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lzsa/src/shrink_v2.c

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/*
* shrink_v2.c - LZSA2 block compressor implementation
*
* Copyright (C) 2019 Emmanuel Marty
*
* This software is provided 'as-is', without any express or implied
* warranty. In no event will the authors be held liable for any damages
* arising from the use of this software.
*
* Permission is granted to anyone to use this software for any purpose,
* including commercial applications, and to alter it and redistribute it
* freely, subject to the following restrictions:
*
* 1. The origin of this software must not be misrepresented; you must not
* claim that you wrote the original software. If you use this software
* in a product, an acknowledgment in the product documentation would be
* appreciated but is not required.
* 2. Altered source versions must be plainly marked as such, and must not be
* misrepresented as being the original software.
* 3. This notice may not be removed or altered from any source distribution.
*/
/*
* Uses the libdivsufsort library Copyright (c) 2003-2008 Yuta Mori
*
* Inspired by LZ4 by Yann Collet. https://github.com/lz4/lz4
* With help, ideas, optimizations and speed measurements by spke <zxintrospec@gmail.com>
* With ideas from Lizard by Przemyslaw Skibinski and Yann Collet. https://github.com/inikep/lizard
* Also with ideas from smallz4 by Stephan Brumme. https://create.stephan-brumme.com/smallz4/
*
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "lib.h"
#include "shrink_v2.h"
#include "format.h"
/**
* Write 4-bit nibble to output (compressed) buffer
*
* @param pOutData pointer to output buffer
* @param nOutOffset current write index into output buffer
* @param nMaxOutDataSize maximum size of output buffer, in bytes
* @param nCurNibbleOffset write index into output buffer, of current byte being filled with nibbles
* @param nCurFreeNibbles current number of free nibbles in byte
* @param nNibbleValue value to write (0..15)
*/
static int lzsa_write_nibble_v2(unsigned char *pOutData, int nOutOffset, const int nMaxOutDataSize, int *nCurNibbleOffset, int *nCurFreeNibbles, int nNibbleValue) {
if (nOutOffset < 0) return -1;
if ((*nCurNibbleOffset) == -1) {
if (nOutOffset >= nMaxOutDataSize) return -1;
(*nCurNibbleOffset) = nOutOffset;
(*nCurFreeNibbles) = 2;
pOutData[nOutOffset++] = 0;
}
pOutData[*nCurNibbleOffset] = (pOutData[*nCurNibbleOffset] << 4) | (nNibbleValue & 0x0f);
(*nCurFreeNibbles)--;
if ((*nCurFreeNibbles) == 0) {
(*nCurNibbleOffset) = -1;
}
return nOutOffset;
}
/**
* Get the number of extra bits required to represent a literals length
*
* @param nLength literals length
*
* @return number of extra bits required
*/
static inline int lzsa_get_literals_varlen_size_v2(const int nLength) {
if (nLength < LITERALS_RUN_LEN_V2) {
return 0;
}
else {
if (nLength < (LITERALS_RUN_LEN_V2 + 15)) {
return 4;
}
else {
if (nLength < 256)
return 4+8;
else {
return 4+24;
}
}
}
}
/**
* Write extra literals length bytes to output (compressed) buffer. The caller must first check that there is enough
* room to write the bytes.
*
* @param pOutData pointer to output buffer
* @param nOutOffset current write index into output buffer
* @param nLength literals length
*/
static inline int lzsa_write_literals_varlen_v2(unsigned char *pOutData, int nOutOffset, const int nMaxOutDataSize, int *nCurNibbleOffset, int *nCurFreeNibbles, int nLength) {
if (nLength >= LITERALS_RUN_LEN_V2) {
if (nLength < (LITERALS_RUN_LEN_V2 + 15)) {
nOutOffset = lzsa_write_nibble_v2(pOutData, nOutOffset, nMaxOutDataSize, nCurNibbleOffset, nCurFreeNibbles, nLength - LITERALS_RUN_LEN_V2);
}
else {
nOutOffset = lzsa_write_nibble_v2(pOutData, nOutOffset, nMaxOutDataSize, nCurNibbleOffset, nCurFreeNibbles, 15);
if (nOutOffset < 0) return -1;
if (nLength < 256)
pOutData[nOutOffset++] = nLength;
else {
pOutData[nOutOffset++] = 0;
pOutData[nOutOffset++] = nLength & 0xff;
pOutData[nOutOffset++] = (nLength >> 8) & 0xff;
}
}
}
return nOutOffset;
}
/**
* Get the number of extra bits required to represent an encoded match length
*
* @param nLength encoded match length (actual match length - MIN_MATCH_SIZE_V2)
*
* @return number of extra bits required
*/
static inline int lzsa_get_match_varlen_size_v2(const int nLength) {
if (nLength < MATCH_RUN_LEN_V2) {
return 0;
}
else {
if (nLength < (MATCH_RUN_LEN_V2 + 15))
return 4;
else {
if ((nLength + MIN_MATCH_SIZE_V2) < 256)
return 4+8;
else {
return 4 + 24;
}
}
}
}
/**
* Write extra encoded match length bytes to output (compressed) buffer. The caller must first check that there is enough
* room to write the bytes.
*
* @param pOutData pointer to output buffer
* @param nOutOffset current write index into output buffer
* @param nLength encoded match length (actual match length - MIN_MATCH_SIZE_V2)
*/
static inline int lzsa_write_match_varlen_v2(unsigned char *pOutData, int nOutOffset, const int nMaxOutDataSize, int *nCurNibbleOffset, int *nCurFreeNibbles, int nLength) {
if (nLength >= MATCH_RUN_LEN_V2) {
if (nLength < (MATCH_RUN_LEN_V2 + 15)) {
nOutOffset = lzsa_write_nibble_v2(pOutData, nOutOffset, nMaxOutDataSize, nCurNibbleOffset, nCurFreeNibbles, nLength - MATCH_RUN_LEN_V2);
}
else {
nOutOffset = lzsa_write_nibble_v2(pOutData, nOutOffset, nMaxOutDataSize, nCurNibbleOffset, nCurFreeNibbles, 15);
if (nOutOffset < 0) return -1;
if ((nLength + MIN_MATCH_SIZE_V2) < 256)
pOutData[nOutOffset++] = nLength + MIN_MATCH_SIZE_V2;
else {
pOutData[nOutOffset++] = 0;
pOutData[nOutOffset++] = (nLength + MIN_MATCH_SIZE_V2) & 0xff;
pOutData[nOutOffset++] = ((nLength + MIN_MATCH_SIZE_V2) >> 8) & 0xff;
}
}
}
return nOutOffset;
}
/**
* Attempt to pick optimal matches, so as to produce the smallest possible output that decompresses to the same input
*
* @param pCompressor compression context
* @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_matches_v2(lsza_compressor *pCompressor, const int nStartOffset, const int nEndOffset) {
int *cost = (int*)pCompressor->pos_data; /* Reuse */
int *prev_match = (int*)pCompressor->intervals; /* Reuse */
lzsa_repmatch_opt *repmatch_opt = pCompressor->repmatch_opt;
lzsa_match *pBestMatch = pCompressor->best_match;
int nLastLiteralsOffset;
int nMinMatchSize = pCompressor->min_match_size;
const int nFavorRatio = (pCompressor->flags & LZSA_FLAG_FAVOR_RATIO) ? 1 : 0;
int i;
cost[nEndOffset - 1] = 8;
prev_match[nEndOffset - 1] = nEndOffset;
nLastLiteralsOffset = nEndOffset;
pCompressor->best_match[nEndOffset - 1].length = 0;
pCompressor->best_match[nEndOffset - 1].offset = 0;
repmatch_opt[nEndOffset - 1].best_slot_for_incoming = -1;
repmatch_opt[nEndOffset - 1].incoming_offset = -1;
repmatch_opt[nEndOffset - 1].expected_repmatch = 0;
for (i = nEndOffset - 2; i != (nStartOffset - 1); i--) {
int nLiteralsCost;
int nLiteralsLen = nLastLiteralsOffset - i;
nLiteralsCost = 8 + cost[i + 1];
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;
}
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;
}
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;
}
if (pCompressor->best_match[i + 1].length >= MIN_MATCH_SIZE_V2)
nLiteralsCost += MODESWITCH_PENALTY;
lzsa_match *pMatch = pCompressor->match + (i << MATCHES_PER_OFFSET_SHIFT);
int *pSlotCost = pCompressor->slot_cost + (i << MATCHES_PER_OFFSET_SHIFT);
int m;
cost[i] = nLiteralsCost;
pCompressor->best_match[i].length = 0;
pCompressor->best_match[i].offset = 0;
repmatch_opt[i].best_slot_for_incoming = -1;
repmatch_opt[i].incoming_offset = -1;
repmatch_opt[i].expected_repmatch = 0;
for (m = 0; m < NMATCHES_PER_OFFSET && pMatch[m].length >= nMinMatchSize; m++) {
int nBestCost, nBestMatchLen, nBestMatchOffset, nBestUpdatedSlot, nBestUpdatedIndex, nBestExpectedRepMatch;
nBestCost = nLiteralsCost;
nBestMatchLen = 0;
nBestMatchOffset = 0;
nBestUpdatedSlot = -1;
nBestUpdatedIndex = -1;
nBestExpectedRepMatch = 0;
if (pMatch[m].length >= LEAVE_ALONE_MATCH_SIZE) {
int nCurCost;
int nMatchLen = pMatch[m].length;
if ((i + nMatchLen) > (nEndOffset - LAST_LITERALS))
nMatchLen = nEndOffset - LAST_LITERALS - i;
int nCurIndex = prev_match[i + nMatchLen];
int nMatchOffsetSize = 0;
int nCurExpectedRepMatch = 1;
if (nCurIndex >= nEndOffset || pCompressor->best_match[nCurIndex].length < MIN_MATCH_SIZE_V2 ||
pCompressor->best_match[nCurIndex].offset != pMatch[m].offset) {
nMatchOffsetSize = (pMatch[m].offset <= 32) ? 4 : ((pMatch[m].offset <= 512) ? 8 : ((pMatch[m].offset <= (8192 + 512)) ? 12 : 16));
nCurExpectedRepMatch = 0;
}
nCurCost = 8 + nMatchOffsetSize + lzsa_get_match_varlen_size_v2(nMatchLen - MIN_MATCH_SIZE_V2);
nCurCost += cost[i + nMatchLen];
if (pCompressor->best_match[i + nMatchLen].length >= MIN_MATCH_SIZE_V2)
nCurCost += MODESWITCH_PENALTY;
if (nBestCost > (nCurCost - nFavorRatio)) {
nBestCost = nCurCost;
nBestMatchLen = nMatchLen;
nBestMatchOffset = pMatch[m].offset;
nBestUpdatedSlot = -1;
nBestUpdatedIndex = -1;
nBestExpectedRepMatch = nCurExpectedRepMatch;
}
}
else {
int nMatchLen = pMatch[m].length;
int k, nMatchRunLen;
if ((i + nMatchLen) > (nEndOffset - LAST_LITERALS))
nMatchLen = nEndOffset - LAST_LITERALS - i;
nMatchRunLen = nMatchLen;
if (nMatchRunLen > MATCH_RUN_LEN_V2)
nMatchRunLen = MATCH_RUN_LEN_V2;
for (k = nMinMatchSize; k < nMatchRunLen; k++) {
int nCurCost;
int nCurIndex = prev_match[i + k];
int nMatchOffsetSize = 0;
int nCurExpectedRepMatch = 1;
if (nCurIndex >= nEndOffset || pCompressor->best_match[nCurIndex].length < MIN_MATCH_SIZE_V2 ||
pCompressor->best_match[nCurIndex].offset != pMatch[m].offset) {
nMatchOffsetSize = (pMatch[m].offset <= 32) ? 4 : ((pMatch[m].offset <= 512) ? 8 : ((pMatch[m].offset <= (8192 + 512)) ? 12 : 16));
nCurExpectedRepMatch = 0;
}
nCurCost = 8 + nMatchOffsetSize /* no extra match len bytes */;
nCurCost += cost[i + k];
if (pCompressor->best_match[i + k].length >= MIN_MATCH_SIZE_V2)
nCurCost += MODESWITCH_PENALTY;
int nCurUpdatedSlot = -1;
int nCurUpdatedIndex = -1;
if (nMatchOffsetSize && nCurIndex < nEndOffset && pCompressor->best_match[nCurIndex].length >= MIN_MATCH_SIZE_V2 && !repmatch_opt[nCurIndex].expected_repmatch) {
int r;
for (r = 0; r < NMATCHES_PER_OFFSET && pCompressor->match[(nCurIndex << MATCHES_PER_OFFSET_SHIFT) + r].length >= MIN_MATCH_SIZE_V2; r++) {
if (pCompressor->match[(nCurIndex << MATCHES_PER_OFFSET_SHIFT) + r].offset == pMatch[m].offset) {
int nAltCost = nCurCost - nMatchOffsetSize + pCompressor->slot_cost[(nCurIndex << MATCHES_PER_OFFSET_SHIFT) + r] - cost[nCurIndex];
if (nAltCost <= nCurCost) {
nCurUpdatedSlot = r;
nCurUpdatedIndex = nCurIndex;
nCurCost = nAltCost;
nCurExpectedRepMatch = 2;
}
}
}
}
if (nBestCost > (nCurCost - nFavorRatio)) {
nBestCost = nCurCost;
nBestMatchLen = k;
nBestMatchOffset = pMatch[m].offset;
nBestUpdatedSlot = nCurUpdatedSlot;
nBestUpdatedIndex = nCurUpdatedIndex;
nBestExpectedRepMatch = nCurExpectedRepMatch;
}
}
for (; k <= nMatchLen; k++) {
int nCurCost;
int nCurIndex = prev_match[i + k];
int nMatchOffsetSize = 0;
int nCurExpectedRepMatch = 1;
if (nCurIndex >= nEndOffset || pCompressor->best_match[nCurIndex].length < MIN_MATCH_SIZE_V2 ||
pCompressor->best_match[nCurIndex].offset != pMatch[m].offset) {
nMatchOffsetSize = (pMatch[m].offset <= 32) ? 4 : ((pMatch[m].offset <= 512) ? 8 : ((pMatch[m].offset <= (8192 + 512)) ? 12 : 16));
nCurExpectedRepMatch = 0;
}
nCurCost = 8 + nMatchOffsetSize + lzsa_get_match_varlen_size_v2(k - MIN_MATCH_SIZE_V2);
nCurCost += cost[i + k];
if (pCompressor->best_match[i + k].length >= MIN_MATCH_SIZE_V2)
nCurCost += MODESWITCH_PENALTY;
int nCurUpdatedSlot = -1;
int nCurUpdatedIndex = -1;
if (nMatchOffsetSize && nCurIndex < nEndOffset && pCompressor->best_match[nCurIndex].length >= MIN_MATCH_SIZE_V2 && !repmatch_opt[nCurIndex].expected_repmatch) {
int r;
for (r = 0; r < NMATCHES_PER_OFFSET && pCompressor->match[(nCurIndex << MATCHES_PER_OFFSET_SHIFT) + r].length >= MIN_MATCH_SIZE_V2; r++) {
if (pCompressor->match[(nCurIndex << MATCHES_PER_OFFSET_SHIFT) + r].offset == pMatch[m].offset) {
int nAltCost = nCurCost - nMatchOffsetSize + pCompressor->slot_cost[(nCurIndex << MATCHES_PER_OFFSET_SHIFT) + r] - cost[nCurIndex];
if (nAltCost <= nCurCost) {
nCurUpdatedSlot = r;
nCurUpdatedIndex = nCurIndex;
nCurCost = nAltCost;
nCurExpectedRepMatch = 2;
}
}
}
}
if (nBestCost > (nCurCost - nFavorRatio)) {
nBestCost = nCurCost;
nBestMatchLen = k;
nBestMatchOffset = pMatch[m].offset;
nBestUpdatedSlot = nCurUpdatedSlot;
nBestUpdatedIndex = nCurUpdatedIndex;
nBestExpectedRepMatch = nCurExpectedRepMatch;
}
}
}
pSlotCost[m] = nBestCost;
pMatch[m].length = nBestMatchLen;
pMatch[m].offset = nBestMatchOffset; /* not necessary */
if (m == 0 || (nBestMatchLen && cost[i] >= nBestCost)) {
cost[i] = nBestCost;
pCompressor->best_match[i].length = nBestMatchLen;
pCompressor->best_match[i].offset = nBestMatchOffset;
repmatch_opt[i].expected_repmatch = nBestExpectedRepMatch;
if (nBestUpdatedSlot >= 0 && nBestUpdatedIndex >= 0) {
repmatch_opt[nBestUpdatedIndex].best_slot_for_incoming = nBestUpdatedSlot;
repmatch_opt[nBestUpdatedIndex].incoming_offset = i;
}
}
}
for (; m < NMATCHES_PER_OFFSET; m++) {
pSlotCost[m] = 0;
}
if (pCompressor->best_match[i].length >= MIN_MATCH_SIZE_V2)
nLastLiteralsOffset = i;
prev_match[i] = nLastLiteralsOffset;
}
int nIncomingOffset = -1;
for (i = nStartOffset; i < nEndOffset; ) {
if (pCompressor->best_match[i].length >= MIN_MATCH_SIZE_V2) {
if (nIncomingOffset >= 0 && repmatch_opt[i].incoming_offset == nIncomingOffset && repmatch_opt[i].best_slot_for_incoming >= 0) {
lzsa_match *pMatch = pCompressor->match + (i << MATCHES_PER_OFFSET_SHIFT) + repmatch_opt[i].best_slot_for_incoming;
int *pSlotCost = pCompressor->slot_cost + (i << MATCHES_PER_OFFSET_SHIFT) + repmatch_opt[i].best_slot_for_incoming;
pCompressor->best_match[i].length = pMatch->length;
pCompressor->best_match[i].offset = pMatch->offset;
cost[i] = *pSlotCost;
if (repmatch_opt[i].expected_repmatch == 2)
repmatch_opt[i].expected_repmatch = 1;
}
else {
if (repmatch_opt[i].expected_repmatch == 2)
repmatch_opt[i].expected_repmatch = 0;
}
nIncomingOffset = i;
i += pCompressor->best_match[i].length;
}
else {
i++;
}
}
}
/**
* Attempt to minimize the number of commands issued in the compressed data block, in order to speed up decompression without
* impacting the compression ratio
*
* @param pCompressor compression context
* @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 non-zero if the number of tokens was reduced, 0 if it wasn't
*/
static int lzsa_optimize_command_count_v2(lsza_compressor *pCompressor, const int nStartOffset, const int nEndOffset) {
int i;
int nNumLiterals = 0;
int nDidReduce = 0;
int nPreviousMatchOffset = -1;
lzsa_repmatch_opt *repmatch_opt = pCompressor->repmatch_opt;
for (i = nStartOffset; i < nEndOffset; ) {
lzsa_match *pMatch = pCompressor->best_match + i;
if (pMatch->length >= MIN_MATCH_SIZE_V2) {
int nMatchLen = pMatch->length;
int nReduce = 0;
int nCurrentMatchOffset = i;
if (nMatchLen <= 9 && (i + nMatchLen) < nEndOffset) /* max reducable command size: <token> <EE> <ll> <ll> <offset> <offset> <EE> <mm> <mm> */ {
int nMatchOffset = pMatch->offset;
int nEncodedMatchLen = nMatchLen - MIN_MATCH_SIZE_V2;
int nUndoRepMatchCost = (nPreviousMatchOffset < 0 || !repmatch_opt[nPreviousMatchOffset].expected_repmatch) ? 0 : 16;
if (pCompressor->best_match[i + nMatchLen].length >= MIN_MATCH_SIZE_V2) {
int nCommandSize = 8 /* token */ + lzsa_get_literals_varlen_size_v2(nNumLiterals) + lzsa_get_match_varlen_size_v2(nEncodedMatchLen) - nUndoRepMatchCost;
if (pCompressor->best_match[i + nMatchLen].offset != nMatchOffset) {
nCommandSize += (nMatchOffset <= 32) ? 4 : ((nMatchOffset <= 512) ? 8 : ((nMatchOffset <= (8192 + 512)) ? 12 : 16)) /* match offset */;
}
if (nCommandSize >= ((nMatchLen << 3) + lzsa_get_literals_varlen_size_v2(nNumLiterals + nMatchLen))) {
/* This command is a match; the next command is also a match. The next command currently has no literals; replacing this command by literals will
* make the next command eat the cost of encoding the current number of literals, + nMatchLen extra literals. The size of the current match command is
* at least as much as the number of literal bytes + the extra cost of encoding them in the next match command, so we can safely replace the current
* match command by literals, the output size will not increase and it will remove one command. */
nReduce = 1;
}
}
else {
int nCurIndex = i + nMatchLen;
int nNextNumLiterals = 0;
int nCommandSize = 8 /* token */ + lzsa_get_literals_varlen_size_v2(nNumLiterals) + lzsa_get_match_varlen_size_v2(nEncodedMatchLen) - nUndoRepMatchCost;;
do {
nCurIndex++;
nNextNumLiterals++;
} while (nCurIndex < nEndOffset && pCompressor->best_match[nCurIndex].length < MIN_MATCH_SIZE_V2);
if (nCurIndex >= nEndOffset || pCompressor->best_match[nCurIndex].length < MIN_MATCH_SIZE_V2 ||
pCompressor->best_match[nCurIndex].offset != nMatchOffset) {
nCommandSize += (nMatchOffset <= 32) ? 4 : ((nMatchOffset <= 512) ? 8 : ((nMatchOffset <= (8192 + 512)) ? 12 : 16)) /* match offset */;
}
if (nCommandSize >= ((nMatchLen << 3) + lzsa_get_literals_varlen_size_v2(nNumLiterals + nNextNumLiterals + nMatchLen) - lzsa_get_literals_varlen_size_v2(nNextNumLiterals))) {
/* This command is a match, and is followed by literals, and then another match or the end of the input data. If encoding this match as literals doesn't take
* more room than the match, and doesn't grow the next match command's literals encoding, go ahead and remove the command. */
nReduce = 1;
}
}
}
if (nReduce) {
int j;
for (j = 0; j < nMatchLen; j++) {
pCompressor->best_match[i + j].length = 0;
}
nNumLiterals += nMatchLen;
i += nMatchLen;
nDidReduce = 1;
if (nPreviousMatchOffset >= 0) {
repmatch_opt[nPreviousMatchOffset].expected_repmatch = 0;
nPreviousMatchOffset = -1;
}
}
else {
if ((i + nMatchLen) < nEndOffset && nMatchLen >= LCP_MAX &&
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) {
/* Join */
pMatch->length += pCompressor->best_match[i + nMatchLen].length;
pCompressor->best_match[i + nMatchLen].offset = 0;
pCompressor->best_match[i + nMatchLen].length = -1;
continue;
}
nNumLiterals = 0;
i += nMatchLen;
}
nPreviousMatchOffset = nCurrentMatchOffset;
}
else {
nNumLiterals++;
i++;
}
}
return nDidReduce;
}
/**
* Emit block of compressed data
*
* @param pCompressor compression context
* @param pInWindow pointer to input data window (previously compressed bytes + bytes to compress)
* @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
* @param pOutData pointer to output buffer
* @param nMaxOutDataSize maximum size of output buffer, in bytes
*
* @return size of compressed data in output buffer, or -1 if the data is uncompressible
*/
static int lzsa_write_block_v2(lsza_compressor *pCompressor, const unsigned char *pInWindow, const int nStartOffset, const int nEndOffset, unsigned char *pOutData, const int nMaxOutDataSize) {
int i;
int nNumLiterals = 0;
int nInFirstLiteralOffset = 0;
int nOutOffset = 0;
int nCurNibbleOffset = -1, nCurFreeNibbles = 0;
int nRepMatchOffset = 0;
lzsa_repmatch_opt *repmatch_opt = pCompressor->repmatch_opt;
for (i = nStartOffset; i < nEndOffset; ) {
lzsa_match *pMatch = pCompressor->best_match + i;
if (pMatch->length >= MIN_MATCH_SIZE_V2) {
int nMatchOffset = pMatch->offset;
int nMatchLen = pMatch->length;
int nEncodedMatchLen = nMatchLen - MIN_MATCH_SIZE_V2;
int nTokenLiteralsLen = (nNumLiterals >= LITERALS_RUN_LEN_V2) ? LITERALS_RUN_LEN_V2 : nNumLiterals;
int nTokenMatchLen = (nEncodedMatchLen >= MATCH_RUN_LEN_V2) ? MATCH_RUN_LEN_V2 : nEncodedMatchLen;
int nTokenOffsetMode;
int nOffsetSize;
if (nMatchOffset == nRepMatchOffset) {
nTokenOffsetMode = 0xe0;
nOffsetSize = 0;
}
else {
if (nMatchOffset <= 32) {
nTokenOffsetMode = 0x00 | (((-nMatchOffset) & 0x10) << 1);
nOffsetSize = 4;
}
else if (nMatchOffset <= 512) {
nTokenOffsetMode = 0x40 | (((-nMatchOffset) & 0x100) >> 3);
nOffsetSize = 8;
}
else if (nMatchOffset <= (8192 + 512)) {
nTokenOffsetMode = 0x80 | (((-(nMatchOffset - 512)) & 0x1000) >> 7);
nOffsetSize = 12;
}
else {
nTokenOffsetMode = 0xc0;
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);
if ((nOutOffset + ((nCommandSize + 7) >> 3)) > nMaxOutDataSize)
return -1;
if (nMatchOffset < MIN_OFFSET || nMatchOffset > MAX_OFFSET)
return -1;
pOutData[nOutOffset++] = nTokenOffsetMode | (nTokenLiteralsLen << 3) | nTokenMatchLen;
nOutOffset = lzsa_write_literals_varlen_v2(pOutData, nOutOffset, nMaxOutDataSize, &nCurNibbleOffset, &nCurFreeNibbles, nNumLiterals);
if (nOutOffset < 0) return -1;
if (nNumLiterals != 0) {
memcpy(pOutData + nOutOffset, pInWindow + nInFirstLiteralOffset, nNumLiterals);
nOutOffset += nNumLiterals;
nNumLiterals = 0;
}
if (nTokenOffsetMode == 0x00 || nTokenOffsetMode == 0x20) {
nOutOffset = lzsa_write_nibble_v2(pOutData, nOutOffset, nMaxOutDataSize, &nCurNibbleOffset, &nCurFreeNibbles, (-nMatchOffset) & 0x0f);
if (nOutOffset < 0) return -1;
}
else if (nTokenOffsetMode == 0x40 || nTokenOffsetMode == 0x60) {
pOutData[nOutOffset++] = (-nMatchOffset) & 0xff;
}
else if (nTokenOffsetMode == 0x80 || nTokenOffsetMode == 0xa0) {
pOutData[nOutOffset++] = (-(nMatchOffset - 512)) & 0xff;
nOutOffset = lzsa_write_nibble_v2(pOutData, nOutOffset, nMaxOutDataSize, &nCurNibbleOffset, &nCurFreeNibbles, ((-(nMatchOffset - 512)) >> 8) & 0x0f);
if (nOutOffset < 0) return -1;
}
else if (nTokenOffsetMode == 0xc0) {
pOutData[nOutOffset++] = (-nMatchOffset) & 0xff;
pOutData[nOutOffset++] = (-nMatchOffset) >> 8;
}
nRepMatchOffset = nMatchOffset;
nOutOffset = lzsa_write_match_varlen_v2(pOutData, nOutOffset, nMaxOutDataSize, &nCurNibbleOffset, &nCurFreeNibbles, nEncodedMatchLen);
if (nOutOffset < 0) return -1;
i += nMatchLen;
pCompressor->num_commands++;
}
else {
if (nNumLiterals == 0)
nInFirstLiteralOffset = i;
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);
if ((nOutOffset + ((nCommandSize + 7) >> 3)) > nMaxOutDataSize)
return -1;
if (pCompressor->flags & LZSA_FLAG_RAW_BLOCK)
pOutData[nOutOffset++] = (nTokenLiteralsLen << 3) | 0x47;
else
pOutData[nOutOffset++] = (nTokenLiteralsLen << 3) | 0x00;
nOutOffset = lzsa_write_literals_varlen_v2(pOutData, nOutOffset, nMaxOutDataSize, &nCurNibbleOffset, &nCurFreeNibbles, nNumLiterals);
if (nOutOffset < 0) return -1;
if (nNumLiterals != 0) {
memcpy(pOutData + nOutOffset, pInWindow + nInFirstLiteralOffset, nNumLiterals);
nOutOffset += nNumLiterals;
nNumLiterals = 0;
}
pCompressor->num_commands++;
}
if (pCompressor->flags & LZSA_FLAG_RAW_BLOCK) {
/* Emit EOD marker for raw block */
if (nOutOffset >= nMaxOutDataSize)
return -1;
pOutData[nOutOffset++] = 0; /* Match offset */
nOutOffset = lzsa_write_nibble_v2(pOutData, nOutOffset, nMaxOutDataSize, &nCurNibbleOffset, &nCurFreeNibbles, 15); /* Extended match length nibble */
if (nOutOffset < 0) return -1;
if ((nOutOffset + 3) > nMaxOutDataSize)
return -1;
pOutData[nOutOffset++] = 0; /* Extended match length byte */
pOutData[nOutOffset++] = 0; /* 16-bit match length */
pOutData[nOutOffset++] = 0;
}
if (nCurNibbleOffset != -1) {
nOutOffset = lzsa_write_nibble_v2(pOutData, nOutOffset, nMaxOutDataSize, &nCurNibbleOffset, &nCurFreeNibbles, 0);
if (nOutOffset < 0 || nCurNibbleOffset != -1)
return -1;
}
return nOutOffset;
}
/**
* Select the most optimal matches, reduce the token count if possible, and then emit a block of compressed LZSA2 data
*
* @param pCompressor compression context
* @param pInWindow pointer to input data window (previously compressed bytes + bytes to compress)
* @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
* @param pOutData pointer to output buffer
* @param nMaxOutDataSize maximum size of output buffer, in bytes
*
* @return size of compressed data in output buffer, or -1 if the data is uncompressible
*/
int lzsa_optimize_and_write_block_v2(lsza_compressor *pCompressor, const unsigned char *pInWindow, const int nPreviousBlockSize, const int nInDataSize, unsigned char *pOutData, const int nMaxOutDataSize) {
lzsa_optimize_matches_v2(pCompressor, nPreviousBlockSize, nPreviousBlockSize + nInDataSize);
int nDidReduce;
int nPasses = 0;
do {
nDidReduce = lzsa_optimize_command_count_v2(pCompressor, nPreviousBlockSize, nPreviousBlockSize + nInDataSize);
nPasses++;
} while (nDidReduce && nPasses < 20);
return lzsa_write_block_v2(pCompressor, pInWindow, nPreviousBlockSize, nPreviousBlockSize + nInDataSize, pOutData, nMaxOutDataSize);
}
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