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mikronova/openzl-sys-rs

openzl/deps/zstd/lib/compress/zstd_compress.c

/*
 * Copyright (c) Meta Platforms, Inc. and affiliates.
 * All rights reserved.
 *
 * This source code is licensed under both the BSD-style license (found in the
 * LICENSE file in the root directory of this source tree) and the GPLv2 (found
 * in the COPYING file in the root directory of this source tree).
 * You may select, at your option, one of the above-listed licenses.
 */

/*-*************************************
*  Dependencies
***************************************/
#include "../common/allocations.h"  /* ZSTD_customMalloc, ZSTD_customCalloc, ZSTD_customFree */
#include "../common/zstd_deps.h"  /* INT_MAX, ZSTD_memset, ZSTD_memcpy */
#include "../common/mem.h"
#include "../common/error_private.h"
#include "hist.h"           /* HIST_countFast_wksp */
#define FSE_STATIC_LINKING_ONLY   /* FSE_encodeSymbol */
#include "../common/fse.h"
#include "../common/huf.h"
#include "zstd_compress_internal.h"
#include "zstd_compress_sequences.h"
#include "zstd_compress_literals.h"
#include "zstd_fast.h"
#include "zstd_double_fast.h"
#include "zstd_lazy.h"
#include "zstd_opt.h"
#include "zstd_ldm.h"
#include "zstd_compress_superblock.h"
#include  "../common/bits.h"      /* ZSTD_highbit32, ZSTD_rotateRight_U64 */

/* ***************************************************************
*  Tuning parameters
*****************************************************************/
/*!
 * COMPRESS_HEAPMODE :
 * Select how default decompression function ZSTD_compress() allocates its context,
 * on stack (0, default), or into heap (1).
 * Note that functions with explicit context such as ZSTD_compressCCtx() are unaffected.
 */
#ifndef ZSTD_COMPRESS_HEAPMODE
#  define ZSTD_COMPRESS_HEAPMODE 0
#endif

/*!
 * ZSTD_HASHLOG3_MAX :
 * Maximum size of the hash table dedicated to find 3-bytes matches,
 * in log format, aka 17 => 1 << 17 == 128Ki positions.
 * This structure is only used in zstd_opt.
 * Since allocation is centralized for all strategies, it has to be known here.
 * The actual (selected) size of the hash table is then stored in ZSTD_MatchState_t.hashLog3,
 * so that zstd_opt.c doesn't need to know about this constant.
 */
#ifndef ZSTD_HASHLOG3_MAX
#  define ZSTD_HASHLOG3_MAX 17
#endif

/*-*************************************
*  Helper functions
***************************************/
/* ZSTD_compressBound()
 * Note that the result from this function is only valid for
 * the one-pass compression functions.
 * When employing the streaming mode,
 * if flushes are frequently altering the size of blocks,
 * the overhead from block headers can make the compressed data larger
 * than the return value of ZSTD_compressBound().
 */
size_t ZSTD_compressBound(size_t srcSize) {
    size_t const r = ZSTD_COMPRESSBOUND(srcSize);
    if (r==0) return ERROR(srcSize_wrong);
    return r;
}


/*-*************************************
*  Context memory management
***************************************/
struct ZSTD_CDict_s {
    const void* dictContent;
    size_t dictContentSize;
    ZSTD_dictContentType_e dictContentType; /* The dictContentType the CDict was created with */
    U32* entropyWorkspace; /* entropy workspace of HUF_WORKSPACE_SIZE bytes */
    ZSTD_cwksp workspace;
    ZSTD_MatchState_t matchState;
    ZSTD_compressedBlockState_t cBlockState;
    ZSTD_customMem customMem;
    U32 dictID;
    int compressionLevel; /* 0 indicates that advanced API was used to select CDict params */
    ZSTD_ParamSwitch_e useRowMatchFinder; /* Indicates whether the CDict was created with params that would use
                                           * row-based matchfinder. Unless the cdict is reloaded, we will use
                                           * the same greedy/lazy matchfinder at compression time.
                                           */
};  /* typedef'd to ZSTD_CDict within "zstd.h" */

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

static void ZSTD_initCCtx(ZSTD_CCtx* cctx, ZSTD_customMem memManager)
{
    assert(cctx != NULL);
    ZSTD_memset(cctx, 0, sizeof(*cctx));
    cctx->customMem = memManager;
    cctx->bmi2 = ZSTD_cpuSupportsBmi2();
    {   size_t const err = ZSTD_CCtx_reset(cctx, ZSTD_reset_parameters);
        assert(!ZSTD_isError(err));
        (void)err;
    }
}

ZSTD_CCtx* ZSTD_createCCtx_advanced(ZSTD_customMem customMem)
{
    ZSTD_STATIC_ASSERT(zcss_init==0);
    ZSTD_STATIC_ASSERT(ZSTD_CONTENTSIZE_UNKNOWN==(0ULL - 1));
    if ((!customMem.customAlloc) ^ (!customMem.customFree)) return NULL;
    {   ZSTD_CCtx* const cctx = (ZSTD_CCtx*)ZSTD_customMalloc(sizeof(ZSTD_CCtx), customMem);
        if (!cctx) return NULL;
        ZSTD_initCCtx(cctx, customMem);
        return cctx;
    }
}

ZSTD_CCtx* ZSTD_initStaticCCtx(void* workspace, size_t workspaceSize)
{
    ZSTD_cwksp ws;
    ZSTD_CCtx* cctx;
    if (workspaceSize <= sizeof(ZSTD_CCtx)) return NULL;  /* minimum size */
    if ((size_t)workspace & 7) return NULL;  /* must be 8-aligned */
    ZSTD_cwksp_init(&ws, workspace, workspaceSize, ZSTD_cwksp_static_alloc);

    cctx = (ZSTD_CCtx*)ZSTD_cwksp_reserve_object(&ws, sizeof(ZSTD_CCtx));
    if (cctx == NULL) return NULL;

    ZSTD_memset(cctx, 0, sizeof(ZSTD_CCtx));
    ZSTD_cwksp_move(&cctx->workspace, &ws);
    cctx->staticSize = workspaceSize;

    /* statically sized space. tmpWorkspace never moves (but prev/next block swap places) */
    if (!ZSTD_cwksp_check_available(&cctx->workspace, TMP_WORKSPACE_SIZE + 2 * sizeof(ZSTD_compressedBlockState_t))) return NULL;
    cctx->blockState.prevCBlock = (ZSTD_compressedBlockState_t*)ZSTD_cwksp_reserve_object(&cctx->workspace, sizeof(ZSTD_compressedBlockState_t));
    cctx->blockState.nextCBlock = (ZSTD_compressedBlockState_t*)ZSTD_cwksp_reserve_object(&cctx->workspace, sizeof(ZSTD_compressedBlockState_t));
    cctx->tmpWorkspace = ZSTD_cwksp_reserve_object(&cctx->workspace, TMP_WORKSPACE_SIZE);
    cctx->tmpWkspSize = TMP_WORKSPACE_SIZE;
    cctx->bmi2 = ZSTD_cpuid_bmi2(ZSTD_cpuid());
    return cctx;
}

/**
 * Clears and frees all of the dictionaries in the CCtx.
 */
static void ZSTD_clearAllDicts(ZSTD_CCtx* cctx)
{
    ZSTD_customFree(cctx->localDict.dictBuffer, cctx->customMem);
    ZSTD_freeCDict(cctx->localDict.cdict);
    ZSTD_memset(&cctx->localDict, 0, sizeof(cctx->localDict));
    ZSTD_memset(&cctx->prefixDict, 0, sizeof(cctx->prefixDict));
    cctx->cdict = NULL;
}

static size_t ZSTD_sizeof_localDict(ZSTD_localDict dict)
{
    size_t const bufferSize = dict.dictBuffer != NULL ? dict.dictSize : 0;
    size_t const cdictSize = ZSTD_sizeof_CDict(dict.cdict);
    return bufferSize + cdictSize;
}

static void ZSTD_freeCCtxContent(ZSTD_CCtx* cctx)
{
    assert(cctx != NULL);
    assert(cctx->staticSize == 0);
    ZSTD_clearAllDicts(cctx);
#ifdef ZSTD_MULTITHREAD
    ZSTDMT_freeCCtx(cctx->mtctx); cctx->mtctx = NULL;
#endif
    ZSTD_cwksp_free(&cctx->workspace, cctx->customMem);
}

size_t ZSTD_freeCCtx(ZSTD_CCtx* cctx)
{
    DEBUGLOG(3, "ZSTD_freeCCtx (address: %p)", (void*)cctx);
    if (cctx==NULL) return 0;   /* support free on NULL */
    RETURN_ERROR_IF(cctx->staticSize, memory_allocation,
                    "not compatible with static CCtx");
    {   int cctxInWorkspace = ZSTD_cwksp_owns_buffer(&cctx->workspace, cctx);
        ZSTD_freeCCtxContent(cctx);
        if (!cctxInWorkspace) ZSTD_customFree(cctx, cctx->customMem);
    }
    return 0;
}


static size_t ZSTD_sizeof_mtctx(const ZSTD_CCtx* cctx)
{
#ifdef ZSTD_MULTITHREAD
    return ZSTDMT_sizeof_CCtx(cctx->mtctx);
#else
    (void)cctx;
    return 0;
#endif
}


size_t ZSTD_sizeof_CCtx(const ZSTD_CCtx* cctx)
{
    if (cctx==NULL) return 0;   /* support sizeof on NULL */
    /* cctx may be in the workspace */
    return (cctx->workspace.workspace == cctx ? 0 : sizeof(*cctx))
           + ZSTD_cwksp_sizeof(&cctx->workspace)
           + ZSTD_sizeof_localDict(cctx->localDict)
           + ZSTD_sizeof_mtctx(cctx);
}

size_t ZSTD_sizeof_CStream(const ZSTD_CStream* zcs)
{
    return ZSTD_sizeof_CCtx(zcs);  /* same object */
}

/* private API call, for dictBuilder only */
const SeqStore_t* ZSTD_getSeqStore(const ZSTD_CCtx* ctx) { return &(ctx->seqStore); }

/* Returns true if the strategy supports using a row based matchfinder */
static int ZSTD_rowMatchFinderSupported(const ZSTD_strategy strategy) {
    return (strategy >= ZSTD_greedy && strategy <= ZSTD_lazy2);
}

/* Returns true if the strategy and useRowMatchFinder mode indicate that we will use the row based matchfinder
 * for this compression.
 */
static int ZSTD_rowMatchFinderUsed(const ZSTD_strategy strategy, const ZSTD_ParamSwitch_e mode) {
    assert(mode != ZSTD_ps_auto);
    return ZSTD_rowMatchFinderSupported(strategy) && (mode == ZSTD_ps_enable);
}

/* Returns row matchfinder usage given an initial mode and cParams */
static ZSTD_ParamSwitch_e ZSTD_resolveRowMatchFinderMode(ZSTD_ParamSwitch_e mode,
                                                         const ZSTD_compressionParameters* const cParams) {
    if (mode != ZSTD_ps_auto) return mode; /* if requested enabled, but no SIMD, we still will use row matchfinder */
    mode = ZSTD_ps_disable;
    if (!ZSTD_rowMatchFinderSupported(cParams->strategy)) return mode;
    if (cParams->windowLog > 14) mode = ZSTD_ps_enable;
    return mode;
}

/* Returns block splitter usage (generally speaking, when using slower/stronger compression modes) */
static ZSTD_ParamSwitch_e ZSTD_resolveBlockSplitterMode(ZSTD_ParamSwitch_e mode,
                                                        const ZSTD_compressionParameters* const cParams) {
    if (mode != ZSTD_ps_auto) return mode;
    return (cParams->strategy >= ZSTD_btopt && cParams->windowLog >= 17) ? ZSTD_ps_enable : ZSTD_ps_disable;
}

/* Returns 1 if the arguments indicate that we should allocate a chainTable, 0 otherwise */
static int ZSTD_allocateChainTable(const ZSTD_strategy strategy,
                                   const ZSTD_ParamSwitch_e useRowMatchFinder,
                                   const U32 forDDSDict) {
    assert(useRowMatchFinder != ZSTD_ps_auto);
    /* We always should allocate a chaintable if we are allocating a matchstate for a DDS dictionary matchstate.
     * We do not allocate a chaintable if we are using ZSTD_fast, or are using the row-based matchfinder.
     */
    return forDDSDict || ((strategy != ZSTD_fast) && !ZSTD_rowMatchFinderUsed(strategy, useRowMatchFinder));
}

/* Returns ZSTD_ps_enable if compression parameters are such that we should
 * enable long distance matching (wlog >= 27, strategy >= btopt).
 * Returns ZSTD_ps_disable otherwise.
 */
static ZSTD_ParamSwitch_e ZSTD_resolveEnableLdm(ZSTD_ParamSwitch_e mode,
                                 const ZSTD_compressionParameters* const cParams) {
    if (mode != ZSTD_ps_auto) return mode;
    return (cParams->strategy >= ZSTD_btopt && cParams->windowLog >= 27) ? ZSTD_ps_enable : ZSTD_ps_disable;
}

static int ZSTD_resolveExternalSequenceValidation(int mode) {
    return mode;
}

/* Resolves maxBlockSize to the default if no value is present. */
static size_t ZSTD_resolveMaxBlockSize(size_t maxBlockSize) {
    if (maxBlockSize == 0) {
        return ZSTD_BLOCKSIZE_MAX;
    } else {
        return maxBlockSize;
    }
}

static ZSTD_ParamSwitch_e ZSTD_resolveExternalRepcodeSearch(ZSTD_ParamSwitch_e value, int cLevel) {
    if (value != ZSTD_ps_auto) return value;
    if (cLevel < 10) {
        return ZSTD_ps_disable;
    } else {
        return ZSTD_ps_enable;
    }
}

/* Returns 1 if compression parameters are such that CDict hashtable and chaintable indices are tagged.
 * If so, the tags need to be removed in ZSTD_resetCCtx_byCopyingCDict. */
static int ZSTD_CDictIndicesAreTagged(const ZSTD_compressionParameters* const cParams) {
    return cParams->strategy == ZSTD_fast || cParams->strategy == ZSTD_dfast;
}

static ZSTD_CCtx_params ZSTD_makeCCtxParamsFromCParams(
        ZSTD_compressionParameters cParams)
{
    ZSTD_CCtx_params cctxParams;
    /* should not matter, as all cParams are presumed properly defined */
    ZSTD_CCtxParams_init(&cctxParams, ZSTD_CLEVEL_DEFAULT);
    cctxParams.cParams = cParams;

    /* Adjust advanced params according to cParams */
    cctxParams.ldmParams.enableLdm = ZSTD_resolveEnableLdm(cctxParams.ldmParams.enableLdm, &cParams);
    if (cctxParams.ldmParams.enableLdm == ZSTD_ps_enable) {
        ZSTD_ldm_adjustParameters(&cctxParams.ldmParams, &cParams);
        assert(cctxParams.ldmParams.hashLog >= cctxParams.ldmParams.bucketSizeLog);
        assert(cctxParams.ldmParams.hashRateLog < 32);
    }
    cctxParams.postBlockSplitter = ZSTD_resolveBlockSplitterMode(cctxParams.postBlockSplitter, &cParams);
    cctxParams.useRowMatchFinder = ZSTD_resolveRowMatchFinderMode(cctxParams.useRowMatchFinder, &cParams);
    cctxParams.validateSequences = ZSTD_resolveExternalSequenceValidation(cctxParams.validateSequences);
    cctxParams.maxBlockSize = ZSTD_resolveMaxBlockSize(cctxParams.maxBlockSize);
    cctxParams.searchForExternalRepcodes = ZSTD_resolveExternalRepcodeSearch(cctxParams.searchForExternalRepcodes,
                                                                             cctxParams.compressionLevel);
    assert(!ZSTD_checkCParams(cParams));
    return cctxParams;
}

static ZSTD_CCtx_params* ZSTD_createCCtxParams_advanced(
        ZSTD_customMem customMem)
{
    ZSTD_CCtx_params* params;
    if ((!customMem.customAlloc) ^ (!customMem.customFree)) return NULL;
    params = (ZSTD_CCtx_params*)ZSTD_customCalloc(
            sizeof(ZSTD_CCtx_params), customMem);
    if (!params) { return NULL; }
    ZSTD_CCtxParams_init(params, ZSTD_CLEVEL_DEFAULT);
    params->customMem = customMem;
    return params;
}

ZSTD_CCtx_params* ZSTD_createCCtxParams(void)
{
    return ZSTD_createCCtxParams_advanced(ZSTD_defaultCMem);
}

size_t ZSTD_freeCCtxParams(ZSTD_CCtx_params* params)
{
    if (params == NULL) { return 0; }
    ZSTD_customFree(params, params->customMem);
    return 0;
}

size_t ZSTD_CCtxParams_reset(ZSTD_CCtx_params* params)
{
    return ZSTD_CCtxParams_init(params, ZSTD_CLEVEL_DEFAULT);
}

size_t ZSTD_CCtxParams_init(ZSTD_CCtx_params* cctxParams, int compressionLevel) {
    RETURN_ERROR_IF(!cctxParams, GENERIC, "NULL pointer!");
    ZSTD_memset(cctxParams, 0, sizeof(*cctxParams));
    cctxParams->compressionLevel = compressionLevel;
    cctxParams->fParams.contentSizeFlag = 1;
    return 0;
}

#define ZSTD_NO_CLEVEL 0

/**
 * Initializes `cctxParams` from `params` and `compressionLevel`.
 * @param compressionLevel If params are derived from a compression level then that compression level, otherwise ZSTD_NO_CLEVEL.
 */
static void
ZSTD_CCtxParams_init_internal(ZSTD_CCtx_params* cctxParams,
                        const ZSTD_parameters* params,
                              int compressionLevel)
{
    assert(!ZSTD_checkCParams(params->cParams));
    ZSTD_memset(cctxParams, 0, sizeof(*cctxParams));
    cctxParams->cParams = params->cParams;
    cctxParams->fParams = params->fParams;
    /* Should not matter, as all cParams are presumed properly defined.
     * But, set it for tracing anyway.
     */
    cctxParams->compressionLevel = compressionLevel;
    cctxParams->useRowMatchFinder = ZSTD_resolveRowMatchFinderMode(cctxParams->useRowMatchFinder, &params->cParams);
    cctxParams->postBlockSplitter = ZSTD_resolveBlockSplitterMode(cctxParams->postBlockSplitter, &params->cParams);
    cctxParams->ldmParams.enableLdm = ZSTD_resolveEnableLdm(cctxParams->ldmParams.enableLdm, &params->cParams);
    cctxParams->validateSequences = ZSTD_resolveExternalSequenceValidation(cctxParams->validateSequences);
    cctxParams->maxBlockSize = ZSTD_resolveMaxBlockSize(cctxParams->maxBlockSize);
    cctxParams->searchForExternalRepcodes = ZSTD_resolveExternalRepcodeSearch(cctxParams->searchForExternalRepcodes, compressionLevel);
    DEBUGLOG(4, "ZSTD_CCtxParams_init_internal: useRowMatchFinder=%d, useBlockSplitter=%d ldm=%d",
                cctxParams->useRowMatchFinder, cctxParams->postBlockSplitter, cctxParams->ldmParams.enableLdm);
}

size_t ZSTD_CCtxParams_init_advanced(ZSTD_CCtx_params* cctxParams, ZSTD_parameters params)
{
    RETURN_ERROR_IF(!cctxParams, GENERIC, "NULL pointer!");
    FORWARD_IF_ERROR( ZSTD_checkCParams(params.cParams) , "");
    ZSTD_CCtxParams_init_internal(cctxParams, &params, ZSTD_NO_CLEVEL);
    return 0;
}

/**
 * Sets cctxParams' cParams and fParams from params, but otherwise leaves them alone.
 * @param params Validated zstd parameters.
 */
static void ZSTD_CCtxParams_setZstdParams(
        ZSTD_CCtx_params* cctxParams, const ZSTD_parameters* params)
{
    assert(!ZSTD_checkCParams(params->cParams));
    cctxParams->cParams = params->cParams;
    cctxParams->fParams = params->fParams;
    /* Should not matter, as all cParams are presumed properly defined.
     * But, set it for tracing anyway.
     */
    cctxParams->compressionLevel = ZSTD_NO_CLEVEL;
}

ZSTD_bounds ZSTD_cParam_getBounds(ZSTD_cParameter param)
{
    ZSTD_bounds bounds = { 0, 0, 0 };

    switch(param)
    {
    case ZSTD_c_compressionLevel:
        bounds.lowerBound = ZSTD_minCLevel();
        bounds.upperBound = ZSTD_maxCLevel();
        return bounds;

    case ZSTD_c_windowLog:
        bounds.lowerBound = ZSTD_WINDOWLOG_MIN;
        bounds.upperBound = ZSTD_WINDOWLOG_MAX;
        return bounds;

    case ZSTD_c_hashLog:
        bounds.lowerBound = ZSTD_HASHLOG_MIN;
        bounds.upperBound = ZSTD_HASHLOG_MAX;
        return bounds;

    case ZSTD_c_chainLog:
        bounds.lowerBound = ZSTD_CHAINLOG_MIN;
        bounds.upperBound = ZSTD_CHAINLOG_MAX;
        return bounds;

    case ZSTD_c_searchLog:
        bounds.lowerBound = ZSTD_SEARCHLOG_MIN;
        bounds.upperBound = ZSTD_SEARCHLOG_MAX;
        return bounds;

    case ZSTD_c_minMatch:
        bounds.lowerBound = ZSTD_MINMATCH_MIN;
        bounds.upperBound = ZSTD_MINMATCH_MAX;
        return bounds;

    case ZSTD_c_targetLength:
        bounds.lowerBound = ZSTD_TARGETLENGTH_MIN;
        bounds.upperBound = ZSTD_TARGETLENGTH_MAX;
        return bounds;

    case ZSTD_c_strategy:
        bounds.lowerBound = ZSTD_STRATEGY_MIN;
        bounds.upperBound = ZSTD_STRATEGY_MAX;
        return bounds;

    case ZSTD_c_contentSizeFlag:
        bounds.lowerBound = 0;
        bounds.upperBound = 1;
        return bounds;

    case ZSTD_c_checksumFlag:
        bounds.lowerBound = 0;
        bounds.upperBound = 1;
        return bounds;

    case ZSTD_c_dictIDFlag:
        bounds.lowerBound = 0;
        bounds.upperBound = 1;
        return bounds;

    case ZSTD_c_nbWorkers:
        bounds.lowerBound = 0;
#ifdef ZSTD_MULTITHREAD
        bounds.upperBound = ZSTDMT_NBWORKERS_MAX;
#else
        bounds.upperBound = 0;
#endif
        return bounds;

    case ZSTD_c_jobSize:
        bounds.lowerBound = 0;
#ifdef ZSTD_MULTITHREAD
        bounds.upperBound = ZSTDMT_JOBSIZE_MAX;
#else
        bounds.upperBound = 0;
#endif
        return bounds;

    case ZSTD_c_overlapLog:
#ifdef ZSTD_MULTITHREAD
        bounds.lowerBound = ZSTD_OVERLAPLOG_MIN;
        bounds.upperBound = ZSTD_OVERLAPLOG_MAX;
#else
        bounds.lowerBound = 0;
        bounds.upperBound = 0;
#endif
        return bounds;

    case ZSTD_c_enableDedicatedDictSearch:
        bounds.lowerBound = 0;
        bounds.upperBound = 1;
        return bounds;

    case ZSTD_c_enableLongDistanceMatching:
        bounds.lowerBound = (int)ZSTD_ps_auto;
        bounds.upperBound = (int)ZSTD_ps_disable;
        return bounds;

    case ZSTD_c_ldmHashLog:
        bounds.lowerBound = ZSTD_LDM_HASHLOG_MIN;
        bounds.upperBound = ZSTD_LDM_HASHLOG_MAX;
        return bounds;

    case ZSTD_c_ldmMinMatch:
        bounds.lowerBound = ZSTD_LDM_MINMATCH_MIN;
        bounds.upperBound = ZSTD_LDM_MINMATCH_MAX;
        return bounds;

    case ZSTD_c_ldmBucketSizeLog:
        bounds.lowerBound = ZSTD_LDM_BUCKETSIZELOG_MIN;
        bounds.upperBound = ZSTD_LDM_BUCKETSIZELOG_MAX;
        return bounds;

    case ZSTD_c_ldmHashRateLog:
        bounds.lowerBound = ZSTD_LDM_HASHRATELOG_MIN;
        bounds.upperBound = ZSTD_LDM_HASHRATELOG_MAX;
        return bounds;

    /* experimental parameters */
    case ZSTD_c_rsyncable:
        bounds.lowerBound = 0;
        bounds.upperBound = 1;
        return bounds;

    case ZSTD_c_forceMaxWindow :
        bounds.lowerBound = 0;
        bounds.upperBound = 1;
        return bounds;

    case ZSTD_c_format:
        ZSTD_STATIC_ASSERT(ZSTD_f_zstd1 < ZSTD_f_zstd1_magicless);
        bounds.lowerBound = ZSTD_f_zstd1;
        bounds.upperBound = ZSTD_f_zstd1_magicless;   /* note : how to ensure at compile time that this is the highest value enum ? */
        return bounds;

    case ZSTD_c_forceAttachDict:
        ZSTD_STATIC_ASSERT(ZSTD_dictDefaultAttach < ZSTD_dictForceLoad);
        bounds.lowerBound = ZSTD_dictDefaultAttach;
        bounds.upperBound = ZSTD_dictForceLoad;       /* note : how to ensure at compile time that this is the highest value enum ? */
        return bounds;

    case ZSTD_c_literalCompressionMode:
        ZSTD_STATIC_ASSERT(ZSTD_ps_auto < ZSTD_ps_enable && ZSTD_ps_enable < ZSTD_ps_disable);
        bounds.lowerBound = (int)ZSTD_ps_auto;
        bounds.upperBound = (int)ZSTD_ps_disable;
        return bounds;

    case ZSTD_c_targetCBlockSize:
        bounds.lowerBound = ZSTD_TARGETCBLOCKSIZE_MIN;
        bounds.upperBound = ZSTD_TARGETCBLOCKSIZE_MAX;
        return bounds;

    case ZSTD_c_srcSizeHint:
        bounds.lowerBound = ZSTD_SRCSIZEHINT_MIN;
        bounds.upperBound = ZSTD_SRCSIZEHINT_MAX;
        return bounds;

    case ZSTD_c_stableInBuffer:
    case ZSTD_c_stableOutBuffer:
        bounds.lowerBound = (int)ZSTD_bm_buffered;
        bounds.upperBound = (int)ZSTD_bm_stable;
        return bounds;

    case ZSTD_c_blockDelimiters:
        bounds.lowerBound = (int)ZSTD_sf_noBlockDelimiters;
        bounds.upperBound = (int)ZSTD_sf_explicitBlockDelimiters;
        return bounds;

    case ZSTD_c_validateSequences:
        bounds.lowerBound = 0;
        bounds.upperBound = 1;
        return bounds;

    case ZSTD_c_splitAfterSequences:
        bounds.lowerBound = (int)ZSTD_ps_auto;
        bounds.upperBound = (int)ZSTD_ps_disable;
        return bounds;

    case ZSTD_c_blockSplitterLevel:
        bounds.lowerBound = 0;
        bounds.upperBound = ZSTD_BLOCKSPLITTER_LEVEL_MAX;
        return bounds;

    case ZSTD_c_useRowMatchFinder:
        bounds.lowerBound = (int)ZSTD_ps_auto;
        bounds.upperBound = (int)ZSTD_ps_disable;
        return bounds;

    case ZSTD_c_deterministicRefPrefix:
        bounds.lowerBound = 0;
        bounds.upperBound = 1;
        return bounds;

    case ZSTD_c_prefetchCDictTables:
        bounds.lowerBound = (int)ZSTD_ps_auto;
        bounds.upperBound = (int)ZSTD_ps_disable;
        return bounds;

    case ZSTD_c_enableSeqProducerFallback:
        bounds.lowerBound = 0;
        bounds.upperBound = 1;
        return bounds;

    case ZSTD_c_maxBlockSize:
        bounds.lowerBound = ZSTD_BLOCKSIZE_MAX_MIN;
        bounds.upperBound = ZSTD_BLOCKSIZE_MAX;
        return bounds;

    case ZSTD_c_repcodeResolution:
        bounds.lowerBound = (int)ZSTD_ps_auto;
        bounds.upperBound = (int)ZSTD_ps_disable;
        return bounds;

    default:
        bounds.error = ERROR(parameter_unsupported);
        return bounds;
    }
}

/* ZSTD_cParam_clampBounds:
 * Clamps the value into the bounded range.
 */
static size_t ZSTD_cParam_clampBounds(ZSTD_cParameter cParam, int* value)
{
    ZSTD_bounds const bounds = ZSTD_cParam_getBounds(cParam);
    if (ZSTD_isError(bounds.error)) return bounds.error;
    if (*value < bounds.lowerBound) *value = bounds.lowerBound;
    if (*value > bounds.upperBound) *value = bounds.upperBound;
    return 0;
}

#define BOUNDCHECK(cParam, val)                                       \
    do {                                                              \
        RETURN_ERROR_IF(!ZSTD_cParam_withinBounds(cParam,val),        \
                        parameter_outOfBound, "Param out of bounds"); \
    } while (0)


static int ZSTD_isUpdateAuthorized(ZSTD_cParameter param)
{
    switch(param)
    {
    case ZSTD_c_compressionLevel:
    case ZSTD_c_hashLog:
    case ZSTD_c_chainLog:
    case ZSTD_c_searchLog:
    case ZSTD_c_minMatch:
    case ZSTD_c_targetLength:
    case ZSTD_c_strategy:
    case ZSTD_c_blockSplitterLevel:
        return 1;

    case ZSTD_c_format:
    case ZSTD_c_windowLog:
    case ZSTD_c_contentSizeFlag:
    case ZSTD_c_checksumFlag:
    case ZSTD_c_dictIDFlag:
    case ZSTD_c_forceMaxWindow :
    case ZSTD_c_nbWorkers:
    case ZSTD_c_jobSize:
    case ZSTD_c_overlapLog:
    case ZSTD_c_rsyncable:
    case ZSTD_c_enableDedicatedDictSearch:
    case ZSTD_c_enableLongDistanceMatching:
    case ZSTD_c_ldmHashLog:
    case ZSTD_c_ldmMinMatch:
    case ZSTD_c_ldmBucketSizeLog:
    case ZSTD_c_ldmHashRateLog:
    case ZSTD_c_forceAttachDict:
    case ZSTD_c_literalCompressionMode:
    case ZSTD_c_targetCBlockSize:
    case ZSTD_c_srcSizeHint:
    case ZSTD_c_stableInBuffer:
    case ZSTD_c_stableOutBuffer:
    case ZSTD_c_blockDelimiters:
    case ZSTD_c_validateSequences:
    case ZSTD_c_splitAfterSequences:
    case ZSTD_c_useRowMatchFinder:
    case ZSTD_c_deterministicRefPrefix:
    case ZSTD_c_prefetchCDictTables:
    case ZSTD_c_enableSeqProducerFallback:
    case ZSTD_c_maxBlockSize:
    case ZSTD_c_repcodeResolution:
    default:
        return 0;
    }
}

size_t ZSTD_CCtx_setParameter(ZSTD_CCtx* cctx, ZSTD_cParameter param, int value)
{
    DEBUGLOG(4, "ZSTD_CCtx_setParameter (%i, %i)", (int)param, value);
    if (cctx->streamStage != zcss_init) {
        if (ZSTD_isUpdateAuthorized(param)) {
            cctx->cParamsChanged = 1;
        } else {
            RETURN_ERROR(stage_wrong, "can only set params in cctx init stage");
    }   }

    switch(param)
    {
    case ZSTD_c_nbWorkers:
        RETURN_ERROR_IF((value!=0) && cctx->staticSize, parameter_unsupported,
                        "MT not compatible with static alloc");
        break;

    case ZSTD_c_compressionLevel:
    case ZSTD_c_windowLog:
    case ZSTD_c_hashLog:
    case ZSTD_c_chainLog:
    case ZSTD_c_searchLog:
    case ZSTD_c_minMatch:
    case ZSTD_c_targetLength:
    case ZSTD_c_strategy:
    case ZSTD_c_ldmHashRateLog:
    case ZSTD_c_format:
    case ZSTD_c_contentSizeFlag:
    case ZSTD_c_checksumFlag:
    case ZSTD_c_dictIDFlag:
    case ZSTD_c_forceMaxWindow:
    case ZSTD_c_forceAttachDict:
    case ZSTD_c_literalCompressionMode:
    case ZSTD_c_jobSize:
    case ZSTD_c_overlapLog:
    case ZSTD_c_rsyncable:
    case ZSTD_c_enableDedicatedDictSearch:
    case ZSTD_c_enableLongDistanceMatching:
    case ZSTD_c_ldmHashLog:
    case ZSTD_c_ldmMinMatch:
    case ZSTD_c_ldmBucketSizeLog:
    case ZSTD_c_targetCBlockSize:
    case ZSTD_c_srcSizeHint:
    case ZSTD_c_stableInBuffer:
    case ZSTD_c_stableOutBuffer:
    case ZSTD_c_blockDelimiters:
    case ZSTD_c_validateSequences:
    case ZSTD_c_splitAfterSequences:
    case ZSTD_c_blockSplitterLevel:
    case ZSTD_c_useRowMatchFinder:
    case ZSTD_c_deterministicRefPrefix:
    case ZSTD_c_prefetchCDictTables:
    case ZSTD_c_enableSeqProducerFallback:
    case ZSTD_c_maxBlockSize:
    case ZSTD_c_repcodeResolution:
        break;

    default: RETURN_ERROR(parameter_unsupported, "unknown parameter");
    }
    return ZSTD_CCtxParams_setParameter(&cctx->requestedParams, param, value);
}

size_t ZSTD_CCtxParams_setParameter(ZSTD_CCtx_params* CCtxParams,
                                    ZSTD_cParameter param, int value)
{
    DEBUGLOG(4, "ZSTD_CCtxParams_setParameter (%i, %i)", (int)param, value);
    switch(param)
    {
    case ZSTD_c_format :
        BOUNDCHECK(ZSTD_c_format, value);
        CCtxParams->format = (ZSTD_format_e)value;
        return (size_t)CCtxParams->format;

    case ZSTD_c_compressionLevel : {
        FORWARD_IF_ERROR(ZSTD_cParam_clampBounds(param, &value), "");
        if (value == 0)
            CCtxParams->compressionLevel = ZSTD_CLEVEL_DEFAULT; /* 0 == default */
        else
            CCtxParams->compressionLevel = value;
        if (CCtxParams->compressionLevel >= 0) return (size_t)CCtxParams->compressionLevel;
        return 0;  /* return type (size_t) cannot represent negative values */
    }

    case ZSTD_c_windowLog :
        if (value!=0)   /* 0 => use default */
            BOUNDCHECK(ZSTD_c_windowLog, value);
        CCtxParams->cParams.windowLog = (U32)value;
        return CCtxParams->cParams.windowLog;

    case ZSTD_c_hashLog :
        if (value!=0)   /* 0 => use default */
            BOUNDCHECK(ZSTD_c_hashLog, value);
        CCtxParams->cParams.hashLog = (U32)value;
        return CCtxParams->cParams.hashLog;

    case ZSTD_c_chainLog :
        if (value!=0)   /* 0 => use default */
            BOUNDCHECK(ZSTD_c_chainLog, value);
        CCtxParams->cParams.chainLog = (U32)value;
        return CCtxParams->cParams.chainLog;

    case ZSTD_c_searchLog :
        if (value!=0)   /* 0 => use default */
            BOUNDCHECK(ZSTD_c_searchLog, value);
        CCtxParams->cParams.searchLog = (U32)value;
        return (size_t)value;

    case ZSTD_c_minMatch :
        if (value!=0)   /* 0 => use default */
            BOUNDCHECK(ZSTD_c_minMatch, value);
        CCtxParams->cParams.minMatch = (U32)value;
        return CCtxParams->cParams.minMatch;

    case ZSTD_c_targetLength :
        BOUNDCHECK(ZSTD_c_targetLength, value);
        CCtxParams->cParams.targetLength = (U32)value;
        return CCtxParams->cParams.targetLength;

    case ZSTD_c_strategy :
        if (value!=0)   /* 0 => use default */
            BOUNDCHECK(ZSTD_c_strategy, value);
        CCtxParams->cParams.strategy = (ZSTD_strategy)value;
        return (size_t)CCtxParams->cParams.strategy;

    case ZSTD_c_contentSizeFlag :
        /* Content size written in frame header _when known_ (default:1) */
        DEBUGLOG(4, "set content size flag = %u", (value!=0));
        CCtxParams->fParams.contentSizeFlag = value != 0;
        return (size_t)CCtxParams->fParams.contentSizeFlag;

    case ZSTD_c_checksumFlag :
        /* A 32-bits content checksum will be calculated and written at end of frame (default:0) */
        CCtxParams->fParams.checksumFlag = value != 0;
        return (size_t)CCtxParams->fParams.checksumFlag;

    case ZSTD_c_dictIDFlag : /* When applicable, dictionary's dictID is provided in frame header (default:1) */
        DEBUGLOG(4, "set dictIDFlag = %u", (value!=0));
        CCtxParams->fParams.noDictIDFlag = !value;
        return !CCtxParams->fParams.noDictIDFlag;

    case ZSTD_c_forceMaxWindow :
        CCtxParams->forceWindow = (value != 0);
        return (size_t)CCtxParams->forceWindow;

    case ZSTD_c_forceAttachDict : {
        const ZSTD_dictAttachPref_e pref = (ZSTD_dictAttachPref_e)value;
        BOUNDCHECK(ZSTD_c_forceAttachDict, (int)pref);
        CCtxParams->attachDictPref = pref;
        return CCtxParams->attachDictPref;
    }

    case ZSTD_c_literalCompressionMode : {
        const ZSTD_ParamSwitch_e lcm = (ZSTD_ParamSwitch_e)value;
        BOUNDCHECK(ZSTD_c_literalCompressionMode, (int)lcm);
        CCtxParams->literalCompressionMode = lcm;
        return CCtxParams->literalCompressionMode;
    }

    case ZSTD_c_nbWorkers :
#ifndef ZSTD_MULTITHREAD
        RETURN_ERROR_IF(value!=0, parameter_unsupported, "not compiled with multithreading");
        return 0;
#else
        FORWARD_IF_ERROR(ZSTD_cParam_clampBounds(param, &value), "");
        CCtxParams->nbWorkers = value;
        return (size_t)(CCtxParams->nbWorkers);
#endif

    case ZSTD_c_jobSize :
#ifndef ZSTD_MULTITHREAD
        RETURN_ERROR_IF(value!=0, parameter_unsupported, "not compiled with multithreading");
        return 0;
#else
        /* Adjust to the minimum non-default value. */
        if (value != 0 && value < ZSTDMT_JOBSIZE_MIN)
            value = ZSTDMT_JOBSIZE_MIN;
        FORWARD_IF_ERROR(ZSTD_cParam_clampBounds(param, &value), "");
        assert(value >= 0);
        CCtxParams->jobSize = (size_t)value;
        return CCtxParams->jobSize;
#endif

    case ZSTD_c_overlapLog :
#ifndef ZSTD_MULTITHREAD
        RETURN_ERROR_IF(value!=0, parameter_unsupported, "not compiled with multithreading");
        return 0;
#else
        FORWARD_IF_ERROR(ZSTD_cParam_clampBounds(ZSTD_c_overlapLog, &value), "");
        CCtxParams->overlapLog = value;
        return (size_t)CCtxParams->overlapLog;
#endif

    case ZSTD_c_rsyncable :
#ifndef ZSTD_MULTITHREAD
        RETURN_ERROR_IF(value!=0, parameter_unsupported, "not compiled with multithreading");
        return 0;
#else
        FORWARD_IF_ERROR(ZSTD_cParam_clampBounds(ZSTD_c_overlapLog, &value), "");
        CCtxParams->rsyncable = value;
        return (size_t)CCtxParams->rsyncable;
#endif

    case ZSTD_c_enableDedicatedDictSearch :
        CCtxParams->enableDedicatedDictSearch = (value!=0);
        return (size_t)CCtxParams->enableDedicatedDictSearch;

    case ZSTD_c_enableLongDistanceMatching :
        BOUNDCHECK(ZSTD_c_enableLongDistanceMatching, value);
        CCtxParams->ldmParams.enableLdm = (ZSTD_ParamSwitch_e)value;
        return CCtxParams->ldmParams.enableLdm;

    case ZSTD_c_ldmHashLog :
        if (value!=0)   /* 0 ==> auto */
            BOUNDCHECK(ZSTD_c_ldmHashLog, value);
        CCtxParams->ldmParams.hashLog = (U32)value;
        return CCtxParams->ldmParams.hashLog;

    case ZSTD_c_ldmMinMatch :
        if (value!=0)   /* 0 ==> default */
            BOUNDCHECK(ZSTD_c_ldmMinMatch, value);
        CCtxParams->ldmParams.minMatchLength = (U32)value;
        return CCtxParams->ldmParams.minMatchLength;

    case ZSTD_c_ldmBucketSizeLog :
        if (value!=0)   /* 0 ==> default */
            BOUNDCHECK(ZSTD_c_ldmBucketSizeLog, value);
        CCtxParams->ldmParams.bucketSizeLog = (U32)value;
        return CCtxParams->ldmParams.bucketSizeLog;

    case ZSTD_c_ldmHashRateLog :
        if (value!=0)   /* 0 ==> default */
            BOUNDCHECK(ZSTD_c_ldmHashRateLog, value);
        CCtxParams->ldmParams.hashRateLog = (U32)value;
        return CCtxParams->ldmParams.hashRateLog;

    case ZSTD_c_targetCBlockSize :
        if (value!=0) {  /* 0 ==> default */
            value = MAX(value, ZSTD_TARGETCBLOCKSIZE_MIN);
            BOUNDCHECK(ZSTD_c_targetCBlockSize, value);
        }
        CCtxParams->targetCBlockSize = (U32)value;
        return CCtxParams->targetCBlockSize;

    case ZSTD_c_srcSizeHint :
        if (value!=0)    /* 0 ==> default */
            BOUNDCHECK(ZSTD_c_srcSizeHint, value);
        CCtxParams->srcSizeHint = value;
        return (size_t)CCtxParams->srcSizeHint;

    case ZSTD_c_stableInBuffer:
        BOUNDCHECK(ZSTD_c_stableInBuffer, value);
        CCtxParams->inBufferMode = (ZSTD_bufferMode_e)value;
        return CCtxParams->inBufferMode;

    case ZSTD_c_stableOutBuffer:
        BOUNDCHECK(ZSTD_c_stableOutBuffer, value);
        CCtxParams->outBufferMode = (ZSTD_bufferMode_e)value;
        return CCtxParams->outBufferMode;

    case ZSTD_c_blockDelimiters:
        BOUNDCHECK(ZSTD_c_blockDelimiters, value);
        CCtxParams->blockDelimiters = (ZSTD_SequenceFormat_e)value;
        return CCtxParams->blockDelimiters;

    case ZSTD_c_validateSequences:
        BOUNDCHECK(ZSTD_c_validateSequences, value);
        CCtxParams->validateSequences = value;
        return (size_t)CCtxParams->validateSequences;

    case ZSTD_c_splitAfterSequences:
        BOUNDCHECK(ZSTD_c_splitAfterSequences, value);
        CCtxParams->postBlockSplitter = (ZSTD_ParamSwitch_e)value;
        return CCtxParams->postBlockSplitter;

    case ZSTD_c_blockSplitterLevel:
        BOUNDCHECK(ZSTD_c_blockSplitterLevel, value);
        CCtxParams->preBlockSplitter_level = value;
        return (size_t)CCtxParams->preBlockSplitter_level;

    case ZSTD_c_useRowMatchFinder:
        BOUNDCHECK(ZSTD_c_useRowMatchFinder, value);
        CCtxParams->useRowMatchFinder = (ZSTD_ParamSwitch_e)value;
        return CCtxParams->useRowMatchFinder;

    case ZSTD_c_deterministicRefPrefix:
        BOUNDCHECK(ZSTD_c_deterministicRefPrefix, value);
        CCtxParams->deterministicRefPrefix = !!value;
        return (size_t)CCtxParams->deterministicRefPrefix;

    case ZSTD_c_prefetchCDictTables:
        BOUNDCHECK(ZSTD_c_prefetchCDictTables, value);
        CCtxParams->prefetchCDictTables = (ZSTD_ParamSwitch_e)value;
        return CCtxParams->prefetchCDictTables;

    case ZSTD_c_enableSeqProducerFallback:
        BOUNDCHECK(ZSTD_c_enableSeqProducerFallback, value);
        CCtxParams->enableMatchFinderFallback = value;
        return (size_t)CCtxParams->enableMatchFinderFallback;

    case ZSTD_c_maxBlockSize:
        if (value!=0)    /* 0 ==> default */
            BOUNDCHECK(ZSTD_c_maxBlockSize, value);
        assert(value>=0);
        CCtxParams->maxBlockSize = (size_t)value;
        return CCtxParams->maxBlockSize;

    case ZSTD_c_repcodeResolution:
        BOUNDCHECK(ZSTD_c_repcodeResolution, value);
        CCtxParams->searchForExternalRepcodes = (ZSTD_ParamSwitch_e)value;
        return CCtxParams->searchForExternalRepcodes;

    default: RETURN_ERROR(parameter_unsupported, "unknown parameter");
    }
}

size_t ZSTD_CCtx_getParameter(ZSTD_CCtx const* cctx, ZSTD_cParameter param, int* value)
{
    return ZSTD_CCtxParams_getParameter(&cctx->requestedParams, param, value);
}

size_t ZSTD_CCtxParams_getParameter(
        ZSTD_CCtx_params const* CCtxParams, ZSTD_cParameter param, int* value)
{
    switch(param)
    {
    case ZSTD_c_format :
        *value = (int)CCtxParams->format;
        break;
    case ZSTD_c_compressionLevel :
        *value = CCtxParams->compressionLevel;
        break;
    case ZSTD_c_windowLog :
        *value = (int)CCtxParams->cParams.windowLog;
        break;
    case ZSTD_c_hashLog :
        *value = (int)CCtxParams->cParams.hashLog;
        break;
    case ZSTD_c_chainLog :
        *value = (int)CCtxParams->cParams.chainLog;
        break;
    case ZSTD_c_searchLog :
        *value = (int)CCtxParams->cParams.searchLog;
        break;
    case ZSTD_c_minMatch :
        *value = (int)CCtxParams->cParams.minMatch;
        break;
    case ZSTD_c_targetLength :
        *value = (int)CCtxParams->cParams.targetLength;
        break;
    case ZSTD_c_strategy :
        *value = (int)CCtxParams->cParams.strategy;
        break;
    case ZSTD_c_contentSizeFlag :
        *value = CCtxParams->fParams.contentSizeFlag;
        break;
    case ZSTD_c_checksumFlag :
        *value = CCtxParams->fParams.checksumFlag;
        break;
    case ZSTD_c_dictIDFlag :
        *value = !CCtxParams->fParams.noDictIDFlag;
        break;
    case ZSTD_c_forceMaxWindow :
        *value = CCtxParams->forceWindow;
        break;
    case ZSTD_c_forceAttachDict :
        *value = (int)CCtxParams->attachDictPref;
        break;
    case ZSTD_c_literalCompressionMode :
        *value = (int)CCtxParams->literalCompressionMode;
        break;
    case ZSTD_c_nbWorkers :
#ifndef ZSTD_MULTITHREAD
        assert(CCtxParams->nbWorkers == 0);
#endif
        *value = CCtxParams->nbWorkers;
        break;
    case ZSTD_c_jobSize :
#ifndef ZSTD_MULTITHREAD
        RETURN_ERROR(parameter_unsupported, "not compiled with multithreading");
#else
        assert(CCtxParams->jobSize <= INT_MAX);
        *value = (int)CCtxParams->jobSize;
        break;
#endif
    case ZSTD_c_overlapLog :
#ifndef ZSTD_MULTITHREAD
        RETURN_ERROR(parameter_unsupported, "not compiled with multithreading");
#else
        *value = CCtxParams->overlapLog;
        break;
#endif
    case ZSTD_c_rsyncable :
#ifndef ZSTD_MULTITHREAD
        RETURN_ERROR(parameter_unsupported, "not compiled with multithreading");
#else
        *value = CCtxParams->rsyncable;
        break;
#endif
    case ZSTD_c_enableDedicatedDictSearch :
        *value = CCtxParams->enableDedicatedDictSearch;
        break;
    case ZSTD_c_enableLongDistanceMatching :
        *value = (int)CCtxParams->ldmParams.enableLdm;
        break;
    case ZSTD_c_ldmHashLog :
        *value = (int)CCtxParams->ldmParams.hashLog;
        break;
    case ZSTD_c_ldmMinMatch :
        *value = (int)CCtxParams->ldmParams.minMatchLength;
        break;
    case ZSTD_c_ldmBucketSizeLog :
        *value = (int)CCtxParams->ldmParams.bucketSizeLog;
        break;
    case ZSTD_c_ldmHashRateLog :
        *value = (int)CCtxParams->ldmParams.hashRateLog;
        break;
    case ZSTD_c_targetCBlockSize :
        *value = (int)CCtxParams->targetCBlockSize;
        break;
    case ZSTD_c_srcSizeHint :
        *value = (int)CCtxParams->srcSizeHint;
        break;
    case ZSTD_c_stableInBuffer :
        *value = (int)CCtxParams->inBufferMode;
        break;
    case ZSTD_c_stableOutBuffer :
        *value = (int)CCtxParams->outBufferMode;
        break;
    case ZSTD_c_blockDelimiters :
        *value = (int)CCtxParams->blockDelimiters;
        break;
    case ZSTD_c_validateSequences :
        *value = (int)CCtxParams->validateSequences;
        break;
    case ZSTD_c_splitAfterSequences :
        *value = (int)CCtxParams->postBlockSplitter;
        break;
    case ZSTD_c_blockSplitterLevel :
        *value = CCtxParams->preBlockSplitter_level;
        break;
    case ZSTD_c_useRowMatchFinder :
        *value = (int)CCtxParams->useRowMatchFinder;
        break;
    case ZSTD_c_deterministicRefPrefix:
        *value = (int)CCtxParams->deterministicRefPrefix;
        break;
    case ZSTD_c_prefetchCDictTables:
        *value = (int)CCtxParams->prefetchCDictTables;
        break;
    case ZSTD_c_enableSeqProducerFallback:
        *value = CCtxParams->enableMatchFinderFallback;
        break;
    case ZSTD_c_maxBlockSize:
        *value = (int)CCtxParams->maxBlockSize;
        break;
    case ZSTD_c_repcodeResolution:
        *value = (int)CCtxParams->searchForExternalRepcodes;
        break;
    default: RETURN_ERROR(parameter_unsupported, "unknown parameter");
    }
    return 0;
}

/** ZSTD_CCtx_setParametersUsingCCtxParams() :
 *  just applies `params` into `cctx`
 *  no action is performed, parameters are merely stored.
 *  If ZSTDMT is enabled, parameters are pushed to cctx->mtctx.
 *    This is possible even if a compression is ongoing.
 *    In which case, new parameters will be applied on the fly, starting with next compression job.
 */
size_t ZSTD_CCtx_setParametersUsingCCtxParams(
        ZSTD_CCtx* cctx, const ZSTD_CCtx_params* params)
{
    DEBUGLOG(4, "ZSTD_CCtx_setParametersUsingCCtxParams");
    RETURN_ERROR_IF(cctx->streamStage != zcss_init, stage_wrong,
                    "The context is in the wrong stage!");
    RETURN_ERROR_IF(cctx->cdict, stage_wrong,
                    "Can't override parameters with cdict attached (some must "
                    "be inherited from the cdict).");

    cctx->requestedParams = *params;
    return 0;
}

size_t ZSTD_CCtx_setCParams(ZSTD_CCtx* cctx, ZSTD_compressionParameters cparams)
{
    ZSTD_STATIC_ASSERT(sizeof(cparams) == 7 * 4 /* all params are listed below */);
    DEBUGLOG(4, "ZSTD_CCtx_setCParams");
    /* only update if all parameters are valid */
    FORWARD_IF_ERROR(ZSTD_checkCParams(cparams), "");
    FORWARD_IF_ERROR(ZSTD_CCtx_setParameter(cctx, ZSTD_c_windowLog, (int)cparams.windowLog), "");
    FORWARD_IF_ERROR(ZSTD_CCtx_setParameter(cctx, ZSTD_c_chainLog, (int)cparams.chainLog), "");
    FORWARD_IF_ERROR(ZSTD_CCtx_setParameter(cctx, ZSTD_c_hashLog, (int)cparams.hashLog), "");
    FORWARD_IF_ERROR(ZSTD_CCtx_setParameter(cctx, ZSTD_c_searchLog, (int)cparams.searchLog), "");
    FORWARD_IF_ERROR(ZSTD_CCtx_setParameter(cctx, ZSTD_c_minMatch, (int)cparams.minMatch), "");
    FORWARD_IF_ERROR(ZSTD_CCtx_setParameter(cctx, ZSTD_c_targetLength, (int)cparams.targetLength), "");
    FORWARD_IF_ERROR(ZSTD_CCtx_setParameter(cctx, ZSTD_c_strategy, (int)cparams.strategy), "");
    return 0;
}

size_t ZSTD_CCtx_setFParams(ZSTD_CCtx* cctx, ZSTD_frameParameters fparams)
{
    ZSTD_STATIC_ASSERT(sizeof(fparams) == 3 * 4 /* all params are listed below */);
    DEBUGLOG(4, "ZSTD_CCtx_setFParams");
    FORWARD_IF_ERROR(ZSTD_CCtx_setParameter(cctx, ZSTD_c_contentSizeFlag, fparams.contentSizeFlag != 0), "");
    FORWARD_IF_ERROR(ZSTD_CCtx_setParameter(cctx, ZSTD_c_checksumFlag, fparams.checksumFlag != 0), "");
    FORWARD_IF_ERROR(ZSTD_CCtx_setParameter(cctx, ZSTD_c_dictIDFlag, fparams.noDictIDFlag == 0), "");
    return 0;
}

size_t ZSTD_CCtx_setParams(ZSTD_CCtx* cctx, ZSTD_parameters params)
{
    DEBUGLOG(4, "ZSTD_CCtx_setParams");
    /* First check cParams, because we want to update all or none. */
    FORWARD_IF_ERROR(ZSTD_checkCParams(params.cParams), "");
    /* Next set fParams, because this could fail if the cctx isn't in init stage. */
    FORWARD_IF_ERROR(ZSTD_CCtx_setFParams(cctx, params.fParams), "");
    /* Finally set cParams, which should succeed. */
    FORWARD_IF_ERROR(ZSTD_CCtx_setCParams(cctx, params.cParams), "");
    return 0;
}

size_t ZSTD_CCtx_setPledgedSrcSize(ZSTD_CCtx* cctx, unsigned long long pledgedSrcSize)
{
    DEBUGLOG(4, "ZSTD_CCtx_setPledgedSrcSize to %llu bytes", pledgedSrcSize);
    RETURN_ERROR_IF(cctx->streamStage != zcss_init, stage_wrong,
                    "Can't set pledgedSrcSize when not in init stage.");
    cctx->pledgedSrcSizePlusOne = pledgedSrcSize+1;
    return 0;
}

static ZSTD_compressionParameters ZSTD_dedicatedDictSearch_getCParams(
        int const compressionLevel,
        size_t const dictSize);
static int ZSTD_dedicatedDictSearch_isSupported(
        const ZSTD_compressionParameters* cParams);
static void ZSTD_dedicatedDictSearch_revertCParams(
        ZSTD_compressionParameters* cParams);

/**
 * Initializes the local dictionary using requested parameters.
 * NOTE: Initialization does not employ the pledged src size,
 * because the dictionary may be used for multiple compressions.
 */
static size_t ZSTD_initLocalDict(ZSTD_CCtx* cctx)
{
    ZSTD_localDict* const dl = &cctx->localDict;
    if (dl->dict == NULL) {
        /* No local dictionary. */
        assert(dl->dictBuffer == NULL);
        assert(dl->cdict == NULL);
        assert(dl->dictSize == 0);
        return 0;
    }
    if (dl->cdict != NULL) {
        /* Local dictionary already initialized. */
        assert(cctx->cdict == dl->cdict);
        return 0;
    }
    assert(dl->dictSize > 0);
    assert(cctx->cdict == NULL);
    assert(cctx->prefixDict.dict == NULL);

    dl->cdict = ZSTD_createCDict_advanced2(
            dl->dict,
            dl->dictSize,
            ZSTD_dlm_byRef,
            dl->dictContentType,
            &cctx->requestedParams,
            cctx->customMem);
    RETURN_ERROR_IF(!dl->cdict, memory_allocation, "ZSTD_createCDict_advanced failed");
    cctx->cdict = dl->cdict;
    return 0;
}

size_t ZSTD_CCtx_loadDictionary_advanced(
        ZSTD_CCtx* cctx,
        const void* dict, size_t dictSize,
        ZSTD_dictLoadMethod_e dictLoadMethod,
        ZSTD_dictContentType_e dictContentType)
{
    DEBUGLOG(4, "ZSTD_CCtx_loadDictionary_advanced (size: %u)", (U32)dictSize);
    RETURN_ERROR_IF(cctx->streamStage != zcss_init, stage_wrong,
                    "Can't load a dictionary when cctx is not in init stage.");
    ZSTD_clearAllDicts(cctx);  /* erase any previously set dictionary */
    if (dict == NULL || dictSize == 0)  /* no dictionary */
        return 0;
    if (dictLoadMethod == ZSTD_dlm_byRef) {
        cctx->localDict.dict = dict;
    } else {
        /* copy dictionary content inside CCtx to own its lifetime */
        void* dictBuffer;
        RETURN_ERROR_IF(cctx->staticSize, memory_allocation,
                        "static CCtx can't allocate for an internal copy of dictionary");
        dictBuffer = ZSTD_customMalloc(dictSize, cctx->customMem);
        RETURN_ERROR_IF(dictBuffer==NULL, memory_allocation,
                        "allocation failed for dictionary content");
        ZSTD_memcpy(dictBuffer, dict, dictSize);
        cctx->localDict.dictBuffer = dictBuffer;  /* owned ptr to free */
        cctx->localDict.dict = dictBuffer;        /* read-only reference */
    }
    cctx->localDict.dictSize = dictSize;
    cctx->localDict.dictContentType = dictContentType;
    return 0;
}

size_t ZSTD_CCtx_loadDictionary_byReference(
      ZSTD_CCtx* cctx, const void* dict, size_t dictSize)
{
    return ZSTD_CCtx_loadDictionary_advanced(
            cctx, dict, dictSize, ZSTD_dlm_byRef, ZSTD_dct_auto);
}

size_t ZSTD_CCtx_loadDictionary(ZSTD_CCtx* cctx, const void* dict, size_t dictSize)
{
    return ZSTD_CCtx_loadDictionary_advanced(
            cctx, dict, dictSize, ZSTD_dlm_byCopy, ZSTD_dct_auto);
}


size_t ZSTD_CCtx_refCDict(ZSTD_CCtx* cctx, const ZSTD_CDict* cdict)
{
    RETURN_ERROR_IF(cctx->streamStage != zcss_init, stage_wrong,
                    "Can't ref a dict when ctx not in init stage.");
    /* Free the existing local cdict (if any) to save memory. */
    ZSTD_clearAllDicts(cctx);
    cctx->cdict = cdict;
    return 0;
}

size_t ZSTD_CCtx_refThreadPool(ZSTD_CCtx* cctx, ZSTD_threadPool* pool)
{
    RETURN_ERROR_IF(cctx->streamStage != zcss_init, stage_wrong,
                    "Can't ref a pool when ctx not in init stage.");
    cctx->pool = pool;
    return 0;
}

size_t ZSTD_CCtx_refPrefix(ZSTD_CCtx* cctx, const void* prefix, size_t prefixSize)
{
    return ZSTD_CCtx_refPrefix_advanced(cctx, prefix, prefixSize, ZSTD_dct_rawContent);
}

size_t ZSTD_CCtx_refPrefix_advanced(
        ZSTD_CCtx* cctx, const void* prefix, size_t prefixSize, ZSTD_dictContentType_e dictContentType)
{
    RETURN_ERROR_IF(cctx->streamStage != zcss_init, stage_wrong,
                    "Can't ref a prefix when ctx not in init stage.");
    ZSTD_clearAllDicts(cctx);
    if (prefix != NULL && prefixSize > 0) {
        cctx->prefixDict.dict = prefix;
        cctx->prefixDict.dictSize = prefixSize;
        cctx->prefixDict.dictContentType = dictContentType;
    }
    return 0;
}

/*! ZSTD_CCtx_reset() :
 *  Also dumps dictionary */
size_t ZSTD_CCtx_reset(ZSTD_CCtx* cctx, ZSTD_ResetDirective reset)
{
    if ( (reset == ZSTD_reset_session_only)
      || (reset == ZSTD_reset_session_and_parameters) ) {
        cctx->streamStage = zcss_init;
        cctx->pledgedSrcSizePlusOne = 0;
    }
    if ( (reset == ZSTD_reset_parameters)
      || (reset == ZSTD_reset_session_and_parameters) ) {
        RETURN_ERROR_IF(cctx->streamStage != zcss_init, stage_wrong,
                        "Reset parameters is only possible during init stage.");
        ZSTD_clearAllDicts(cctx);
        return ZSTD_CCtxParams_reset(&cctx->requestedParams);
    }
    return 0;
}


/** ZSTD_checkCParams() :
    control CParam 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)
{
    BOUNDCHECK(ZSTD_c_windowLog, (int)cParams.windowLog);
    BOUNDCHECK(ZSTD_c_chainLog,  (int)cParams.chainLog);
    BOUNDCHECK(ZSTD_c_hashLog,   (int)cParams.hashLog);
    BOUNDCHECK(ZSTD_c_searchLog, (int)cParams.searchLog);
    BOUNDCHECK(ZSTD_c_minMatch,  (int)cParams.minMatch);
    BOUNDCHECK(ZSTD_c_targetLength,(int)cParams.targetLength);
    BOUNDCHECK(ZSTD_c_strategy,  (int)cParams.strategy);
    return 0;
}

/** ZSTD_clampCParams() :
 *  make CParam values within valid range.
 *  @return : valid CParams */
static ZSTD_compressionParameters
ZSTD_clampCParams(ZSTD_compressionParameters cParams)
{
#   define CLAMP_TYPE(cParam, val, type)                                      \
        do {                                                                  \
            ZSTD_bounds const bounds = ZSTD_cParam_getBounds(cParam);         \
            if ((int)val<bounds.lowerBound) val=(type)bounds.lowerBound;      \
            else if ((int)val>bounds.upperBound) val=(type)bounds.upperBound; \
        } while (0)
#   define CLAMP(cParam, val) CLAMP_TYPE(cParam, val, unsigned)
    CLAMP(ZSTD_c_windowLog, cParams.windowLog);
    CLAMP(ZSTD_c_chainLog,  cParams.chainLog);
    CLAMP(ZSTD_c_hashLog,   cParams.hashLog);
    CLAMP(ZSTD_c_searchLog, cParams.searchLog);
    CLAMP(ZSTD_c_minMatch,  cParams.minMatch);
    CLAMP(ZSTD_c_targetLength,cParams.targetLength);
    CLAMP_TYPE(ZSTD_c_strategy,cParams.strategy, ZSTD_strategy);
    return cParams;
}

/** ZSTD_cycleLog() :
 *  condition for correct operation : hashLog > 1 */
U32 ZSTD_cycleLog(U32 hashLog, ZSTD_strategy strat)
{
    U32 const btScale = ((U32)strat >= (U32)ZSTD_btlazy2);
    return hashLog - btScale;
}

/** ZSTD_dictAndWindowLog() :
 * Returns an adjusted window log that is large enough to fit the source and the dictionary.
 * The zstd format says that the entire dictionary is valid if one byte of the dictionary
 * is within the window. So the hashLog and chainLog should be large enough to reference both
 * the dictionary and the window. So we must use this adjusted dictAndWindowLog when downsizing
 * the hashLog and windowLog.
 * NOTE: srcSize must not be ZSTD_CONTENTSIZE_UNKNOWN.
 */
static U32 ZSTD_dictAndWindowLog(U32 windowLog, U64 srcSize, U64 dictSize)
{
    const U64 maxWindowSize = 1ULL << ZSTD_WINDOWLOG_MAX;
    /* No dictionary ==> No change */
    if (dictSize == 0) {
        return windowLog;
    }
    assert(windowLog <= ZSTD_WINDOWLOG_MAX);
    assert(srcSize != ZSTD_CONTENTSIZE_UNKNOWN); /* Handled in ZSTD_adjustCParams_internal() */
    {
        U64 const windowSize = 1ULL << windowLog;
        U64 const dictAndWindowSize = dictSize + windowSize;
        /* If the window size is already large enough to fit both the source and the dictionary
         * then just use the window size. Otherwise adjust so that it fits the dictionary and
         * the window.
         */
        if (windowSize >= dictSize + srcSize) {
            return windowLog; /* Window size large enough already */
        } else if (dictAndWindowSize >= maxWindowSize) {
            return ZSTD_WINDOWLOG_MAX; /* Larger than max window log */
        } else  {
            return ZSTD_highbit32((U32)dictAndWindowSize - 1) + 1;
        }
    }
}

/** ZSTD_adjustCParams_internal() :
 *  optimize `cPar` for a specified input (`srcSize` and `dictSize`).
 *  mostly downsize to reduce memory consumption and initialization latency.
 * `srcSize` can be ZSTD_CONTENTSIZE_UNKNOWN when not known.
 * `mode` is the mode for parameter adjustment. See docs for `ZSTD_CParamMode_e`.
 *  note : `srcSize==0` means 0!
 *  condition : cPar is presumed validated (can be checked using ZSTD_checkCParams()). */
static ZSTD_compressionParameters
ZSTD_adjustCParams_internal(ZSTD_compressionParameters cPar,
                            unsigned long long srcSize,
                            size_t dictSize,
                            ZSTD_CParamMode_e mode,
                            ZSTD_ParamSwitch_e useRowMatchFinder)
{
    const U64 minSrcSize = 513; /* (1<<9) + 1 */
    const U64 maxWindowResize = 1ULL << (ZSTD_WINDOWLOG_MAX-1);
    assert(ZSTD_checkCParams(cPar)==0);

    /* Cascade the selected strategy down to the next-highest one built into
     * this binary. */
#ifdef ZSTD_EXCLUDE_BTULTRA_BLOCK_COMPRESSOR
    if (cPar.strategy == ZSTD_btultra2) {
        cPar.strategy = ZSTD_btultra;
    }
    if (cPar.strategy == ZSTD_btultra) {
        cPar.strategy = ZSTD_btopt;
    }
#endif
#ifdef ZSTD_EXCLUDE_BTOPT_BLOCK_COMPRESSOR
    if (cPar.strategy == ZSTD_btopt) {
        cPar.strategy = ZSTD_btlazy2;
    }
#endif
#ifdef ZSTD_EXCLUDE_BTLAZY2_BLOCK_COMPRESSOR
    if (cPar.strategy == ZSTD_btlazy2) {
        cPar.strategy = ZSTD_lazy2;
    }
#endif
#ifdef ZSTD_EXCLUDE_LAZY2_BLOCK_COMPRESSOR
    if (cPar.strategy == ZSTD_lazy2) {
        cPar.strategy = ZSTD_lazy;
    }
#endif
#ifdef ZSTD_EXCLUDE_LAZY_BLOCK_COMPRESSOR
    if (cPar.strategy == ZSTD_lazy) {
        cPar.strategy = ZSTD_greedy;
    }
#endif
#ifdef ZSTD_EXCLUDE_GREEDY_BLOCK_COMPRESSOR
    if (cPar.strategy == ZSTD_greedy) {
        cPar.strategy = ZSTD_dfast;
    }
#endif
#ifdef ZSTD_EXCLUDE_DFAST_BLOCK_COMPRESSOR
    if (cPar.strategy == ZSTD_dfast) {
        cPar.strategy = ZSTD_fast;
        cPar.targetLength = 0;
    }
#endif

    switch (mode) {
    case ZSTD_cpm_unknown:
    case ZSTD_cpm_noAttachDict:
        /* If we don't know the source size, don't make any
         * assumptions about it. We will already have selected
         * smaller parameters if a dictionary is in use.
         */
        break;
    case ZSTD_cpm_createCDict:
        /* Assume a small source size when creating a dictionary
         * with an unknown source size.
         */
        if (dictSize && srcSize == ZSTD_CONTENTSIZE_UNKNOWN)
            srcSize = minSrcSize;
        break;
    case ZSTD_cpm_attachDict:
        /* Dictionary has its own dedicated parameters which have
         * already been selected. We are selecting parameters
         * for only the source.
         */
        dictSize = 0;
        break;
    default:
        assert(0);
        break;
    }

    /* resize windowLog if input is small enough, to use less memory */
    if ( (srcSize <= maxWindowResize)
      && (dictSize <= maxWindowResize) )  {
        U32 const tSize = (U32)(srcSize + dictSize);
        static U32 const hashSizeMin = 1 << ZSTD_HASHLOG_MIN;
        U32 const srcLog = (tSize < hashSizeMin) ? ZSTD_HASHLOG_MIN :
                            ZSTD_highbit32(tSize-1) + 1;
        if (cPar.windowLog > srcLog) cPar.windowLog = srcLog;
    }
    if (srcSize != ZSTD_CONTENTSIZE_UNKNOWN) {
        U32 const dictAndWindowLog = ZSTD_dictAndWindowLog(cPar.windowLog, (U64)srcSize, (U64)dictSize);
        U32 const cycleLog = ZSTD_cycleLog(cPar.chainLog, cPar.strategy);
        if (cPar.hashLog > dictAndWindowLog+1) cPar.hashLog = dictAndWindowLog+1;
        if (cycleLog > dictAndWindowLog)
            cPar.chainLog -= (cycleLog - dictAndWindowLog);
    }

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

    /* We can't use more than 32 bits of hash in total, so that means that we require:
     * (hashLog + 8) <= 32 && (chainLog + 8) <= 32
     */
    if (mode == ZSTD_cpm_createCDict && ZSTD_CDictIndicesAreTagged(&cPar)) {
        U32 const maxShortCacheHashLog = 32 - ZSTD_SHORT_CACHE_TAG_BITS;
        if (cPar.hashLog > maxShortCacheHashLog) {
            cPar.hashLog = maxShortCacheHashLog;
        }
        if (cPar.chainLog > maxShortCacheHashLog) {
            cPar.chainLog = maxShortCacheHashLog;
        }
    }


    /* At this point, we aren't 100% sure if we are using the row match finder.
     * Unless it is explicitly disabled, conservatively assume that it is enabled.
     * In this case it will only be disabled for small sources, so shrinking the
     * hash log a little bit shouldn't result in any ratio loss.
     */
    if (useRowMatchFinder == ZSTD_ps_auto)
        useRowMatchFinder = ZSTD_ps_enable;

    /* We can't hash more than 32-bits in total. So that means that we require:
     * (hashLog - rowLog + 8) <= 32
     */
    if (ZSTD_rowMatchFinderUsed(cPar.strategy, useRowMatchFinder)) {
        /* Switch to 32-entry rows if searchLog is 5 (or more) */
        U32 const rowLog = BOUNDED(4, cPar.searchLog, 6);
        U32 const maxRowHashLog = 32 - ZSTD_ROW_HASH_TAG_BITS;
        U32 const maxHashLog = maxRowHashLog + rowLog;
        assert(cPar.hashLog >= rowLog);
        if (cPar.hashLog > maxHashLog) {
            cPar.hashLog = maxHashLog;
        }
    }

    return cPar;
}

ZSTD_compressionParameters
ZSTD_adjustCParams(ZSTD_compressionParameters cPar,
                   unsigned long long srcSize,
                   size_t dictSize)
{
    cPar = ZSTD_clampCParams(cPar);   /* resulting cPar is necessarily valid (all parameters within range) */
    if (srcSize == 0) srcSize = ZSTD_CONTENTSIZE_UNKNOWN;
    return ZSTD_adjustCParams_internal(cPar, srcSize, dictSize, ZSTD_cpm_unknown, ZSTD_ps_auto);
}

static ZSTD_compressionParameters ZSTD_getCParams_internal(int compressionLevel, unsigned long long srcSizeHint, size_t dictSize, ZSTD_CParamMode_e mode);
static ZSTD_parameters ZSTD_getParams_internal(int compressionLevel, unsigned long long srcSizeHint, size_t dictSize, ZSTD_CParamMode_e mode);

static void ZSTD_overrideCParams(
              ZSTD_compressionParameters* cParams,
        const ZSTD_compressionParameters* overrides)
{
    if (overrides->windowLog)    cParams->windowLog    = overrides->windowLog;
    if (overrides->hashLog)      cParams->hashLog      = overrides->hashLog;
    if (overrides->chainLog)     cParams->chainLog     = overrides->chainLog;
    if (overrides->searchLog)    cParams->searchLog    = overrides->searchLog;
    if (overrides->minMatch)     cParams->minMatch     = overrides->minMatch;
    if (overrides->targetLength) cParams->targetLength = overrides->targetLength;
    if (overrides->strategy)     cParams->strategy     = overrides->strategy;
}

ZSTD_compressionParameters ZSTD_getCParamsFromCCtxParams(
        const ZSTD_CCtx_params* CCtxParams, U64 srcSizeHint, size_t dictSize, ZSTD_CParamMode_e mode)
{
    ZSTD_compressionParameters cParams;
    if (srcSizeHint == ZSTD_CONTENTSIZE_UNKNOWN && CCtxParams->srcSizeHint > 0) {
        assert(CCtxParams->srcSizeHint>=0);
        srcSizeHint = (U64)CCtxParams->srcSizeHint;
    }
    cParams = ZSTD_getCParams_internal(CCtxParams->compressionLevel, srcSizeHint, dictSize, mode);
    if (CCtxParams->ldmParams.enableLdm == ZSTD_ps_enable) cParams.windowLog = ZSTD_LDM_DEFAULT_WINDOW_LOG;
    ZSTD_overrideCParams(&cParams, &CCtxParams->cParams);
    assert(!ZSTD_checkCParams(cParams));
    /* srcSizeHint == 0 means 0 */
    return ZSTD_adjustCParams_internal(cParams, srcSizeHint, dictSize, mode, CCtxParams->useRowMatchFinder);
}

static size_t
ZSTD_sizeof_matchState(const ZSTD_compressionParameters* const cParams,
                       const ZSTD_ParamSwitch_e useRowMatchFinder,
                       const int enableDedicatedDictSearch,
                       const U32 forCCtx)
{
    /* chain table size should be 0 for fast or row-hash strategies */
    size_t const chainSize = ZSTD_allocateChainTable(cParams->strategy, useRowMatchFinder, enableDedicatedDictSearch && !forCCtx)
                                ? ((size_t)1 << cParams->chainLog)
                                : 0;
    size_t const hSize = ((size_t)1) << cParams->hashLog;
    U32    const hashLog3 = (forCCtx && cParams->minMatch==3) ? MIN(ZSTD_HASHLOG3_MAX, cParams->windowLog) : 0;
    size_t const h3Size = hashLog3 ? ((size_t)1) << hashLog3 : 0;
    /* We don't use ZSTD_cwksp_alloc_size() here because the tables aren't
     * surrounded by redzones in ASAN. */
    size_t const tableSpace = chainSize * sizeof(U32)
                            + hSize * sizeof(U32)
                            + h3Size * sizeof(U32);
    size_t const optPotentialSpace =
        ZSTD_cwksp_aligned64_alloc_size((MaxML+1) * sizeof(U32))
      + ZSTD_cwksp_aligned64_alloc_size((MaxLL+1) * sizeof(U32))
      + ZSTD_cwksp_aligned64_alloc_size((MaxOff+1) * sizeof(U32))
      + ZSTD_cwksp_aligned64_alloc_size((1<<Litbits) * sizeof(U32))
      + ZSTD_cwksp_aligned64_alloc_size(ZSTD_OPT_SIZE * sizeof(ZSTD_match_t))
      + ZSTD_cwksp_aligned64_alloc_size(ZSTD_OPT_SIZE * sizeof(ZSTD_optimal_t));
    size_t const lazyAdditionalSpace = ZSTD_rowMatchFinderUsed(cParams->strategy, useRowMatchFinder)
                                            ? ZSTD_cwksp_aligned64_alloc_size(hSize)
                                            : 0;
    size_t const optSpace = (forCCtx && (cParams->strategy >= ZSTD_btopt))
                                ? optPotentialSpace
                                : 0;
    size_t const slackSpace = ZSTD_cwksp_slack_space_required();

    /* tables are guaranteed to be sized in multiples of 64 bytes (or 16 uint32_t) */
    ZSTD_STATIC_ASSERT(ZSTD_HASHLOG_MIN >= 4 && ZSTD_WINDOWLOG_MIN >= 4 && ZSTD_CHAINLOG_MIN >= 4);
    assert(useRowMatchFinder != ZSTD_ps_auto);

    DEBUGLOG(4, "chainSize: %u - hSize: %u - h3Size: %u",
                (U32)chainSize, (U32)hSize, (U32)h3Size);
    return tableSpace + optSpace + slackSpace + lazyAdditionalSpace;
}

/* Helper function for calculating memory requirements.
 * Gives a tighter bound than ZSTD_sequenceBound() by taking minMatch into account. */
static size_t ZSTD_maxNbSeq(size_t blockSize, unsigned minMatch, int useSequenceProducer) {
    U32 const divider = (minMatch==3 || useSequenceProducer) ? 3 : 4;
    return blockSize / divider;
}

static size_t ZSTD_estimateCCtxSize_usingCCtxParams_internal(
        const ZSTD_compressionParameters* cParams,
        const ldmParams_t* ldmParams,
        const int isStatic,
        const ZSTD_ParamSwitch_e useRowMatchFinder,
        const size_t buffInSize,
        const size_t buffOutSize,
        const U64 pledgedSrcSize,
        int useSequenceProducer,
        size_t maxBlockSize)
{
    size_t const windowSize = (size_t) BOUNDED(1ULL, 1ULL << cParams->windowLog, pledgedSrcSize);
    size_t const blockSize = MIN(ZSTD_resolveMaxBlockSize(maxBlockSize), windowSize);
    size_t const maxNbSeq = ZSTD_maxNbSeq(blockSize, cParams->minMatch, useSequenceProducer);
    size_t const tokenSpace = ZSTD_cwksp_alloc_size(WILDCOPY_OVERLENGTH + blockSize)
                            + ZSTD_cwksp_aligned64_alloc_size(maxNbSeq * sizeof(SeqDef))
                            + 3 * ZSTD_cwksp_alloc_size(maxNbSeq * sizeof(BYTE));
    size_t const tmpWorkSpace = ZSTD_cwksp_alloc_size(TMP_WORKSPACE_SIZE);
    size_t const blockStateSpace = 2 * ZSTD_cwksp_alloc_size(sizeof(ZSTD_compressedBlockState_t));
    size_t const matchStateSize = ZSTD_sizeof_matchState(cParams, useRowMatchFinder, /* enableDedicatedDictSearch */ 0, /* forCCtx */ 1);

    size_t const ldmSpace = ZSTD_ldm_getTableSize(*ldmParams);
    size_t const maxNbLdmSeq = ZSTD_ldm_getMaxNbSeq(*ldmParams, blockSize);
    size_t const ldmSeqSpace = ldmParams->enableLdm == ZSTD_ps_enable ?
        ZSTD_cwksp_aligned64_alloc_size(maxNbLdmSeq * sizeof(rawSeq)) : 0;


    size_t const bufferSpace = ZSTD_cwksp_alloc_size(buffInSize)
                             + ZSTD_cwksp_alloc_size(buffOutSize);

    size_t const cctxSpace = isStatic ? ZSTD_cwksp_alloc_size(sizeof(ZSTD_CCtx)) : 0;

    size_t const maxNbExternalSeq = ZSTD_sequenceBound(blockSize);
    size_t const externalSeqSpace = useSequenceProducer
        ? ZSTD_cwksp_aligned64_alloc_size(maxNbExternalSeq * sizeof(ZSTD_Sequence))
        : 0;

    size_t const neededSpace =
        cctxSpace +
        tmpWorkSpace +
        blockStateSpace +
        ldmSpace +
        ldmSeqSpace +
        matchStateSize +
        tokenSpace +
        bufferSpace +
        externalSeqSpace;

    DEBUGLOG(5, "estimate workspace : %u", (U32)neededSpace);
    return neededSpace;
}

size_t ZSTD_estimateCCtxSize_usingCCtxParams(const ZSTD_CCtx_params* params)
{
    ZSTD_compressionParameters const cParams =
                ZSTD_getCParamsFromCCtxParams(params, ZSTD_CONTENTSIZE_UNKNOWN, 0, ZSTD_cpm_noAttachDict);
    ZSTD_ParamSwitch_e const useRowMatchFinder = ZSTD_resolveRowMatchFinderMode(params->useRowMatchFinder,
                                                                               &cParams);

    RETURN_ERROR_IF(params->nbWorkers > 0, GENERIC, "Estimate CCtx size is supported for single-threaded compression only.");
    /* estimateCCtxSize is for one-shot compression. So no buffers should
     * be needed. However, we still allocate two 0-sized buffers, which can
     * take space under ASAN. */
    return ZSTD_estimateCCtxSize_usingCCtxParams_internal(
        &cParams, &params->ldmParams, 1, useRowMatchFinder, 0, 0, ZSTD_CONTENTSIZE_UNKNOWN, ZSTD_hasExtSeqProd(params), params->maxBlockSize);
}

size_t ZSTD_estimateCCtxSize_usingCParams(ZSTD_compressionParameters cParams)
{
    ZSTD_CCtx_params initialParams = ZSTD_makeCCtxParamsFromCParams(cParams);
    if (ZSTD_rowMatchFinderSupported(cParams.strategy)) {
        /* Pick bigger of not using and using row-based matchfinder for greedy and lazy strategies */
        size_t noRowCCtxSize;
        size_t rowCCtxSize;
        initialParams.useRowMatchFinder = ZSTD_ps_disable;
        noRowCCtxSize = ZSTD_estimateCCtxSize_usingCCtxParams(&initialParams);
        initialParams.useRowMatchFinder = ZSTD_ps_enable;
        rowCCtxSize = ZSTD_estimateCCtxSize_usingCCtxParams(&initialParams);
        return MAX(noRowCCtxSize, rowCCtxSize);
    } else {
        return ZSTD_estimateCCtxSize_usingCCtxParams(&initialParams);
    }
}

static size_t ZSTD_estimateCCtxSize_internal(int compressionLevel)
{
    int tier = 0;
    size_t largestSize = 0;
    static const unsigned long long srcSizeTiers[4] = {16 KB, 128 KB, 256 KB, ZSTD_CONTENTSIZE_UNKNOWN};
    for (; tier < 4; ++tier) {
        /* Choose the set of cParams for a given level across all srcSizes that give the largest cctxSize */
        ZSTD_compressionParameters const cParams = ZSTD_getCParams_internal(compressionLevel, srcSizeTiers[tier], 0, ZSTD_cpm_noAttachDict);
        largestSize = MAX(ZSTD_estimateCCtxSize_usingCParams(cParams), largestSize);
    }
    return largestSize;
}

size_t ZSTD_estimateCCtxSize(int compressionLevel)
{
    int level;
    size_t memBudget = 0;
    for (level=MIN(compressionLevel, 1); level<=compressionLevel; level++) {
        /* Ensure monotonically increasing memory usage as compression level increases */
        size_t const newMB = ZSTD_estimateCCtxSize_internal(level);
        if (newMB > memBudget) memBudget = newMB;
    }
    return memBudget;
}

size_t ZSTD_estimateCStreamSize_usingCCtxParams(const ZSTD_CCtx_params* params)
{
    RETURN_ERROR_IF(params->nbWorkers > 0, GENERIC, "Estimate CCtx size is supported for single-threaded compression only.");
    {   ZSTD_compressionParameters const cParams =
                ZSTD_getCParamsFromCCtxParams(params, ZSTD_CONTENTSIZE_UNKNOWN, 0, ZSTD_cpm_noAttachDict);
        size_t const blockSize = MIN(ZSTD_resolveMaxBlockSize(params->maxBlockSize), (size_t)1 << cParams.windowLog);
        size_t const inBuffSize = (params->inBufferMode == ZSTD_bm_buffered)
                ? ((size_t)1 << cParams.windowLog) + blockSize
                : 0;
        size_t const outBuffSize = (params->outBufferMode == ZSTD_bm_buffered)
                ? ZSTD_compressBound(blockSize) + 1
                : 0;
        ZSTD_ParamSwitch_e const useRowMatchFinder = ZSTD_resolveRowMatchFinderMode(params->useRowMatchFinder, &params->cParams);

        return ZSTD_estimateCCtxSize_usingCCtxParams_internal(
            &cParams, &params->ldmParams, 1, useRowMatchFinder, inBuffSize, outBuffSize,
            ZSTD_CONTENTSIZE_UNKNOWN, ZSTD_hasExtSeqProd(params), params->maxBlockSize);
    }
}

size_t ZSTD_estimateCStreamSize_usingCParams(ZSTD_compressionParameters cParams)
{
    ZSTD_CCtx_params initialParams = ZSTD_makeCCtxParamsFromCParams(cParams);
    if (ZSTD_rowMatchFinderSupported(cParams.strategy)) {
        /* Pick bigger of not using and using row-based matchfinder for greedy and lazy strategies */
        size_t noRowCCtxSize;
        size_t rowCCtxSize;
        initialParams.useRowMatchFinder = ZSTD_ps_disable;
        noRowCCtxSize = ZSTD_estimateCStreamSize_usingCCtxParams(&initialParams);
        initialParams.useRowMatchFinder = ZSTD_ps_enable;
        rowCCtxSize = ZSTD_estimateCStreamSize_usingCCtxParams(&initialParams);
        return MAX(noRowCCtxSize, rowCCtxSize);
    } else {
        return ZSTD_estimateCStreamSize_usingCCtxParams(&initialParams);
    }
}

static size_t ZSTD_estimateCStreamSize_internal(int compressionLevel)
{
    ZSTD_compressionParameters const cParams = ZSTD_getCParams_internal(compressionLevel, ZSTD_CONTENTSIZE_UNKNOWN, 0, ZSTD_cpm_noAttachDict);
    return ZSTD_estimateCStreamSize_usingCParams(cParams);
}

size_t ZSTD_estimateCStreamSize(int compressionLevel)
{
    int level;
    size_t memBudget = 0;
    for (level=MIN(compressionLevel, 1); level<=compressionLevel; level++) {
        size_t const newMB = ZSTD_estimateCStreamSize_internal(level);
        if (newMB > memBudget) memBudget = newMB;
    }
    return memBudget;
}

/* ZSTD_getFrameProgression():
 * tells how much data has been consumed (input) and produced (output) for current frame.
 * able to count progression inside worker threads (non-blocking mode).
 */
ZSTD_frameProgression ZSTD_getFrameProgression(const ZSTD_CCtx* cctx)
{
#ifdef ZSTD_MULTITHREAD
    if (cctx->appliedParams.nbWorkers > 0) {
        return ZSTDMT_getFrameProgression(cctx->mtctx);
    }
#endif
    {   ZSTD_frameProgression fp;
        size_t const buffered = (cctx->inBuff == NULL) ? 0 :
                                cctx->inBuffPos - cctx->inToCompress;
        if (buffered) assert(cctx->inBuffPos >= cctx->inToCompress);
        assert(buffered <= ZSTD_BLOCKSIZE_MAX);
        fp.ingested = cctx->consumedSrcSize + buffered;
        fp.consumed = cctx->consumedSrcSize;
        fp.produced = cctx->producedCSize;
        fp.flushed  = cctx->producedCSize;   /* simplified; some data might still be left within streaming output buffer */
        fp.currentJobID = 0;
        fp.nbActiveWorkers = 0;
        return fp;
}   }

/*! ZSTD_toFlushNow()
 *  Only useful for multithreading scenarios currently (nbWorkers >= 1).
 */
size_t ZSTD_toFlushNow(ZSTD_CCtx* cctx)
{
#ifdef ZSTD_MULTITHREAD
    if (cctx->appliedParams.nbWorkers > 0) {
        return ZSTDMT_toFlushNow(cctx->mtctx);
    }
#endif
    (void)cctx;
    return 0;   /* over-simplification; could also check if context is currently running in streaming mode, and in which case, report how many bytes are left to be flushed within output buffer */
}

static void ZSTD_assertEqualCParams(ZSTD_compressionParameters cParams1,
                                    ZSTD_compressionParameters cParams2)
{
    (void)cParams1;
    (void)cParams2;
    assert(cParams1.windowLog    == cParams2.windowLog);
    assert(cParams1.chainLog     == cParams2.chainLog);
    assert(cParams1.hashLog      == cParams2.hashLog);
    assert(cParams1.searchLog    == cParams2.searchLog);
    assert(cParams1.minMatch     == cParams2.minMatch);
    assert(cParams1.targetLength == cParams2.targetLength);
    assert(cParams1.strategy     == cParams2.strategy);
}

void ZSTD_reset_compressedBlockState(ZSTD_compressedBlockState_t* bs)
{
    int i;
    for (i = 0; i < ZSTD_REP_NUM; ++i)
        bs->rep[i] = repStartValue[i];
    bs->entropy.huf.repeatMode = HUF_repeat_none;
    bs->entropy.fse.offcode_repeatMode = FSE_repeat_none;
    bs->entropy.fse.matchlength_repeatMode = FSE_repeat_none;
    bs->entropy.fse.litlength_repeatMode = FSE_repeat_none;
}

/*! ZSTD_invalidateMatchState()
 *  Invalidate all the matches in the match finder tables.
 *  Requires nextSrc and base to be set (can be NULL).
 */
static void ZSTD_invalidateMatchState(ZSTD_MatchState_t* ms)
{
    ZSTD_window_clear(&ms->window);

    ms->nextToUpdate = ms->window.dictLimit;
    ms->loadedDictEnd = 0;
    ms->opt.litLengthSum = 0;  /* force reset of btopt stats */
    ms->dictMatchState = NULL;
}

/**
 * Controls, for this matchState reset, whether the tables need to be cleared /
 * prepared for the coming compression (ZSTDcrp_makeClean), or whether the
 * tables can be left unclean (ZSTDcrp_leaveDirty), because we know that a
 * subsequent operation will overwrite the table space anyways (e.g., copying
 * the matchState contents in from a CDict).
 */
typedef enum {
    ZSTDcrp_makeClean,
    ZSTDcrp_leaveDirty
} ZSTD_compResetPolicy_e;

/**
 * Controls, for this matchState reset, whether indexing can continue where it
 * left off (ZSTDirp_continue), or whether it needs to be restarted from zero
 * (ZSTDirp_reset).
 */
typedef enum {
    ZSTDirp_continue,
    ZSTDirp_reset
} ZSTD_indexResetPolicy_e;

typedef enum {
    ZSTD_resetTarget_CDict,
    ZSTD_resetTarget_CCtx
} ZSTD_resetTarget_e;

/* Mixes bits in a 64 bits in a value, based on XXH3_rrmxmx */
static U64 ZSTD_bitmix(U64 val, U64 len) {
    val ^= ZSTD_rotateRight_U64(val, 49) ^ ZSTD_rotateRight_U64(val, 24);
    val *= 0x9FB21C651E98DF25ULL;
    val ^= (val >> 35) + len ;
    val *= 0x9FB21C651E98DF25ULL;
    return val ^ (val >> 28);
}

/* Mixes in the hashSalt and hashSaltEntropy to create a new hashSalt */
static void ZSTD_advanceHashSalt(ZSTD_MatchState_t* ms) {
    ms->hashSalt = ZSTD_bitmix(ms->hashSalt, 8) ^ ZSTD_bitmix((U64) ms->hashSaltEntropy, 4);
}

static size_t
ZSTD_reset_matchState(ZSTD_MatchState_t* ms,
                      ZSTD_cwksp* ws,
                const ZSTD_compressionParameters* cParams,
                const ZSTD_ParamSwitch_e useRowMatchFinder,
                const ZSTD_compResetPolicy_e crp,
                const ZSTD_indexResetPolicy_e forceResetIndex,
                const ZSTD_resetTarget_e forWho)
{
    /* disable chain table allocation for fast or row-based strategies */
    size_t const chainSize = ZSTD_allocateChainTable(cParams->strategy, useRowMatchFinder,
                                                     ms->dedicatedDictSearch && (forWho == ZSTD_resetTarget_CDict))
                                ? ((size_t)1 << cParams->chainLog)
                                : 0;
    size_t const hSize = ((size_t)1) << cParams->hashLog;
    U32    const hashLog3 = ((forWho == ZSTD_resetTarget_CCtx) && cParams->minMatch==3) ? MIN(ZSTD_HASHLOG3_MAX, cParams->windowLog) : 0;
    size_t const h3Size = hashLog3 ? ((size_t)1) << hashLog3 : 0;

    DEBUGLOG(4, "reset indices : %u", forceResetIndex == ZSTDirp_reset);
    assert(useRowMatchFinder != ZSTD_ps_auto);
    if (forceResetIndex == ZSTDirp_reset) {
        ZSTD_window_init(&ms->window);
        ZSTD_cwksp_mark_tables_dirty(ws);
    }

    ms->hashLog3 = hashLog3;
    ms->lazySkipping = 0;

    ZSTD_invalidateMatchState(ms);

    assert(!ZSTD_cwksp_reserve_failed(ws)); /* check that allocation hasn't already failed */

    ZSTD_cwksp_clear_tables(ws);

    DEBUGLOG(5, "reserving table space");
    /* table Space */
    ms->hashTable = (U32*)ZSTD_cwksp_reserve_table(ws, hSize * sizeof(U32));
    ms->chainTable = (U32*)ZSTD_cwksp_reserve_table(ws, chainSize * sizeof(U32));
    ms->hashTable3 = (U32*)ZSTD_cwksp_reserve_table(ws, h3Size * sizeof(U32));
    RETURN_ERROR_IF(ZSTD_cwksp_reserve_failed(ws), memory_allocation,
                    "failed a workspace allocation in ZSTD_reset_matchState");

    DEBUGLOG(4, "reset table : %u", crp!=ZSTDcrp_leaveDirty);
    if (crp!=ZSTDcrp_leaveDirty) {
        /* reset tables only */
        ZSTD_cwksp_clean_tables(ws);
    }

    if (ZSTD_rowMatchFinderUsed(cParams->strategy, useRowMatchFinder)) {
        /* Row match finder needs an additional table of hashes ("tags") */
        size_t const tagTableSize = hSize;
        /* We want to generate a new salt in case we reset a Cctx, but we always want to use
         * 0 when we reset a Cdict */
        if(forWho == ZSTD_resetTarget_CCtx) {
            ms->tagTable = (BYTE*) ZSTD_cwksp_reserve_aligned_init_once(ws, tagTableSize);
            ZSTD_advanceHashSalt(ms);
        } else {
            /* When we are not salting we want to always memset the memory */
            ms->tagTable = (BYTE*) ZSTD_cwksp_reserve_aligned64(ws, tagTableSize);
            ZSTD_memset(ms->tagTable, 0, tagTableSize);
            ms->hashSalt = 0;
        }
        {   /* Switch to 32-entry rows if searchLog is 5 (or more) */
            U32 const rowLog = BOUNDED(4, cParams->searchLog, 6);
            assert(cParams->hashLog >= rowLog);
            ms->rowHashLog = cParams->hashLog - rowLog;
        }
    }

    /* opt parser space */
    if ((forWho == ZSTD_resetTarget_CCtx) && (cParams->strategy >= ZSTD_btopt)) {
        DEBUGLOG(4, "reserving optimal parser space");
        ms->opt.litFreq = (unsigned*)ZSTD_cwksp_reserve_aligned64(ws, (1<<Litbits) * sizeof(unsigned));
        ms->opt.litLengthFreq = (unsigned*)ZSTD_cwksp_reserve_aligned64(ws, (MaxLL+1) * sizeof(unsigned));
        ms->opt.matchLengthFreq = (unsigned*)ZSTD_cwksp_reserve_aligned64(ws, (MaxML+1) * sizeof(unsigned));
        ms->opt.offCodeFreq = (unsigned*)ZSTD_cwksp_reserve_aligned64(ws, (MaxOff+1) * sizeof(unsigned));
        ms->opt.matchTable = (ZSTD_match_t*)ZSTD_cwksp_reserve_aligned64(ws, ZSTD_OPT_SIZE * sizeof(ZSTD_match_t));
        ms->opt.priceTable = (ZSTD_optimal_t*)ZSTD_cwksp_reserve_aligned64(ws, ZSTD_OPT_SIZE * sizeof(ZSTD_optimal_t));
    }

    ms->cParams = *cParams;

    RETURN_ERROR_IF(ZSTD_cwksp_reserve_failed(ws), memory_allocation,
                    "failed a workspace allocation in ZSTD_reset_matchState");
    return 0;
}

/* ZSTD_indexTooCloseToMax() :
 * minor optimization : prefer memset() rather than reduceIndex()
 * which is measurably slow in some circumstances (reported for Visual Studio).
 * Works when re-using a context for a lot of smallish inputs :
 * if all inputs are smaller than ZSTD_INDEXOVERFLOW_MARGIN,
 * memset() will be triggered before reduceIndex().
 */
#define ZSTD_INDEXOVERFLOW_MARGIN (16 MB)
static int ZSTD_indexTooCloseToMax(ZSTD_window_t w)
{
    return (size_t)(w.nextSrc - w.base) > (ZSTD_CURRENT_MAX - ZSTD_INDEXOVERFLOW_MARGIN);
}

/** ZSTD_dictTooBig():
 * When dictionaries are larger than ZSTD_CHUNKSIZE_MAX they can't be loaded in
 * one go generically. So we ensure that in that case we reset the tables to zero,
 * so that we can load as much of the dictionary as possible.
 */
static int ZSTD_dictTooBig(size_t const loadedDictSize)
{
    return loadedDictSize > ZSTD_CHUNKSIZE_MAX;
}

/*! ZSTD_resetCCtx_internal() :
 * @param loadedDictSize The size of the dictionary to be loaded
 * into the context, if any. If no dictionary is used, or the
 * dictionary is being attached / copied, then pass 0.
 * note : `params` are assumed fully validated at this stage.
 */
static size_t ZSTD_resetCCtx_internal(ZSTD_CCtx* zc,
                                      ZSTD_CCtx_params const* params,
                                      U64 const pledgedSrcSize,
                                      size_t const loadedDictSize,
                                      ZSTD_compResetPolicy_e const crp,
                                      ZSTD_buffered_policy_e const zbuff)
{
    ZSTD_cwksp* const ws = &zc->workspace;
    DEBUGLOG(4, "ZSTD_resetCCtx_internal: pledgedSrcSize=%u, wlog=%u, useRowMatchFinder=%d useBlockSplitter=%d",
                (U32)pledgedSrcSize, params->cParams.windowLog, (int)params->useRowMatchFinder, (int)params->postBlockSplitter);
    assert(!ZSTD_isError(ZSTD_checkCParams(params->cParams)));

    zc->isFirstBlock = 1;

    /* Set applied params early so we can modify them for LDM,
     * and point params at the applied params.
     */
    zc->appliedParams = *params;
    params = &zc->appliedParams;

    assert(params->useRowMatchFinder != ZSTD_ps_auto);
    assert(params->postBlockSplitter != ZSTD_ps_auto);
    assert(params->ldmParams.enableLdm != ZSTD_ps_auto);
    assert(params->maxBlockSize != 0);
    if (params->ldmParams.enableLdm == ZSTD_ps_enable) {
        /* Adjust long distance matching parameters */
        ZSTD_ldm_adjustParameters(&zc->appliedParams.ldmParams, &params->cParams);
        assert(params->ldmParams.hashLog >= params->ldmParams.bucketSizeLog);
        assert(params->ldmParams.hashRateLog < 32);
    }

    {   size_t const windowSize = MAX(1, (size_t)MIN(((U64)1 << params->cParams.windowLog), pledgedSrcSize));
        size_t const blockSize = MIN(params->maxBlockSize, windowSize);
        size_t const maxNbSeq = ZSTD_maxNbSeq(blockSize, params->cParams.minMatch, ZSTD_hasExtSeqProd(params));
        size_t const buffOutSize = (zbuff == ZSTDb_buffered && params->outBufferMode == ZSTD_bm_buffered)
                ? ZSTD_compressBound(blockSize) + 1
                : 0;
        size_t const buffInSize = (zbuff == ZSTDb_buffered && params->inBufferMode == ZSTD_bm_buffered)
                ? windowSize + blockSize
                : 0;
        size_t const maxNbLdmSeq = ZSTD_ldm_getMaxNbSeq(params->ldmParams, blockSize);

        int const indexTooClose = ZSTD_indexTooCloseToMax(zc->blockState.matchState.window);
        int const dictTooBig = ZSTD_dictTooBig(loadedDictSize);
        ZSTD_indexResetPolicy_e needsIndexReset =
            (indexTooClose || dictTooBig || !zc->initialized) ? ZSTDirp_reset : ZSTDirp_continue;

        size_t const neededSpace =
            ZSTD_estimateCCtxSize_usingCCtxParams_internal(
                &params->cParams, &params->ldmParams, zc->staticSize != 0, params->useRowMatchFinder,
                buffInSize, buffOutSize, pledgedSrcSize, ZSTD_hasExtSeqProd(params), params->maxBlockSize);

        FORWARD_IF_ERROR(neededSpace, "cctx size estimate failed!");

        if (!zc->staticSize) ZSTD_cwksp_bump_oversized_duration(ws, 0);

        {   /* Check if workspace is large enough, alloc a new one if needed */
            int const workspaceTooSmall = ZSTD_cwksp_sizeof(ws) < neededSpace;
            int const workspaceWasteful = ZSTD_cwksp_check_wasteful(ws, neededSpace);
            int resizeWorkspace = workspaceTooSmall || workspaceWasteful;
            DEBUGLOG(4, "Need %zu B workspace", neededSpace);
            DEBUGLOG(4, "windowSize: %zu - blockSize: %zu", windowSize, blockSize);

            if (resizeWorkspace) {
                DEBUGLOG(4, "Resize workspaceSize from %zuKB to %zuKB",
                            ZSTD_cwksp_sizeof(ws) >> 10,
                            neededSpace >> 10);

                RETURN_ERROR_IF(zc->staticSize, memory_allocation, "static cctx : no resize");

                needsIndexReset = ZSTDirp_reset;

                ZSTD_cwksp_free(ws, zc->customMem);
                FORWARD_IF_ERROR(ZSTD_cwksp_create(ws, neededSpace, zc->customMem), "");

                DEBUGLOG(5, "reserving object space");
                /* Statically sized space.
                 * tmpWorkspace never moves,
                 * though prev/next block swap places */
                assert(ZSTD_cwksp_check_available(ws, 2 * sizeof(ZSTD_compressedBlockState_t)));
                zc->blockState.prevCBlock = (ZSTD_compressedBlockState_t*) ZSTD_cwksp_reserve_object(ws, sizeof(ZSTD_compressedBlockState_t));
                RETURN_ERROR_IF(zc->blockState.prevCBlock == NULL, memory_allocation, "couldn't allocate prevCBlock");
                zc->blockState.nextCBlock = (ZSTD_compressedBlockState_t*) ZSTD_cwksp_reserve_object(ws, sizeof(ZSTD_compressedBlockState_t));
                RETURN_ERROR_IF(zc->blockState.nextCBlock == NULL, memory_allocation, "couldn't allocate nextCBlock");
                zc->tmpWorkspace = ZSTD_cwksp_reserve_object(ws, TMP_WORKSPACE_SIZE);
                RETURN_ERROR_IF(zc->tmpWorkspace == NULL, memory_allocation, "couldn't allocate tmpWorkspace");
                zc->tmpWkspSize = TMP_WORKSPACE_SIZE;
        }   }

        ZSTD_cwksp_clear(ws);

        /* init params */
        zc->blockState.matchState.cParams = params->cParams;
        zc->blockState.matchState.prefetchCDictTables = params->prefetchCDictTables == ZSTD_ps_enable;
        zc->pledgedSrcSizePlusOne = pledgedSrcSize+1;
        zc->consumedSrcSize = 0;
        zc->producedCSize = 0;
        if (pledgedSrcSize == ZSTD_CONTENTSIZE_UNKNOWN)
            zc->appliedParams.fParams.contentSizeFlag = 0;
        DEBUGLOG(4, "pledged content size : %u ; flag : %u",
            (unsigned)pledgedSrcSize, zc->appliedParams.fParams.contentSizeFlag);
        zc->blockSizeMax = blockSize;

        XXH64_reset(&zc->xxhState, 0);
        zc->stage = ZSTDcs_init;
        zc->dictID = 0;
        zc->dictContentSize = 0;

        ZSTD_reset_compressedBlockState(zc->blockState.prevCBlock);

        FORWARD_IF_ERROR(ZSTD_reset_matchState(
                &zc->blockState.matchState,
                ws,
                &params->cParams,
                params->useRowMatchFinder,
                crp,
                needsIndexReset,
                ZSTD_resetTarget_CCtx), "");

        zc->seqStore.sequencesStart = (SeqDef*)ZSTD_cwksp_reserve_aligned64(ws, maxNbSeq * sizeof(SeqDef));

        /* ldm hash table */
        if (params->ldmParams.enableLdm == ZSTD_ps_enable) {
            /* TODO: avoid memset? */
            size_t const ldmHSize = ((size_t)1) << params->ldmParams.hashLog;
            zc->ldmState.hashTable = (ldmEntry_t*)ZSTD_cwksp_reserve_aligned64(ws, ldmHSize * sizeof(ldmEntry_t));
            ZSTD_memset(zc->ldmState.hashTable, 0, ldmHSize * sizeof(ldmEntry_t));
            zc->ldmSequences = (rawSeq*)ZSTD_cwksp_reserve_aligned64(ws, maxNbLdmSeq * sizeof(rawSeq));
            zc->maxNbLdmSequences = maxNbLdmSeq;

            ZSTD_window_init(&zc->ldmState.window);
            zc->ldmState.loadedDictEnd = 0;
        }

        /* reserve space for block-level external sequences */
        if (ZSTD_hasExtSeqProd(params)) {
            size_t const maxNbExternalSeq = ZSTD_sequenceBound(blockSize);
            zc->extSeqBufCapacity = maxNbExternalSeq;
            zc->extSeqBuf =
                (ZSTD_Sequence*)ZSTD_cwksp_reserve_aligned64(ws, maxNbExternalSeq * sizeof(ZSTD_Sequence));
        }

        /* buffers */

        /* ZSTD_wildcopy() is used to copy into the literals buffer,
         * so we have to oversize the buffer by WILDCOPY_OVERLENGTH bytes.
         */
        zc->seqStore.litStart = ZSTD_cwksp_reserve_buffer(ws, blockSize + WILDCOPY_OVERLENGTH);
        zc->seqStore.maxNbLit = blockSize;

        zc->bufferedPolicy = zbuff;
        zc->inBuffSize = buffInSize;
        zc->inBuff = (char*)ZSTD_cwksp_reserve_buffer(ws, buffInSize);
        zc->outBuffSize = buffOutSize;
        zc->outBuff = (char*)ZSTD_cwksp_reserve_buffer(ws, buffOutSize);

        /* ldm bucketOffsets table */
        if (params->ldmParams.enableLdm == ZSTD_ps_enable) {
            /* TODO: avoid memset? */
            size_t const numBuckets =
                  ((size_t)1) << (params->ldmParams.hashLog -
                                  params->ldmParams.bucketSizeLog);
            zc->ldmState.bucketOffsets = ZSTD_cwksp_reserve_buffer(ws, numBuckets);
            ZSTD_memset(zc->ldmState.bucketOffsets, 0, numBuckets);
        }

        /* sequences storage */
        ZSTD_referenceExternalSequences(zc, NULL, 0);
        zc->seqStore.maxNbSeq = maxNbSeq;
        zc->seqStore.llCode = ZSTD_cwksp_reserve_buffer(ws, maxNbSeq * sizeof(BYTE));
        zc->seqStore.mlCode = ZSTD_cwksp_reserve_buffer(ws, maxNbSeq * sizeof(BYTE));
        zc->seqStore.ofCode = ZSTD_cwksp_reserve_buffer(ws, maxNbSeq * sizeof(BYTE));

        DEBUGLOG(3, "wksp: finished allocating, %zd bytes remain available", ZSTD_cwksp_available_space(ws));
        assert(ZSTD_cwksp_estimated_space_within_bounds(ws, neededSpace));

        zc->initialized = 1;

        return 0;
    }
}

/* ZSTD_invalidateRepCodes() :
 * ensures next compression will not use repcodes from previous block.
 * Note : only works with regular variant;
 *        do not use with extDict variant ! */
void ZSTD_invalidateRepCodes(ZSTD_CCtx* cctx) {
    int i;
    for (i=0; i<ZSTD_REP_NUM; i++) cctx->blockState.prevCBlock->rep[i] = 0;
    assert(!ZSTD_window_hasExtDict(cctx->blockState.matchState.window));
}

/* These are the approximate sizes for each strategy past which copying the
 * dictionary tables into the working context is faster than using them
 * in-place.
 */
static const size_t attachDictSizeCutoffs[ZSTD_STRATEGY_MAX+1] = {
    8 KB,  /* unused */
    8 KB,  /* ZSTD_fast */
    16 KB, /* ZSTD_dfast */
    32 KB, /* ZSTD_greedy */
    32 KB, /* ZSTD_lazy */
    32 KB, /* ZSTD_lazy2 */
    32 KB, /* ZSTD_btlazy2 */
    32 KB, /* ZSTD_btopt */
    8 KB,  /* ZSTD_btultra */
    8 KB   /* ZSTD_btultra2 */
};

static int ZSTD_shouldAttachDict(const ZSTD_CDict* cdict,
                                 const ZSTD_CCtx_params* params,
                                 U64 pledgedSrcSize)
{
    size_t cutoff = attachDictSizeCutoffs[cdict->matchState.cParams.strategy];
    int const dedicatedDictSearch = cdict->matchState.dedicatedDictSearch;
    return dedicatedDictSearch
        || ( ( pledgedSrcSize <= cutoff
            || pledgedSrcSize == ZSTD_CONTENTSIZE_UNKNOWN
            || params->attachDictPref == ZSTD_dictForceAttach )
          && params->attachDictPref != ZSTD_dictForceCopy
          && !params->forceWindow ); /* dictMatchState isn't correctly
                                      * handled in _enforceMaxDist */
}

static size_t
ZSTD_resetCCtx_byAttachingCDict(ZSTD_CCtx* cctx,
                        const ZSTD_CDict* cdict,
                        ZSTD_CCtx_params params,
                        U64 pledgedSrcSize,
                        ZSTD_buffered_policy_e zbuff)
{
    DEBUGLOG(4, "ZSTD_resetCCtx_byAttachingCDict() pledgedSrcSize=%llu",
                (unsigned long long)pledgedSrcSize);
    {
        ZSTD_compressionParameters adjusted_cdict_cParams = cdict->matchState.cParams;
        unsigned const windowLog = params.cParams.windowLog;
        assert(windowLog != 0);
        /* Resize working context table params for input only, since the dict
         * has its own tables. */
        /* pledgedSrcSize == 0 means 0! */

        if (cdict->matchState.dedicatedDictSearch) {
            ZSTD_dedicatedDictSearch_revertCParams(&adjusted_cdict_cParams);
        }

        params.cParams = ZSTD_adjustCParams_internal(adjusted_cdict_cParams, pledgedSrcSize,
                                                     cdict->dictContentSize, ZSTD_cpm_attachDict,
                                                     params.useRowMatchFinder);
        params.cParams.windowLog = windowLog;
        params.useRowMatchFinder = cdict->useRowMatchFinder;    /* cdict overrides */
        FORWARD_IF_ERROR(ZSTD_resetCCtx_internal(cctx, &params, pledgedSrcSize,
                                                 /* loadedDictSize */ 0,
                                                 ZSTDcrp_makeClean, zbuff), "");
        assert(cctx->appliedParams.cParams.strategy == adjusted_cdict_cParams.strategy);
    }

    {   const U32 cdictEnd = (U32)( cdict->matchState.window.nextSrc
                                  - cdict->matchState.window.base);
        const U32 cdictLen = cdictEnd - cdict->matchState.window.dictLimit;
        if (cdictLen == 0) {
            /* don't even attach dictionaries with no contents */
            DEBUGLOG(4, "skipping attaching empty dictionary");
        } else {
            DEBUGLOG(4, "attaching dictionary into context");
            cctx->blockState.matchState.dictMatchState = &cdict->matchState;

            /* prep working match state so dict matches never have negative indices
             * when they are translated to the working context's index space. */
            if (cctx->blockState.matchState.window.dictLimit < cdictEnd) {
                cctx->blockState.matchState.window.nextSrc =
                    cctx->blockState.matchState.window.base + cdictEnd;
                ZSTD_window_clear(&cctx->blockState.matchState.window);
            }
            /* loadedDictEnd is expressed within the referential of the active context */
            cctx->blockState.matchState.loadedDictEnd = cctx->blockState.matchState.window.dictLimit;
    }   }

    cctx->dictID = cdict->dictID;
    cctx->dictContentSize = cdict->dictContentSize;

    /* copy block state */
    ZSTD_memcpy(cctx->blockState.prevCBlock, &cdict->cBlockState, sizeof(cdict->cBlockState));

    return 0;
}

static void ZSTD_copyCDictTableIntoCCtx(U32* dst, U32 const* src, size_t tableSize,
                                        ZSTD_compressionParameters const* cParams) {
    if (ZSTD_CDictIndicesAreTagged(cParams)){
        /* Remove tags from the CDict table if they are present.
         * See docs on "short cache" in zstd_compress_internal.h for context. */
        size_t i;
        for (i = 0; i < tableSize; i++) {
            U32 const taggedIndex = src[i];
            U32 const index = taggedIndex >> ZSTD_SHORT_CACHE_TAG_BITS;
            dst[i] = index;
        }
    } else {
        ZSTD_memcpy(dst, src, tableSize * sizeof(U32));
    }
}

static size_t ZSTD_resetCCtx_byCopyingCDict(ZSTD_CCtx* cctx,
                            const ZSTD_CDict* cdict,
                            ZSTD_CCtx_params params,
                            U64 pledgedSrcSize,
                            ZSTD_buffered_policy_e zbuff)
{
    const ZSTD_compressionParameters *cdict_cParams = &cdict->matchState.cParams;

    assert(!cdict->matchState.dedicatedDictSearch);
    DEBUGLOG(4, "ZSTD_resetCCtx_byCopyingCDict() pledgedSrcSize=%llu",
                (unsigned long long)pledgedSrcSize);

    {   unsigned const windowLog = params.cParams.windowLog;
        assert(windowLog != 0);
        /* Copy only compression parameters related to tables. */
        params.cParams = *cdict_cParams;
        params.cParams.windowLog = windowLog;
        params.useRowMatchFinder = cdict->useRowMatchFinder;
        FORWARD_IF_ERROR(ZSTD_resetCCtx_internal(cctx, &params, pledgedSrcSize,
                                                 /* loadedDictSize */ 0,
                                                 ZSTDcrp_leaveDirty, zbuff), "");
        assert(cctx->appliedParams.cParams.strategy == cdict_cParams->strategy);
        assert(cctx->appliedParams.cParams.hashLog == cdict_cParams->hashLog);
        assert(cctx->appliedParams.cParams.chainLog == cdict_cParams->chainLog);
    }

    ZSTD_cwksp_mark_tables_dirty(&cctx->workspace);
    assert(params.useRowMatchFinder != ZSTD_ps_auto);

    /* copy tables */
    {   size_t const chainSize = ZSTD_allocateChainTable(cdict_cParams->strategy, cdict->useRowMatchFinder, 0 /* DDS guaranteed disabled */)
                                                            ? ((size_t)1 << cdict_cParams->chainLog)
                                                            : 0;
        size_t const hSize =  (size_t)1 << cdict_cParams->hashLog;

        ZSTD_copyCDictTableIntoCCtx(cctx->blockState.matchState.hashTable,
                                cdict->matchState.hashTable,
                                hSize, cdict_cParams);

        /* Do not copy cdict's chainTable if cctx has parameters such that it would not use chainTable */
        if (ZSTD_allocateChainTable(cctx->appliedParams.cParams.strategy, cctx->appliedParams.useRowMatchFinder, 0 /* forDDSDict */)) {
            ZSTD_copyCDictTableIntoCCtx(cctx->blockState.matchState.chainTable,
                                    cdict->matchState.chainTable,
                                    chainSize, cdict_cParams);
        }
        /* copy tag table */
        if (ZSTD_rowMatchFinderUsed(cdict_cParams->strategy, cdict->useRowMatchFinder)) {
            size_t const tagTableSize = hSize;
            ZSTD_memcpy(cctx->blockState.matchState.tagTable,
                        cdict->matchState.tagTable,
                        tagTableSize);
            cctx->blockState.matchState.hashSalt = cdict->matchState.hashSalt;
        }
    }

    /* Zero the hashTable3, since the cdict never fills it */
    assert(cctx->blockState.matchState.hashLog3 <= 31);
    {   U32 const h3log = cctx->blockState.matchState.hashLog3;
        size_t const h3Size = h3log ? ((size_t)1 << h3log) : 0;
        assert(cdict->matchState.hashLog3 == 0);
        ZSTD_memset(cctx->blockState.matchState.hashTable3, 0, h3Size * sizeof(U32));
    }

    ZSTD_cwksp_mark_tables_clean(&cctx->workspace);

    /* copy dictionary offsets */
    {   ZSTD_MatchState_t const* srcMatchState = &cdict->matchState;
        ZSTD_MatchState_t* dstMatchState = &cctx->blockState.matchState;
        dstMatchState->window       = srcMatchState->window;
        dstMatchState->nextToUpdate = srcMatchState->nextToUpdate;
        dstMatchState->loadedDictEnd= srcMatchState->loadedDictEnd;
    }

    cctx->dictID = cdict->dictID;
    cctx->dictContentSize = cdict->dictContentSize;

    /* copy block state */
    ZSTD_memcpy(cctx->blockState.prevCBlock, &cdict->cBlockState, sizeof(cdict->cBlockState));

    return 0;
}

/* We have a choice between copying the dictionary context into the working
 * context, or referencing the dictionary context from the working context
 * in-place. We decide here which strategy to use. */
static size_t ZSTD_resetCCtx_usingCDict(ZSTD_CCtx* cctx,
                            const ZSTD_CDict* cdict,
                            const ZSTD_CCtx_params* params,
                            U64 pledgedSrcSize,
                            ZSTD_buffered_policy_e zbuff)
{

    DEBUGLOG(4, "ZSTD_resetCCtx_usingCDict (pledgedSrcSize=%u)",
                (unsigned)pledgedSrcSize);

    if (ZSTD_shouldAttachDict(cdict, params, pledgedSrcSize)) {
        return ZSTD_resetCCtx_byAttachingCDict(
            cctx, cdict, *params, pledgedSrcSize, zbuff);
    } else {
        return ZSTD_resetCCtx_byCopyingCDict(
            cctx, cdict, *params, pledgedSrcSize, zbuff);
    }
}

/*! ZSTD_copyCCtx_internal() :
 *  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()).
 *  The "context", in this case, refers to the hash and chain tables,
 *  entropy tables, and dictionary references.
 * `windowLog` value is enforced if != 0, otherwise value is copied from srcCCtx.
 * @return : 0, or an error code */
static size_t ZSTD_copyCCtx_internal(ZSTD_CCtx* dstCCtx,
                            const ZSTD_CCtx* srcCCtx,
                            ZSTD_frameParameters fParams,
                            U64 pledgedSrcSize,
                            ZSTD_buffered_policy_e zbuff)
{
    RETURN_ERROR_IF(srcCCtx->stage!=ZSTDcs_init, stage_wrong,
                    "Can't copy a ctx that's not in init stage.");
    DEBUGLOG(5, "ZSTD_copyCCtx_internal");
    ZSTD_memcpy(&dstCCtx->customMem, &srcCCtx->customMem, sizeof(ZSTD_customMem));
    {   ZSTD_CCtx_params params = dstCCtx->requestedParams;
        /* Copy only compression parameters related to tables. */
        params.cParams = srcCCtx->appliedParams.cParams;
        assert(srcCCtx->appliedParams.useRowMatchFinder != ZSTD_ps_auto);
        assert(srcCCtx->appliedParams.postBlockSplitter != ZSTD_ps_auto);
        assert(srcCCtx->appliedParams.ldmParams.enableLdm != ZSTD_ps_auto);
        params.useRowMatchFinder = srcCCtx->appliedParams.useRowMatchFinder;
        params.postBlockSplitter = srcCCtx->appliedParams.postBlockSplitter;
        params.ldmParams = srcCCtx->appliedParams.ldmParams;
        params.fParams = fParams;
        params.maxBlockSize = srcCCtx->appliedParams.maxBlockSize;
        ZSTD_resetCCtx_internal(dstCCtx, &params, pledgedSrcSize,
                                /* loadedDictSize */ 0,
                                ZSTDcrp_leaveDirty, zbuff);
        assert(dstCCtx->appliedParams.cParams.windowLog == srcCCtx->appliedParams.cParams.windowLog);
        assert(dstCCtx->appliedParams.cParams.strategy == srcCCtx->appliedParams.cParams.strategy);
        assert(dstCCtx->appliedParams.cParams.hashLog == srcCCtx->appliedParams.cParams.hashLog);
        assert(dstCCtx->appliedParams.cParams.chainLog == srcCCtx->appliedParams.cParams.chainLog);
        assert(dstCCtx->blockState.matchState.hashLog3 == srcCCtx->blockState.matchState.hashLog3);
    }

    ZSTD_cwksp_mark_tables_dirty(&dstCCtx->workspace);

    /* copy tables */
    {   size_t const chainSize = ZSTD_allocateChainTable(srcCCtx->appliedParams.cParams.strategy,
                                                         srcCCtx->appliedParams.useRowMatchFinder,
                                                         0 /* forDDSDict */)
                                    ? ((size_t)1 << srcCCtx->appliedParams.cParams.chainLog)
                                    : 0;
        size_t const hSize =  (size_t)1 << srcCCtx->appliedParams.cParams.hashLog;
        U32 const h3log = srcCCtx->blockState.matchState.hashLog3;
        size_t const h3Size = h3log ? ((size_t)1 << h3log) : 0;

        ZSTD_memcpy(dstCCtx->blockState.matchState.hashTable,
               srcCCtx->blockState.matchState.hashTable,
               hSize * sizeof(U32));
        ZSTD_memcpy(dstCCtx->blockState.matchState.chainTable,
               srcCCtx->blockState.matchState.chainTable,
               chainSize * sizeof(U32));
        ZSTD_memcpy(dstCCtx->blockState.matchState.hashTable3,
               srcCCtx->blockState.matchState.hashTable3,
               h3Size * sizeof(U32));
    }

    ZSTD_cwksp_mark_tables_clean(&dstCCtx->workspace);

    /* copy dictionary offsets */
    {
        const ZSTD_MatchState_t* srcMatchState = &srcCCtx->blockState.matchState;
        ZSTD_MatchState_t* dstMatchState = &dstCCtx->blockState.matchState;
        dstMatchState->window       = srcMatchState->window;
        dstMatchState->nextToUpdate = srcMatchState->nextToUpdate;
        dstMatchState->loadedDictEnd= srcMatchState->loadedDictEnd;
    }
    dstCCtx->dictID = srcCCtx->dictID;
    dstCCtx->dictContentSize = srcCCtx->dictContentSize;

    /* copy block state */
    ZSTD_memcpy(dstCCtx->blockState.prevCBlock, srcCCtx->blockState.prevCBlock, sizeof(*srcCCtx->blockState.prevCBlock));

    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()).
 *  pledgedSrcSize==0 means "unknown".
*   @return : 0, or an error code */
size_t ZSTD_copyCCtx(ZSTD_CCtx* dstCCtx, const ZSTD_CCtx* srcCCtx, unsigned long long pledgedSrcSize)
{
    ZSTD_frameParameters fParams = { 1 /*content*/, 0 /*checksum*/, 0 /*noDictID*/ };
    ZSTD_buffered_policy_e const zbuff = srcCCtx->bufferedPolicy;
    ZSTD_STATIC_ASSERT((U32)ZSTDb_buffered==1);
    if (pledgedSrcSize==0) pledgedSrcSize = ZSTD_CONTENTSIZE_UNKNOWN;
    fParams.contentSizeFlag = (pledgedSrcSize != ZSTD_CONTENTSIZE_UNKNOWN);

    return ZSTD_copyCCtx_internal(dstCCtx, srcCCtx,
                                fParams, pledgedSrcSize,
                                zbuff);
}


#define ZSTD_ROWSIZE 16
/*! ZSTD_reduceTable() :
 *  reduce table indexes by `reducerValue`, or squash to zero.
 *  PreserveMark preserves "unsorted mark" for btlazy2 strategy.
 *  It must be set to a clear 0/1 value, to remove branch during inlining.
 *  Presume table size is a multiple of ZSTD_ROWSIZE
 *  to help auto-vectorization */
FORCE_INLINE_TEMPLATE void
ZSTD_reduceTable_internal (U32* const table, U32 const size, U32 const reducerValue, int const preserveMark)
{
    int const nbRows = (int)size / ZSTD_ROWSIZE;
    int cellNb = 0;
    int rowNb;
    /* Protect special index values < ZSTD_WINDOW_START_INDEX. */
    U32 const reducerThreshold = reducerValue + ZSTD_WINDOW_START_INDEX;
    assert((size & (ZSTD_ROWSIZE-1)) == 0);  /* multiple of ZSTD_ROWSIZE */
    assert(size < (1U<<31));   /* can be cast to int */

#if ZSTD_MEMORY_SANITIZER && !defined (ZSTD_MSAN_DONT_POISON_WORKSPACE)
    /* To validate that the table reuse logic is sound, and that we don't
     * access table space that we haven't cleaned, we re-"poison" the table
     * space every time we mark it dirty.
     *
     * This function however is intended to operate on those dirty tables and
     * re-clean them. So when this function is used correctly, we can unpoison
     * the memory it operated on. This introduces a blind spot though, since
     * if we now try to operate on __actually__ poisoned memory, we will not
     * detect that. */
    __msan_unpoison(table, size * sizeof(U32));
#endif

    for (rowNb=0 ; rowNb < nbRows ; rowNb++) {
        int column;
        for (column=0; column<ZSTD_ROWSIZE; column++) {
            U32 newVal;
            if (preserveMark && table[cellNb] == ZSTD_DUBT_UNSORTED_MARK) {
                /* This write is pointless, but is required(?) for the compiler
                 * to auto-vectorize the loop. */
                newVal = ZSTD_DUBT_UNSORTED_MARK;
            } else if (table[cellNb] < reducerThreshold) {
                newVal = 0;
            } else {
                newVal = table[cellNb] - reducerValue;
            }
            table[cellNb] = newVal;
            cellNb++;
    }   }
}

static void ZSTD_reduceTable(U32* const table, U32 const size, U32 const reducerValue)
{
    ZSTD_reduceTable_internal(table, size, reducerValue, 0);
}

static void ZSTD_reduceTable_btlazy2(U32* const table, U32 const size, U32 const reducerValue)
{
    ZSTD_reduceTable_internal(table, size, reducerValue, 1);
}

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

    if (ZSTD_allocateChainTable(params->cParams.strategy, params->useRowMatchFinder, (U32)ms->dedicatedDictSearch)) {
        U32 const chainSize = (U32)1 << params->cParams.chainLog;
        if (params->cParams.strategy == ZSTD_btlazy2)
            ZSTD_reduceTable_btlazy2(ms->chainTable, chainSize, reducerValue);
        else
            ZSTD_reduceTable(ms->chainTable, chainSize, reducerValue);
    }

    if (ms->hashLog3) {
        U32 const h3Size = (U32)1 << ms->hashLog3;
        ZSTD_reduceTable(ms->hashTable3, h3Size, reducerValue);
    }
}


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

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

int ZSTD_seqToCodes(const SeqStore_t* seqStorePtr)
{
    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;
    int longOffsets = 0;
    assert(nbSeq <= seqStorePtr->maxNbSeq);
    for (u=0; u<nbSeq; u++) {
        U32 const llv = sequences[u].litLength;
        U32 const ofCode = ZSTD_highbit32(sequences[u].offBase);
        U32 const mlv = sequences[u].mlBase;
        llCodeTable[u] = (BYTE)ZSTD_LLcode(llv);
        ofCodeTable[u] = (BYTE)ofCode;
        mlCodeTable[u] = (BYTE)ZSTD_MLcode(mlv);
        assert(!(MEM_64bits() && ofCode >= STREAM_ACCUMULATOR_MIN));
        if (MEM_32bits() && ofCode >= STREAM_ACCUMULATOR_MIN)
            longOffsets = 1;
    }
    if (seqStorePtr->longLengthType==ZSTD_llt_literalLength)
        llCodeTable[seqStorePtr->longLengthPos] = MaxLL;
    if (seqStorePtr->longLengthType==ZSTD_llt_matchLength)
        mlCodeTable[seqStorePtr->longLengthPos] = MaxML;
    return longOffsets;
}

/* ZSTD_useTargetCBlockSize():
 * Returns if target compressed block size param is being used.
 * If used, compression will do best effort to make a compressed block size to be around targetCBlockSize.
 * Returns 1 if true, 0 otherwise. */
static int ZSTD_useTargetCBlockSize(const ZSTD_CCtx_params* cctxParams)
{
    DEBUGLOG(5, "ZSTD_useTargetCBlockSize (targetCBlockSize=%zu)", cctxParams->targetCBlockSize);
    return (cctxParams->targetCBlockSize != 0);
}

/* ZSTD_blockSplitterEnabled():
 * Returns if block splitting param is being used
 * If used, compression will do best effort to split a block in order to improve compression ratio.
 * At the time this function is called, the parameter must be finalized.
 * Returns 1 if true, 0 otherwise. */
static int ZSTD_blockSplitterEnabled(ZSTD_CCtx_params* cctxParams)
{
    DEBUGLOG(5, "ZSTD_blockSplitterEnabled (postBlockSplitter=%d)", cctxParams->postBlockSplitter);
    assert(cctxParams->postBlockSplitter != ZSTD_ps_auto);
    return (cctxParams->postBlockSplitter == ZSTD_ps_enable);
}

/* Type returned by ZSTD_buildSequencesStatistics containing finalized symbol encoding types
 * and size of the sequences statistics
 */
typedef struct {
    U32 LLtype;
    U32 Offtype;
    U32 MLtype;
    size_t size;
    size_t lastCountSize; /* Accounts for bug in 1.3.4. More detail in ZSTD_entropyCompressSeqStore_internal() */
    int longOffsets;
} ZSTD_symbolEncodingTypeStats_t;

/* ZSTD_buildSequencesStatistics():
 * Returns a ZSTD_symbolEncodingTypeStats_t, or a zstd error code in the `size` field.
 * Modifies `nextEntropy` to have the appropriate values as a side effect.
 * nbSeq must be greater than 0.
 *
 * entropyWkspSize must be of size at least ENTROPY_WORKSPACE_SIZE - (MaxSeq + 1)*sizeof(U32)
 */
static ZSTD_symbolEncodingTypeStats_t
ZSTD_buildSequencesStatistics(
                const SeqStore_t* seqStorePtr, size_t nbSeq,
                const ZSTD_fseCTables_t* prevEntropy, ZSTD_fseCTables_t* nextEntropy,
                      BYTE* dst, const BYTE* const dstEnd,
                      ZSTD_strategy strategy, unsigned* countWorkspace,
                      void* entropyWorkspace, size_t entropyWkspSize)
{
    BYTE* const ostart = dst;
    const BYTE* const oend = dstEnd;
    BYTE* op = ostart;
    FSE_CTable* CTable_LitLength = nextEntropy->litlengthCTable;
    FSE_CTable* CTable_OffsetBits = nextEntropy->offcodeCTable;
    FSE_CTable* CTable_MatchLength = nextEntropy->matchlengthCTable;
    const BYTE* const ofCodeTable = seqStorePtr->ofCode;
    const BYTE* const llCodeTable = seqStorePtr->llCode;
    const BYTE* const mlCodeTable = seqStorePtr->mlCode;
    ZSTD_symbolEncodingTypeStats_t stats;

    stats.lastCountSize = 0;
    /* convert length/distances into codes */
    stats.longOffsets = ZSTD_seqToCodes(seqStorePtr);
    assert(op <= oend);
    assert(nbSeq != 0); /* ZSTD_selectEncodingType() divides by nbSeq */
    /* build CTable for Literal Lengths */
    {   unsigned max = MaxLL;
        size_t const mostFrequent = HIST_countFast_wksp(countWorkspace, &max, llCodeTable, nbSeq, entropyWorkspace, entropyWkspSize);   /* can't fail */
        DEBUGLOG(5, "Building LL table");
        nextEntropy->litlength_repeatMode = prevEntropy->litlength_repeatMode;
        stats.LLtype = ZSTD_selectEncodingType(&nextEntropy->litlength_repeatMode,
                                        countWorkspace, max, mostFrequent, nbSeq,
                                        LLFSELog, prevEntropy->litlengthCTable,
                                        LL_defaultNorm, LL_defaultNormLog,
                                        ZSTD_defaultAllowed, strategy);
        assert(set_basic < set_compressed && set_rle < set_compressed);
        assert(!(stats.LLtype < set_compressed && nextEntropy->litlength_repeatMode != FSE_repeat_none)); /* We don't copy tables */
        {   size_t const countSize = ZSTD_buildCTable(
                op, (size_t)(oend - op),
                CTable_LitLength, LLFSELog, (SymbolEncodingType_e)stats.LLtype,
                countWorkspace, max, llCodeTable, nbSeq,
                LL_defaultNorm, LL_defaultNormLog, MaxLL,
                prevEntropy->litlengthCTable,
                sizeof(prevEntropy->litlengthCTable),
                entropyWorkspace, entropyWkspSize);
            if (ZSTD_isError(countSize)) {
                DEBUGLOG(3, "ZSTD_buildCTable for LitLens failed");
                stats.size = countSize;
                return stats;
            }
            if (stats.LLtype == set_compressed)
                stats.lastCountSize = countSize;
            op += countSize;
            assert(op <= oend);
    }   }
    /* build CTable for Offsets */
    {   unsigned max = MaxOff;
        size_t const mostFrequent = HIST_countFast_wksp(
            countWorkspace, &max, ofCodeTable, nbSeq, entropyWorkspace, entropyWkspSize);  /* can't fail */
        /* We can only use the basic table if max <= DefaultMaxOff, otherwise the offsets are too large */
        ZSTD_DefaultPolicy_e const defaultPolicy = (max <= DefaultMaxOff) ? ZSTD_defaultAllowed : ZSTD_defaultDisallowed;
        DEBUGLOG(5, "Building OF table");
        nextEntropy->offcode_repeatMode = prevEntropy->offcode_repeatMode;
        stats.Offtype = ZSTD_selectEncodingType(&nextEntropy->offcode_repeatMode,
                                        countWorkspace, max, mostFrequent, nbSeq,
                                        OffFSELog, prevEntropy->offcodeCTable,
                                        OF_defaultNorm, OF_defaultNormLog,
                                        defaultPolicy, strategy);
        assert(!(stats.Offtype < set_compressed && nextEntropy->offcode_repeatMode != FSE_repeat_none)); /* We don't copy tables */
        {   size_t const countSize = ZSTD_buildCTable(
                op, (size_t)(oend - op),
                CTable_OffsetBits, OffFSELog, (SymbolEncodingType_e)stats.Offtype,
                countWorkspace, max, ofCodeTable, nbSeq,
                OF_defaultNorm, OF_defaultNormLog, DefaultMaxOff,
                prevEntropy->offcodeCTable,
                sizeof(prevEntropy->offcodeCTable),
                entropyWorkspace, entropyWkspSize);
            if (ZSTD_isError(countSize)) {
                DEBUGLOG(3, "ZSTD_buildCTable for Offsets failed");
                stats.size = countSize;
                return stats;
            }
            if (stats.Offtype == set_compressed)
                stats.lastCountSize = countSize;
            op += countSize;
            assert(op <= oend);
    }   }
    /* build CTable for MatchLengths */
    {   unsigned max = MaxML;
        size_t const mostFrequent = HIST_countFast_wksp(
            countWorkspace, &max, mlCodeTable, nbSeq, entropyWorkspace, entropyWkspSize);   /* can't fail */
        DEBUGLOG(5, "Building ML table (remaining space : %i)", (int)(oend-op));
        nextEntropy->matchlength_repeatMode = prevEntropy->matchlength_repeatMode;
        stats.MLtype = ZSTD_selectEncodingType(&nextEntropy->matchlength_repeatMode,
                                        countWorkspace, max, mostFrequent, nbSeq,
                                        MLFSELog, prevEntropy->matchlengthCTable,
                                        ML_defaultNorm, ML_defaultNormLog,
                                        ZSTD_defaultAllowed, strategy);
        assert(!(stats.MLtype < set_compressed && nextEntropy->matchlength_repeatMode != FSE_repeat_none)); /* We don't copy tables */
        {   size_t const countSize = ZSTD_buildCTable(
                op, (size_t)(oend - op),
                CTable_MatchLength, MLFSELog, (SymbolEncodingType_e)stats.MLtype,
                countWorkspace, max, mlCodeTable, nbSeq,
                ML_defaultNorm, ML_defaultNormLog, MaxML,
                prevEntropy->matchlengthCTable,
                sizeof(prevEntropy->matchlengthCTable),
                entropyWorkspace, entropyWkspSize);
            if (ZSTD_isError(countSize)) {
                DEBUGLOG(3, "ZSTD_buildCTable for MatchLengths failed");
                stats.size = countSize;
                return stats;
            }
            if (stats.MLtype == set_compressed)
                stats.lastCountSize = countSize;
            op += countSize;
            assert(op <= oend);
    }   }
    stats.size = (size_t)(op-ostart);
    return stats;
}

/* ZSTD_entropyCompressSeqStore_internal():
 * compresses both literals and sequences
 * Returns compressed size of block, or a zstd error.
 */
#define SUSPECT_UNCOMPRESSIBLE_LITERAL_RATIO 20
MEM_STATIC size_t
ZSTD_entropyCompressSeqStore_internal(
                              void* dst, size_t dstCapacity,
                        const void* literals, size_t litSize,
                        const SeqStore_t* seqStorePtr,
                        const ZSTD_entropyCTables_t* prevEntropy,
                              ZSTD_entropyCTables_t* nextEntropy,
                        const ZSTD_CCtx_params* cctxParams,
                              void* entropyWorkspace, size_t entropyWkspSize,
                        const int bmi2)
{
    ZSTD_strategy const strategy = cctxParams->cParams.strategy;
    unsigned* count = (unsigned*)entropyWorkspace;
    FSE_CTable* CTable_LitLength = nextEntropy->fse.litlengthCTable;
    FSE_CTable* CTable_OffsetBits = nextEntropy->fse.offcodeCTable;
    FSE_CTable* CTable_MatchLength = nextEntropy->fse.matchlengthCTable;
    const SeqDef* const sequences = seqStorePtr->sequencesStart;
    const size_t nbSeq = (size_t)(seqStorePtr->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 lastCountSize;
    int longOffsets = 0;

    entropyWorkspace = count + (MaxSeq + 1);
    entropyWkspSize -= (MaxSeq + 1) * sizeof(*count);

    DEBUGLOG(5, "ZSTD_entropyCompressSeqStore_internal (nbSeq=%zu, dstCapacity=%zu)", nbSeq, dstCapacity);
    ZSTD_STATIC_ASSERT(HUF_WORKSPACE_SIZE >= (1<<MAX(MLFSELog,LLFSELog)));
    assert(entropyWkspSize >= HUF_WORKSPACE_SIZE);

    /* Compress literals */
    {   size_t const numSequences = (size_t)(seqStorePtr->sequences - seqStorePtr->sequencesStart);
        /* Base suspicion of uncompressibility on ratio of literals to sequences */
        int const suspectUncompressible = (numSequences == 0) || (litSize / numSequences >= SUSPECT_UNCOMPRESSIBLE_LITERAL_RATIO);

        size_t const cSize = ZSTD_compressLiterals(
                                    op, dstCapacity,
                                    literals, litSize,
                                    entropyWorkspace, entropyWkspSize,
                                    &prevEntropy->huf, &nextEntropy->huf,
                                    cctxParams->cParams.strategy,
                                    ZSTD_literalsCompressionIsDisabled(cctxParams),
                                    suspectUncompressible, bmi2);
        FORWARD_IF_ERROR(cSize, "ZSTD_compressLiterals failed");
        assert(cSize <= dstCapacity);
        op += cSize;
    }

    /* Sequences Header */
    RETURN_ERROR_IF((oend-op) < 3 /*max nbSeq Size*/ + 1 /*seqHead*/,
                    dstSize_tooSmall, "Can't fit seq hdr in output buf!");
    if (nbSeq < 128) {
        *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;
    }
    assert(op <= oend);
    if (nbSeq==0) {
        /* Copy the old tables over as if we repeated them */
        ZSTD_memcpy(&nextEntropy->fse, &prevEntropy->fse, sizeof(prevEntropy->fse));
        return (size_t)(op - ostart);
    }
    {   BYTE* const seqHead = op++;
        /* build stats for sequences */
        const ZSTD_symbolEncodingTypeStats_t stats =
                ZSTD_buildSequencesStatistics(seqStorePtr, nbSeq,
                                             &prevEntropy->fse, &nextEntropy->fse,
                                              op, oend,
                                              strategy, count,
                                              entropyWorkspace, entropyWkspSize);
        FORWARD_IF_ERROR(stats.size, "ZSTD_buildSequencesStatistics failed!");
        *seqHead = (BYTE)((stats.LLtype<<6) + (stats.Offtype<<4) + (stats.MLtype<<2));
        lastCountSize = stats.lastCountSize;
        op += stats.size;
        longOffsets = stats.longOffsets;
    }

    {   size_t const bitstreamSize = ZSTD_encodeSequences(
                                        op, (size_t)(oend - op),
                                        CTable_MatchLength, mlCodeTable,
                                        CTable_OffsetBits, ofCodeTable,
                                        CTable_LitLength, llCodeTable,
                                        sequences, nbSeq,
                                        longOffsets, bmi2);
        FORWARD_IF_ERROR(bitstreamSize, "ZSTD_encodeSequences failed");
        op += bitstreamSize;
        assert(op <= oend);
        /* zstd versions <= 1.3.4 mistakenly report corruption when
         * FSE_readNCount() receives a buffer < 4 bytes.
         * Fixed by https://github.com/facebook/zstd/pull/1146.
         * This can happen when the last set_compressed table present is 2
         * bytes and the bitstream is only one byte.
         * In this exceedingly rare case, we will simply emit an uncompressed
         * block, since it isn't worth optimizing.
         */
        if (lastCountSize && (lastCountSize + bitstreamSize) < 4) {
            /* lastCountSize >= 2 && bitstreamSize > 0 ==> lastCountSize == 3 */
            assert(lastCountSize + bitstreamSize == 3);
            DEBUGLOG(5, "Avoiding bug in zstd decoder in versions <= 1.3.4 by "
                        "emitting an uncompressed block.");
            return 0;
        }
    }

    DEBUGLOG(5, "compressed block size : %u", (unsigned)(op - ostart));
    return (size_t)(op - ostart);
}

static size_t
ZSTD_entropyCompressSeqStore_wExtLitBuffer(
                          void* dst, size_t dstCapacity,
                    const void* literals, size_t litSize,
                          size_t blockSize,
                    const SeqStore_t* seqStorePtr,
                    const ZSTD_entropyCTables_t* prevEntropy,
                          ZSTD_entropyCTables_t* nextEntropy,
                    const ZSTD_CCtx_params* cctxParams,
                          void* entropyWorkspace, size_t entropyWkspSize,
                          int bmi2)
{
    size_t const cSize = ZSTD_entropyCompressSeqStore_internal(
                            dst, dstCapacity,
                            literals, litSize,
                            seqStorePtr, prevEntropy, nextEntropy, cctxParams,
                            entropyWorkspace, entropyWkspSize, bmi2);
    if (cSize == 0) return 0;
    /* When srcSize <= dstCapacity, there is enough space to write a raw uncompressed block.
     * Since we ran out of space, block must be not compressible, so fall back to raw uncompressed block.
     */
    if ((cSize == ERROR(dstSize_tooSmall)) & (blockSize <= dstCapacity)) {
        DEBUGLOG(4, "not enough dstCapacity (%zu) for ZSTD_entropyCompressSeqStore_internal()=> do not compress block", dstCapacity);
        return 0;  /* block not compressed */
    }
    FORWARD_IF_ERROR(cSize, "ZSTD_entropyCompressSeqStore_internal failed");

    /* Check compressibility */
    {   size_t const maxCSize = blockSize - ZSTD_minGain(blockSize, cctxParams->cParams.strategy);
        if (cSize >= maxCSize) return 0;  /* block not compressed */
    }
    DEBUGLOG(5, "ZSTD_entropyCompressSeqStore() cSize: %zu", cSize);
    /* libzstd decoder before  > v1.5.4 is not compatible with compressed blocks of size ZSTD_BLOCKSIZE_MAX exactly.
     * This restriction is indirectly already fulfilled by respecting ZSTD_minGain() condition above.
     */
    assert(cSize < ZSTD_BLOCKSIZE_MAX);
    return cSize;
}

static size_t
ZSTD_entropyCompressSeqStore(
                    const SeqStore_t* seqStorePtr,
                    const ZSTD_entropyCTables_t* prevEntropy,
                          ZSTD_entropyCTables_t* nextEntropy,
                    const ZSTD_CCtx_params* cctxParams,
                          void* dst, size_t dstCapacity,
                          size_t srcSize,
                          void* entropyWorkspace, size_t entropyWkspSize,
                          int bmi2)
{
    return ZSTD_entropyCompressSeqStore_wExtLitBuffer(
                dst, dstCapacity,
                seqStorePtr->litStart, (size_t)(seqStorePtr->lit - seqStorePtr->litStart),
                srcSize,
                seqStorePtr,
                prevEntropy, nextEntropy,
                cctxParams,
                entropyWorkspace, entropyWkspSize,
                bmi2);
}

/* ZSTD_selectBlockCompressor() :
 * Not static, but internal use only (used by long distance matcher)
 * assumption : strat is a valid strategy */
ZSTD_BlockCompressor_f ZSTD_selectBlockCompressor(ZSTD_strategy strat, ZSTD_ParamSwitch_e useRowMatchFinder, ZSTD_dictMode_e dictMode)
{
    static const ZSTD_BlockCompressor_f blockCompressor[4][ZSTD_STRATEGY_MAX+1] = {
        { ZSTD_compressBlock_fast  /* default for 0 */,
          ZSTD_compressBlock_fast,
          ZSTD_COMPRESSBLOCK_DOUBLEFAST,
          ZSTD_COMPRESSBLOCK_GREEDY,
          ZSTD_COMPRESSBLOCK_LAZY,
          ZSTD_COMPRESSBLOCK_LAZY2,
          ZSTD_COMPRESSBLOCK_BTLAZY2,
          ZSTD_COMPRESSBLOCK_BTOPT,
          ZSTD_COMPRESSBLOCK_BTULTRA,
          ZSTD_COMPRESSBLOCK_BTULTRA2
        },
        { ZSTD_compressBlock_fast_extDict  /* default for 0 */,
          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_BTULTRA_EXTDICT,
          ZSTD_COMPRESSBLOCK_BTULTRA_EXTDICT
        },
        { ZSTD_compressBlock_fast_dictMatchState  /* default for 0 */,
          ZSTD_compressBlock_fast_dictMatchState,
          ZSTD_COMPRESSBLOCK_DOUBLEFAST_DICTMATCHSTATE,
          ZSTD_COMPRESSBLOCK_GREEDY_DICTMATCHSTATE,
          ZSTD_COMPRESSBLOCK_LAZY_DICTMATCHSTATE,
          ZSTD_COMPRESSBLOCK_LAZY2_DICTMATCHSTATE,
          ZSTD_COMPRESSBLOCK_BTLAZY2_DICTMATCHSTATE,
          ZSTD_COMPRESSBLOCK_BTOPT_DICTMATCHSTATE,
          ZSTD_COMPRESSBLOCK_BTULTRA_DICTMATCHSTATE,
          ZSTD_COMPRESSBLOCK_BTULTRA_DICTMATCHSTATE
        },
        { NULL  /* default for 0 */,
          NULL,
          NULL,
          ZSTD_COMPRESSBLOCK_GREEDY_DEDICATEDDICTSEARCH,
          ZSTD_COMPRESSBLOCK_LAZY_DEDICATEDDICTSEARCH,
          ZSTD_COMPRESSBLOCK_LAZY2_DEDICATEDDICTSEARCH,
          NULL,
          NULL,
          NULL,
          NULL }
    };
    ZSTD_BlockCompressor_f selectedCompressor;
    ZSTD_STATIC_ASSERT((unsigned)ZSTD_fast == 1);

    assert(ZSTD_cParam_withinBounds(ZSTD_c_strategy, (int)strat));
    DEBUGLOG(5, "Selected block compressor: dictMode=%d strat=%d rowMatchfinder=%d", (int)dictMode, (int)strat, (int)useRowMatchFinder);
    if (ZSTD_rowMatchFinderUsed(strat, useRowMatchFinder)) {
        static const ZSTD_BlockCompressor_f rowBasedBlockCompressors[4][3] = {
            {
                ZSTD_COMPRESSBLOCK_GREEDY_ROW,
                ZSTD_COMPRESSBLOCK_LAZY_ROW,
                ZSTD_COMPRESSBLOCK_LAZY2_ROW
            },
            {
                ZSTD_COMPRESSBLOCK_GREEDY_EXTDICT_ROW,
                ZSTD_COMPRESSBLOCK_LAZY_EXTDICT_ROW,
                ZSTD_COMPRESSBLOCK_LAZY2_EXTDICT_ROW
            },
            {
                ZSTD_COMPRESSBLOCK_GREEDY_DICTMATCHSTATE_ROW,
                ZSTD_COMPRESSBLOCK_LAZY_DICTMATCHSTATE_ROW,
                ZSTD_COMPRESSBLOCK_LAZY2_DICTMATCHSTATE_ROW
            },
            {
                ZSTD_COMPRESSBLOCK_GREEDY_DEDICATEDDICTSEARCH_ROW,
                ZSTD_COMPRESSBLOCK_LAZY_DEDICATEDDICTSEARCH_ROW,
                ZSTD_COMPRESSBLOCK_LAZY2_DEDICATEDDICTSEARCH_ROW
            }
        };
        DEBUGLOG(5, "Selecting a row-based matchfinder");
        assert(useRowMatchFinder != ZSTD_ps_auto);
        selectedCompressor = rowBasedBlockCompressors[(int)dictMode][(int)strat - (int)ZSTD_greedy];
    } else {
        selectedCompressor = blockCompressor[(int)dictMode][(int)strat];
    }
    assert(selectedCompressor != NULL);
    return selectedCompressor;
}

static void ZSTD_storeLastLiterals(SeqStore_t* seqStorePtr,
                                   const BYTE* anchor, size_t lastLLSize)
{
    ZSTD_memcpy(seqStorePtr->lit, anchor, lastLLSize);
    seqStorePtr->lit += lastLLSize;
}

void ZSTD_resetSeqStore(SeqStore_t* ssPtr)
{
    ssPtr->lit = ssPtr->litStart;
    ssPtr->sequences = ssPtr->sequencesStart;
    ssPtr->longLengthType = ZSTD_llt_none;
}

/* ZSTD_postProcessSequenceProducerResult() :
 * Validates and post-processes sequences obtained through the external matchfinder API:
 *   - Checks whether nbExternalSeqs represents an error condition.
 *   - Appends a block delimiter to outSeqs if one is not already present.
 *     See zstd.h for context regarding block delimiters.
 * Returns the number of sequences after post-processing, or an error code. */
static size_t ZSTD_postProcessSequenceProducerResult(
    ZSTD_Sequence* outSeqs, size_t nbExternalSeqs, size_t outSeqsCapacity, size_t srcSize
) {
    RETURN_ERROR_IF(
        nbExternalSeqs > outSeqsCapacity,
        sequenceProducer_failed,
        "External sequence producer returned error code %lu",
        (unsigned long)nbExternalSeqs
    );

    RETURN_ERROR_IF(
        nbExternalSeqs == 0 && srcSize > 0,
        sequenceProducer_failed,
        "Got zero sequences from external sequence producer for a non-empty src buffer!"
    );

    if (srcSize == 0) {
        ZSTD_memset(&outSeqs[0], 0, sizeof(ZSTD_Sequence));
        return 1;
    }

    {
        ZSTD_Sequence const lastSeq = outSeqs[nbExternalSeqs - 1];

        /* We can return early if lastSeq is already a block delimiter. */
        if (lastSeq.offset == 0 && lastSeq.matchLength == 0) {
            return nbExternalSeqs;
        }

        /* This error condition is only possible if the external matchfinder
         * produced an invalid parse, by definition of ZSTD_sequenceBound(). */
        RETURN_ERROR_IF(
            nbExternalSeqs == outSeqsCapacity,
            sequenceProducer_failed,
            "nbExternalSeqs == outSeqsCapacity but lastSeq is not a block delimiter!"
        );

        /* lastSeq is not a block delimiter, so we need to append one. */
        ZSTD_memset(&outSeqs[nbExternalSeqs], 0, sizeof(ZSTD_Sequence));
        return nbExternalSeqs + 1;
    }
}

/* ZSTD_fastSequenceLengthSum() :
 * Returns sum(litLen) + sum(matchLen) + lastLits for *seqBuf*.
 * Similar to another function in zstd_compress.c (determine_blockSize),
 * except it doesn't check for a block delimiter to end summation.
 * Removing the early exit allows the compiler to auto-vectorize (https://godbolt.org/z/cY1cajz9P).
 * This function can be deleted and replaced by determine_blockSize after we resolve issue #3456. */
static size_t ZSTD_fastSequenceLengthSum(ZSTD_Sequence const* seqBuf, size_t seqBufSize) {
    size_t matchLenSum, litLenSum, i;
    matchLenSum = 0;
    litLenSum = 0;
    for (i = 0; i < seqBufSize; i++) {
        litLenSum += seqBuf[i].litLength;
        matchLenSum += seqBuf[i].matchLength;
    }
    return litLenSum + matchLenSum;
}

/**
 * Function to validate sequences produced by a block compressor.
 */
static void ZSTD_validateSeqStore(const SeqStore_t* seqStore, const ZSTD_compressionParameters* cParams)
{
#if DEBUGLEVEL >= 1
    const SeqDef* seq = seqStore->sequencesStart;
    const SeqDef* const seqEnd = seqStore->sequences;
    size_t const matchLenLowerBound = cParams->minMatch == 3 ? 3 : 4;
    for (; seq < seqEnd; ++seq) {
        const ZSTD_SequenceLength seqLength = ZSTD_getSequenceLength(seqStore, seq);
        assert(seqLength.matchLength >= matchLenLowerBound);
        (void)seqLength;
        (void)matchLenLowerBound;
    }
#else
    (void)seqStore;
    (void)cParams;
#endif
}

static size_t
ZSTD_transferSequences_wBlockDelim(ZSTD_CCtx* cctx,
                                   ZSTD_SequencePosition* seqPos,
                             const ZSTD_Sequence* const inSeqs, size_t inSeqsSize,
                             const void* src, size_t blockSize,
                                   ZSTD_ParamSwitch_e externalRepSearch);

typedef enum { ZSTDbss_compress, ZSTDbss_noCompress } ZSTD_BuildSeqStore_e;

static size_t ZSTD_buildSeqStore(ZSTD_CCtx* zc, const void* src, size_t srcSize)
{
    ZSTD_MatchState_t* const ms = &zc->blockState.matchState;
    DEBUGLOG(5, "ZSTD_buildSeqStore (srcSize=%zu)", srcSize);
    assert(srcSize <= ZSTD_BLOCKSIZE_MAX);
    /* Assert that we have correctly flushed the ctx params into the ms's copy */
    ZSTD_assertEqualCParams(zc->appliedParams.cParams, ms->cParams);
    /* TODO: See 3090. We reduced MIN_CBLOCK_SIZE from 3 to 2 so to compensate we are adding
     * additional 1. We need to revisit and change this logic to be more consistent */
    if (srcSize < MIN_CBLOCK_SIZE+ZSTD_blockHeaderSize+1+1) {
        if (zc->appliedParams.cParams.strategy >= ZSTD_btopt) {
            ZSTD_ldm_skipRawSeqStoreBytes(&zc->externSeqStore, srcSize);
        } else {
            ZSTD_ldm_skipSequences(&zc->externSeqStore, srcSize, zc->appliedParams.cParams.minMatch);
        }
        return ZSTDbss_noCompress; /* don't even attempt compression below a certain srcSize */
    }
    ZSTD_resetSeqStore(&(zc->seqStore));
    /* required for optimal parser to read stats from dictionary */
    ms->opt.symbolCosts = &zc->blockState.prevCBlock->entropy;
    /* tell the optimal parser how we expect to compress literals */
    ms->opt.literalCompressionMode = zc->appliedParams.literalCompressionMode;
    /* a gap between an attached dict and the current window is not safe,
     * they must remain adjacent,
     * and when that stops being the case, the dict must be unset */
    assert(ms->dictMatchState == NULL || ms->loadedDictEnd == ms->window.dictLimit);

    /* limited update after a very long match */
    {   const BYTE* const base = ms->window.base;
        const BYTE* const istart = (const BYTE*)src;
        const U32 curr = (U32)(istart-base);
        if (sizeof(ptrdiff_t)==8) assert(istart - base < (ptrdiff_t)(U32)(-1));   /* ensure no overflow */
        if (curr > ms->nextToUpdate + 384)
            ms->nextToUpdate = curr - MIN(192, (U32)(curr - ms->nextToUpdate - 384));
    }

    /* select and store sequences */
    {   ZSTD_dictMode_e const dictMode = ZSTD_matchState_dictMode(ms);
        size_t lastLLSize;
        {   int i;
            for (i = 0; i < ZSTD_REP_NUM; ++i)
                zc->blockState.nextCBlock->rep[i] = zc->blockState.prevCBlock->rep[i];
        }
        if (zc->externSeqStore.pos < zc->externSeqStore.size) {
            assert(zc->appliedParams.ldmParams.enableLdm == ZSTD_ps_disable);

            /* External matchfinder + LDM is technically possible, just not implemented yet.
             * We need to revisit soon and implement it. */
            RETURN_ERROR_IF(
                ZSTD_hasExtSeqProd(&zc->appliedParams),
                parameter_combination_unsupported,
                "Long-distance matching with external sequence producer enabled is not currently supported."
            );

            /* Updates ldmSeqStore.pos */
            lastLLSize =
                ZSTD_ldm_blockCompress(&zc->externSeqStore,
                                       ms, &zc->seqStore,
                                       zc->blockState.nextCBlock->rep,
                                       zc->appliedParams.useRowMatchFinder,
                                       src, srcSize);
            assert(zc->externSeqStore.pos <= zc->externSeqStore.size);
        } else if (zc->appliedParams.ldmParams.enableLdm == ZSTD_ps_enable) {
            RawSeqStore_t ldmSeqStore = kNullRawSeqStore;

            /* External matchfinder + LDM is technically possible, just not implemented yet.
             * We need to revisit soon and implement it. */
            RETURN_ERROR_IF(
                ZSTD_hasExtSeqProd(&zc->appliedParams),
                parameter_combination_unsupported,
                "Long-distance matching with external sequence producer enabled is not currently supported."
            );

            ldmSeqStore.seq = zc->ldmSequences;
            ldmSeqStore.capacity = zc->maxNbLdmSequences;
            /* Updates ldmSeqStore.size */
            FORWARD_IF_ERROR(ZSTD_ldm_generateSequences(&zc->ldmState, &ldmSeqStore,
                                               &zc->appliedParams.ldmParams,
                                               src, srcSize), "");
            /* Updates ldmSeqStore.pos */
            lastLLSize =
                ZSTD_ldm_blockCompress(&ldmSeqStore,
                                       ms, &zc->seqStore,
                                       zc->blockState.nextCBlock->rep,
                                       zc->appliedParams.useRowMatchFinder,
                                       src, srcSize);
            assert(ldmSeqStore.pos == ldmSeqStore.size);
        } else if (ZSTD_hasExtSeqProd(&zc->appliedParams)) {
            assert(
                zc->extSeqBufCapacity >= ZSTD_sequenceBound(srcSize)
            );
            assert(zc->appliedParams.extSeqProdFunc != NULL);

            {   U32 const windowSize = (U32)1 << zc->appliedParams.cParams.windowLog;

                size_t const nbExternalSeqs = (zc->appliedParams.extSeqProdFunc)(
                    zc->appliedParams.extSeqProdState,
                    zc->extSeqBuf,
                    zc->extSeqBufCapacity,
                    src, srcSize,
                    NULL, 0,  /* dict and dictSize, currently not supported */
                    zc->appliedParams.compressionLevel,
                    windowSize
                );

                size_t const nbPostProcessedSeqs = ZSTD_postProcessSequenceProducerResult(
                    zc->extSeqBuf,
                    nbExternalSeqs,
                    zc->extSeqBufCapacity,
                    srcSize
                );

                /* Return early if there is no error, since we don't need to worry about last literals */
                if (!ZSTD_isError(nbPostProcessedSeqs)) {
                    ZSTD_SequencePosition seqPos = {0,0,0};
                    size_t const seqLenSum = ZSTD_fastSequenceLengthSum(zc->extSeqBuf, nbPostProcessedSeqs);
                    RETURN_ERROR_IF(seqLenSum > srcSize, externalSequences_invalid, "External sequences imply too large a block!");
                    FORWARD_IF_ERROR(
                        ZSTD_transferSequences_wBlockDelim(
                            zc, &seqPos,
                            zc->extSeqBuf, nbPostProcessedSeqs,
                            src, srcSize,
                            zc->appliedParams.searchForExternalRepcodes
                        ),
                        "Failed to copy external sequences to seqStore!"
                    );
                    ms->ldmSeqStore = NULL;
                    DEBUGLOG(5, "Copied %lu sequences from external sequence producer to internal seqStore.", (unsigned long)nbExternalSeqs);
                    return ZSTDbss_compress;
                }

                /* Propagate the error if fallback is disabled */
                if (!zc->appliedParams.enableMatchFinderFallback) {
                    return nbPostProcessedSeqs;
                }

                /* Fallback to software matchfinder */
                {   ZSTD_BlockCompressor_f const blockCompressor =
                        ZSTD_selectBlockCompressor(
                            zc->appliedParams.cParams.strategy,
                            zc->appliedParams.useRowMatchFinder,
                            dictMode);
                    ms->ldmSeqStore = NULL;
                    DEBUGLOG(
                        5,
                        "External sequence producer returned error code %lu. Falling back to internal parser.",
                        (unsigned long)nbExternalSeqs
                    );
                    lastLLSize = blockCompressor(ms, &zc->seqStore, zc->blockState.nextCBlock->rep, src, srcSize);
            }   }
        } else {   /* not long range mode and no external matchfinder */
            ZSTD_BlockCompressor_f const blockCompressor = ZSTD_selectBlockCompressor(
                    zc->appliedParams.cParams.strategy,
                    zc->appliedParams.useRowMatchFinder,
                    dictMode);
            ms->ldmSeqStore = NULL;
            lastLLSize = blockCompressor(ms, &zc->seqStore, zc->blockState.nextCBlock->rep, src, srcSize);
        }
        {   const BYTE* const lastLiterals = (const BYTE*)src + srcSize - lastLLSize;
            ZSTD_storeLastLiterals(&zc->seqStore, lastLiterals, lastLLSize);
    }   }
    ZSTD_validateSeqStore(&zc->seqStore, &zc->appliedParams.cParams);
    return ZSTDbss_compress;
}

static size_t ZSTD_copyBlockSequences(SeqCollector* seqCollector, const SeqStore_t* seqStore, const U32 prevRepcodes[ZSTD_REP_NUM])
{
    const SeqDef* inSeqs = seqStore->sequencesStart;
    const size_t nbInSequences = (size_t)(seqStore->sequences - inSeqs);
    const size_t nbInLiterals = (size_t)(seqStore->lit - seqStore->litStart);

    ZSTD_Sequence* outSeqs = seqCollector->seqIndex == 0 ? seqCollector->seqStart : seqCollector->seqStart + seqCollector->seqIndex;
    const size_t nbOutSequences = nbInSequences + 1;
    size_t nbOutLiterals = 0;
    Repcodes_t repcodes;
    size_t i;

    /* Bounds check that we have enough space for every input sequence
     * and the block delimiter
     */
    assert(seqCollector->seqIndex <= seqCollector->maxSequences);
    RETURN_ERROR_IF(
        nbOutSequences > (size_t)(seqCollector->maxSequences - seqCollector->seqIndex),
        dstSize_tooSmall,
        "Not enough space to copy sequences");

    ZSTD_memcpy(&repcodes, prevRepcodes, sizeof(repcodes));
    for (i = 0; i < nbInSequences; ++i) {
        U32 rawOffset;
        outSeqs[i].litLength = inSeqs[i].litLength;
        outSeqs[i].matchLength = inSeqs[i].mlBase + MINMATCH;
        outSeqs[i].rep = 0;

        /* Handle the possible single length >= 64K
         * There can only be one because we add MINMATCH to every match length,
         * and blocks are at most 128K.
         */
        if (i == seqStore->longLengthPos) {
            if (seqStore->longLengthType == ZSTD_llt_literalLength) {
                outSeqs[i].litLength += 0x10000;
            } else if (seqStore->longLengthType == ZSTD_llt_matchLength) {
                outSeqs[i].matchLength += 0x10000;
            }
        }

        /* Determine the raw offset given the offBase, which may be a repcode. */
        if (OFFBASE_IS_REPCODE(inSeqs[i].offBase)) {
            const U32 repcode = OFFBASE_TO_REPCODE(inSeqs[i].offBase);
            assert(repcode > 0);
            outSeqs[i].rep = repcode;
            if (outSeqs[i].litLength != 0) {
                rawOffset = repcodes.rep[repcode - 1];
            } else {
                if (repcode == 3) {
                    assert(repcodes.rep[0] > 1);
                    rawOffset = repcodes.rep[0] - 1;
                } else {
                    rawOffset = repcodes.rep[repcode];
                }
            }
        } else {
            rawOffset = OFFBASE_TO_OFFSET(inSeqs[i].offBase);
        }
        outSeqs[i].offset = rawOffset;

        /* Update repcode history for the sequence */
        ZSTD_updateRep(repcodes.rep,
                       inSeqs[i].offBase,
                       inSeqs[i].litLength == 0);

        nbOutLiterals += outSeqs[i].litLength;
    }
    /* Insert last literals (if any exist) in the block as a sequence with ml == off == 0.
     * If there are no last literals, then we'll emit (of: 0, ml: 0, ll: 0), which is a marker
     * for the block boundary, according to the API.
     */
    assert(nbInLiterals >= nbOutLiterals);
    {
        const size_t lastLLSize = nbInLiterals - nbOutLiterals;
        outSeqs[nbInSequences].litLength = (U32)lastLLSize;
        outSeqs[nbInSequences].matchLength = 0;
        outSeqs[nbInSequences].offset = 0;
        assert(nbOutSequences == nbInSequences + 1);
    }
    seqCollector->seqIndex += nbOutSequences;
    assert(seqCollector->seqIndex <= seqCollector->maxSequences);

    return 0;
}

size_t ZSTD_sequenceBound(size_t srcSize) {
    const size_t maxNbSeq = (srcSize / ZSTD_MINMATCH_MIN) + 1;
    const size_t maxNbDelims = (srcSize / ZSTD_BLOCKSIZE_MAX_MIN) + 1;
    return maxNbSeq + maxNbDelims;
}

size_t ZSTD_generateSequences(ZSTD_CCtx* zc, ZSTD_Sequence* outSeqs,
                              size_t outSeqsSize, const void* src, size_t srcSize)
{
    const size_t dstCapacity = ZSTD_compressBound(srcSize);
    void* dst; /* Make C90 happy. */
    SeqCollector seqCollector;
    {
        int targetCBlockSize;
        FORWARD_IF_ERROR(ZSTD_CCtx_getParameter(zc, ZSTD_c_targetCBlockSize, &targetCBlockSize), "");
        RETURN_ERROR_IF(targetCBlockSize != 0, parameter_unsupported, "targetCBlockSize != 0");
    }
    {
        int nbWorkers;
        FORWARD_IF_ERROR(ZSTD_CCtx_getParameter(zc, ZSTD_c_nbWorkers, &nbWorkers), "");
        RETURN_ERROR_IF(nbWorkers != 0, parameter_unsupported, "nbWorkers != 0");
    }

    dst = ZSTD_customMalloc(dstCapacity, ZSTD_defaultCMem);
    RETURN_ERROR_IF(dst == NULL, memory_allocation, "NULL pointer!");

    seqCollector.collectSequences = 1;
    seqCollector.seqStart = outSeqs;
    seqCollector.seqIndex = 0;
    seqCollector.maxSequences = outSeqsSize;
    zc->seqCollector = seqCollector;

    {
        const size_t ret = ZSTD_compress2(zc, dst, dstCapacity, src, srcSize);
        ZSTD_customFree(dst, ZSTD_defaultCMem);
        FORWARD_IF_ERROR(ret, "ZSTD_compress2 failed");
    }
    assert(zc->seqCollector.seqIndex <= ZSTD_sequenceBound(srcSize));
    return zc->seqCollector.seqIndex;
}

size_t ZSTD_mergeBlockDelimiters(ZSTD_Sequence* sequences, size_t seqsSize) {
    size_t in = 0;
    size_t out = 0;
    for (; in < seqsSize; ++in) {
        if (sequences[in].offset == 0 && sequences[in].matchLength == 0) {
            if (in != seqsSize - 1) {
                sequences[in+1].litLength += sequences[in].litLength;
            }
        } else {
            sequences[out] = sequences[in];
            ++out;
        }
    }
    return out;
}

/* Unrolled loop to read four size_ts of input at a time. Returns 1 if is RLE, 0 if not. */
static int ZSTD_isRLE(const BYTE* src, size_t length) {
    const BYTE* ip = src;
    const BYTE value = ip[0];
    const size_t valueST = (size_t)((U64)value * 0x0101010101010101ULL);
    const size_t unrollSize = sizeof(size_t) * 4;
    const size_t unrollMask = unrollSize - 1;
    const size_t prefixLength = length & unrollMask;
    size_t i;
    if (length == 1) return 1;
    /* Check if prefix is RLE first before using unrolled loop */
    if (prefixLength && ZSTD_count(ip+1, ip, ip+prefixLength) != prefixLength-1) {
        return 0;
    }
    for (i = prefixLength; i != length; i += unrollSize) {
        size_t u;
        for (u = 0; u < unrollSize; u += sizeof(size_t)) {
            if (MEM_readST(ip + i + u) != valueST) {
                return 0;
    }   }   }
    return 1;
}

/* Returns true if the given block may be RLE.
 * This is just a heuristic based on the compressibility.
 * It may return both false positives and false negatives.
 */
static int ZSTD_maybeRLE(SeqStore_t const* seqStore)
{
    size_t const nbSeqs = (size_t)(seqStore->sequences - seqStore->sequencesStart);
    size_t const nbLits = (size_t)(seqStore->lit - seqStore->litStart);

    return nbSeqs < 4 && nbLits < 10;
}

static void
ZSTD_blockState_confirmRepcodesAndEntropyTables(ZSTD_blockState_t* const bs)
{
    ZSTD_compressedBlockState_t* const tmp = bs->prevCBlock;
    bs->prevCBlock = bs->nextCBlock;
    bs->nextCBlock = tmp;
}

/* Writes the block header */
static void
writeBlockHeader(void* op, size_t cSize, size_t blockSize, U32 lastBlock)
{
    U32 const cBlockHeader = cSize == 1 ?
                        lastBlock + (((U32)bt_rle)<<1) + (U32)(blockSize << 3) :
                        lastBlock + (((U32)bt_compressed)<<1) + (U32)(cSize << 3);
    MEM_writeLE24(op, cBlockHeader);
    DEBUGLOG(5, "writeBlockHeader: cSize: %zu blockSize: %zu lastBlock: %u", cSize, blockSize, lastBlock);
}

/** ZSTD_buildBlockEntropyStats_literals() :
 *  Builds entropy for the literals.
 *  Stores literals block type (raw, rle, compressed, repeat) and
 *  huffman description table to hufMetadata.
 *  Requires ENTROPY_WORKSPACE_SIZE workspace
 * @return : size of huffman description table, or an error code
 */
static size_t
ZSTD_buildBlockEntropyStats_literals(void* const src, size_t srcSize,
                               const ZSTD_hufCTables_t* prevHuf,
                                     ZSTD_hufCTables_t* nextHuf,
                                     ZSTD_hufCTablesMetadata_t* hufMetadata,
                               const int literalsCompressionIsDisabled,
                                     void* workspace, size_t wkspSize,
                                     int hufFlags)
{
    BYTE* const wkspStart = (BYTE*)workspace;
    BYTE* const wkspEnd = wkspStart + wkspSize;
    BYTE* const countWkspStart = wkspStart;
    unsigned* const countWksp = (unsigned*)workspace;
    const size_t countWkspSize = (HUF_SYMBOLVALUE_MAX + 1) * sizeof(unsigned);
    BYTE* const nodeWksp = countWkspStart + countWkspSize;
    const size_t nodeWkspSize = (size_t)(wkspEnd - nodeWksp);
    unsigned maxSymbolValue = HUF_SYMBOLVALUE_MAX;
    unsigned huffLog = LitHufLog;
    HUF_repeat repeat = prevHuf->repeatMode;
    DEBUGLOG(5, "ZSTD_buildBlockEntropyStats_literals (srcSize=%zu)", srcSize);

    /* Prepare nextEntropy assuming reusing the existing table */
    ZSTD_memcpy(nextHuf, prevHuf, sizeof(*prevHuf));

    if (literalsCompressionIsDisabled) {
        DEBUGLOG(5, "set_basic - disabled");
        hufMetadata->hType = set_basic;
        return 0;
    }

    /* small ? don't even attempt compression (speed opt) */
#ifndef COMPRESS_LITERALS_SIZE_MIN
# define COMPRESS_LITERALS_SIZE_MIN 63  /* heuristic */
#endif
    {   size_t const minLitSize = (prevHuf->repeatMode == HUF_repeat_valid) ? 6 : COMPRESS_LITERALS_SIZE_MIN;
        if (srcSize <= minLitSize) {
            DEBUGLOG(5, "set_basic - too small");
            hufMetadata->hType = set_basic;
            return 0;
    }   }

    /* Scan input and build symbol stats */
    {   size_t const largest =
            HIST_count_wksp (countWksp, &maxSymbolValue,
                            (const BYTE*)src, srcSize,
                            workspace, wkspSize);
        FORWARD_IF_ERROR(largest, "HIST_count_wksp failed");
        if (largest == srcSize) {
            /* only one literal symbol */
            DEBUGLOG(5, "set_rle");
            hufMetadata->hType = set_rle;
            return 0;
        }
        if (largest <= (srcSize >> 7)+4) {
            /* heuristic: likely not compressible */
            DEBUGLOG(5, "set_basic - no gain");
            hufMetadata->hType = set_basic;
            return 0;
    }   }

    /* Validate the previous Huffman table */
    if (repeat == HUF_repeat_check
      && !HUF_validateCTable((HUF_CElt const*)prevHuf->CTable, countWksp, maxSymbolValue)) {
        repeat = HUF_repeat_none;
    }

    /* Build Huffman Tree */
    ZSTD_memset(nextHuf->CTable, 0, sizeof(nextHuf->CTable));
    huffLog = HUF_optimalTableLog(huffLog, srcSize, maxSymbolValue, nodeWksp, nodeWkspSize, nextHuf->CTable, countWksp, hufFlags);
    assert(huffLog <= LitHufLog);
    {   size_t const maxBits = HUF_buildCTable_wksp((HUF_CElt*)nextHuf->CTable, countWksp,
                                                    maxSymbolValue, huffLog,
                                                    nodeWksp, nodeWkspSize);
        FORWARD_IF_ERROR(maxBits, "HUF_buildCTable_wksp");
        huffLog = (U32)maxBits;
    }
    {   /* Build and write the CTable */
        size_t const newCSize = HUF_estimateCompressedSize(
                (HUF_CElt*)nextHuf->CTable, countWksp, maxSymbolValue);
        size_t const hSize = HUF_writeCTable_wksp(
                hufMetadata->hufDesBuffer, sizeof(hufMetadata->hufDesBuffer),
                (HUF_CElt*)nextHuf->CTable, maxSymbolValue, huffLog,
                nodeWksp, nodeWkspSize);
        /* Check against repeating the previous CTable */
        if (repeat != HUF_repeat_none) {
            size_t const oldCSize = HUF_estimateCompressedSize(
                    (HUF_CElt const*)prevHuf->CTable, countWksp, maxSymbolValue);
            if (oldCSize < srcSize && (oldCSize <= hSize + newCSize || hSize + 12 >= srcSize)) {
                DEBUGLOG(5, "set_repeat - smaller");
                ZSTD_memcpy(nextHuf, prevHuf, sizeof(*prevHuf));
                hufMetadata->hType = set_repeat;
                return 0;
        }   }
        if (newCSize + hSize >= srcSize) {
            DEBUGLOG(5, "set_basic - no gains");
            ZSTD_memcpy(nextHuf, prevHuf, sizeof(*prevHuf));
            hufMetadata->hType = set_basic;
            return 0;
        }
        DEBUGLOG(5, "set_compressed (hSize=%u)", (U32)hSize);
        hufMetadata->hType = set_compressed;
        nextHuf->repeatMode = HUF_repeat_check;
        return hSize;
    }
}


/* ZSTD_buildDummySequencesStatistics():
 * Returns a ZSTD_symbolEncodingTypeStats_t with all encoding types as set_basic,
 * and updates nextEntropy to the appropriate repeatMode.
 */
static ZSTD_symbolEncodingTypeStats_t
ZSTD_buildDummySequencesStatistics(ZSTD_fseCTables_t* nextEntropy)
{
    ZSTD_symbolEncodingTypeStats_t stats = {set_basic, set_basic, set_basic, 0, 0, 0};
    nextEntropy->litlength_repeatMode = FSE_repeat_none;
    nextEntropy->offcode_repeatMode = FSE_repeat_none;
    nextEntropy->matchlength_repeatMode = FSE_repeat_none;
    return stats;
}

/** ZSTD_buildBlockEntropyStats_sequences() :
 *  Builds entropy for the sequences.
 *  Stores symbol compression modes and fse table to fseMetadata.
 *  Requires ENTROPY_WORKSPACE_SIZE wksp.
 * @return : size of fse tables or error code */
static size_t
ZSTD_buildBlockEntropyStats_sequences(
                const SeqStore_t* seqStorePtr,
                const ZSTD_fseCTables_t* prevEntropy,
                      ZSTD_fseCTables_t* nextEntropy,
                const ZSTD_CCtx_params* cctxParams,
                      ZSTD_fseCTablesMetadata_t* fseMetadata,
                      void* workspace, size_t wkspSize)
{
    ZSTD_strategy const strategy = cctxParams->cParams.strategy;
    size_t const nbSeq = (size_t)(seqStorePtr->sequences - seqStorePtr->sequencesStart);
    BYTE* const ostart = fseMetadata->fseTablesBuffer;
    BYTE* const oend = ostart + sizeof(fseMetadata->fseTablesBuffer);
    BYTE* op = ostart;
    unsigned* countWorkspace = (unsigned*)workspace;
    unsigned* entropyWorkspace = countWorkspace + (MaxSeq + 1);
    size_t entropyWorkspaceSize = wkspSize - (MaxSeq + 1) * sizeof(*countWorkspace);
    ZSTD_symbolEncodingTypeStats_t stats;

    DEBUGLOG(5, "ZSTD_buildBlockEntropyStats_sequences (nbSeq=%zu)", nbSeq);
    stats = nbSeq != 0 ? ZSTD_buildSequencesStatistics(seqStorePtr, nbSeq,
                                          prevEntropy, nextEntropy, op, oend,
                                          strategy, countWorkspace,
                                          entropyWorkspace, entropyWorkspaceSize)
                       : ZSTD_buildDummySequencesStatistics(nextEntropy);
    FORWARD_IF_ERROR(stats.size, "ZSTD_buildSequencesStatistics failed!");
    fseMetadata->llType = (SymbolEncodingType_e) stats.LLtype;
    fseMetadata->ofType = (SymbolEncodingType_e) stats.Offtype;
    fseMetadata->mlType = (SymbolEncodingType_e) stats.MLtype;
    fseMetadata->lastCountSize = stats.lastCountSize;
    return stats.size;
}


/** ZSTD_buildBlockEntropyStats() :
 *  Builds entropy for the block.
 *  Requires workspace size ENTROPY_WORKSPACE_SIZE
 * @return : 0 on success, or an error code
 *  Note : also employed in superblock
 */
size_t ZSTD_buildBlockEntropyStats(
            const SeqStore_t* seqStorePtr,
            const ZSTD_entropyCTables_t* prevEntropy,
                  ZSTD_entropyCTables_t* nextEntropy,
            const ZSTD_CCtx_params* cctxParams,
                  ZSTD_entropyCTablesMetadata_t* entropyMetadata,
                  void* workspace, size_t wkspSize)
{
    size_t const litSize = (size_t)(seqStorePtr->lit - seqStorePtr->litStart);
    int const huf_useOptDepth = (cctxParams->cParams.strategy >= HUF_OPTIMAL_DEPTH_THRESHOLD);
    int const hufFlags = huf_useOptDepth ? HUF_flags_optimalDepth : 0;

    entropyMetadata->hufMetadata.hufDesSize =
        ZSTD_buildBlockEntropyStats_literals(seqStorePtr->litStart, litSize,
                                            &prevEntropy->huf, &nextEntropy->huf,
                                            &entropyMetadata->hufMetadata,
                                            ZSTD_literalsCompressionIsDisabled(cctxParams),
                                            workspace, wkspSize, hufFlags);

    FORWARD_IF_ERROR(entropyMetadata->hufMetadata.hufDesSize, "ZSTD_buildBlockEntropyStats_literals failed");
    entropyMetadata->fseMetadata.fseTablesSize =
        ZSTD_buildBlockEntropyStats_sequences(seqStorePtr,
                                              &prevEntropy->fse, &nextEntropy->fse,
                                              cctxParams,
                                              &entropyMetadata->fseMetadata,
                                              workspace, wkspSize);
    FORWARD_IF_ERROR(entropyMetadata->fseMetadata.fseTablesSize, "ZSTD_buildBlockEntropyStats_sequences failed");
    return 0;
}

/* Returns the size estimate for the literals section (header + content) of a block */
static size_t
ZSTD_estimateBlockSize_literal(const BYTE* literals, size_t litSize,
                               const ZSTD_hufCTables_t* huf,
                               const ZSTD_hufCTablesMetadata_t* hufMetadata,
                               void* workspace, size_t wkspSize,
                               int writeEntropy)
{
    unsigned* const countWksp = (unsigned*)workspace;
    unsigned maxSymbolValue = HUF_SYMBOLVALUE_MAX;
    size_t literalSectionHeaderSize = 3 + (litSize >= 1 KB) + (litSize >= 16 KB);
    U32 singleStream = litSize < 256;

    if (hufMetadata->hType == set_basic) return litSize;
    else if (hufMetadata->hType == set_rle) return 1;
    else if (hufMetadata->hType == set_compressed || hufMetadata->hType == set_repeat) {
        size_t const largest = HIST_count_wksp (countWksp, &maxSymbolValue, (const BYTE*)literals, litSize, workspace, wkspSize);
        if (ZSTD_isError(largest)) return litSize;
        {   size_t cLitSizeEstimate = HUF_estimateCompressedSize((const HUF_CElt*)huf->CTable, countWksp, maxSymbolValue);
            if (writeEntropy) cLitSizeEstimate += hufMetadata->hufDesSize;
            if (!singleStream) cLitSizeEstimate += 6; /* multi-stream huffman uses 6-byte jump table */
            return cLitSizeEstimate + literalSectionHeaderSize;
    }   }
    assert(0); /* impossible */
    return 0;
}

/* Returns the size estimate for the FSE-compressed symbols (of, ml, ll) of a block */
static size_t
ZSTD_estimateBlockSize_symbolType(SymbolEncodingType_e type,
                    const BYTE* codeTable, size_t nbSeq, unsigned maxCode,
                    const FSE_CTable* fseCTable,
                    const U8* additionalBits,
                    short const* defaultNorm, U32 defaultNormLog, U32 defaultMax,
                    void* workspace, size_t wkspSize)
{
    unsigned* const countWksp = (unsigned*)workspace;
    const BYTE* ctp = codeTable;
    const BYTE* const ctStart = ctp;
    const BYTE* const ctEnd = ctStart + nbSeq;
    size_t cSymbolTypeSizeEstimateInBits = 0;
    unsigned max = maxCode;

    HIST_countFast_wksp(countWksp, &max, codeTable, nbSeq, workspace, wkspSize);  /* can't fail */
    if (type == set_basic) {
        /* We selected this encoding type, so it must be valid. */
        assert(max <= defaultMax);
        (void)defaultMax;
        cSymbolTypeSizeEstimateInBits = ZSTD_crossEntropyCost(defaultNorm, defaultNormLog, countWksp, max);
    } else if (type == set_rle) {
        cSymbolTypeSizeEstimateInBits = 0;
    } else if (type == set_compressed || type == set_repeat) {
        cSymbolTypeSizeEstimateInBits = ZSTD_fseBitCost(fseCTable, countWksp, max);
    }
    if (ZSTD_isError(cSymbolTypeSizeEstimateInBits)) {
        return nbSeq * 10;
    }
    while (ctp < ctEnd) {
        if (additionalBits) cSymbolTypeSizeEstimateInBits += additionalBits[*ctp];
        else cSymbolTypeSizeEstimateInBits += *ctp; /* for offset, offset code is also the number of additional bits */
        ctp++;
    }
    return cSymbolTypeSizeEstimateInBits >> 3;
}

/* Returns the size estimate for the sequences section (header + content) of a block */
static size_t
ZSTD_estimateBlockSize_sequences(const BYTE* ofCodeTable,
                                 const BYTE* llCodeTable,
                                 const BYTE* mlCodeTable,
                                 size_t nbSeq,
                                 const ZSTD_fseCTables_t* fseTables,
                                 const ZSTD_fseCTablesMetadata_t* fseMetadata,
                                 void* workspace, size_t wkspSize,
                                 int writeEntropy)
{
    size_t sequencesSectionHeaderSize = 1 /* seqHead */ + 1 /* min seqSize size */ + (nbSeq >= 128) + (nbSeq >= LONGNBSEQ);
    size_t cSeqSizeEstimate = 0;
    cSeqSizeEstimate += ZSTD_estimateBlockSize_symbolType(fseMetadata->ofType, ofCodeTable, nbSeq, MaxOff,
                                    fseTables->offcodeCTable, NULL,
                                    OF_defaultNorm, OF_defaultNormLog, DefaultMaxOff,
                                    workspace, wkspSize);
    cSeqSizeEstimate += ZSTD_estimateBlockSize_symbolType(fseMetadata->llType, llCodeTable, nbSeq, MaxLL,
                                    fseTables->litlengthCTable, LL_bits,
                                    LL_defaultNorm, LL_defaultNormLog, MaxLL,
                                    workspace, wkspSize);
    cSeqSizeEstimate += ZSTD_estimateBlockSize_symbolType(fseMetadata->mlType, mlCodeTable, nbSeq, MaxML,
                                    fseTables->matchlengthCTable, ML_bits,
                                    ML_defaultNorm, ML_defaultNormLog, MaxML,
                                    workspace, wkspSize);
    if (writeEntropy) cSeqSizeEstimate += fseMetadata->fseTablesSize;
    return cSeqSizeEstimate + sequencesSectionHeaderSize;
}

/* Returns the size estimate for a given stream of literals, of, ll, ml */
static size_t
ZSTD_estimateBlockSize(const BYTE* literals, size_t litSize,
                       const BYTE* ofCodeTable,
                       const BYTE* llCodeTable,
                       const BYTE* mlCodeTable,
                       size_t nbSeq,
                       const ZSTD_entropyCTables_t* entropy,
                       const ZSTD_entropyCTablesMetadata_t* entropyMetadata,
                       void* workspace, size_t wkspSize,
                       int writeLitEntropy, int writeSeqEntropy)
{
    size_t const literalsSize = ZSTD_estimateBlockSize_literal(literals, litSize,
                                    &entropy->huf, &entropyMetadata->hufMetadata,
                                    workspace, wkspSize, writeLitEntropy);
    size_t const seqSize = ZSTD_estimateBlockSize_sequences(ofCodeTable, llCodeTable, mlCodeTable,
                                    nbSeq, &entropy->fse, &entropyMetadata->fseMetadata,
                                    workspace, wkspSize, writeSeqEntropy);
    return seqSize + literalsSize + ZSTD_blockHeaderSize;
}

/* Builds entropy statistics and uses them for blocksize estimation.
 *
 * @return: estimated compressed size of the seqStore, or a zstd error.
 */
static size_t
ZSTD_buildEntropyStatisticsAndEstimateSubBlockSize(SeqStore_t* seqStore, ZSTD_CCtx* zc)
{
    ZSTD_entropyCTablesMetadata_t* const entropyMetadata = &zc->blockSplitCtx.entropyMetadata;
    DEBUGLOG(6, "ZSTD_buildEntropyStatisticsAndEstimateSubBlockSize()");
    FORWARD_IF_ERROR(ZSTD_buildBlockEntropyStats(seqStore,
                    &zc->blockState.prevCBlock->entropy,
                    &zc->blockState.nextCBlock->entropy,
                    &zc->appliedParams,
                    entropyMetadata,
                    zc->tmpWorkspace, zc->tmpWkspSize), "");
    return ZSTD_estimateBlockSize(
                    seqStore->litStart, (size_t)(seqStore->lit - seqStore->litStart),
                    seqStore->ofCode, seqStore->llCode, seqStore->mlCode,
                    (size_t)(seqStore->sequences - seqStore->sequencesStart),
                    &zc->blockState.nextCBlock->entropy,
                    entropyMetadata,
                    zc->tmpWorkspace, zc->tmpWkspSize,
                    (int)(entropyMetadata->hufMetadata.hType == set_compressed), 1);
}

/* Returns literals bytes represented in a seqStore */
static size_t ZSTD_countSeqStoreLiteralsBytes(const SeqStore_t* const seqStore)
{
    size_t literalsBytes = 0;
    size_t const nbSeqs = (size_t)(seqStore->sequences - seqStore->sequencesStart);
    size_t i;
    for (i = 0; i < nbSeqs; ++i) {
        SeqDef const seq = seqStore->sequencesStart[i];
        literalsBytes += seq.litLength;
        if (i == seqStore->longLengthPos && seqStore->longLengthType == ZSTD_llt_literalLength) {
            literalsBytes += 0x10000;
    }   }
    return literalsBytes;
}

/* Returns match bytes represented in a seqStore */
static size_t ZSTD_countSeqStoreMatchBytes(const SeqStore_t* const seqStore)
{
    size_t matchBytes = 0;
    size_t const nbSeqs = (size_t)(seqStore->sequences - seqStore->sequencesStart);
    size_t i;
    for (i = 0; i < nbSeqs; ++i) {
        SeqDef seq = seqStore->sequencesStart[i];
        matchBytes += seq.mlBase + MINMATCH;
        if (i == seqStore->longLengthPos && seqStore->longLengthType == ZSTD_llt_matchLength) {
            matchBytes += 0x10000;
    }   }
    return matchBytes;
}

/* Derives the seqStore that is a chunk of the originalSeqStore from [startIdx, endIdx).
 * Stores the result in resultSeqStore.
 */

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