81 lines
2.3 KiB
C
81 lines
2.3 KiB
C
/*
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* Copyright (c) Yann Collet, Meta Platforms, 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_compress_internal.h"
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#include "sequence_producer.h"
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#define HSIZE 1024
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static U32 const HLOG = 10;
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static U32 const MLS = 4;
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static U32 const BADIDX = 0xffffffff;
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size_t simpleSequenceProducer(
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void* sequenceProducerState,
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ZSTD_Sequence* outSeqs, size_t outSeqsCapacity,
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const void* src, size_t srcSize,
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const void* dict, size_t dictSize,
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int compressionLevel,
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size_t windowSize
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) {
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const BYTE* const istart = (const BYTE*)src;
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const BYTE* const iend = istart + srcSize;
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const BYTE* ip = istart;
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const BYTE* anchor = istart;
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size_t seqCount = 0;
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U32 hashTable[HSIZE];
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(void)sequenceProducerState;
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(void)dict;
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(void)dictSize;
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(void)outSeqsCapacity;
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(void)compressionLevel;
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{ int i;
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for (i=0; i < HSIZE; i++) {
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hashTable[i] = BADIDX;
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} }
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while (ip + MLS < iend) {
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size_t const hash = ZSTD_hashPtr(ip, HLOG, MLS);
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U32 const matchIndex = hashTable[hash];
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hashTable[hash] = (U32)(ip - istart);
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if (matchIndex != BADIDX) {
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const BYTE* const match = istart + matchIndex;
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U32 const matchLen = (U32)ZSTD_count(ip, match, iend);
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if (matchLen >= ZSTD_MINMATCH_MIN) {
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U32 const litLen = (U32)(ip - anchor);
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U32 const offset = (U32)(ip - match);
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ZSTD_Sequence const seq = {
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offset, litLen, matchLen, 0
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};
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/* Note: it's crucial to stay within the window size! */
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if (offset <= windowSize) {
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outSeqs[seqCount++] = seq;
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ip += matchLen;
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anchor = ip;
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continue;
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}
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}
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}
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ip++;
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}
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{ ZSTD_Sequence const finalSeq = {
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0, (U32)(iend - anchor), 0, 0
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};
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outSeqs[seqCount++] = finalSeq;
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}
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return seqCount;
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}
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