_READ32, iLimit, dictEnd, prefixStart) + EQUAL_READ32;
        }

        /* save best solution */
        if (currentMl > ml) { ml = currentMl; *offsetPtr = current - matchIndex + ZSTD_REP_MOVE; if (ip+currentMl == iLimit) break; /* best possible, and avoid read overflow*/ }

        if (matchIndex <= minChain) break;
        matchIndex = NEXT_IN_CHAIN(matchIndex, chainMask);
    }

    return ml;
}


FORCE_INLINE size_t ZSTD_HcFindBestMatch_selectMLS (
                        ZSTD_CCtx* zc,
                        const BYTE* ip, const BYTE* const iLimit,
                        size_t* offsetPtr,
                        const U32 maxNbAttempts, const U32 matchLengthSearch)
{
    switch(matchLengthSearch)
    {
    default :
    case 4 : return ZSTD_HcFindBestMatch_generic(zc, ip, iLimit, offsetPtr, maxNbAttempts, 4, 0);
    case 5 : return ZSTD_HcFindBestMatch_generic(zc, ip, iLimit, offsetPtr, maxNbAttempts, 5, 0);
    case 6 : return ZSTD_HcFindBestMatch_generic(zc, ip, iLimit, offsetPtr, maxNbAttempts, 6, 0);
    }
}


FORCE_INLINE size_t ZSTD_HcFindBestMatch_extDict_selectMLS (
                        ZSTD_CCtx* zc,
                        const BYTE* ip, const BYTE* const iLimit,
                        size_t* offsetPtr,
                        const U32 maxNbAttempts, const U32 matchLengthSearch)
{
    switch(matchLengthSearch)
    {
    default :
    case 4 : return ZSTD_HcFindBestMatch_generic(zc, ip, iLimit, offsetPtr, maxNbAttempts, 4, 1);
    case 5 : return ZSTD_HcFindBestMatch_generic(zc, ip, iLimit, offsetPtr, maxNbAttempts, 5, 1);
    case 6 : return ZSTD_HcFindBestMatch_generic(zc, ip, iLimit, offsetPtr, maxNbAttempts, 6, 1);
    }
}


/* *******************************
*  Common parser - lazy strategy
*********************************/
FORCE_INLINE
void ZSTD_compressBlock_lazy_generic(ZSTD_CCtx* ctx,
                                     const void* src, size_t srcSize,
                                     const U32 searchMethod, const U32 depth)
{
    seqStore_t* seqStorePtr = &(ctx->seqStore);
    const BYTE* const istart = (const BYTE*)src;
    const BYTE* ip = istart;
    const BYTE* anchor = istart;
    const BYTE* const iend = istart + srcSize;
    const BYTE* const ilimit = iend - 8;
    const BYTE* const base = ctx->base + ctx->dictLimit;

    U32 const maxSearches = 1 << ctx->params.cParams.searchLog;
    U32 const mls = ctx->params.cParams.searchLength;

    typedef size_t (*searchMax_f)(ZSTD_CCtx* zc, const BYTE* ip, const BYTE* iLimit,
                        size_t* offsetPtr,
                        U32 maxNbAttempts, U32 matchLengthSearch);
    searchMax_f const searchMax = searchMethod ? ZSTD_BtFindBestMatch_selectMLS : ZSTD_HcFindBestMatch_selectMLS;
    U32 offset_1 = ctx->rep[0], offset_2 = ctx->rep[1], savedOffset=0;

    /* init */
    ip += (ip==base);
    ctx->nextToUpdate3 = ctx->nextToUpdate;
    {   U32 const maxRep = (U32)(ip-base);
        if (offset_2 > maxRep) savedOffset = offset_2, offset_2 = 0;
        if (offset_1 > maxRep) savedOffset = offset_1, offset_1 = 0;
    }

    /* Match Loop */
    while (ip < ilimit) {
        size_t matchLength=0;
        size_t offset=0;
        const BYTE* start=ip+1;

        /* check repCode */
        if ((offset_1>0) & (MEM_read32(ip+1) == MEM_read32(ip+1 - offset_1))) {
            /* repcode : we take it */
            matchLength = ZSTD_count(ip+1+EQUAL_READ32, ip+1+EQUAL_READ32-offset_1, iend) + EQUAL_READ32;
            if (depth==0) goto _storeSequence;
        }

        /* first search (depth 0) */
        {   size_t offsetFound = 99999999;
            size_t const ml2 = searchMax(ctx, ip, iend, &offsetFound, maxSearches, mls);
            if (ml2 > matchLength)
                matchLength = ml2, start = ip, offset=offsetFound;
        }

        if (matchLength < EQUAL_READ32) {
            ip += ((ip-anchor) >> g_searchStrength) + 1;   /* jump faster over incompressible sections */
            continue;
        }

        /* let's try to find a better solution */
        if (depth>=1)
        while (ip<ilimit) {
            ip ++;
            if ((offset) && ((offset_1>0) & (MEM_read32(ip) == MEM_read32(ip - offset_1)))) {
                size_t const mlRep = ZSTD_count(ip+EQUAL_READ32, ip+EQUAL_READ32-offset_1, iend) + EQUAL_READ32;
                int const gain2 = (int)(mlRep * 3);
                int const gain1 = (int)(matchLength*3 - ZSTD_highbit32((U32)offset+1) + 1);
                if ((mlRep >= EQUAL_READ32) && (gain2 > gain1))
                    matchLength = mlRep, offset = 0, start = ip;
            }
            {   size_t offset2=99999999;
                size_t const ml2 = searchMax(ctx, ip, iend, &offset2, maxSearches, mls);
                int const gain2 = (int)(ml2*4 - ZSTD_highbit32((U32)offset2+1));   /* raw approx */
                int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)offset+1) + 4);
                if ((ml2 >= EQUAL_READ32) && (gain2 > gain1)) {
                    matchLength = ml2, offset = offset2, start = ip;
                    continue;   /* search a better one */
            }   }

            /* let's find an even better one */
            if ((depth==2) && (ip<ilimit)) {
                ip ++;
                if ((offset) && ((offset_1>0) & (MEM_read32(ip) == MEM_read32(ip - offset_1)))) {
                    size_t const ml2 = ZSTD_count(ip+EQUAL_READ32, ip+EQUAL_READ32-offset_1, iend) + EQUAL_READ32;
                    int const gain2 = (int)(ml2 * 4);
                    int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)offset+1) + 1);
                    if ((ml2 >= EQUAL_READ32) && (gain2 > gain1))
                        matchLength = ml2, offset = 0, start = ip;
                }
                {   size_t offset2=99999999;
                    size_t const ml2 = searchMax(ctx, ip, iend, &offset2, maxSearches, mls);
                    int const gain2 = (int)(ml2*4 - ZSTD_highbit32((U32)offset2+1));   /* raw approx */
                    int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)offset+1) + 7);
                    if ((ml2 >= EQUAL_READ32) && (gain2 > gain1)) {
                        matchLength = ml2, offset = offset2, start = ip;
                        continue;
            }   }   }
            break;  /* nothing found : store previous solution */
        }

        /* catch up */
        if (offset) {
            while ((start>anchor) && (start>base+offset-ZSTD_REP_MOVE) && (start[-1] == start[-1-offset+ZSTD_REP_MOVE]))   /* only search for offset within prefix */
                { start--; matchLength++; }
            offset_2 = offset_1; offset_1 = (U32)(offset - ZSTD_REP_MOVE);
        }

        /* store sequence */
_storeSequence:
        {   size_t const litLength = start - anchor;
            ZSTD_storeSeq(seqStorePtr, litLength, anchor, (U32)offset, matchLength-MINMATCH);
            anchor = ip = start + matchLength;
        }

        /* check immediate repcode */
        while ( (ip <= ilimit)
             && ((offset_2>0)
             & (MEM_read32(ip) == MEM_read32(ip - offset_2)) )) {
            /* store sequence */
            matchLength = ZSTD_count(ip+EQUAL_READ32, ip+EQUAL_READ32-offset_2, iend) + EQUAL_READ32;
            offset = offset_2; offset_2 = offset_1; offset_1 = (U32)offset; /* swap repcodes */
            ZSTD_storeSeq(seqStorePtr, 0, anchor, 0, matchLength-MINMATCH);
            ip += matchLength;
            anchor = ip;
            continue;   /* faster when present ... (?) */
    }   }

    /* Save reps for next block */
    ctx->savedRep[0] = offset_1 ? offset_1 : savedOffset;
    ctx->savedRep[1] = offset_2 ? offset_2 : savedOffset;

    /* Last Literals */
    {   size_t const lastLLSize = iend - anchor;
        memcpy(seqStorePtr->lit, anchor, lastLLSize);
        seqStorePtr->lit += lastLLSize;
    }
}


static void ZSTD_compressBlock_btlazy2(ZSTD_CCtx* ctx, const void* src, size_t srcSize)
{
    ZSTD_compressBlock_lazy_generic(ctx, src, srcSize, 1, 2);
}

static void ZSTD_compressBlock_lazy2(ZSTD_CCtx* ctx, const void* src, size_t srcSize)
{
    ZSTD_compressBlock_lazy_generic(ctx, src, srcSize, 0, 2);
}

static void ZSTD_compressBlock_lazy(ZSTD_CCtx* ctx, const void* src, size_t srcSize)
{
    ZSTD_compressBlock_lazy_generic(ctx, src, srcSize, 0, 1);
}

static void ZSTD_compressBlock_greedy(ZSTD_CCtx* ctx, const void* src, size_t srcSize)
{
    ZSTD_compressBlock_lazy_generic(ctx, src, srcSize, 0, 0);
}


FORCE_INLINE
void ZSTD_compressBlock_lazy_extDict_generic(ZSTD_CCtx* ctx,
                                     const void* src, size_t srcSize,
                                     const U32 searchMethod, const U32 depth)
{
    seqStore_t* seqStorePtr = &(ctx->seqStore);
    const BYTE* const istart = (const BYTE*)src;
    const BYTE* ip = istart;
    const BYTE* anchor = istart;
    const BYTE* const iend = istart + srcSize;
    const BYTE* const ilimit = iend - 8;
    const BYTE* const base = ctx->base;
    const U32 dictLimit = ctx->dictLimit;
    const U32 lowestIndex = ctx->lowLimit;
    const BYTE* const prefixStart = base + dictLimit;
    const BYTE* const dictBase = ctx->dictBase;
    const BYTE* const dictEnd  = dictBase + dictLimit;
    const BYTE* const dictStart  = dictBase + ctx->lowLimit;

    const U32 maxSearches = 1 << ctx->params.cParams.searchLog;
    const U32 mls = ctx->params.cParams.searchLength;

    typedef size_t (*searchMax_f)(ZSTD_CCtx* zc, const BYTE* ip, const BYTE* iLimit,
                        size_t* offsetPtr,
                        U32 maxNbAttempts, U32 matchLengthSearch);
    searchMax_f searchMax = searchMethod ? ZSTD_BtFindBestMatch_selectMLS_extDict : ZSTD_HcFindBestMatch_extDict_selectMLS;

    U32 offset_1 = ctx->rep[0], offset_2 = ctx->rep[1];

    /* init */
    ctx->nextToUpdate3 = ctx->nextToUpdate;
    ip += (ip == prefixStart);

    /* Match Loop */
    while (ip < ilimit) {
        size_t matchLength=0;
        size_t offset=0;
        const BYTE* start=ip+1;
        U32 current = (U32)(ip-base);

        /* check repCode */
        {   const U32 repIndex = (U32)(current+1 - offset_1);
            const BYTE* const repBase = repIndex < dictLimit ? dictBase : base;
            const BYTE* const repMatch = repBase + repIndex;
            if (((U32)((dictLimit-1) - repIndex) >= 3) & (repIndex > lowestIndex))   /* intentional overflow */
            if (MEM_read32(ip+1) == MEM_read32(repMatch)) {
                /* repcode detected we should take it */
                const BYTE* const repEnd = repIndex < dictLimit ? dictEnd : iend;
                matchLength = ZSTD_count_2segments(ip+1+EQUAL_READ32, repMatch+EQUAL_READ32, iend, repEnd, prefixStart) + EQUAL_READ32;
                if (depth==0) goto _storeSequence;
        }   }

        /* first search (depth 0) */
        {   size_t offsetFound = 99999999;
            size_t const ml2 = searchMax(ctx, ip, iend, &offsetFound, maxSearches, mls);
            if (ml2 > matchLength)
                matchLength = ml2, start = ip, offset=offsetFound;
        }

         if (matchLength < EQUAL_READ32) {
            ip += ((ip-anchor) >> g_searchStrength) + 1;   /* jump faster over incompressible sections */
            continue;
        }

        /* let's try to find a better solution */
        if (depth>=1)
        while (ip<ilimit) {
            ip ++;
            current++;
            /* check repCode */
            if (offset) {
                const U32 repIndex = (U32)(current - offset_1);
                const BYTE* const repBase = repIndex < dictLimit ? dictBase : base;
                const BYTE* const repMatch = repBase + repIndex;
                if (((U32)((dictLimit-1) - repIndex) >= 3) & (repIndex > lowestIndex))  /* intentional overflow */
                if (MEM_read32(ip) == MEM_read32(repMatch)) {
                    /* repcode detected */
                    const BYTE* const repEnd = repIndex < dictLimit ? dictEnd : iend;
                    size_t const repLength = ZSTD_count_2segments(ip+EQUAL_READ32, repMatch+EQUAL_READ32, iend, repEnd, prefixStart) + EQUAL_READ32;
                    int const gain2 = (int)(repLength * 3);
                    int const gain1 = (int)(matchLength*3 - ZSTD_highbit32((U32)offset+1) + 1);
                    if ((repLength >= EQUAL_READ32) && (gain2 > gain1))
                        matchLength = repLength, offset = 0, start = ip;
            }   }

            /* search match, depth 1 */
            {   size_t offset2=99999999;
                size_t const ml2 = searchMax(ctx, ip, iend, &offset2, maxSearches, mls);
                int const gain2 = (int)(ml2*4 - ZSTD_highbit32((U32)offset2+1));   /* raw approx */
                int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)offset+1) + 4);
                if ((ml2 >= EQUAL_READ32) && (gain2 > gain1)) {
                    matchLength = ml2, offset = offset2, start = ip;
                    continue;   /* search a better one */
            }   }

            /* let's find an even better one */
            if ((depth==2) && (ip<ilimit)) {
                ip ++;
                current++;
                /* check repCode */
                if (offset) {
                    const U32 repIndex = (U32)(current - offset_1);
                    const BYTE* const repBase = repIndex < dictLimit ? dictBase : base;
                    const BYTE* const repMatch = repBase + repIndex;
                    if (((U32)((dictLimit-1) - repIndex) >= 3) & (repIndex > lowestIndex))  /* intentional overflow */
                    if (MEM_read32(ip) == MEM_read32(repMatch)) {
                        /* repcode detected */
                        const BYTE* const repEnd = repIndex < dictLimit ? dictEnd : iend;
                        size_t repLength = ZSTD_count_2segments(ip+EQUAL_READ32, repMatch+EQUAL_READ32, iend, repEnd, prefixStart) + EQUAL_READ32;
                        int gain2 = (int)(repLength * 4);
                        int gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)offset+1) + 1);
                        if ((repLength >= EQUAL_READ32) && (gain2 > gain1))
                            matchLength = repLength, offset = 0, start = ip;
                }   }

                /* search match, depth 2 */
                {   size_t offset2=99999999;
                    size_t const ml2 = searchMax(ctx, ip, iend, &offset2, maxSearches, mls);
                    int const gain2 = (int)(ml2*4 - ZSTD_highbit32((U32)offset2+1));   /* raw approx */
                    int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)offset+1) + 7);
                    if ((ml2 >= EQUAL_READ32) && (gain2 > gain1)) {
                        matchLength = ml2, offset = offset2, start = ip;
                        continue;
            }   }   }
            break;  /* nothing found : store previous solution */
        }

        /* catch up */
        if (offset) {
            U32 const matchIndex = (U32)((start-base) - (offset - ZSTD_REP_MOVE));
            const BYTE* match = (matchIndex < dictLimit) ? dictBase + matchIndex : base + matchIndex;
            const BYTE* const mStart = (matchIndex < dictLimit) ? dictStart : prefixStart;
            while ((start>anchor) && (match>mStart) && (start[-1] == match[-1])) { start--; match--; matchLength++; }  /* catch up */
            offset_2 = offset_1; offset_1 = (U32)(offset - ZSTD_REP_MOVE);
        }

        /* store sequence */
_storeSequence:
        {   size_t const litLength = start - anchor;
            ZSTD_storeSeq(seqStorePtr, litLength, anchor, (U32)offset, matchLength-MINMATCH);
            anchor = ip = start + matchLength;
        }

        /* check immediate repcode */
        while (ip <= ilimit) {
            const U32 repIndex = (U32)((ip-base) - offset_2);
            const BYTE* const repBase = repIndex < dictLimit ? dictBase : base;
            const BYTE* const repMatch = repBase + repIndex;
            if (((U32)((dictLimit-1) - repIndex) >= 3) & (repIndex > lowestIndex))  /* intentional overflow */
            if (MEM_read32(ip) == MEM_read32(repMatch)) {
                /* repcode detected we should take it */
                const BYTE* const repEnd = repIndex < dictLimit ? dictEnd : iend;
                matchLength = ZSTD_count_2segments(ip+EQUAL_READ32, repMatch+EQUAL_READ32, iend, repEnd, prefixStart) + EQUAL_READ32;
                offset = offset_2; offset_2 = offset_1; offset_1 = (U32)offset;   /* swap offset history */
                ZSTD_storeSeq(seqStorePtr, 0, anchor, 0, matchLength-MINMATCH);
                ip += matchLength;
                anchor = ip;
                continue;   /* faster when present ... (?) */
            }
            break;
    }   }

    /* Save reps for next block */
    ctx->savedRep[0] = offset_1; ctx->savedRep[1] = offset_2;

    /* Last Literals */
    {   size_t const lastLLSize = iend - anchor;
        memcpy(seqStorePtr->lit, anchor, lastLLSize);
        seqStorePtr->lit += lastLLSize;
    }
}


void ZSTD_compressBlock_greedy_extDict(ZSTD_CCtx* ctx, const void* src, size_t srcSize)
{
    ZSTD_compressBlock_lazy_extDict_generic(ctx, src, srcSize, 0, 0);
}

static void ZSTD_compressBlock_lazy_extDict(ZSTD_CCtx* ctx, const void* src, size_t srcSize)
{
    ZSTD_compressBlock_lazy_extDict_generic(ctx, src, srcSize, 0, 1);
}

static void ZSTD_compressBlock_lazy2_extDict(ZSTD_CCtx* ctx, const void* src, size_t srcSize)
{
    ZSTD_compressBlock_lazy_extDict_generic(ctx, src, srcSize, 0, 2);
}

static void ZSTD_compressBlock_btlazy2_extDict(ZSTD_CCtx* ctx, const void* src, size_t srcSize)
{
    ZSTD_compressBlock_lazy_extDict_generic(ctx, src, srcSize, 1, 2);
}


/* The optimal parser */
#include "zstd_opt.h"

static void ZSTD_compressBlock_btopt(ZSTD_CCtx* ctx, const void* src, size_t srcSize)
{
#ifdef ZSTD_OPT_H_91842398743
    ZSTD_compressBlock_opt_generic(ctx, src, srcSize, 0);
#else
    (void)ctx; (void)src; (void)srcSize;
    return;
#endif
}

static void ZSTD_compressBlock_btopt2(ZSTD_CCtx* ctx, const void* src, size_t srcSize)
{
#ifdef ZSTD_OPT_H_91842398743
    ZSTD_compressBlock_opt_generic(ctx, src, srcSize, 1);
#else
    (void)ctx; (void)src; (void)srcSize;
    return;
#endif
}

static void ZSTD_compressBlock_btopt_extDict(ZSTD_CCtx* ctx, const void* src, size_t srcSize)
{
#ifdef ZSTD_OPT_H_91842398743
    ZSTD_compressBlock_opt_extDict_generic(ctx, src, srcSize, 0);
#else
    (void)ctx; (void)src; (void)srcSize;
    return;
#endif
}

static void ZSTD_compressBlock_btopt2_extDict(ZSTD_CCtx* ctx, const void* src, size_t srcSize)
{
#ifdef ZSTD_OPT_H_91842398743
    ZSTD_compressBlock_opt_extDict_generic(ctx, src, srcSize, 1);
#else
    (void)ctx; (void)src; (void)srcSize;
    return;
#endif
}


typedef void (*ZSTD_blockCompressor) (ZSTD_CCtx* ctx, const void* src, size_t srcSize);

static ZSTD_blockCompressor ZSTD_selectBlockCompressor(ZSTD_strategy strat, int extDict)
{
    static const ZSTD_blockCompressor blockCompressor[2][8] = {
        { ZSTD_compressBlock_fast, ZSTD_compressBlock_doubleFast, ZSTD_compressBlock_greedy, ZSTD_compressBlock_lazy, ZSTD_compressBlock_lazy2, ZSTD_compressBlock_btlazy2, ZSTD_compressBlock_btopt, ZSTD_compressBlock_btopt2 },
        { ZSTD_compressBlock_fast_extDict, ZSTD_compressBlock_doubleFast_extDict, ZSTD_compressBlock_greedy_extDict, ZSTD_compressBlock_lazy_extDict,ZSTD_compressBlock_lazy2_extDict, ZSTD_compressBlock_btlazy2_extDict, ZSTD_compressBlock_btopt_extDict, ZSTD_compressBlock_btopt2_extDict }
    };

    return blockCompressor[extDict][(U32)strat];
}


static size_t ZSTD_compressBlock_internal(ZSTD_CCtx* zc, void* dst, size_t dstCapacity, const void* src, size_t srcSize)
{
    ZSTD_blockCompressor const blockCompressor = ZSTD_selectBlockCompressor(zc->params.cParams.strategy, zc->lowLimit < zc->dictLimit);
    const BYTE* const base = zc->base;
    const BYTE* const istart = (const BYTE*)src;
    const U32 current = (U32)(istart-base);
    if (srcSize < MIN_CBLOCK_SIZE+ZSTD_blockHeaderSize+1) return 0;   /* don't even attempt compression below a certain srcSize */
    ZSTD_resetSeqStore(&(zc->seqStore));
    if (current > zc->nextToUpdate + 384)
        zc->nextToUpdate = current - MIN(192, (U32)(current - zc->nextToUpdate - 384));   /* update tree not updated after finding very long rep matches */
    blockCompressor(zc, src, srcSize);
    return ZSTD_compressSequences(zc, dst, dstCapacity, srcSize);
}


/*! ZSTD_compress_generic() :
*   Compress a chunk of data into one or multiple blocks.
*   All blocks will be terminated, all input will be consumed.
*   Function will issue an error if there is not enough `dstCapacity` to hold the compressed content.
*   Frame is supposed already started (header already produced)
*   @return : compressed size, or an error code
*/
static size_t ZSTD_compress_generic (ZSTD_CCtx* cctx,
                                     void* dst, size_t dstCapacity,
                               const void* src, size_t srcSize,
                                     U32 lastFrameChunk)
{
    size_t blockSize = cctx->blockSize;
    size_t remaining = srcSize;
    const BYTE* ip = (const BYTE*)src;
    BYTE* const ostart = (BYTE*)dst;
    BYTE* op = ostart;
    U32 const maxDist = 1 << cctx->params.cParams.windowLog;

    if (cctx->params.fParams.checksumFlag && srcSize)
        XXH64_update(&cctx->xxhState, src, srcSize);

    while (remaining) {
        U32 const lastBlock = lastFrameChunk & (blockSize >= remaining);
        size_t cSize;

        if (dstCapacity < ZSTD_blockHeaderSize + MIN_CBLOCK_SIZE) return ERROR(dstSize_tooSmall);   /* not enough space to store compressed block */
        if (remaining < blockSize) blockSize = remaining;

        /* preemptive overflow correction */
        if (cctx->lowLimit > (1<<30)) {
            U32 const btplus = (cctx->params.cParams.strategy == ZSTD_btlazy2) | (cctx->params.cParams.strategy == ZSTD_btopt) | (cctx->params.cParams.strategy == ZSTD_btopt2);
            U32 const chainMask = (1 << (cctx->params.cParams.chainLog - btplus)) - 1;
            U32 const supLog = MAX(cctx->params.cParams.chainLog, 17 /* blockSize */);
            U32 const newLowLimit = (cctx->lowLimit & chainMask) + (1 << supLog);   /* preserve position % chainSize, ensure current-repcode doesn't underflow */
            U32 const correction = cctx->lowLimit - newLowLimit;
            ZSTD_reduceIndex(cctx, correction);
            cctx->base += correction;
            cctx->dictBase += correction;
            cctx->lowLimit = newLowLimit;
            cctx->dictLimit -= correction;
            if (cctx->nextToUpdate < correction) cctx->nextToUpdate = 0;
            else cctx->nextToUpdate -= correction;
        }

        if ((U32)(ip+blockSize - cctx->base) > cctx->loadedDictEnd + maxDist) {
            /* enforce maxDist */
            U32 const newLowLimit = (U32)(ip+blockSize - cctx->base) - maxDist;
            if (cctx->lowLimit < newLowLimit) cctx->lowLimit = newLowLimit;
            if (cctx->dictLimit < cctx->lowLimit) cctx->dictLimit = cctx->lowLimit;
        }

        cSize = ZSTD_compressBlock_internal(cctx, op+ZSTD_blockHeaderSize, dstCapacity-ZSTD_blockHeaderSize, ip, blockSize);
        if (ZSTD_isError(cSize)) return cSize;

        if (cSize == 0) {  /* block is not compressible */
            U32 const cBlockHeader24 = lastBlock + (((U32)bt_raw)<<1) + (U32)(blockSize << 3);
            if (blockSize + ZSTD_blockHeaderSize > dstCapacity) return ERROR(dstSize_tooSmall);
            MEM_writeLE32(op, cBlockHeader24);   /* no pb, 4th byte will be overwritten */
            memcpy(op + ZSTD_blockHeaderSize, ip, blockSize);
            cSize = ZSTD_blockHeaderSize+blockSize;
        } else {
            U32 const cBlockHeader24 = lastBlock + (((U32)bt_compressed)<<1) + (U32)(cSize << 3);
            MEM_writeLE24(op, cBlockHeader24);
            cSize += ZSTD_blockHeaderSize;
        }

        remaining -= blockSize;
        dstCapacity -= cSize;
        ip += blockSize;
        op += cSize;
    }

    if (lastFrameChunk && (op>ostart)) cctx->stage = ZSTDcs_ending;
    return op-ostart;
}


static size_t ZSTD_writeFrameHeader(void* dst, size_t dstCapacity,
                                    ZSTD_parameters params, U64 pledgedSrcSize, U32 dictID)
{   BYTE* const op = (BYTE*)dst;
    U32   const dictIDSizeCode = (dictID>0) + (dictID>=256) + (dictID>=65536);   /* 0-3 */
    U32   const checksumFlag = params.fParams.checksumFlag>0;
    U32   const windowSize = 1U << params.cParams.windowLog;
    U32   const singleSegment = params.fParams.contentSizeFlag && (windowSize > (pledgedSrcSize-1));
    BYTE  const windowLogByte = (BYTE)((params.cParams.windowLog - ZSTD_WINDOWLOG_ABSOLUTEMIN) << 3);
    U32   const fcsCode = params.fParams.contentSizeFlag ?
                     (pledgedSrcSize>=256) + (pledgedSrcSize>=65536+256) + (pledgedSrcSize>=0xFFFFFFFFU) :   /* 0-3 */
                      0;
    BYTE  const frameHeaderDecriptionByte = (BYTE)(dictIDSizeCode + (checksumFlag<<2) + (singleSegment<<5) + (fcsCode<<6) );
    size_t pos;

    if (dstCapacity < ZSTD_frameHeaderSize_max) return ERROR(dstSize_tooSmall);

    MEM_writeLE32(dst, ZSTD_MAGICNUMBER);
    op[4] = frameHeaderDecriptionByte; pos=5;
    if (!singleSegment) op[pos++] = windowLogByte;
    switch(dictIDSizeCode)
    {
        default:   /* impossible */
        case 0 : break;
        case 1 : op[pos] = (BYTE)(dictID); pos++; break;
        case 2 : MEM_writeLE16(op+pos, (U16)dictID); pos+=2; break;
        case 3 : MEM_writeLE32(op+pos, dictID); pos+=4; break;
    }
    switch(fcsCode)
    {
        default:   /* impossible */
        case 0 : if (singleSegment) op[pos++] = (BYTE)(pledgedSrcSize); break;
        case 1 : MEM_writeLE16(op+pos, (U16)(pledgedSrcSize-256)); pos+=2; break;
        case 2 : MEM_writeLE32(op+pos, (U32)(pledgedSrcSize)); pos+=4; break;
        case 3 : MEM_writeLE64(op+pos, (U64)(pledgedSrcSize)); pos+=8; break;
    }
    return pos;
}


static size_t ZSTD_compressContinue_internal (ZSTD_CCtx* cctx,
                              void* dst, size_t dstCapacity,
                        const void* src, size_t srcSize,
                               U32 frame, U32 lastFrameChunk)
{
    const BYTE* const ip = (const BYTE*) src;
    size_t fhSize = 0;

    if (cctx->stage==ZSTDcs_created) return ERROR(stage_wrong);   /* missing init (ZSTD_compressBegin) */

    if (frame && (cctx->stage==ZSTDcs_init)) {
        fhSize = ZSTD_writeFrameHeader(dst, dstCapacity, cctx->params, cctx->frameContentSize, cctx->dictID);
        if (ZSTD_isError(fhSize)) return fhSize;
        dstCapacity -= fhSize;
        dst = (char*)dst + fhSize;
        cctx->stage = ZSTDcs_ongoing;
    }

    /* Check if blocks follow each other */
    if (src != cctx->nextSrc) {
        /* not contiguous */
        ptrdiff_t const delta = cctx->nextSrc - ip;
        cctx->lowLimit = cctx->dictLimit;
        cctx->dictLimit = (U32)(cctx->nextSrc - cctx->base);
        cctx->dictBase = cctx->base;
        cctx->base -= delta;
        cctx->nextToUpdate = cctx->dictLimit;
        if (cctx->dictLimit - cctx->lowLimit < HASH_READ_SIZE) cctx->lowLimit = cctx->dictLimit;   /* too small extDict */
    }

    /* if input and dictionary overlap : reduce dictionary (area presumed modified by input) */
    if ((ip+srcSize > cctx->dictBase + cctx->lowLimit) & (ip < cctx->dictBase + cctx->dictLimit)) {
        ptrdiff_t const highInputIdx = (ip + srcSize) - cctx->dictBase;
        U32 const lowLimitMax = (highInputIdx > (ptrdiff_t)cctx->dictLimit) ? cctx->dictLimit : (U32)highInputIdx;
        cctx->lowLimit = lowLimitMax;
    }

    cctx->nextSrc = ip + srcSize;

    {   size_t const cSize = frame ?
                             ZSTD_compress_generic (cctx, dst, dstCapacity, src, srcSize, lastFrameChunk) :
                             ZSTD_compressBlock_internal (cctx, dst, dstCapacity, src, srcSize);
        if (ZSTD_isError(cSize)) return cSize;
        return cSize + fhSize;
    }
}


size_t ZSTD_compressContinue (ZSTD_CCtx* cctx,
                              void* dst, size_t dstCapacity,
                        const void* src, size_t srcSize)
{
    return ZSTD_compressContinue_internal(cctx, dst, dstCapacity, src, srcSize, 1, 0);
}


size_t ZSTD_getBlockSizeMax(ZSTD_CCtx* cctx)
{
    return MIN (ZSTD_BLOCKSIZE_ABSOLUTEMAX, 1 << cctx->params.cParams.windowLog);
}

size_t ZSTD_compressBlock(ZSTD_CCtx* cctx, void* dst, size_t dstCapacity, const void* src, size_t srcSize)
{
    size_t const blockSizeMax = ZSTD_getBlockSizeMax(cctx);
    if (srcSize > blockSizeMax) return ERROR(srcSize_wrong);
    return ZSTD_compressContinue_internal(cctx, dst, dstCapacity, src, srcSize, 0, 0);
}


static size_t ZSTD_loadDictionaryContent(ZSTD_CCtx* zc, const void* src, size_t srcSize)
{
    const BYTE* const ip = (const BYTE*) src;
    const BYTE* const iend = ip + srcSize;

    /* input becomes current prefix */
    zc->lowLimit = zc->dictLimit;
    zc->dictLimit = (U32)(zc->nextSrc - zc->base);
    zc->dictBase = zc->base;
    zc->base += ip - zc->nextSrc;
    zc->nextToUpdate = zc->dictLimit;
    zc->loadedDictEnd = (U32)(iend - zc->base);

    zc->nextSrc = iend;
    if (srcSize <= HASH_READ_SIZE) return 0;

    switch(zc->params.cParams.strategy)
    {
    case ZSTD_fast:
        ZSTD_fillHashTable (zc, iend, zc->params.cParams.searchLength);
        break;

    case ZSTD_dfast:
        ZSTD_fillDoubleHashTable (zc, iend, zc->params.cParams.searchLength);
        break;

    case ZSTD_greedy:
    case ZSTD_lazy:
    case ZSTD_lazy2:
        ZSTD_insertAndFindFirstIndex (zc, iend-HASH_READ_SIZE, zc->params.cParams.searchLength);
        break;

    case ZSTD_btlazy2:
    case ZSTD_btopt:
    case ZSTD_btopt2:
        ZSTD_updateTree(zc, iend-HASH_READ_SIZE, iend, 1 << zc->params.cParams.searchLog, zc->params.cParams.searchLength);
        break;

    default:
        return ERROR(GENERIC);   /* strategy doesn't exist; impossible */
    }

    zc->nextToUpdate = zc->loadedDictEnd;
    return 0;
}


/* Dictionaries that assign zero probability to symbols that show up causes problems
   when FSE encoding.  Refuse dictionaries that assign zero probability to symbols
   that we may encounter during compression.
   NOTE: This behavior is not standard and could be improved in the future. */
static size_t ZSTD_checkDictNCount(short* normalizedCounter, unsigned dictMaxSymbolValue, unsigned maxSymbolValue) {
    U32 s;
    if (dictMaxSymbolValue < maxSymbolValue) return ERROR(dictionary_corrupted);
    for (s = 0; s <= maxSymbolValue; ++s) {
        if (normalizedCounter[s] == 0) return ERROR(dictionary_corrupted);
    }
    return 0;
}


/* Dictionary format :
    Magic == ZSTD_DICT_MAGIC (4 bytes)
    HUF_writeCTable(256)
    FSE_writeNCount(off)
    FSE_writeNCount(ml)
    FSE_writeNCount(ll)
    RepOffsets
    Dictionary content
*/
/*! ZSTD_loadDictEntropyStats() :
    @return : size read from dictionary
    note : magic number supposed already checked */
static size_t ZSTD_loadDictEntropyStats(ZSTD_CCtx* cctx, const void* dict, size_t dictSize)
{
    const BYTE* dictPtr = (const BYTE*)dict;
    const BYTE* const dictEnd = dictPtr + dictSize;
    short offcodeNCount[MaxOff+1];
    unsigned offcodeMaxValue = MaxOff;

    {   size_t const hufHeaderSize = HUF_readCTable(cctx->hufTable, 255, dict, dictSize);
        if (HUF_isError(hufHeaderSize)) return ERROR(dictionary_corrupted);
        dictPtr += hufHeaderSize;
    }

    {   unsigned 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);
        /* Defer checking offcodeMaxValue because we need to know the size of the dictionary content */
        CHECK_E (FSE_buildCTable(cctx->offcodeCTable, 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);
        /* Every match length code must have non-zero probability */
        CHECK_F (ZSTD_checkDictNCount(matchlengthNCount, matchlengthMaxValue, MaxML));
        CHECK_E (FSE_buildCTable(cctx->matchlengthCTable, 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);
        /* Every literal length code must have non-zero probability */
        CHECK_F (ZSTD_checkDictNCount(litlengthNCount, litlengthMaxValue, MaxLL));
        CHECK_E(FSE_buildCTable(cctx->litlengthCTable, litlengthNCount, litlengthMaxValue, litlengthLog), dictionary_corrupted);
        dictPtr += litlengthHeaderSize;
    }

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

    {   U32 offcodeMax = MaxOff;
        if ((size_t)(dictEnd - dictPtr) <= ((U32)-1) - 128 KB) {
            U32 const maxOffset = (U32)(dictEnd - dictPtr) + 128 KB; /* The maximum offset that must be supported */
            /* Calculate minimum offset code required to represent maxOffset */
            offcodeMax = ZSTD_highbit32(maxOffset);
        }
        /* Every possible supported offset <= dictContentSize + 128 KB must be representable */
        CHECK_F (ZSTD_checkDictNCount(offcodeNCount, offcodeMaxValue, MIN(offcodeMax, MaxOff)));
    }

    cctx->flagStaticTables = 1;
    return dictPtr - (const BYTE*)dict;
}

/** ZSTD_compress_insertDictionary() :
*   @return : 0, or an error code */
static size_t ZSTD_compress_insertDictionary(ZSTD_CCtx* zc, const void* dict, size_t dictSize)
{
    if ((dict==NULL) || (dictSize<=8)) return 0;

    /* default : dict is pure content */
    if (MEM_readLE32(dict) != ZSTD_DICT_MAGIC) return ZSTD_loadDictionaryContent(zc, dict, dictSize);
    zc->dictID = zc->params.fParams.noDictIDFlag ? 0 :  MEM_readLE32((const char*)dict+4);

    /* known magic number : dict is parsed for entropy stats and content */
    {   size_t const loadError = ZSTD_loadDictEntropyStats(zc, (const char*)dict+8 /* skip dictHeader */, dictSize-8);
        size_t const eSize = loadError + 8;
        if (ZSTD_isError(loadError)) return loadError;
        return ZSTD_loadDictionaryContent(zc, (const char*)dict+eSize, dictSize-eSize);
    }
}


/*! ZSTD_compressBegin_internal() :
*   @return : 0, or an error code */
static size_t ZSTD_compressBegin_internal(ZSTD_CCtx* cctx,
                             const void* dict, size_t dictSize,
                                   ZSTD_parameters params, U64 pledgedSrcSize)
{
    ZSTD_compResetPolicy_e const crp = dictSize ? ZSTDcrp_fullReset : ZSTDcrp_continue;
    CHECK_F(ZSTD_resetCCtx_advanced(cctx, params, pledgedSrcSize, crp));
    return ZSTD_compress_insertDictionary(cctx, dict, dictSize);
}


/*! ZSTD_compressBegin_advanced() :
*   @return : 0, or an error code */
size_t ZSTD_compressBegin_advanced(ZSTD_CCtx* cctx,
                             const void* dict, size_t dictSize,
                                   ZSTD_parameters params, unsigned long long pledgedSrcSize)
{
    /* compression parameters verification and optimization */
    CHECK_F(ZSTD_checkCParams(params.cParams));
    return ZSTD_compressBegin_internal(cctx, dict, dictSize, params, pledgedSrcSize);
}


size_t ZSTD_compressBegin_usingDict(ZSTD_CCtx* cctx, const void* dict, size_t dictSize, int compressionLevel)
{
    ZSTD_parameters const params = ZSTD_getParams(compressionLevel, 0, dictSize);
    return ZSTD_compressBegin_internal(cctx, dict, dictSize, params, 0);
}


size_t ZSTD_compressBegin(ZSTD_CCtx* zc, int compressionLevel)
{
    return ZSTD_compressBegin_usingDict(zc, NULL, 0, compressionLevel);
}


/*! ZSTD_writeEpilogue() :
*   Ends a frame.
*   @return : nb of bytes written into dst (or an error code) */
static size_t ZSTD_writeEpilogue(ZSTD_CCtx* cctx, void* dst, size_t dstCapacity)
{
    BYTE* const ostart = (BYTE*)dst;
    BYTE* op = ostart;
    size_t fhSize = 0;

    if (cctx->stage == ZSTDcs_created) return ERROR(stage_wrong);  /* init missing */

    /* special case : empty frame */
    if (cctx->stage == ZSTDcs_init) {
        fhSize = ZSTD_writeFrameHeader(dst, dstCapacity, cctx->params, 0, 0);
        if (ZSTD_isError(fhSize)) return fhSize;
        dstCapacity -= fhSize;
        op += fhSize;
        cctx->stage = ZSTDcs_ongoing;
    }

    if (cctx->stage != ZSTDcs_ending) {
        /* write one last empty block, make it the "last" block */
        U32 const cBlockHeader24 = 1 /* last block */ + (((U32)bt_raw)<<1) + 0;
        if (dstCapacity<4) return ERROR(dstSize_tooSmall);
        MEM_writeLE32(op, cBlockHeader24);
        op += ZSTD_blockHeaderSize;
        dstCapacity -= ZSTD_blockHeaderSize;
    }

    if (cctx->params.fParams.checksumFlag) {
        U32 const checksum = (U32) XXH64_digest(&cctx->xxhState);
        if (dstCapacity<4) return ERROR(dstSize_tooSmall);
        MEM_writeLE32(op, checksum);
        op += 4;
    }

    cctx->stage = ZSTDcs_created;  /* return to "created but no init" status */
    return op-ostart;
}


size_t ZSTD_compressEnd (ZSTD_CCtx* cctx,
                         void* dst, size_t dstCapacity,
                   const void* src, size_t srcSize)
{
    size_t endResult;
    size_t const cSize = ZSTD_compressContinue_internal(cctx, dst, dstCapacity, src, srcSize, 1, 1);
    if (ZSTD_isError(cSize)) return cSize;
    endResult = ZSTD_writeEpilogue(cctx, (char*)dst + cSize, dstCapacity-cSize);
    if (ZSTD_isError(endResult)) return endResult;
    return cSize + endResult;
}


static size_t ZSTD_compress_internal (ZSTD_CCtx* cctx,
                               void* dst, size_t dstCapacity,
                         const void* src, size_t srcSize,
                         const void* dict,size_t dictSize,
                               ZSTD_parameters params)
{
    CHECK_F(ZSTD_compressBegin_internal(cctx, dict, dictSize, params, srcSize));
    return ZSTD_compressEnd(cctx, dst,  dstCapacity, src, srcSize);
}

size_t ZSTD_compress_advanced (ZSTD_CCtx* ctx,
                               void* dst, size_t dstCapacity,
                         const void* src, size_t srcSize,
                         const void* dict,size_t dictSize,
                               ZSTD_parameters params)
{
    CHECK_F(ZSTD_checkCParams(params.cParams));
    return ZSTD_compress_internal(ctx, dst, dstCapacity, src, srcSize, dict, dictSize, params);
}

size_t ZSTD_compress_usingDict(ZSTD_CCtx* ctx, void* dst, size_t dstCapacity, const void* src, size_t srcSize, const void* dict, size_t dictSize, int compressionLevel)
{
    ZSTD_parameters params = ZSTD_getParams(compressionLevel, srcSize, dictSize);
    params.fParams.contentSizeFlag = 1;
    return ZSTD_compress_internal(ctx, dst, dstCapacity, src, srcSize, dict, dictSize, params);
}

size_t ZSTD_compressCCtx (ZSTD_CCtx* ctx, void* dst, size_t dstCapacity, const void* src, size_t srcSize, int compressionLevel)
{
    return ZSTD_compress_usingDict(ctx, dst, dstCapacity, src, srcSize, NULL, 0, compressionLevel);
}

size_t ZSTD_compress(void* dst, size_t dstCapacity, const void* src, size_t srcSize, int compressionLevel)
{
    size_t result;
    ZSTD_CCtx ctxBody;
    memset(&ctxBody, 0, sizeof(ctxBody));
    memcpy(&ctxBody.customMem, &defaultCustomMem, sizeof(ZSTD_customMem));
    result = ZSTD_compressCCtx(&ctxBody, dst, dstCapacity, src, srcSize, compressionLevel);
    ZSTD_free(ctxBody.workSpace, defaultCustomMem);  /* can't free ctxBody itself, as it's on stack; free only heap content */
    return result;
}


/* =====  Dictionary API  ===== */

struct ZSTD_CDict_s {
    void* dictContent;
    size_t dictContentSize;
    ZSTD_CCtx* refContext;
};  /* typedef'd tp ZSTD_CDict within "zstd.h" */

size_t ZSTD_sizeof_CDict(const ZSTD_CDict* cdict)
{
    if (cdict==NULL) return 0;   /* support sizeof on NULL */
    return ZSTD_sizeof_CCtx(cdict->refContext) + cdict->dictContentSize;
}

ZSTD_CDict* ZSTD_createCDict_advanced(const void* dict, size_t dictSize, ZSTD_parameters params, ZSTD_customMem customMem)
{
    if (!customMem.customAlloc && !customMem.customFree) customMem = defaultCustomMem;
    if (!customMem.customAlloc || !customMem.customFree) return NULL;

    {   ZSTD_CDict* const cdict = (ZSTD_CDict*) ZSTD_malloc(sizeof(ZSTD_CDict), customMem);
        void* const dictContent = ZSTD_malloc(dictSize, customMem);
        ZSTD_CCtx* const cctx = ZSTD_createCCtx_advanced(customMem);

        if (!dictContent || !cdict || !cctx) {
            ZSTD_free(dictContent, customMem);
            ZSTD_free(cdict, customMem);
            ZSTD_free(cctx, customMem);
            return NULL;
        }

        if (dictSize) {
            memcpy(dictContent, dict, dictSize);
        }
        {   size_t const errorCode = ZSTD_compressBegin_advanced(cctx, dictContent, dictSize, params, 0);
            if (ZSTD_isError(errorCode)) {
                ZSTD_free(dictContent, customMem);
                ZSTD_free(cdict, customMem);
                ZSTD_free(cctx, customMem);
                return NULL;
        }   }

        cdict->dictContent = dictContent;
        cdict->dictContentSize = dictSize;
        cdict->refContext = cctx;
        return cdict;
    }
}

ZSTD_CDict* ZSTD_createCDict(const void* dict, size_t dictSize, int compressionLevel)
{
    ZSTD_customMem const allocator = { NULL, NULL, NULL };
    ZSTD_parameters params = ZSTD_getParams(compressionLevel, 0, dictSize);
    params.fParams.contentSizeFlag = 1;
    return ZSTD_createCDict_advanced(dict, dictSize, params, allocator);
}

size_t ZSTD_freeCDict(ZSTD_CDict* cdict)
{
    if (cdict==NULL) return 0;   /* support free on NULL */
    {   ZSTD_customMem const cMem = cdict->refContext->customMem;
        ZSTD_freeCCtx(cdict->refContext);
        ZSTD_free(cdict->dictContent, cMem);
        ZSTD_free(cdict, cMem);
        return 0;
    }
}

static ZSTD_parameters ZSTD_getParamsFromCDict(const ZSTD_CDict* cdict) {
    return ZSTD_getParamsFromCCtx(cdict->refContext);
}

size_t ZSTD_compressBegin_usingCDict(ZSTD_CCtx* cctx, const ZSTD_CDict* cdict, U64 pledgedSrcSize)
{
    if (cdict->dictContentSize) CHECK_F(ZSTD_copyCCtx(cctx, cdict->refContext, pledgedSrcSize))
    else CHECK_F(ZSTD_compressBegin_advanced(cctx, NULL, 0, cdict->refContext->params, pledgedSrcSize));
    return 0;
}

/*! ZSTD_compress_usingCDict() :
*   Compression using a digested Dictionary.
*   Faster startup than ZSTD_compress_usingDict(), recommended when same dictionary is used multiple times.
*   Note that compression level is decided during dictionary creation */
size_t ZSTD_compress_usingCDict(ZSTD_CCtx* cctx,
                                void* dst, size_t dstCapacity,
                                const void* src, size_t srcSize,
                                const ZSTD_CDict* cdict)
{
    CHECK_F(ZSTD_compressBegin_usingCDict(cctx, cdict, srcSize));

    if (cdict->refContext->params.fParams.contentSizeFlag==1) {
        cctx->params.fParams.contentSizeFlag = 1;
        cctx->frameContentSize = srcSize;
    }

    return ZSTD_compressEnd(cctx, dst, dstCapacity, src, srcSize);
}



/* ******************************************************************
*  Streaming
********************************************************************/

typedef enum { zcss_init, zcss_load, zcss_flush, zcss_final } ZSTD_cStreamStage;

struct ZSTD_CStream_s {
    ZSTD_CCtx* cctx;
    ZSTD_CDict* cdictLocal;
    const ZSTD_CDict* cdict;
    char*  inBuff;
    size_t inBuffSize;
    size_t inToCompress;
    size_t inBuffPos;
    size_t inBuffTarget;
    size_t blockSize;
    char*  outBuff;
    size_t outBuffSize;
    size_t outBuffContentSize;
    size_t outBuffFlushedSize;
    ZSTD_cStreamStage stage;
    U32    checksum;
    U32    frameEnded;
    ZSTD_parameters params;
    ZSTD_customMem customMem;
};   /* typedef'd to ZSTD_CStream within "zstd.h" */

ZSTD_CStream* ZSTD_createCStream(void)
{
    return ZSTD_createCStream_advanced(defaultCustomMem);
}

ZSTD_CStream* ZSTD_createCStream_advanced(ZSTD_customMem customMem)
{
    ZSTD_CStream* zcs;

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

    zcs = (ZSTD_CStream*)ZSTD_malloc(sizeof(ZSTD_CStream), customMem);
    if (zcs==NULL) return NULL;
    memset(zcs, 0, sizeof(ZSTD_CStream));
    memcpy(&zcs->customMem, &customMem, sizeof(ZSTD_customMem));
    zcs->cctx = ZSTD_createCCtx_advanced(customMem);
    if (zcs->cctx == NULL) { ZSTD_freeCStream(zcs); return NULL; }
    return zcs;
}

size_t ZSTD_freeCStream(ZSTD_CStream* zcs)
{
    if (zcs==NULL) return 0;   /* support free on NULL */
    {   ZSTD_customMem const cMem = zcs->customMem;
        ZSTD_freeCCtx(zcs->cctx);
        ZSTD_freeCDict(zcs->cdictLocal);
        ZSTD_free(zcs->inBuff, cMem);
        ZSTD_free(zcs->outBuff, cMem);
        ZSTD_free(zcs, cMem);
        return 0;
    }
}


/*======   Initialization   ======*/

size_t ZSTD_CStreamInSize(void)  { return ZSTD_BLOCKSIZE_ABSOLUTEMAX; }
size_t ZSTD_CStreamOutSize(void) { return ZSTD_compressBound(ZSTD_BLOCKSIZE_ABSOLUTEMAX) + ZSTD_blockHeaderSize + 4 /* 32-bits hash */ ; }

size_t ZSTD_resetCStream(ZSTD_CStream* zcs, unsigned long long pledgedSrcSize)
{
    if (zcs->inBuffSize==0) return ERROR(stage_wrong);   /* zcs has not been init at least once */

    if (zcs->cdict) CHECK_F(ZSTD_compressBegin_usingCDict(zcs->cctx, zcs->cdict, pledgedSrcSize))
    else CHECK_F(ZSTD_compressBegin_advanced(zcs->cctx, NULL, 0, zcs->params, pledgedSrcSize));

    zcs->inToCompress = 0;
    zcs->inBuffPos = 0;
    zcs->inBuffTarget = zcs->blockSize;
    zcs->outBuffContentSize = zcs->outBuffFlushedSize = 0;
    zcs->stage = zcss_load;
    zcs->frameEnded = 0;
    return 0;   /* ready to go */
}

size_t ZSTD_initCStream_advanced(ZSTD_CStream* zcs,
                                 const void* dict, size_t dictSize,
                                 ZSTD_parameters params, unsigned long long pledgedSrcSize)
{
    /* allocate buffers */
    {   size_t const neededInBuffSize = (size_t)1 << params.cParams.windowLog;
        if (zcs->inBuffSize < neededInBuffSize) {
            zcs->inBuffSize = neededInBuffSize;
            ZSTD_free(zcs->inBuff, zcs->customMem);
            zcs->inBuff = (char*) ZSTD_malloc(neededInBuffSize, zcs->customMem);
            if (zcs->inBuff == NULL) return ERROR(memory_allocation);
        }
        zcs->blockSize = MIN(ZSTD_BLOCKSIZE_ABSOLUTEMAX, neededInBuffSize);
    }
    if (zcs->outBuffSize < ZSTD_compressBound(zcs->blockSize)+1) {
        zcs->outBuffSize = ZSTD_compressBound(zcs->blockSize)+1;
        ZSTD_free(zcs->outBuff, zcs->customMem);
        zcs->outBuff = (char*) ZSTD_malloc(zcs->outBuffSize, zcs->customMem);
        if (zcs->outBuff == NULL) return ERROR(memory_allocation);
    }

    if (dict) {
        ZSTD_freeCDict(zcs->cdictLocal);
        zcs->cdictLocal = ZSTD_createCDict_advanced(dict, dictSize, params, zcs->customMem);
        if (zcs->cdictLocal == NULL) return ERROR(memory_allocation);
        zcs->cdict = zcs->cdictLocal;
    } else zcs->cdict = NULL;

    zcs->checksum = params.fParams.checksumFlag > 0;
    zcs->params = params;

    return ZSTD_resetCStream(zcs, pledgedSrcSize);
}

/* note : cdict must outlive compression session */
size_t ZSTD_initCStream_usingCDict(ZSTD_CStream* zcs, const ZSTD_CDict* cdict)
{
    ZSTD_parameters const params = ZSTD_getParamsFromCDict(cdict);
    size_t const initError =  ZSTD_initCStream_advanced(zcs, NULL, 0, params, 0);
    zcs->cdict = cdict;
    return initError;
}

size_t ZSTD_initCStream_usingDict(ZSTD_CStream* zcs, const void* dict, size_t dictSize, int compressionLevel)
{
    ZSTD_parameters const params = ZSTD_getParams(compressionLevel, 0, dictSize);
    return ZSTD_initCStream_advanced(zcs, dict, dictSize, params, 0);
}

size_t ZSTD_initCStream(ZSTD_CStream* zcs, int compressionLevel)
{
    return ZSTD_initCStream_usingDict(zcs, NULL, 0, compressionLevel);
}

size_t ZSTD_sizeof_CStream(const ZSTD_CStream* zcs)
{
    if (zcs==NULL) return 0;   /* support sizeof on NULL */
    return sizeof(zcs) + ZSTD_sizeof_CCtx(zcs->cctx) + ZSTD_sizeof_CDict(zcs->cdictLocal) + zcs->outBuffSize + zcs->inBuffSize;
}

/*======   Compression   ======*/

typedef enum { zsf_gather, zsf_flush, zsf_end } ZSTD_flush_e;

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;
}

static size_t ZSTD_compressStream_generic(ZSTD_CStream* zcs,
                              void* dst, size_t* dstCapacityPtr,
                        const void* src, size_t* srcSizePtr,
                              ZSTD_flush_e const flush)
{
    U32 someMoreWork = 1;
    const char* const istart = (const char*)src;
    const char* const iend = istart + *srcSizePtr;
    const char* ip = istart;
    char* const ostart = (char*)dst;
    char* const oend = ostart + *dstCapacityPtr;
    char* op = ostart;

    while (someMoreWork) {
        switch(zcs->stage)
        {
        case zcss_init: return ERROR(init_missing);   /* call ZBUFF_compressInit() first ! */

        case zcss_load:
            /* complete inBuffer */
            {   size_t const toLoad = zcs->inBuffTarget - zcs->inBuffPos;
                size_t const loaded = ZSTD_limitCopy(zcs->inBuff + zcs->inBuffPos, toLoad, ip, iend-ip);
                zcs->inBuffPos += loaded;
                ip += loaded;
                if ( (zcs->inBuffPos==zcs->inToCompress) || (!flush && (toLoad != loaded)) ) {
                    someMoreWork = 0; break;  /* not enough input to get a full block : stop there, wait for more */
            }   }
            /* compress current block (note : this stage cannot be stopped in the middle) */
            {   void* cDst;
                size_t cSize;
                size_t const iSize = zcs->inBuffPos - zcs->inToCompress;
                size_t oSize = oend-op;
                if (oSize >= ZSTD_compressBound(iSize))
                    cDst = op;   /* compress directly into output buffer (avoid flush stage) */
                else
                    cDst = zcs->outBuff, oSize = zcs->outBuffSize;
                cSize = (flush == zsf_end) ?
                        ZSTD_compressEnd(zcs->cctx, cDst, oSize, zcs->inBuff + zcs->inToCompress, iSize) :
                        ZSTD_compressContinue(zcs->cctx, cDst, oSize, zcs->inBuff + zcs->inToCompress, iSize);
                if (ZSTD_isError(cSize)) return cSize;
                if (flush == zsf_end) zcs->frameEnded = 1;
                /* prepare next block */
                zcs->inBuffTarget = zcs->inBuffPos + zcs->blockSize;
                if (zcs->inBuffTarget > zcs->inBuffSize)
                    zcs->inBuffPos = 0, zcs->inBuffTarget = zcs->blockSize;   /* note : inBuffSize >= blockSize */
                zcs->inToCompress = zcs->inBuffPos;
                if (cDst == op) { op += cSize; break; }   /* no need to flush */
                zcs->outBuffContentSize = cSize;
                zcs->outBuffFlushedSize = 0;
                zcs->stage = zcss_flush;   /* pass-through to flush stage */
            }

        case zcss_flush:
            {   size_t const toFlush = zcs->outBuffContentSize - zcs->outBuffFlushedSize;
                size_t const flushed = ZSTD_limitCopy(op, oend-op, zcs->outBuff + zcs->outBuffFlushedSize, toFlush);
                op += flushed;
                zcs->outBuffFlushedSize += flushed;
                if (toFlush!=flushed) { someMoreWork = 0; break; }  /* dst too small to store flushed data : stop there */
                zcs->outBuffContentSize = zcs->outBuffFlushedSize = 0;
                zcs->stage = zcss_load;
                break;
            }

        case zcss_final:
            someMoreWork = 0;   /* do nothing */
            break;

        default:
            return ERROR(GENERIC);   /* impossible */
        }
    }

    *srcSizePtr = ip - istart;
    *dstCapacityPtr = op - ostart;
    if (zcs->frameEnded) return 0;
    {   size_t hintInSize = zcs->inBuffTarget - zcs->inBuffPos;
        if (hintInSize==0) hintInSize = zcs->blockSize;
        return hintInSize;
    }
}

size_t ZSTD_compressStream(ZSTD_CStream* zcs, ZSTD_outBuffer* output, ZSTD_inBuffer* input)
{
    size_t sizeRead = input->size - input->pos;
    size_t sizeWritten = output->size - output->pos;
    size_t const result = ZSTD_compressStream_generic(zcs,
                                                      (char*)(output->dst) + output->pos, &sizeWritten,
                                                      (const char*)(input->src) + input->pos, &sizeRead, zsf_gather);
    input->pos += sizeRead;
    output->pos += sizeWritten;
    return result;
}


/*======   Finalize   ======*/

/*! ZSTD_flushStream() :
*   @return : amount of data remaining to flush */
size_t ZSTD_flushStream(ZSTD_CStream* zcs, ZSTD_outBuffer* output)
{
    size_t srcSize = 0;
    size_t sizeWritten = output->size - output->pos;
    size_t const result = ZSTD_compressStream_generic(zcs,
                                                     (char*)(output->dst) + output->pos, &sizeWritten,
                                                     &srcSize, &srcSize, /* use a valid src address instead of NULL */
                                                      zsf_flush);
    output->pos += sizeWritten;
    if (ZSTD_isError(result)) return result;
    return zcs->outBuffContentSize - zcs->outBuffFlushedSize;   /* remaining to flush */
}


size_t ZSTD_endStream(ZSTD_CStream* zcs, ZSTD_outBuffer* output)
{
    BYTE* const ostart = (BYTE*)(output->dst) + output->pos;
    BYTE* const oend = (BYTE*)(output->dst) + output->size;
    BYTE* op = ostart;

    if (zcs->stage != zcss_final) {
        /* flush whatever remains */
        size_t srcSize = 0;
        size_t sizeWritten = output->size - output->pos;
        size_t const notEnded = ZSTD_compressStream_generic(zcs, ostart, &sizeWritten, &srcSize, &srcSize, zsf_end);  /* use a valid src address instead of NULL */
        size_t const remainingToFlush = zcs->outBuffContentSize - zcs->outBuffFlushedSize;
        op += sizeWritten;
        if (remainingToFlush) {
            output->pos += sizeWritten;
            return remainingToFlush + ZSTD_BLOCKHEADERSIZE /* final empty block */ + (zcs->checksum * 4);
        }
        /* create epilogue */
        zcs->stage = zcss_final;
        zcs->outBuffContentSize = !notEnded ? 0 :
            ZSTD_compressEnd(zcs->cctx, zcs->outBuff, zcs->outBuffSize, NULL, 0);  /* write epilogue, including final empty block, into outBuff */
    }

    /* flush epilogue */
    {   size_t const toFlush = zcs->outBuffContentSize - zcs->outBuffFlushedSize;
        size_t const flushed = ZSTD_limitCopy(op, oend-op, zcs->outBuff + zcs->outBuffFlushedSize, toFlush);
        op += flushed;
        zcs->outBuffFlushedSize += flushed;
        output->pos += op-ostart;
        if (toFlush==flushed) zcs->stage = zcss_init;  /* end reached */
        return toFlush - flushed;
    }
}



/*-=====  Pre-defined compression levels  =====-*/

#define ZSTD_DEFAULT_CLEVEL 1
#define ZSTD_MAX_CLEVEL     22
int ZSTD_maxCLevel(void) { return ZSTD_MAX_CLEVEL; }

static const ZSTD_compressionParameters ZSTD_defaultCParameters[4][ZSTD_MAX_CLEVEL+1] = {
{   /* "default" */
    /* W,  C,  H,  S,  L, TL, strat */
    { 18, 12, 12,  1,  7, 16, ZSTD_fast    },  /* level  0 - never used */
    { 19, 13, 14,  1,  7, 16, ZSTD_fast    },  /* level  1 */
    { 19, 15, 16,  1,  6, 16, ZSTD_fast    },  /* level  2 */
    { 20, 16, 17,  1,  5, 16, ZSTD_dfast   },  /* level  3.*/
    { 20, 18, 18,  1,  5, 16, ZSTD_dfast   },  /* level  4.*/
    { 20, 15, 18,  3,  5, 16, ZSTD_greedy  },  /* level  5 */
    { 21, 16, 19,  2,  5, 16, ZSTD_lazy    },  /* level  6 */
    { 21, 17, 20,  3,  5, 16, ZSTD_lazy    },  /* level  7 */
    { 21, 18, 20,  3,  5, 16, ZSTD_lazy2   },  /* level  8 */
    { 21, 20, 20,  3,  5, 16, ZSTD_lazy2   },  /* level  9 */
    { 21, 19, 21,  4,  5, 16, ZSTD_lazy2   },  /* level 10 */
    { 22, 20, 22,  4,  5, 16, ZSTD_lazy2   },  /* level 11 */
    { 22, 20, 22,  5,  5, 16, ZSTD_lazy2   },  /* level 12 */
    { 22, 21, 22,  5,  5, 16, ZSTD_lazy2   },  /* level 13 */
    { 22, 21, 22,  6,  5, 16, ZSTD_lazy2   },  /* level 14 */
    { 22, 21, 21,  5,  5, 16, ZSTD_btlazy2 },  /* level 15 */
    { 23, 22, 22,  5,  5, 16, ZSTD_btlazy2 },  /* level 16 */
    { 23, 21, 22,  4,  5, 24, ZSTD_btopt   },  /* level 17 */
    { 23, 23, 22,  6,  5, 32, ZSTD_btopt   },  /* level 18 */
    { 23, 23, 22,  6,  3, 48, ZSTD_btopt   },  /* level 19 */
    { 25, 25, 23,  7,  3, 64, ZSTD_btopt2  },  /* level 20 */
    { 26, 26, 23,  7,  3,256, ZSTD_btopt2  },  /* level 21 */
    { 27, 27, 25,  9,  3,512, ZSTD_btopt2  },  /* level 22 */
},
{   /* for srcSize <= 256 KB */
    /* W,  C,  H,  S,  L,  T, strat */
    {  0,  0,  0,  0,  0,  0, ZSTD_fast    },  /* level  0 - not used */
    { 18, 13, 14,  1,  6,  8, ZSTD_fast    },  /* level  1 */
    { 18, 14, 13,  1,  5,  8, ZSTD_dfast   },  /* level  2 */
    { 18, 16, 15,  1,  5,  8, ZSTD_dfast   },  /* level  3 */
    { 18, 15, 17,  1,  5,  8, ZSTD_greedy  },  /* level  4.*/
    { 18, 16, 17,  4,  5,  8, ZSTD_greedy  },  /* level  5.*/
    { 18, 16, 17,  3,  5,  8, ZSTD_lazy    },  /* level  6.*/
    { 18, 17, 17,  4,  4,  8, ZSTD_lazy    },  /* level  7 */
    { 18, 17, 17,  4,  4,  8, ZSTD_lazy2   },  /* level  8 */
    { 18, 17, 17,  5,  4,  8, ZSTD_lazy2   },  /* level  9 */
    { 18, 17, 17,  6,  4,  8, ZSTD_lazy2   },  /* level 10 */
    { 18, 18, 17,  6,  4,  8, ZSTD_lazy2   },  /* level 11.*/
    { 18, 18, 17,  7,  4,  8, ZSTD_lazy2   },  /* level 12.*/
    { 18, 19, 17,  6,  4,  8, ZSTD_btlazy2 },  /* level 13 */
    { 18, 18, 18,  4,  4, 16, ZSTD_btopt   },  /* level 14.*/
    { 18, 18, 18,  4,  3, 16, ZSTD_btopt   },  /* level 15.*/
    { 18, 19, 18,  6,  3, 32, ZSTD_btopt   },  /* level 16.*/
    { 18, 19, 18,  8,  3, 64, ZSTD_btopt   },  /* level 17.*/
    { 18, 19, 18,  9,  3,128, ZSTD_btopt   },  /* level 18.*/
    { 18, 19, 18, 10,  3,256, ZSTD_btopt   },  /* level 19.*/
    { 18, 19, 18, 11,  3,512, ZSTD_btopt2  },  /* level 20.*/
    { 18, 19, 18, 12,  3,512, ZSTD_btopt2  },  /* level 21.*/
    { 18, 19, 18, 13,  3,512, ZSTD_btopt2  },  /* level 22.*/
},
{   /* for srcSize <= 128 KB */
    /* W,  C,  H,  S,  L,  T, strat */
    { 17, 12, 12,  1,  7,  8, ZSTD_fast    },  /* level  0 - not used */
    { 17, 12, 13,  1,  6,  8, ZSTD_fast    },  /* level  1 */
    { 17, 13, 16,  1,  5,  8, ZSTD_fast    },  /* level  2 */
    { 17, 16, 16,  2,  5,  8, ZSTD_dfast   },  /* level  3 */
    { 17, 13, 15,  3,  4,  8, ZSTD_greedy  },  /* level  4 */
    { 17, 15, 17,  4,  4,  8, ZSTD_greedy  },  /* level  5 */
    { 17, 16, 17,  3,  4,  8, ZSTD_lazy    },  /* level  6 */
    { 17, 15, 17,  4,  4,  8, ZSTD_lazy2   },  /* level  7 */
    { 17, 17, 17,  4,  4,  8, ZSTD_lazy2   },  /* level  8 */
    { 17, 17, 17,  5,  4,  8, ZSTD_lazy2   },  /* level  9 */
    { 17, 17, 17,  6,  4,  8, ZSTD_lazy2   },  /* level 10 */
    { 17, 17, 17,  7,  4,  8, ZSTD_lazy2   },  /* level 11 */
    { 17, 17, 17,  8,  4,  8, ZSTD_lazy2   },  /* level 12 */
    { 17, 18, 17,  6,  4,  8, ZSTD_btlazy2 },  /* level 13.*/
    { 17, 17, 17,  7,  3,  8, ZSTD_btopt   },  /* level 14.*/
    { 17, 17, 17,  7,  3, 16, ZSTD_btopt   },  /* level 15.*/
    { 17, 18, 17,  7,  3, 32, ZSTD_btopt   },  /* level 16.*/
    { 17, 18, 17,  7,  3, 64, ZSTD_btopt   },  /* level 17.*/
    { 17, 18, 17,  7,  3,256, ZSTD_btopt   },  /* level 18.*/
    { 17, 18, 17,  8,  3,256, ZSTD_btopt   },  /* level 19.*/
    { 17, 18, 17,  9,  3,256, ZSTD_btopt2  },  /* level 20.*/
    { 17, 18, 17, 10,  3,256, ZSTD_btopt2  },  /* level 21.*/
    { 17, 18, 17, 11,  3,512, ZSTD_btopt2  },  /* level 22.*/
},
{   /* for srcSize <= 16 KB */
    /* W,  C,  H,  S,  L,  T, strat */
    { 14, 12, 12,  1,  7,  6, ZSTD_fast    },  /* level  0 - not used */
    { 14, 14, 14,  1,  6,  6, ZSTD_fast    },  /* level  1 */
    { 14, 14, 14,  1,  4,  6, ZSTD_fast    },  /* level  2 */
    { 14, 14, 14,  1,  4,  6, ZSTD_dfast   },  /* level  3.*/
    { 14, 14, 14,  4,  4,  6, ZSTD_greedy  },  /* level  4.*/
    { 14, 14, 14,  3,  4,  6, ZSTD_lazy    },  /* level  5.*/
    { 14, 14, 14,  4,  4,  6, ZSTD_lazy2   },  /* level  6 */
    { 14, 14, 14,  5,  4,  6, ZSTD_lazy2   },  /* level  7 */
    { 14, 14, 14,  6,  4,  6, ZSTD_lazy2   },  /* level  8.*/
    { 14, 15, 14,  6,  4,  6, ZSTD_btlazy2 },  /* level  9.*/
    { 14, 15, 14,  3,  3,  6, ZSTD_btopt   },  /* level 10.*/
    { 14, 15, 14,  6,  3,  8, ZSTD_btopt   },  /* level 11.*/
    { 14, 15, 14,  6,  3, 16, ZSTD_btopt   },  /* level 12.*/
    { 14, 15, 14,  6,  3, 24, ZSTD_btopt   },  /* level 13.*/
    { 14, 15, 15,  6,  3, 48, ZSTD_btopt   },  /* level 14.*/
    { 14, 15, 15,  6,  3, 64, ZSTD_btopt   },  /* level 15.*/
    { 14, 15, 15,  6,  3, 96, ZSTD_btopt   },  /* level 16.*/
    { 14, 15, 15,  6,  3,128, ZSTD_btopt   },  /* level 17.*/
    { 14, 15, 15,  6,  3,256, ZSTD_btopt   },  /* level 18.*/
    { 14, 15, 15,  7,  3,256, ZSTD_btopt   },  /* level 19.*/
    { 14, 15, 15,  8,  3,256, ZSTD_btopt2  },  /* level 20.*/
    { 14, 15, 15,  9,  3,256, ZSTD_btopt2  },  /* level 21.*/
    { 14, 15, 15, 10,  3,256, ZSTD_btopt2  },  /* level 22.*/
},
};

/*! ZSTD_getCParams() :
*   @return ZSTD_compressionParameters structure for a selected compression level, `srcSize` and `dictSize`.
*   Size values are optional, provide 0 if not known or unused */
ZSTD_compressionParameters ZSTD_getCParams(int compressionLevel, unsigned long long srcSize, size_t dictSize)
{
    ZSTD_compressionParameters cp;
    size_t const addedSize = srcSize ? 0 : 500;
    U64 const rSize = srcSize+dictSize ? srcSize+dictSize+addedSize : (U64)-1;
    U32 const tableID = (rSize <= 256 KB) + (rSize <= 128 KB) + (rSize <= 16 KB);   /* intentional underflow for srcSizeHint == 0 */
    if (compressionLevel <= 0) compressionLevel = ZSTD_DEFAULT_CLEVEL;   /* 0 == default; no negative compressionLevel yet */
    if (compressionLevel > ZSTD_MAX_CLEVEL) compressionLevel = ZSTD_MAX_CLEVEL;
    cp = ZSTD_defaultCParameters[tableID][compressionLevel];
    if (MEM_32bits()) {   /* auto-correction, for 32-bits mode */
        if (cp.windowLog > ZSTD_WINDOWLOG_MAX) cp.windowLog = ZSTD_WINDOWLOG_MAX;
        if (cp.chainLog > ZSTD_CHAINLOG_MAX) cp.chainLog = ZSTD_CHAINLOG_MAX;
        if (cp.hashLog > ZSTD_HASHLOG_MAX) cp.hashLog = ZSTD_HASHLOG_MAX;
    }
    cp = ZSTD_adjustCParams(cp, srcSize, dictSize);
    return cp;
}

/*! ZSTD_getParams() :
*   same as ZSTD_getCParams(), but @return a `ZSTD_parameters` object (instead of `ZSTD_compressionParameters`).
*   All fields of `ZSTD_frameParameters` are set to default (0) */
ZSTD_parameters ZSTD_getParams(int compressionLevel, unsigned long long srcSize, size_t dictSize) {
    ZSTD_parameters params;
    ZSTD_compressionParameters const cParams = ZSTD_getCParams(compressionLevel, srcSize, dictSize);
    memset(&params, 0, sizeof(params));
    params.cParams = cParams;
    return params;
}