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Speed up LZSA2 compression (same binary output)

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Emmanuel Marty 2019-09-23 16:58:03 +02:00 committed by GitHub
parent 81e15d10f0
commit 74040890fc
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GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 33 additions and 30 deletions
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63
src/shrink_block_v2.c
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@ -225,9 +225,11 @@ static void lzsa_optimize_forward_v2(lzsa_compressor *pCompressor, const unsigne
if (pDestArrival->from_slot == 0 ||
nCodingChoiceCost <= pDestArrival->cost) {
memmove(&arrival[((i + 1) << MATCHES_PER_OFFSET_SHIFT) + n + 1],
&arrival[((i + 1) << MATCHES_PER_OFFSET_SHIFT) + n],
sizeof(lzsa_arrival) * (NMATCHES_PER_OFFSET - n - 1));
if (pDestArrival->from_slot) {
memmove(&arrival[((i + 1) << MATCHES_PER_OFFSET_SHIFT) + n + 1],
&arrival[((i + 1) << MATCHES_PER_OFFSET_SHIFT) + n],
sizeof(lzsa_arrival) * (NMATCHES_PER_OFFSET - n - 1));
}
pDestArrival->cost = nCodingChoiceCost;
pDestArrival->from_pos = i;
@ -248,10 +250,6 @@ static void lzsa_optimize_forward_v2(lzsa_compressor *pCompressor, const unsigne
int nMatchOffset = match[m].offset;
int nNoRepmatchOffsetCost = (nMatchOffset <= 32) ? 4 : ((nMatchOffset <= 512) ? 8 : ((nMatchOffset <= (8192 + 512)) ? 12 : 16));
int nStartingMatchLen, k;
int nRepMatchLenForArrival[NMATCHES_PER_OFFSET];
for (j = 0; j < NMATCHES_PER_OFFSET; j++)
nRepMatchLenForArrival[j] = 0;
if ((i + nMatchLen) > (nEndOffset - LAST_LITERALS))
nMatchLen = nEndOffset - LAST_LITERALS - i;
@ -260,14 +258,24 @@ static void lzsa_optimize_forward_v2(lzsa_compressor *pCompressor, const unsigne
nStartingMatchLen = nMatchLen;
else
nStartingMatchLen = nMinMatchSize;
for (k = nStartingMatchLen; k <= nMatchLen; k++) {
int nMatchLenCost = lzsa_get_match_varlen_size_v2(k - MIN_MATCH_SIZE_V2);
lzsa_arrival *pDestSlots = &arrival[(i + k) << MATCHES_PER_OFFSET_SHIFT];
for (j = 0; j < NMATCHES_PER_OFFSET && arrival[(i << MATCHES_PER_OFFSET_SHIFT) + j].from_slot; j++) {
const int nPrevCost = arrival[(i << MATCHES_PER_OFFSET_SHIFT) + j].cost;
int nRepOffset = arrival[(i << MATCHES_PER_OFFSET_SHIFT) + j].rep_offset;
int nMaxRepLen = 0;
if (nMatchOffset != nRepOffset &&
nRepOffset &&
i >= nRepOffset &&
(i - nRepOffset + nMatchLen) <= (nEndOffset - LAST_LITERALS)) {
while (nMaxRepLen < nMatchLen && pInWindow[i - nRepOffset + nMaxRepLen] == pInWindow[i - nMatchOffset + nMaxRepLen])
nMaxRepLen++;
}
for (k = nStartingMatchLen; k <= nMatchLen; k++) {
int nMatchLenCost = lzsa_get_match_varlen_size_v2(k - MIN_MATCH_SIZE_V2);
lzsa_arrival *pDestSlots = &arrival[(i + k) << MATCHES_PER_OFFSET_SHIFT];
for (j = 0; j < NMATCHES_PER_OFFSET && arrival[(i << MATCHES_PER_OFFSET_SHIFT) + j].from_slot; j++) {
int nRepOffset = arrival[(i << MATCHES_PER_OFFSET_SHIFT) + j].rep_offset;
int nMatchOffsetCost = (nMatchOffset == nRepOffset) ? 0 : nNoRepmatchOffsetCost;
int nPrevCost = arrival[(i << MATCHES_PER_OFFSET_SHIFT) + j].cost;
int nCodingChoiceCost = nPrevCost + 8 /* token */ /* the actual cost of the literals themselves accumulates up the chain */ + nMatchOffsetCost + nMatchLenCost;
int exists = 0;
@ -286,9 +294,11 @@ static void lzsa_optimize_forward_v2(lzsa_compressor *pCompressor, const unsigne
if (pDestArrival->from_slot == 0 ||
nCodingChoiceCost <= pDestArrival->cost) {
memmove(&pDestSlots[n + 1],
&pDestSlots[n],
sizeof(lzsa_arrival) * (NMATCHES_PER_OFFSET - n - 1));
if (pDestArrival->from_slot) {
memmove(&pDestSlots[n + 1],
&pDestSlots[n],
sizeof(lzsa_arrival) * (NMATCHES_PER_OFFSET - n - 1));
}
pDestArrival->cost = nCodingChoiceCost;
pDestArrival->from_pos = i;
@ -301,21 +311,13 @@ static void lzsa_optimize_forward_v2(lzsa_compressor *pCompressor, const unsigne
}
}
/* This coding choice doesn't rep-match; see if we still get a match by using the current repmatch offset for this arrival. This can occur (and not have the
/* If this coding choice doesn't rep-match, see if we still get a match by using the current repmatch offset for this arrival. This can occur (and not have the
* matchfinder offer the offset in the first place, or have too many choices with the same cost to retain the repmatchable offset) when compressing regions
* of identical bytes, for instance. Checking for this provides a big compression win on some files. */
if (nMatchOffset != nRepOffset &&
nRepOffset &&
i >= nRepOffset &&
k > nRepMatchLenForArrival[j] &&
!memcmp(pInWindow + i - nRepOffset + nRepMatchLenForArrival[j], pInWindow + i - nMatchOffset + nRepMatchLenForArrival[j], k - nRepMatchLenForArrival[j])) {
nRepMatchLenForArrival[j] = k;
if (i >= nRepOffset && nMaxRepLen >= k) {
/* A match is possible at the rep offset; insert the extra coding choice. */
nPrevCost = arrival[(i << MATCHES_PER_OFFSET_SHIFT) + j].cost;
nCodingChoiceCost = nPrevCost + 8 /* token */ /* the actual cost of the literals themselves accumulates up the chain */ + /* rep match - no offset cost */ nMatchLenCost;
exists = 0;
@ -334,9 +336,11 @@ static void lzsa_optimize_forward_v2(lzsa_compressor *pCompressor, const unsigne
if (pDestArrival->from_slot == 0 ||
nCodingChoiceCost <= pDestArrival->cost) {
memmove(&pDestSlots[n + 1],
&pDestSlots[n],
sizeof(lzsa_arrival) * (NMATCHES_PER_OFFSET - n - 1));
if (pDestArrival->from_slot) {
memmove(&pDestSlots[n + 1],
&pDestSlots[n],
sizeof(lzsa_arrival) * (NMATCHES_PER_OFFSET - n - 1));
}
pDestArrival->cost = nCodingChoiceCost;
pDestArrival->from_pos = i;
@ -674,7 +678,6 @@ static int lzsa_optimize_command_count_v2(lzsa_compressor *pCompressor, const un
}
if (pMatch->length < 9 /* Don't waste time considering large matches, they will always win over literals */) {
/* Calculate this command's current cost (excluding 'nNumLiterals' bytes) */
int nCurCommandSize = 8 /* token */ + lzsa_get_literals_varlen_size_v2(nNumLiterals) + lzsa_get_match_varlen_size_v2(pMatch->length - MIN_MATCH_SIZE_V2);