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/*
* expand_block_v2.c - LZSA2 block decompressor 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 <stdlib.h>
#include <string.h>
#include "format.h"
#include "expand_block_v2.h"
#ifdef _MSC_VER
#define FORCE_INLINE __forceinline
#else /* _MSC_VER */
#define FORCE_INLINE __attribute__((always_inline))
#endif /* _MSC_VER */
static inline FORCE_INLINE unsigned int lzsa_get_nibble_v2(const unsigned char **ppInBlock, const unsigned char *pInBlockEnd, int *nCurNibbles, unsigned char *nibbles, unsigned int *nValue) {
if ((*nCurNibbles ^= 1) != 0) {
const unsigned char *pInBlock = *ppInBlock;
if (pInBlock < pInBlockEnd) {
(*nibbles) = *pInBlock++;
*ppInBlock = pInBlock;
(*nValue) = ((unsigned int)((*nibbles) & 0xf0)) >> 4;
return 0;
}
else {
return -1;
}
}
(*nValue) = (unsigned int)((*nibbles) & 0x0f);
return 0;
}
static inline FORCE_INLINE int lzsa_build_len_v2(const unsigned char **ppInBlock, const unsigned char *pInBlockEnd, int *nCurNibbles, unsigned char *nibbles, unsigned int *nLength) {
unsigned int nValue;
if (!lzsa_get_nibble_v2(ppInBlock, pInBlockEnd, nCurNibbles, nibbles, &nValue)) {
(*nLength) += nValue;
if (nValue == 15) {
const unsigned char *pInBlock = *ppInBlock;
if (pInBlock < pInBlockEnd) {
(*nLength) += ((unsigned int)*pInBlock++);
if ((*nLength) == 257) {
if ((pInBlock + 1) < pInBlockEnd) {
(*nLength) = ((unsigned int)*pInBlock++);
(*nLength) |= (((unsigned int)*pInBlock++) << 8);
}
else {
return -1;
}
}
else if ((*nLength) == 256) {
(*nLength) = 0;
}
}
else {
return -1;
}
*ppInBlock = pInBlock;
}
return 0;
}
else {
return -1;
}
}
/**
* Decompress one LZSA2 data block
*
* @param pInBlock pointer to compressed data
* @param nBlockSize size of compressed data, in bytes
* @param pOutData pointer to output decompression buffer (previously decompressed bytes + room for decompressing this block)
* @param nOutDataOffset starting index of where to store decompressed bytes in output buffer (and size of previously decompressed bytes)
* @param nBlockMaxSize total size of output decompression buffer, in bytes
*
* @return size of decompressed data in bytes, or -1 for error
*/
int lzsa_decompressor_expand_block_v2(const unsigned char *pInBlock, int nBlockSize, unsigned char *pOutData, int nOutDataOffset, int nBlockMaxSize) {
const unsigned char *pInBlockEnd = pInBlock + nBlockSize;
unsigned char *pCurOutData = pOutData + nOutDataOffset;
const unsigned char *pOutDataEnd = pCurOutData + nBlockMaxSize;
const unsigned char *pOutDataFastEnd = pOutDataEnd - 20;
int nCurNibbles = 0;
unsigned char nibbles;
int nMatchOffset = 0;
while (pInBlock < pInBlockEnd) {
const unsigned char token = *pInBlock++;
unsigned int nLiterals = (unsigned int)((token & 0x18) >> 3);
if (nLiterals != LITERALS_RUN_LEN_V2 && (pInBlock + 4) <= pInBlockEnd && pCurOutData < pOutDataFastEnd) {
memcpy(pCurOutData, pInBlock, 4);
pInBlock += nLiterals;
pCurOutData += nLiterals;
}
else {
if (nLiterals == LITERALS_RUN_LEN_V2) {
if (lzsa_build_len_v2(&pInBlock, pInBlockEnd, &nCurNibbles, &nibbles, &nLiterals))
return -1;
}
if (nLiterals != 0) {
if ((pInBlock + nLiterals) <= pInBlockEnd &&
(pCurOutData + nLiterals) <= pOutDataEnd) {
memcpy(pCurOutData, pInBlock, nLiterals);
pInBlock += nLiterals;
pCurOutData += nLiterals;
}
else {
return -1;
}
}
}
if (pInBlock < pInBlockEnd) { /* The last token in the block does not include match information */
unsigned char nOffsetMode = token & 0xc0;
unsigned int nValue;
switch (nOffsetMode) {
case 0x00:
/* 5 bit offset */
if (lzsa_get_nibble_v2(&pInBlock, pInBlockEnd, &nCurNibbles, &nibbles, &nValue))
return -1;
nMatchOffset = nValue << 1;
nMatchOffset |= ((token & 0x20) >> 5);
nMatchOffset ^= 0x1e;
nMatchOffset++;
break;
case 0x40:
/* 9 bit offset */
nMatchOffset = (unsigned int)(*pInBlock++);
nMatchOffset |= (((unsigned int)(token & 0x20)) << 3);
nMatchOffset ^= 0x0ff;
nMatchOffset++;
break;
case 0x80:
/* 13 bit offset */
if (lzsa_get_nibble_v2(&pInBlock, pInBlockEnd, &nCurNibbles, &nibbles, &nValue))
return -1;
nMatchOffset = (unsigned int)(*pInBlock++);
nMatchOffset |= (nValue << 9);
nMatchOffset |= (((unsigned int)(token & 0x20)) << 3);
nMatchOffset ^= 0x1eff;
nMatchOffset += (512 + 1);
break;
default:
/* Check if this is a 16 bit offset or a rep-match */
if ((token & 0x20) == 0) {
/* 16 bit offset */
nMatchOffset = (((unsigned int)(*pInBlock++)) << 8);
if (pInBlock >= pInBlockEnd) return -1;
nMatchOffset |= (unsigned int)(*pInBlock++);
nMatchOffset ^= 0xffff;
nMatchOffset++;
}
break;
}
const unsigned char *pSrc = pCurOutData - nMatchOffset;
if (pSrc >= pOutData) {
unsigned int nMatchLen = (unsigned int)(token & 0x07);
if (nMatchLen != MATCH_RUN_LEN_V2 && nMatchOffset >= 8 && pCurOutData < pOutDataFastEnd && (pSrc + 10) <= pOutDataEnd) {
memcpy(pCurOutData, pSrc, 8);
memcpy(pCurOutData + 8, pSrc + 8, 2);
pCurOutData += (MIN_MATCH_SIZE_V2 + nMatchLen);
}
else {
nMatchLen += MIN_MATCH_SIZE_V2;
if (nMatchLen == (MATCH_RUN_LEN_V2 + MIN_MATCH_SIZE_V2)) {
if (lzsa_build_len_v2(&pInBlock, pInBlockEnd, &nCurNibbles, &nibbles, &nMatchLen))
return -1;
if (nMatchLen == 0)
break;
}
if ((pSrc + nMatchLen) <= pOutDataEnd) {
if ((pCurOutData + nMatchLen) <= pOutDataEnd) {
/* Do a deterministic, left to right byte copy instead of memcpy() so as to handle overlaps */
if (nMatchOffset >= 16 && (pCurOutData + nMatchLen) < (pOutDataFastEnd - 15)) {
const unsigned char *pCopySrc = pSrc;
unsigned char *pCopyDst = pCurOutData;
const unsigned char *pCopyEndDst = pCurOutData + nMatchLen;
do {
memcpy(pCopyDst, pCopySrc, 16);
pCopySrc += 16;
pCopyDst += 16;
} while (pCopyDst < pCopyEndDst);
pCurOutData += nMatchLen;
}
else {
while (nMatchLen) {
*pCurOutData++ = *pSrc++;
nMatchLen--;
}
}
}
else {
return -1;
}
}
else {
return -1;
}
}
}
else {
return -1;
}
}
}
return (int)(pCurOutData - (pOutData + nOutDataOffset));
}
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