diff --git a/src/shrink_block_v2.c b/src/shrink_block_v2.c
index 96452c4..4d2ff7d 100644
--- a/src/shrink_block_v2.c
+++ b/src/shrink_block_v2.c
@@ -183,12 +183,12 @@ static inline int lzsa_write_match_varlen_v2(unsigned char *pOutData, int nOutOf
* @param nStartOffset current offset in input window (typically the number of previously compressed bytes)
* @param nEndOffset offset to end finding matches at (typically the size of the total input window in bytes
*/
-static void lzsa_optimize_forward_v2(lzsa_compressor *pCompressor, const unsigned char *pInWindow, const int nStartOffset, const int nEndOffset) {
+static void lzsa_optimize_forward_v2(lzsa_compressor *pCompressor, const unsigned char *pInWindow, lzsa_match *pBestMatch, const int nStartOffset, const int nEndOffset, const int nReduce) {
lzsa_arrival *arrival = pCompressor->arrival;
const int nFavorRatio = (pCompressor->flags & LZSA_FLAG_FAVOR_RATIO) ? 1 : 0;
const int nMinMatchSize = pCompressor->min_match_size;
+ const int nDisableScore = nReduce ? 0 : (2 * BLOCK_SIZE);
int i, j, n;
- lzsa_match match[32];
memset(arrival + (nStartOffset << MATCHES_PER_OFFSET_SHIFT), 0, sizeof(lzsa_arrival) * ((nEndOffset - nStartOffset) << MATCHES_PER_OFFSET_SHIFT));
@@ -199,7 +199,7 @@ static void lzsa_optimize_forward_v2(lzsa_compressor *pCompressor, const unsigne
arrival[nStartOffset << MATCHES_PER_OFFSET_SHIFT].from_slot = -1;
for (i = nStartOffset; i != (nEndOffset - 1); i++) {
- int m, nMatches;
+ int m;
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 & 0x3fffffff;
@@ -232,9 +232,11 @@ static void lzsa_optimize_forward_v2(lzsa_compressor *pCompressor, const unsigne
}
if (!exists) {
+ int nScore = arrival[(i << MATCHES_PER_OFFSET_SHIFT) + j].score + 1;
for (n = 0; n < NMATCHES_PER_OFFSET; n++) {
lzsa_arrival *pDestArrival = &pDestSlots[n];
- if (nCodingChoiceCost <= pDestArrival->cost) {
+ if (nCodingChoiceCost < pDestArrival->cost ||
+ (nCodingChoiceCost == pDestArrival->cost && nScore < (pDestArrival->score + nDisableScore))) {
if (pDestArrival->from_slot) {
memmove(&pDestSlots[n + 1],
@@ -248,6 +250,7 @@ static void lzsa_optimize_forward_v2(lzsa_compressor *pCompressor, const unsigne
pDestArrival->match_offset = 0;
pDestArrival->match_len = 0;
pDestArrival->num_literals = nNumLiterals;
+ pDestArrival->score = nScore;
pDestArrival->rep_offset = arrival[(i << MATCHES_PER_OFFSET_SHIFT) + j].rep_offset;
break;
}
@@ -256,9 +259,9 @@ static void lzsa_optimize_forward_v2(lzsa_compressor *pCompressor, const unsigne
}
}
- nMatches = lzsa_find_matches_at(pCompressor, i, match, 32);
+ lzsa_match *match = pCompressor->match + (i << 5);
- for (m = 0; m < nMatches; m++) {
+ for (m = 0; m < 32 && match[m].length; m++) {
int nMatchLen = match[m].length;
int nMatchOffset = match[m].offset;
int nNoRepmatchOffsetCost = (nMatchOffset <= 32) ? 4 : ((nMatchOffset <= 512) ? 8 : ((nMatchOffset <= (8192 + 512)) ? 12 : 16));
@@ -319,10 +322,13 @@ static void lzsa_optimize_forward_v2(lzsa_compressor *pCompressor, const unsigne
}
if (!exists) {
+ int nScore = arrival[(i << MATCHES_PER_OFFSET_SHIFT) + j].score + ((nMatchOffset == nRepOffset) ? 2 : 3);
+
for (n = 0; n < NMATCHES_PER_OFFSET; n++) {
lzsa_arrival *pDestArrival = &pDestSlots[n];
- if (nCodingChoiceCost <= pDestArrival->cost) {
+ if (nCodingChoiceCost < pDestArrival->cost ||
+ (nCodingChoiceCost == pDestArrival->cost && nScore < (pDestArrival->score + nDisableScore))) {
if (pDestArrival->from_slot) {
memmove(&pDestSlots[n + 1],
&pDestSlots[n],
@@ -335,6 +341,7 @@ static void lzsa_optimize_forward_v2(lzsa_compressor *pCompressor, const unsigne
pDestArrival->match_offset = nMatchOffset;
pDestArrival->match_len = k;
pDestArrival->num_literals = 0;
+ pDestArrival->score = nScore;
pDestArrival->rep_offset = nMatchOffset;
break;
}
@@ -361,10 +368,13 @@ static void lzsa_optimize_forward_v2(lzsa_compressor *pCompressor, const unsigne
}
if (!exists) {
+ int nScore = arrival[(i << MATCHES_PER_OFFSET_SHIFT) + j].score + 2;
+
for (n = 0; n < NMATCHES_PER_OFFSET; n++) {
lzsa_arrival *pDestArrival = &pDestSlots[n];
- if (nRepCodingChoiceCost <= pDestArrival->cost) {
+ if (nRepCodingChoiceCost < pDestArrival->cost ||
+ (nRepCodingChoiceCost == pDestArrival->cost && nScore < (pDestArrival->score + nDisableScore))) {
if (pDestArrival->from_slot) {
memmove(&pDestSlots[n + 1],
&pDestSlots[n],
@@ -377,6 +387,7 @@ static void lzsa_optimize_forward_v2(lzsa_compressor *pCompressor, const unsigne
pDestArrival->match_offset = nRepOffset;
pDestArrival->match_len = k;
pDestArrival->num_literals = 0;
+ pDestArrival->score = nScore;
pDestArrival->rep_offset = nRepOffset;
break;
}
@@ -390,12 +401,12 @@ static void lzsa_optimize_forward_v2(lzsa_compressor *pCompressor, const unsigne
}
lzsa_arrival *end_arrival = &arrival[(i << MATCHES_PER_OFFSET_SHIFT) + 0];
- pCompressor->best_match[i].length = 0;
- pCompressor->best_match[i].offset = 0;
+ pBestMatch[i].length = 0;
+ pBestMatch[i].offset = 0;
while (end_arrival->from_slot > 0 && end_arrival->from_pos >= 0) {
- pCompressor->best_match[end_arrival->from_pos].length = end_arrival->match_len;
- pCompressor->best_match[end_arrival->from_pos].offset = end_arrival->match_offset;
+ pBestMatch[end_arrival->from_pos].length = end_arrival->match_len;
+ pBestMatch[end_arrival->from_pos].offset = end_arrival->match_offset;
end_arrival = &arrival[(end_arrival->from_pos << MATCHES_PER_OFFSET_SHIFT) + (end_arrival->from_slot - 1)];
}
}
@@ -568,6 +579,78 @@ static int lzsa_optimize_command_count_v2(lzsa_compressor *pCompressor, const un
return nDidReduce;
}
+/**
+ * Get compressed data block size
+ *
+ * @param pCompressor compression context
+ * @param pBestMatch optimal matches to emit
+ * @param nStartOffset current offset in input window (typically the number of previously compressed bytes)
+ * @param nEndOffset offset to end finding matches at (typically the size of the total input window in bytes
+ *
+ * @return size of compressed data that will be written to output buffer
+ */
+static int lzsa_get_compressed_size_v2(lzsa_compressor *pCompressor, lzsa_match *pBestMatch, const int nStartOffset, const int nEndOffset) {
+ int i;
+ int nNumLiterals = 0;
+ int nOutOffset = 0;
+ int nRepMatchOffset = 0;
+ int nCompressedSize = 0;
+
+ for (i = nStartOffset; i < nEndOffset; ) {
+ const lzsa_match *pMatch = pBestMatch + i;
+
+ if (pMatch->length >= MIN_MATCH_SIZE_V2) {
+ int nMatchOffset = pMatch->offset;
+ int nMatchLen = pMatch->length;
+ int nEncodedMatchLen = nMatchLen - MIN_MATCH_SIZE_V2;
+ int nOffsetSize;
+
+ if (nMatchOffset == nRepMatchOffset) {
+ nOffsetSize = 0;
+ }
+ else {
+ if (nMatchOffset <= 32) {
+ nOffsetSize = 4;
+ }
+ else if (nMatchOffset <= 512) {
+ nOffsetSize = 8;
+ }
+ else if (nMatchOffset <= (8192 + 512)) {
+ nOffsetSize = 12;
+ }
+ else {
+ nOffsetSize = 16;
+ }
+ }
+
+ int nCommandSize = 8 /* token */ + lzsa_get_literals_varlen_size_v2(nNumLiterals) + (nNumLiterals << 3) + nOffsetSize /* match offset */ + lzsa_get_match_varlen_size_v2(nEncodedMatchLen);
+ nCompressedSize += nCommandSize;
+
+ nNumLiterals = 0;
+ nRepMatchOffset = nMatchOffset;
+ i += nMatchLen;
+ }
+ else {
+ nNumLiterals++;
+ i++;
+ }
+ }
+
+ {
+ int nTokenLiteralsLen = (nNumLiterals >= LITERALS_RUN_LEN_V2) ? LITERALS_RUN_LEN_V2 : nNumLiterals;
+ int nCommandSize = 8 /* token */ + lzsa_get_literals_varlen_size_v2(nNumLiterals) + (nNumLiterals << 3);
+
+ nCompressedSize += nCommandSize;
+ nNumLiterals = 0;
+ }
+
+ if (pCompressor->flags & LZSA_FLAG_RAW_BLOCK) {
+ nCompressedSize += (8 + 4 + 8);
+ }
+
+ return nCompressedSize;
+}
+
/**
* Emit block of compressed data
*
@@ -852,9 +935,21 @@ static int lzsa_write_raw_uncompressed_block_v2(lzsa_compressor *pCompressor, co
* @return size of compressed data in output buffer, or -1 if the data is uncompressible
*/
int lzsa_optimize_and_write_block_v2(lzsa_compressor *pCompressor, const unsigned char *pInWindow, const int nPreviousBlockSize, const int nInDataSize, unsigned char *pOutData, const int nMaxOutDataSize) {
- int nResult;
+ int i, nResult, nBaseCompressedSize;
- lzsa_optimize_forward_v2(pCompressor, pInWindow, nPreviousBlockSize, nPreviousBlockSize + nInDataSize);
+ /* Find matches */
+ for (i = nPreviousBlockSize; i != (nPreviousBlockSize + nInDataSize - 1); i++) {
+ int nMatches = lzsa_find_matches_at(pCompressor, i, pCompressor->match + (i << 5), 32);
+ while (nMatches < 32) {
+ pCompressor->match[(i << 5) + nMatches].offset = 0;
+ pCompressor->match[(i << 5) + nMatches].length = 0;
+ nMatches++;
+ }
+ }
+
+ /* Compress optimally without breaking ties in favor of less tokens */
+
+ lzsa_optimize_forward_v2(pCompressor, pInWindow, pCompressor->best_match, nPreviousBlockSize, nPreviousBlockSize + nInDataSize, 0 /* reduce */);
int nDidReduce;
int nPasses = 0;
@@ -863,7 +958,29 @@ int lzsa_optimize_and_write_block_v2(lzsa_compressor *pCompressor, const unsigne
nPasses++;
} while (nDidReduce && nPasses < 20);
- nResult = lzsa_write_block_v2(pCompressor, pCompressor->best_match, pInWindow, nPreviousBlockSize, nPreviousBlockSize + nInDataSize, pOutData, nMaxOutDataSize);
+ nBaseCompressedSize = lzsa_get_compressed_size_v2(pCompressor, pCompressor->best_match, nPreviousBlockSize, nPreviousBlockSize + nInDataSize);
+ lzsa_match *pBestMatch = pCompressor->best_match;
+
+ if (nBaseCompressedSize > 0 && nInDataSize < 65536) {
+ int nReducedCompressedSize;
+
+ /* Compress optimally and do break ties in favor of less tokens */
+ lzsa_optimize_forward_v2(pCompressor, pInWindow, pCompressor->improved_match, nPreviousBlockSize, nPreviousBlockSize + nInDataSize, 1 /* reduce */);
+
+ nPasses = 0;
+ do {
+ nDidReduce = lzsa_optimize_command_count_v2(pCompressor, pInWindow, pCompressor->improved_match, nPreviousBlockSize, nPreviousBlockSize + nInDataSize);
+ nPasses++;
+ } while (nDidReduce && nPasses < 20);
+
+ nReducedCompressedSize = lzsa_get_compressed_size_v2(pCompressor, pCompressor->improved_match, nPreviousBlockSize, nPreviousBlockSize + nInDataSize);
+ if (nReducedCompressedSize > 0 && nReducedCompressedSize <= nBaseCompressedSize) {
+ /* Pick the parse with the reduced number of tokens as it didn't negatively affect the size */
+ pBestMatch = pCompressor->improved_match;
+ }
+ }
+
+ nResult = lzsa_write_block_v2(pCompressor, pBestMatch, pInWindow, nPreviousBlockSize, nPreviousBlockSize + nInDataSize, pOutData, nMaxOutDataSize);
if (nResult < 0 && pCompressor->flags & LZSA_FLAG_RAW_BLOCK) {
nResult = lzsa_write_raw_uncompressed_block_v2(pCompressor, pInWindow, nPreviousBlockSize, nPreviousBlockSize + nInDataSize, pOutData, nMaxOutDataSize);
}
diff --git a/src/shrink_context.c b/src/shrink_context.c
index f3ec444..74a7a16 100644
--- a/src/shrink_context.c
+++ b/src/shrink_context.c
@@ -58,7 +58,9 @@ int lzsa_compressor_init(lzsa_compressor *pCompressor, const int nMaxWindowSize,
pCompressor->intervals = NULL;
pCompressor->pos_data = NULL;
pCompressor->open_intervals = NULL;
+ pCompressor->match = NULL;
pCompressor->best_match = NULL;
+ pCompressor->improved_match = NULL;
pCompressor->arrival = NULL;
pCompressor->min_match_size = nMinMatchSize;
if (pCompressor->min_match_size < nMinMatchSizeForFormat)
@@ -93,7 +95,18 @@ int lzsa_compressor_init(lzsa_compressor *pCompressor, const int nMaxWindowSize,
pCompressor->best_match = (lzsa_match *)malloc(nMaxWindowSize * sizeof(lzsa_match));
if (pCompressor->best_match) {
- return 0;
+ if (pCompressor->format_version == 2) {
+ pCompressor->improved_match = (lzsa_match *)malloc(nMaxWindowSize * sizeof(lzsa_match));
+
+ if (pCompressor->improved_match) {
+ pCompressor->match = (lzsa_match *)malloc(nMaxWindowSize * 32 * sizeof(lzsa_match));
+ if (pCompressor->match)
+ return 0;
+ }
+ }
+ else {
+ return 0;
+ }
}
}
}
@@ -113,6 +126,16 @@ int lzsa_compressor_init(lzsa_compressor *pCompressor, const int nMaxWindowSize,
void lzsa_compressor_destroy(lzsa_compressor *pCompressor) {
divsufsort_destroy(&pCompressor->divsufsort_context);
+ if (pCompressor->match) {
+ free(pCompressor->match);
+ pCompressor->match = NULL;
+ }
+
+ if (pCompressor->improved_match) {
+ free(pCompressor->improved_match);
+ pCompressor->improved_match = NULL;
+ }
+
if (pCompressor->arrival) {
free(pCompressor->arrival);
pCompressor->arrival = NULL;
diff --git a/src/shrink_context.h b/src/shrink_context.h
index fd8176b..8e51822 100644
--- a/src/shrink_context.h
+++ b/src/shrink_context.h
@@ -74,6 +74,7 @@ typedef struct {
unsigned short rep_offset;
int num_literals;
+ int score;
unsigned short match_offset;
unsigned short match_len;
@@ -114,7 +115,9 @@ typedef struct _lzsa_compressor {
unsigned int *intervals;
unsigned int *pos_data;
unsigned int *open_intervals;
+ lzsa_match *match;
lzsa_match *best_match;
+ lzsa_match *improved_match;
lzsa_arrival *arrival;
int min_match_size;
int format_version;