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Optimal LZSA1 compression

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Emmanuel Marty 2023-02-27 08:26:42 +01:00 committed by GitHub
parent 6b08bc3990
commit 35ec6d73da
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GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 17 additions and 5 deletions
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22
src/matchfinder.c
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@ -203,6 +203,7 @@ static int lzsa_find_matches_at(lzsa_compressor *pCompressor, const int nOffset,
unsigned int match_pos;
lzsa_match *matchptr;
unsigned int nPrevOffset = 0;
unsigned char nV1OffsetFound[2] = { 0, 0 };
/**
* Find matches using intervals
@ -281,14 +282,25 @@ static int lzsa_find_matches_at(lzsa_compressor *pCompressor, const int nOffset,
if (nMatchOffset <= MAX_OFFSET && nMatchOffset != nPrevOffset) {
if (pCompressor->format_version >= 2) {
matchptr->length = (const unsigned short)(ref >> (LCP_SHIFT + TAG_BITS));
matchptr->offset = (const unsigned short)nMatchOffset;
matchptr++;
nPrevOffset = nMatchOffset;
}
else {
matchptr->length = (const unsigned short)(ref >> LCP_SHIFT);
}
matchptr->offset = (const unsigned short)nMatchOffset;
matchptr++;
unsigned int nV1OffsetType = (nMatchOffset <= 256) ? 0 : 1;
nPrevOffset = nMatchOffset;
if (!nV1OffsetFound[nV1OffsetType]) {
matchptr->length = (const unsigned short)(ref >> LCP_SHIFT);
matchptr->offset = (const unsigned short)nMatchOffset;
if (matchptr->length < 256)
nV1OffsetFound[nV1OffsetType] = 1;
matchptr++;
nPrevOffset = nMatchOffset;
}
}
}
}