81 lines
2.3 KiB
C
81 lines
2.3 KiB
C
|
/*
|
||
|
|
* 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 "zstd_compress_internal.h"
|
||
|
|
#include "sequence_producer.h"
|
||
|
|
|
||
|
|
#define HSIZE 1024
|
||
|
|
static U32 const HLOG = 10;
|
||
|
|
static U32 const MLS = 4;
|
||
|
|
static U32 const BADIDX = 0xffffffff;
|
||
|
|
|
||
|
|
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;
|
||
|
|
}
|