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Faster LZSA1 compression

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Emmanuel Marty 2023-02-02 11:11:14 +01:00 committed by GitHub
parent 583e4db62e
commit 82f03b55e3
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1 changed files with 29 additions and 38 deletions
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67
src/shrink_block_v1.c
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@ -219,23 +219,23 @@ static void lzsa_optimize_forward_v1(lzsa_compressor *pCompressor, const int nSt
const lzsa_match *match = pCompressor->match + ((i - nStartOffset) << MATCHES_PER_INDEX_SHIFT_V1);
const int nNumArrivalsForThisPos = j;
for (m = 0; m < NMATCHES_PER_INDEX_V1 && match[m].length; m++) {
int nMatchLen = match[m].length;
const int nMatchOffsetCost = lzsa_get_offset_cost_v1(match[m].offset);
int nStartingMatchLen, k;
if (nNumArrivalsForThisPos != 0) {
for (m = 0; m < NMATCHES_PER_INDEX_V1 && match[m].length; m++) {
int nMatchLen = match[m].length;
const int nMatchOffsetCost = lzsa_get_offset_cost_v1(match[m].offset);
int nStartingMatchLen, k;
if ((i + nMatchLen) > nEndOffset)
nMatchLen = nEndOffset - i;
if ((i + nMatchLen) > nEndOffset)
nMatchLen = nEndOffset - i;
if (nMatchLen >= LEAVE_ALONE_MATCH_SIZE)
nStartingMatchLen = nMatchLen;
else
nStartingMatchLen = nMinMatchSize;
for (k = nStartingMatchLen; k <= nMatchLen; k++) {
const int nMatchLenCost = lzsa_get_match_varlen_size_v1(k - MIN_MATCH_SIZE_V1);
if (nMatchLen >= LEAVE_ALONE_MATCH_SIZE)
nStartingMatchLen = nMatchLen;
else
nStartingMatchLen = nMinMatchSize;
for (k = nStartingMatchLen; k <= nMatchLen; k++) {
const int nMatchLenCost = lzsa_get_match_varlen_size_v1(k - MIN_MATCH_SIZE_V1);
if (nNumArrivalsForThisPos != 0) {
lzsa_arrival *pDestSlots = &arrival[(i + k) << ARRIVALS_PER_POSITION_SHIFT_V1];
lzsa_arrival* pDestSlots = &cur_arrival[k << ARRIVALS_PER_POSITION_SHIFT_V1];
int nCodingChoiceCost = cur_arrival[0].cost + 8 /* token */ /* the actual cost of the literals themselves accumulates up the chain */ + nMatchOffsetCost + nMatchLenCost;
int exists = 0, n;
@ -253,31 +253,22 @@ static void lzsa_optimize_forward_v1(lzsa_compressor *pCompressor, const int nSt
if (!exists) {
const int nScore = cur_arrival[0].score + 5;
int nNonRepMatchIdx = -1;
for (n = 0; n < NARRIVALS_PER_POSITION_V1 /* we only need the literals + short match cost + long match cost cases */; n++) {
if (nCodingChoiceCost < pDestSlots[n].cost ||
(nCodingChoiceCost == pDestSlots[n].cost && nScore < (pDestSlots[n].score + nDisableScore))) {
nNonRepMatchIdx = n;
break;
}
if (nCodingChoiceCost < pDestSlots[0].cost ||
(nCodingChoiceCost == pDestSlots[0].cost && nScore < (pDestSlots[0].score + nDisableScore))) {
memmove(&pDestSlots[1],
&pDestSlots[0],
sizeof(lzsa_arrival) * (NARRIVALS_PER_POSITION_V1 - 1));
pDestSlots->cost = nCodingChoiceCost;
pDestSlots->rep_offset = match[m].offset;
pDestSlots->from_slot = 1;
pDestSlots->from_pos = i - nStartOffset;
pDestSlots->match_len = k;
pDestSlots->num_literals = 0;
pDestSlots->score = nScore;
}
if (nNonRepMatchIdx >= 0) {
memmove(&pDestSlots[nNonRepMatchIdx + 1],
&pDestSlots[nNonRepMatchIdx],
sizeof(lzsa_arrival) * (NARRIVALS_PER_POSITION_V1 - nNonRepMatchIdx - 1));
lzsa_arrival* pDestArrival = &pDestSlots[nNonRepMatchIdx];
pDestArrival->cost = nCodingChoiceCost;
pDestArrival->rep_offset = match[m].offset;
pDestArrival->from_slot = 1;
pDestArrival->from_pos = i - nStartOffset;
pDestArrival->match_len = k;
pDestArrival->num_literals = 0;
pDestArrival->score = nScore;
}
}
}
}
}
}
@ -375,7 +366,7 @@ static int lzsa_optimize_command_count_v1(lzsa_compressor *pCompressor, const un
pBestMatch[i + pMatch->length].length)) {
int nCurPartialSize = lzsa_get_match_varlen_size_v1(pMatch->length - MIN_MATCH_SIZE_V1);
nCurPartialSize += 8 /* token */ + lzsa_get_literals_varlen_size_v1(0) + ((pBestMatch[i + pMatch->length].offset <= 256) ? 8 : 16) /* match offset */ + lzsa_get_match_varlen_size_v1(pBestMatch[i + pMatch->length].length - MIN_MATCH_SIZE_V1);
nCurPartialSize += 8 /* token */ + /* lzsa_get_literals_varlen_size_v1(0) + */ ((pBestMatch[i + pMatch->length].offset <= 256) ? 8 : 16) /* match offset */ + lzsa_get_match_varlen_size_v1(pBestMatch[i + pMatch->length].length - MIN_MATCH_SIZE_V1);
const int nReducedPartialSize = lzsa_get_match_varlen_size_v1(pMatch->length + pBestMatch[i + pMatch->length].length - MIN_MATCH_SIZE_V1);