mirror of
https://github.com/facebook/zstd.git
synced 2025-11-04 00:02:59 -05:00
243 lines
10 KiB
C
243 lines
10 KiB
C
/*
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* Copyright (c) 2016-present, Yann Collet, Facebook, Inc.
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* All rights reserved.
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*
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* This source code is licensed under both the BSD-style license (found in the
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* LICENSE file in the root directory of this source tree) and the GPLv2 (found
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* in the COPYING file in the root directory of this source tree).
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* You may select, at your option, one of the above-listed licenses.
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*/
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#include "zstd_fast.h"
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void ZSTD_fillHashTable (ZSTD_CCtx* zc, const void* end, const U32 mls)
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{
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U32* const hashTable = zc->hashTable;
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U32 const hBits = zc->appliedParams.cParams.hashLog;
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const BYTE* const base = zc->base;
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const BYTE* ip = base + zc->nextToUpdate;
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const BYTE* const iend = ((const BYTE*)end) - HASH_READ_SIZE;
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const size_t fastHashFillStep = 3;
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while(ip <= iend) {
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hashTable[ZSTD_hashPtr(ip, hBits, mls)] = (U32)(ip - base);
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ip += fastHashFillStep;
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}
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}
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FORCE_INLINE_TEMPLATE
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size_t ZSTD_compressBlock_fast_generic(ZSTD_CCtx* cctx,
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const void* src, size_t srcSize,
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const U32 mls)
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{
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U32* const hashTable = cctx->hashTable;
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U32 const hBits = cctx->appliedParams.cParams.hashLog;
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seqStore_t* seqStorePtr = &(cctx->seqStore);
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const BYTE* const base = cctx->base;
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const BYTE* const istart = (const BYTE*)src;
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const BYTE* ip = istart;
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const BYTE* anchor = istart;
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const U32 lowestIndex = cctx->dictLimit;
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const BYTE* const lowest = base + lowestIndex;
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const BYTE* const iend = istart + srcSize;
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const BYTE* const ilimit = iend - HASH_READ_SIZE;
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U32 offset_1=seqStorePtr->rep[0], offset_2=seqStorePtr->rep[1];
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U32 offsetSaved = 0;
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/* init */
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ip += (ip==lowest);
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{ U32 const maxRep = (U32)(ip-lowest);
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if (offset_2 > maxRep) offsetSaved = offset_2, offset_2 = 0;
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if (offset_1 > maxRep) offsetSaved = offset_1, offset_1 = 0;
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}
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/* Main Search Loop */
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while (ip < ilimit) { /* < instead of <=, because repcode check at (ip+1) */
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size_t mLength;
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size_t const h = ZSTD_hashPtr(ip, hBits, mls);
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U32 const current = (U32)(ip-base);
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U32 const matchIndex = hashTable[h];
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const BYTE* match = base + matchIndex;
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hashTable[h] = current; /* update hash table */
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if ((offset_1 > 0) & (MEM_read32(ip+1-offset_1) == MEM_read32(ip+1))) {
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mLength = ZSTD_count(ip+1+4, ip+1+4-offset_1, iend) + 4;
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ip++;
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ZSTD_storeSeq(seqStorePtr, ip-anchor, anchor, 0, mLength-MINMATCH);
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} else {
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U32 offset;
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if ( (matchIndex <= lowestIndex) || (MEM_read32(match) != MEM_read32(ip)) ) {
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ip += ((ip-anchor) >> g_searchStrength) + 1;
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continue;
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}
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mLength = ZSTD_count(ip+4, match+4, iend) + 4;
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offset = (U32)(ip-match);
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while (((ip>anchor) & (match>lowest)) && (ip[-1] == match[-1])) { ip--; match--; mLength++; } /* catch up */
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offset_2 = offset_1;
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offset_1 = offset;
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ZSTD_storeSeq(seqStorePtr, ip-anchor, anchor, offset + ZSTD_REP_MOVE, mLength-MINMATCH);
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}
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/* match found */
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ip += mLength;
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anchor = ip;
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if (ip <= ilimit) {
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/* Fill Table */
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hashTable[ZSTD_hashPtr(base+current+2, hBits, mls)] = current+2; /* here because current+2 could be > iend-8 */
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hashTable[ZSTD_hashPtr(ip-2, hBits, mls)] = (U32)(ip-2-base);
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/* check immediate repcode */
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while ( (ip <= ilimit)
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&& ( (offset_2>0)
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& (MEM_read32(ip) == MEM_read32(ip - offset_2)) )) {
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/* store sequence */
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size_t const rLength = ZSTD_count(ip+4, ip+4-offset_2, iend) + 4;
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{ U32 const tmpOff = offset_2; offset_2 = offset_1; offset_1 = tmpOff; } /* swap offset_2 <=> offset_1 */
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hashTable[ZSTD_hashPtr(ip, hBits, mls)] = (U32)(ip-base);
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ZSTD_storeSeq(seqStorePtr, 0, anchor, 0, rLength-MINMATCH);
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ip += rLength;
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anchor = ip;
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continue; /* faster when present ... (?) */
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} } }
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/* save reps for next block */
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seqStorePtr->repToConfirm[0] = offset_1 ? offset_1 : offsetSaved;
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seqStorePtr->repToConfirm[1] = offset_2 ? offset_2 : offsetSaved;
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/* Return the last literals size */
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return iend - anchor;
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}
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size_t ZSTD_compressBlock_fast(ZSTD_CCtx* ctx,
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const void* src, size_t srcSize)
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{
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const U32 mls = ctx->appliedParams.cParams.searchLength;
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switch(mls)
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{
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default: /* includes case 3 */
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case 4 :
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return ZSTD_compressBlock_fast_generic(ctx, src, srcSize, 4);
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case 5 :
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return ZSTD_compressBlock_fast_generic(ctx, src, srcSize, 5);
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case 6 :
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return ZSTD_compressBlock_fast_generic(ctx, src, srcSize, 6);
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case 7 :
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return ZSTD_compressBlock_fast_generic(ctx, src, srcSize, 7);
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}
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}
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static size_t ZSTD_compressBlock_fast_extDict_generic(ZSTD_CCtx* ctx,
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const void* src, size_t srcSize,
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const U32 mls)
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{
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U32* hashTable = ctx->hashTable;
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const U32 hBits = ctx->appliedParams.cParams.hashLog;
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seqStore_t* seqStorePtr = &(ctx->seqStore);
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const BYTE* const base = ctx->base;
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const BYTE* const dictBase = ctx->dictBase;
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const BYTE* const istart = (const BYTE*)src;
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const BYTE* ip = istart;
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const BYTE* anchor = istart;
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const U32 lowestIndex = ctx->lowLimit;
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const BYTE* const dictStart = dictBase + lowestIndex;
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const U32 dictLimit = ctx->dictLimit;
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const BYTE* const lowPrefixPtr = base + dictLimit;
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const BYTE* const dictEnd = dictBase + dictLimit;
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const BYTE* const iend = istart + srcSize;
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const BYTE* const ilimit = iend - 8;
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U32 offset_1=seqStorePtr->rep[0], offset_2=seqStorePtr->rep[1];
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/* Search Loop */
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while (ip < ilimit) { /* < instead of <=, because (ip+1) */
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const size_t h = ZSTD_hashPtr(ip, hBits, mls);
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const U32 matchIndex = hashTable[h];
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const BYTE* matchBase = matchIndex < dictLimit ? dictBase : base;
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const BYTE* match = matchBase + matchIndex;
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const U32 current = (U32)(ip-base);
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const U32 repIndex = current + 1 - offset_1; /* offset_1 expected <= current +1 */
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const BYTE* repBase = repIndex < dictLimit ? dictBase : base;
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const BYTE* repMatch = repBase + repIndex;
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size_t mLength;
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hashTable[h] = current; /* update hash table */
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if ( (((U32)((dictLimit-1) - repIndex) >= 3) /* intentional underflow */ & (repIndex > lowestIndex))
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&& (MEM_read32(repMatch) == MEM_read32(ip+1)) ) {
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const BYTE* repMatchEnd = repIndex < dictLimit ? dictEnd : iend;
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mLength = ZSTD_count_2segments(ip+1+4, repMatch+4, iend, repMatchEnd, lowPrefixPtr) + 4;
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ip++;
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ZSTD_storeSeq(seqStorePtr, ip-anchor, anchor, 0, mLength-MINMATCH);
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} else {
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if ( (matchIndex < lowestIndex) ||
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(MEM_read32(match) != MEM_read32(ip)) ) {
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ip += ((ip-anchor) >> g_searchStrength) + 1;
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continue;
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}
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{ const BYTE* matchEnd = matchIndex < dictLimit ? dictEnd : iend;
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const BYTE* lowMatchPtr = matchIndex < dictLimit ? dictStart : lowPrefixPtr;
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U32 offset;
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mLength = ZSTD_count_2segments(ip+4, match+4, iend, matchEnd, lowPrefixPtr) + 4;
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while (((ip>anchor) & (match>lowMatchPtr)) && (ip[-1] == match[-1])) { ip--; match--; mLength++; } /* catch up */
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offset = current - matchIndex;
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offset_2 = offset_1;
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offset_1 = offset;
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ZSTD_storeSeq(seqStorePtr, ip-anchor, anchor, offset + ZSTD_REP_MOVE, mLength-MINMATCH);
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} }
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/* found a match : store it */
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ip += mLength;
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anchor = ip;
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if (ip <= ilimit) {
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/* Fill Table */
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hashTable[ZSTD_hashPtr(base+current+2, hBits, mls)] = current+2;
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hashTable[ZSTD_hashPtr(ip-2, hBits, mls)] = (U32)(ip-2-base);
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/* check immediate repcode */
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while (ip <= ilimit) {
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U32 const current2 = (U32)(ip-base);
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U32 const repIndex2 = current2 - offset_2;
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const BYTE* repMatch2 = repIndex2 < dictLimit ? dictBase + repIndex2 : base + repIndex2;
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if ( (((U32)((dictLimit-1) - repIndex2) >= 3) & (repIndex2 > lowestIndex)) /* intentional overflow */
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&& (MEM_read32(repMatch2) == MEM_read32(ip)) ) {
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const BYTE* const repEnd2 = repIndex2 < dictLimit ? dictEnd : iend;
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size_t const repLength2 = ZSTD_count_2segments(ip+4, repMatch2+4, iend, repEnd2, lowPrefixPtr) + 4;
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U32 tmpOffset = offset_2; offset_2 = offset_1; offset_1 = tmpOffset; /* swap offset_2 <=> offset_1 */
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ZSTD_storeSeq(seqStorePtr, 0, anchor, 0, repLength2-MINMATCH);
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hashTable[ZSTD_hashPtr(ip, hBits, mls)] = current2;
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ip += repLength2;
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anchor = ip;
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continue;
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}
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break;
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} } }
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/* save reps for next block */
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seqStorePtr->repToConfirm[0] = offset_1; seqStorePtr->repToConfirm[1] = offset_2;
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/* Return the last literals size */
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return iend - anchor;
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}
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size_t ZSTD_compressBlock_fast_extDict(ZSTD_CCtx* ctx,
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const void* src, size_t srcSize)
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{
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U32 const mls = ctx->appliedParams.cParams.searchLength;
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switch(mls)
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{
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default: /* includes case 3 */
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case 4 :
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return ZSTD_compressBlock_fast_extDict_generic(ctx, src, srcSize, 4);
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case 5 :
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return ZSTD_compressBlock_fast_extDict_generic(ctx, src, srcSize, 5);
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case 6 :
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return ZSTD_compressBlock_fast_extDict_generic(ctx, src, srcSize, 6);
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case 7 :
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return ZSTD_compressBlock_fast_extDict_generic(ctx, src, srcSize, 7);
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}
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}
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