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Small LZSA2 compression speedup

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Emmanuel Marty 2020-11-02 15:24:08 +01:00 committed by GitHub
parent 34715950fd
commit fc927c783c
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GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 15 additions and 17 deletions
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src/shrink_block_v2.c
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@ -389,19 +389,19 @@ static void lzsa_optimize_forward_v2(lzsa_compressor *pCompressor, const unsigne
int nRepLenForArrival[NARRIVALS_PER_POSITION_V2_BIG];
memset(nRepLenForArrival, 0, nArrivalsPerPosition * sizeof(int));
for (j = 0; j < nNumArrivalsForThisPos; j++) {
int nMaxRepLenForPos = nEndOffset - i;
if (nMaxRepLenForPos > LCP_MAX)
nMaxRepLenForPos = LCP_MAX;
const unsigned char* pInWindowStart = pInWindow + i;
const unsigned char* pInWindowMax = pInWindowStart + nMaxRepLenForPos;
for (j = 0; j < nNumArrivalsForThisPos && (i + MIN_MATCH_SIZE_V2) <= nEndOffset; j++) {
int nRepOffset = cur_arrival[j].rep_offset;
if (nRepOffset) {
if (i > nRepOffset &&
(i + MIN_MATCH_SIZE_V2) <= nEndOffset) {
if (i > nRepOffset) {
if (pInWindow[i] == pInWindow[i - nRepOffset]) {
int nMaxRepLenForPos = nEndOffset - i;
if (nMaxRepLenForPos > LCP_MAX)
nMaxRepLenForPos = LCP_MAX;
const unsigned char* pInWindowAtPos = pInWindow + i;
const unsigned char* pInWindowMax = pInWindow + i + nMaxRepLenForPos;
const unsigned char* pInWindowAtPos;
int nLen0 = rle_end[i - nRepOffset] - (i - nRepOffset);
int nLen1 = rle_end[i] - (i);
@ -409,7 +409,7 @@ static void lzsa_optimize_forward_v2(lzsa_compressor *pCompressor, const unsigne
if (nMinLen > nMaxRepLenForPos)
nMinLen = nMaxRepLenForPos;
pInWindowAtPos += nMinLen;
pInWindowAtPos = pInWindowStart + nMinLen;
while ((pInWindowAtPos + 8) < pInWindowMax && !memcmp(pInWindowAtPos - nRepOffset, pInWindowAtPos, 8))
pInWindowAtPos += 8;
@ -417,7 +417,7 @@ static void lzsa_optimize_forward_v2(lzsa_compressor *pCompressor, const unsigne
pInWindowAtPos += 4;
while (pInWindowAtPos < pInWindowMax && pInWindowAtPos[-nRepOffset] == pInWindowAtPos[0])
pInWindowAtPos++;
nRepLenForArrival[j] = (int)(pInWindowAtPos - (pInWindow + i));
nRepLenForArrival[j] = (int)(pInWindowAtPos - pInWindowStart);
if (nMaxOverallRepLen < nRepLenForArrival[j])
nMaxOverallRepLen = nRepLenForArrival[j];
@ -482,15 +482,13 @@ static void lzsa_optimize_forward_v2(lzsa_compressor *pCompressor, const unsigne
if (nNonRepMatchArrivalIdx >= 0) {
int nRepOffset = cur_arrival[nNonRepMatchArrivalIdx].rep_offset;
j = nNonRepMatchArrivalIdx;
const int nPrevCost = cur_arrival[j].cost & 0x3fffffff;
const int nPrevCost = cur_arrival[nNonRepMatchArrivalIdx].cost & 0x3fffffff;
int nCodingChoiceCost = nPrevCost /* the actual cost of the literals themselves accumulates up the chain */ + nMatchLenCost + nNoRepmatchOffsetCost;
if (!cur_arrival[j].num_literals)
if (!cur_arrival[nNonRepMatchArrivalIdx].num_literals)
nCodingChoiceCost += nModeSwitchPenalty;
int nScore = cur_arrival[j].score + nScorePenalty;
int nScore = cur_arrival[nNonRepMatchArrivalIdx].score + nScorePenalty;
if (nCodingChoiceCost < pDestSlots[nArrivalsPerPosition - 2].cost ||
(nCodingChoiceCost == pDestSlots[nArrivalsPerPosition - 2].cost && nScore < (pDestSlots[nArrivalsPerPosition - 2].score + nDisableScore))) {
int exists = 0;
@ -547,7 +545,7 @@ static void lzsa_optimize_forward_v2(lzsa_compressor *pCompressor, const unsigne
lzsa_arrival* pDestArrival = &pDestSlots[n];
pDestArrival->cost = nCodingChoiceCost;
pDestArrival->from_pos = i;
pDestArrival->from_slot = j + 1;
pDestArrival->from_slot = nNonRepMatchArrivalIdx + 1;
pDestArrival->match_len = k;
pDestArrival->num_literals = 0;
pDestArrival->score = nScore;