diff options
Diffstat (limited to '3rdparty/zstd/contrib/externalSequenceProducer/sequence_producer.c')
-rw-r--r-- | 3rdparty/zstd/contrib/externalSequenceProducer/sequence_producer.c | 80 |
1 files changed, 80 insertions, 0 deletions
diff --git a/3rdparty/zstd/contrib/externalSequenceProducer/sequence_producer.c b/3rdparty/zstd/contrib/externalSequenceProducer/sequence_producer.c new file mode 100644 index 00000000000..60a2f9572b0 --- /dev/null +++ b/3rdparty/zstd/contrib/externalSequenceProducer/sequence_producer.c @@ -0,0 +1,80 @@ +/* + * 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; +} |