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Use real cost of rep offset when considering a reduction; fix small bug in repmatch handling when doing reductions.

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Emmanuel Marty 2019-06-26 13:55:00 +02:00 committed by GitHub
parent 2a265f9cf9
commit 3c8c4283c7
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GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 5 additions and 6 deletions
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11
src/shrink_block_v2.c
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@ -465,7 +465,8 @@ static int lzsa_optimize_command_count_v2(lzsa_compressor *pCompressor, const in
if (nMatchLen <= 9 && (i + nMatchLen) < nEndOffset) /* max reducable command size: <token> <EE> <ll> <ll> <offset> <offset> <EE> <mm> <mm> */ {
int nMatchOffset = pMatch->offset;
int nEncodedMatchLen = nMatchLen - MIN_MATCH_SIZE_V2;
int nUndoRepMatchCost = (nPreviousMatchOffset < 0 || !repmatch_opt[nPreviousMatchOffset].expected_repmatch) ? 0 : 16;
int nRepMatchSize = (nRepMatchOffset <= 32) ? 4 : ((nRepMatchOffset <= 512) ? 8 : ((nRepMatchOffset <= (8192 + 512)) ? 12 : 16)) /* match offset */;
int nUndoRepMatchCost = (nPreviousMatchOffset < 0 || !repmatch_opt[nPreviousMatchOffset].expected_repmatch) ? 0 : nRepMatchSize;
if (pCompressor->best_match[i + nMatchLen].length >= MIN_MATCH_SIZE_V2) {
int nCommandSize = 8 /* token */ + lzsa_get_literals_varlen_size_v2(nNumLiterals) + lzsa_get_match_varlen_size_v2(nEncodedMatchLen) - nUndoRepMatchCost;
@ -484,7 +485,6 @@ static int lzsa_optimize_command_count_v2(lzsa_compressor *pCompressor, const in
else {
if (nMatchOffset != nRepMatchOffset &&
pCompressor->best_match[i + nMatchLen].offset == nRepMatchOffset) {
int nRepMatchSize = (nRepMatchOffset <= 32) ? 4 : ((nRepMatchOffset <= 512) ? 8 : ((nRepMatchOffset <= (8192 + 512)) ? 12 : 16)) /* match offset */;
if (nCommandSize > ((nMatchLen << 3) + lzsa_get_literals_varlen_size_v2(nNumLiterals + nMatchLen) - nRepMatchSize)) {
/* Same case, replacing this command by literals alone isn't enough on its own to have savings, however this match command is inbetween two matches with
@ -519,7 +519,6 @@ static int lzsa_optimize_command_count_v2(lzsa_compressor *pCompressor, const in
if (nCurIndex < nEndOffset && pCompressor->best_match[nCurIndex].length >= MIN_MATCH_SIZE_V2 &&
pCompressor->best_match[nCurIndex].offset != nMatchOffset &&
pCompressor->best_match[nCurIndex].offset == nRepMatchOffset) {
int nRepMatchSize = (nRepMatchOffset <= 32) ? 4 : ((nRepMatchOffset <= 512) ? 8 : ((nRepMatchOffset <= (8192 + 512)) ? 12 : 16)) /* match offset */;
if (nCommandSize > ((nMatchLen << 3) + lzsa_get_literals_varlen_size_v2(nNumLiterals + nNextNumLiterals + nMatchLen) - lzsa_get_literals_varlen_size_v2(nNextNumLiterals) - nRepMatchSize)) {
/* Same case, but now replacing this command allows to use a rep-match and get savings, so do it */
nReduce = 1;
@ -529,9 +528,6 @@ static int lzsa_optimize_command_count_v2(lzsa_compressor *pCompressor, const in
}
}
if (pMatch->length)
nRepMatchOffset = pMatch->offset;
if (nReduce) {
int j;
@ -549,6 +545,9 @@ static int lzsa_optimize_command_count_v2(lzsa_compressor *pCompressor, const in
}
}
else {
if (pMatch->length)
nRepMatchOffset = pMatch->offset;
if ((i + nMatchLen) < nEndOffset && nMatchLen >= LCP_MAX &&
pMatch->offset && pMatch->offset <= 32 && pCompressor->best_match[i + nMatchLen].offset == pMatch->offset && (nMatchLen % pMatch->offset) == 0 &&
(nMatchLen + pCompressor->best_match[i + nMatchLen].length) <= MAX_VARLEN) {