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Clarify optimizer

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This commit is contained in:
emmanuel-marty 2019-05-11 11:42:18 +02:00
parent d70830b525
commit 3caa72c722
3 changed files with 7 additions and 8 deletions
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2
src/format.h
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@ -36,6 +36,8 @@
#define MIN_OFFSET 1 #define MIN_OFFSET 1
#define MAX_OFFSET 0xffff #define MAX_OFFSET 0xffff
#define MAX_VARLEN 0xffff
#define MIN_MATCH_SIZE_V1 3 #define MIN_MATCH_SIZE_V1 3
#define LITERALS_RUN_LEN_V1 7 #define LITERALS_RUN_LEN_V1 7
#define MATCH_RUN_LEN_V1 15 #define MATCH_RUN_LEN_V1 15

2
src/shrink_v1.c
View File

@ -314,7 +314,7 @@ static int lzsa_optimize_command_count_v1(lsza_compressor *pCompressor, const in
else { else {
if ((i + nMatchLen) < nEndOffset && nMatchLen >= LCP_MAX && if ((i + nMatchLen) < nEndOffset && nMatchLen >= LCP_MAX &&
pMatch->offset && pMatch->offset <= 32 && pCompressor->match[(i + nMatchLen) << MATCHES_PER_OFFSET_SHIFT].offset == pMatch->offset && (nMatchLen % pMatch->offset) == 0 && pMatch->offset && pMatch->offset <= 32 && pCompressor->match[(i + nMatchLen) << MATCHES_PER_OFFSET_SHIFT].offset == pMatch->offset && (nMatchLen % pMatch->offset) == 0 &&
(nMatchLen + pCompressor->match[(i + nMatchLen) << MATCHES_PER_OFFSET_SHIFT].length) <= MAX_OFFSET) { (nMatchLen + pCompressor->match[(i + nMatchLen) << MATCHES_PER_OFFSET_SHIFT].length) <= MAX_VARLEN) {
/* Join */ /* Join */
pMatch->length += pCompressor->match[(i + nMatchLen) << MATCHES_PER_OFFSET_SHIFT].length; pMatch->length += pCompressor->match[(i + nMatchLen) << MATCHES_PER_OFFSET_SHIFT].length;

11
src/shrink_v2.c
View File

@ -208,19 +208,16 @@ static void lzsa_optimize_matches_v2(lsza_compressor *pCompressor, const int nSt
int nLiteralsLen = nLastLiteralsOffset - i; int nLiteralsLen = nLastLiteralsOffset - i;
nLiteralsCost = 8 + cost[i + 1]; nLiteralsCost = 8 + cost[i + 1];
/* Add to the cost of encoding literals as their number crosses a variable length encoding boundary.
* The cost automatically accumulates down the chain. */
if (nLiteralsLen == LITERALS_RUN_LEN_V2) { if (nLiteralsLen == LITERALS_RUN_LEN_V2) {
/* Add to the cost of encoding literals as their number crosses a variable length encoding boundary.
* The cost automatically accumulates down the chain. */
nLiteralsCost += 4; nLiteralsCost += 4;
} }
else if (nLiteralsLen == (LITERALS_RUN_LEN_V2 + 15)) { else if (nLiteralsLen == (LITERALS_RUN_LEN_V2 + 15)) {
/* Add to the cost of encoding literals as their number crosses a variable length encoding boundary.
* The cost automatically accumulates down the chain. */
nLiteralsCost += 8; nLiteralsCost += 8;
} }
else if (nLiteralsLen == 256) { else if (nLiteralsLen == 256) {
/* Add to the cost of encoding literals as their number crosses a variable length encoding boundary.
* The cost automatically accumulates down the chain. */
nLiteralsCost += 16; nLiteralsCost += 16;
} }
if (pCompressor->best_match[i + 1].length >= MIN_MATCH_SIZE_V2) if (pCompressor->best_match[i + 1].length >= MIN_MATCH_SIZE_V2)
@ -527,7 +524,7 @@ static int lzsa_optimize_command_count_v2(lsza_compressor *pCompressor, const in
else { else {
if ((i + nMatchLen) < nEndOffset && nMatchLen >= LCP_MAX && if ((i + nMatchLen) < nEndOffset && nMatchLen >= LCP_MAX &&
pMatch->offset && pMatch->offset <= 32 && pCompressor->best_match[i + nMatchLen].offset == pMatch->offset && (nMatchLen % pMatch->offset) == 0 && 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_OFFSET) { (nMatchLen + pCompressor->best_match[i + nMatchLen].length) <= MAX_VARLEN) {
/* Join */ /* Join */
pMatch->length += pCompressor->best_match[i + nMatchLen].length; pMatch->length += pCompressor->best_match[i + nMatchLen].length;