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/*
* Copyright (c) Yann Collet, Meta Platforms, Inc.
* 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.
*/
#include "external_matchfinder.h"
#include <string.h>
#include "zstd_compress_internal.h"
#define HSIZE 1024
static U32 const HLOG = 10;
static U32 const MLS = 4;
static U32 const BADIDX = 0xffffffff;
static size_t simpleSequenceProducer(
void* sequenceProducerState,
ZSTD_Sequence* outSeqs, size_t outSeqsCapacity,
const void* src, size_t srcSize,
const void* dict, size_t dictSize,
int compressionLevel,
size_t windowSize
) {
const BYTE* const istart = (const BYTE*)src;
const BYTE* const iend = istart + srcSize;
const BYTE* ip = istart;
const BYTE* anchor = istart;
size_t seqCount = 0;
U32 hashTable[HSIZE];
(void)sequenceProducerState;
(void)dict;
(void)dictSize;
(void)outSeqsCapacity;
(void)compressionLevel;
{ int i;
for (i=0; i < HSIZE; i++) {
hashTable[i] = BADIDX;
} }
while (ip + MLS < iend) {
size_t const hash = ZSTD_hashPtr(ip, HLOG, MLS);
U32 const matchIndex = hashTable[hash];
hashTable[hash] = (U32)(ip - istart);
if (matchIndex != BADIDX) {
const BYTE* const match = istart + matchIndex;
U32 const matchLen = (U32)ZSTD_count(ip, match, iend);
if (matchLen >= ZSTD_MINMATCH_MIN) {
U32 const litLen = (U32)(ip - anchor);
U32 const offset = (U32)(ip - match);
ZSTD_Sequence const seq = {
offset, litLen, matchLen, 0
};
/* Note: it's crucial to stay within the window size! */
if (offset <= windowSize) {
outSeqs[seqCount++] = seq;
ip += matchLen;
anchor = ip;
continue;
}
}
}
ip++;
}
{ ZSTD_Sequence const finalSeq = {
0, (U32)(iend - anchor), 0, 0
};
outSeqs[seqCount++] = finalSeq;
}
return seqCount;
}
size_t zstreamSequenceProducer(
void* sequenceProducerState,
ZSTD_Sequence* outSeqs, size_t outSeqsCapacity,
const void* src, size_t srcSize,
const void* dict, size_t dictSize,
int compressionLevel,
size_t windowSize
) {
EMF_testCase const testCase = *((EMF_testCase*)sequenceProducerState);
memset(outSeqs, 0, outSeqsCapacity);
switch (testCase) {
case EMF_ZERO_SEQS:
return 0;
case EMF_ONE_BIG_SEQ:
outSeqs[0].offset = 0;
outSeqs[0].matchLength = 0;
outSeqs[0].litLength = (U32)(srcSize);
return 1;
case EMF_LOTS_OF_SEQS:
return simpleSequenceProducer(
sequenceProducerState,
outSeqs, outSeqsCapacity,
src, srcSize,
dict, dictSize,
compressionLevel,
windowSize
);
case EMF_INVALID_OFFSET:
outSeqs[0].offset = 1 << 20;
outSeqs[0].matchLength = 4;
outSeqs[0].litLength = (U32)(srcSize - 4);
return 1;
case EMF_INVALID_MATCHLEN:
outSeqs[0].offset = 1;
outSeqs[0].matchLength = (U32)(srcSize);
outSeqs[0].litLength = 1;
return 1;
case EMF_INVALID_LITLEN:
outSeqs[0].offset = 0;
outSeqs[0].matchLength = 0;
outSeqs[0].litLength = (U32)(srcSize + 1);
return 1;
case EMF_INVALID_LAST_LITS:
outSeqs[0].offset = 1;
outSeqs[0].matchLength = 1;
outSeqs[0].litLength = 1;
outSeqs[1].offset = 0;
outSeqs[1].matchLength = 0;
outSeqs[1].litLength = (U32)(srcSize - 1);
return 2;
case EMF_SMALL_ERROR:
return outSeqsCapacity + 1;
case EMF_BIG_ERROR:
default:
return ZSTD_SEQUENCE_PRODUCER_ERROR;
}
}
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