函数源码

Linux Kernel

v5.5.9

Brick Technologies Co., Ltd

Source File:lib\zstd\compress.c Create Date:2022-07-27 08:00:34
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/*! ZSTD_resetCCtx_advanced() :
    note : `params` must be validated */
static size_t ZSTD_resetCCtx_advanced(ZSTD_CCtx *zc, ZSTD_parameters params, U64 frameContentSize, ZSTD_compResetPolicy_e const crp)
{
    if (crp == ZSTDcrp_continue)
        if (ZSTD_equivalentParams(params, zc->params)) {
            zc->flagStaticTables = 0;
            zc->flagStaticHufTable = HUF_repeat_none;
            return ZSTD_continueCCtx(zc, params, frameContentSize);
        }
 
    {
        size_t const blockSize = MIN(ZSTD_BLOCKSIZE_ABSOLUTEMAX, (size_t)1 << params.cParams.windowLog);
        U32 const divider = (params.cParams.searchLength == 3) ? 3 : 4;
        size_t const maxNbSeq = blockSize / divider;
        size_t const tokenSpace = blockSize + 11 * maxNbSeq;
        size_t const chainSize = (params.cParams.strategy == ZSTD_fast) ? 0 : (1 << params.cParams.chainLog);
        size_t const hSize = ((size_t)1) << params.cParams.hashLog;
        U32 const hashLog3 = (params.cParams.searchLength > 3) ? 0 : MIN(ZSTD_HASHLOG3_MAX, params.cParams.windowLog);
        size_t const h3Size = ((size_t)1) << hashLog3;
        size_t const tableSpace = (chainSize + hSize + h3Size) * sizeof(U32);
        void *ptr;
 
        /* Check if workSpace is large enough, alloc a new one if needed */
        {
            size_t const optSpace = ((MaxML + 1) + (MaxLL + 1) + (MaxOff + 1) + (1 << Litbits)) * sizeof(U32) +
                        (ZSTD_OPT_NUM + 1) * (sizeof(ZSTD_match_t) + sizeof(ZSTD_optimal_t));
            size_t const neededSpace = tableSpace + (256 * sizeof(U32)) /* huffTable */ + tokenSpace +
                           (((params.cParams.strategy == ZSTD_btopt) || (params.cParams.strategy == ZSTD_btopt2)) ? optSpace : 0);
            if (zc->workSpaceSize < neededSpace) {
                ZSTD_free(zc->workSpace, zc->customMem);
                zc->workSpace = ZSTD_malloc(neededSpace, zc->customMem);
                if (zc->workSpace == NULL)
                    return ERROR(memory_allocation);
                zc->workSpaceSize = neededSpace;
            }
        }
 
        if (crp != ZSTDcrp_noMemset)
            memset(zc->workSpace, 0, tableSpace); /* reset tables only */
        xxh64_reset(&zc->xxhState, 0);
        zc->hashLog3 = hashLog3;
        zc->hashTable = (U32 *)(zc->workSpace);
        zc->chainTable = zc->hashTable + hSize;
        zc->hashTable3 = zc->chainTable + chainSize;
        ptr = zc->hashTable3 + h3Size;
        zc->hufTable = (HUF_CElt *)ptr;
        zc->flagStaticTables = 0;
        zc->flagStaticHufTable = HUF_repeat_none;
        ptr = ((U32 *)ptr) + 256; /* note : HUF_CElt* is incomplete type, size is simulated using U32 */
 
        zc->nextToUpdate = 1;
        zc->nextSrc = NULL;
        zc->base = NULL;
        zc->dictBase = NULL;
        zc->dictLimit = 0;
        zc->lowLimit = 0;
        zc->params = params;
        zc->blockSize = blockSize;
        zc->frameContentSize = frameContentSize;
        {
            int i;
            for (i = 0; i < ZSTD_REP_NUM; i++)
                zc->rep[i] = repStartValue[i];
        }
 
        if ((params.cParams.strategy == ZSTD_btopt) || (params.cParams.strategy == ZSTD_btopt2)) {
            zc->seqStore.litFreq = (U32 *)ptr;
            zc->seqStore.litLengthFreq = zc->seqStore.litFreq + (1 << Litbits);
            zc->seqStore.matchLengthFreq = zc->seqStore.litLengthFreq + (MaxLL + 1);
            zc->seqStore.offCodeFreq = zc->seqStore.matchLengthFreq + (MaxML + 1);
            ptr = zc->seqStore.offCodeFreq + (MaxOff + 1);
            zc->seqStore.matchTable = (ZSTD_match_t *)ptr;
            ptr = zc->seqStore.matchTable + ZSTD_OPT_NUM + 1;
            zc->seqStore.priceTable = (ZSTD_optimal_t *)ptr;
            ptr = zc->seqStore.priceTable + ZSTD_OPT_NUM + 1;
            zc->seqStore.litLengthSum = 0;
        }
        zc->seqStore.sequencesStart = (seqDef *)ptr;
        ptr = zc->seqStore.sequencesStart + maxNbSeq;
        zc->seqStore.llCode = (BYTE *)ptr;
        zc->seqStore.mlCode = zc->seqStore.llCode + maxNbSeq;
        zc->seqStore.ofCode = zc->seqStore.mlCode + maxNbSeq;
        zc->seqStore.litStart = zc->seqStore.ofCode + maxNbSeq;
 
        zc->stage = ZSTDcs_init;
        zc->dictID = 0;
        zc->loadedDictEnd = 0;
 
        return 0;
    }
}