242 lines
8.4 KiB
C
Executable File
242 lines
8.4 KiB
C
Executable File
/*
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* expand.c - block decompressor implementation
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*
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* Copyright (C) 2019 Emmanuel Marty
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*
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* This software is provided 'as-is', without any express or implied
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* warranty. In no event will the authors be held liable for any damages
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* arising from the use of this software.
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*
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* Permission is granted to anyone to use this software for any purpose,
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* including commercial applications, and to alter it and redistribute it
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* freely, subject to the following restrictions:
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*
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* 1. The origin of this software must not be misrepresented; you must not
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* claim that you wrote the original software. If you use this software
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* in a product, an acknowledgment in the product documentation would be
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* appreciated but is not required.
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* 2. Altered source versions must be plainly marked as such, and must not be
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* misrepresented as being the original software.
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* 3. This notice may not be removed or altered from any source distribution.
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include "format.h"
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#include "expand.h"
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#ifdef _MSC_VER
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#define FORCE_INLINE __forceinline
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#else /* _MSC_VER */
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#define FORCE_INLINE __attribute__((always_inline))
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#endif /* _MSC_VER */
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static inline FORCE_INLINE int lzsa_expand_literals_slow(const unsigned char **ppInBlock, const unsigned char *pInBlockEnd, int nLiterals, unsigned char **ppCurOutData, const unsigned char *pOutDataEnd) {
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const unsigned char *pInBlock = *ppInBlock;
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unsigned char *pCurOutData = *ppCurOutData;
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if (nLiterals == LITERALS_RUN_LEN) {
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unsigned char nByte;
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if (pInBlock >= pInBlockEnd) return -1;
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nByte = *pInBlock++;
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nLiterals += (int)((unsigned int)nByte);
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if (nByte == 254) {
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if (pInBlock >= pInBlockEnd) return -1;
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nLiterals += (int)((unsigned int)*pInBlock++);
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}
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else if (nByte == 255) {
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int nLargeLiterals;
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if ((pInBlock + 1) >= pInBlockEnd) return -1;
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nLargeLiterals = ((unsigned int)*pInBlock++);
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nLargeLiterals |= (((unsigned int)*pInBlock++) << 8);
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nLiterals += nLargeLiterals;
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}
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}
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if (nLiterals != 0) {
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if ((pInBlock + nLiterals) > pInBlockEnd ||
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(pCurOutData + nLiterals) > pOutDataEnd) {
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return -1;
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}
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memcpy(pCurOutData, pInBlock, nLiterals);
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pInBlock += nLiterals;
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pCurOutData += nLiterals;
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}
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*ppInBlock = pInBlock;
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*ppCurOutData = pCurOutData;
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return 0;
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}
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static inline FORCE_INLINE int lzsa_expand_match_slow(const unsigned char **ppInBlock, const unsigned char *pInBlockEnd, const unsigned char *pSrc, int nMatchLen, unsigned char **ppCurOutData, const unsigned char *pOutDataEnd, const unsigned char *pOutDataFastEnd) {
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const unsigned char *pInBlock = *ppInBlock;
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unsigned char *pCurOutData = *ppCurOutData;
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if (nMatchLen == MATCH_RUN_LEN) {
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unsigned char nByte;
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if (pInBlock >= pInBlockEnd) return -1;
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nByte = *pInBlock++;
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nMatchLen += (int)((unsigned int)nByte);
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if (nByte == 254) {
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if (pInBlock >= pInBlockEnd) return -1;
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nMatchLen += (int)((unsigned int)*pInBlock++);
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}
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else if (nByte == 255) {
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int nLargeMatchLen;
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if ((pInBlock + 1) >= pInBlockEnd) return -1;
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nLargeMatchLen = ((unsigned int)*pInBlock++);
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nLargeMatchLen |= (((unsigned int)*pInBlock++) << 8);
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nMatchLen += nLargeMatchLen;
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}
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}
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nMatchLen += MIN_MATCH_SIZE;
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if ((pCurOutData + nMatchLen) > pOutDataEnd) {
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return -1;
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}
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if ((pSrc + 1) == pCurOutData && nMatchLen >= 16) {
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/* One-byte RLE */
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memset(pCurOutData, *pSrc, nMatchLen);
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pCurOutData += nMatchLen;
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}
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else {
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/* Do a deterministic, left to right byte copy instead of memcpy() so as to handle overlaps */
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int nMaxFast = nMatchLen;
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if (nMaxFast > (pCurOutData - pSrc))
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nMaxFast = (int)(pCurOutData - pSrc);
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if ((pCurOutData + nMaxFast) > pOutDataFastEnd)
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nMaxFast = (int)(pOutDataFastEnd - pCurOutData);
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if (nMaxFast > 0) {
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const unsigned char *pCopySrc = pSrc;
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unsigned char *pCopyDst = pCurOutData;
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const unsigned char *pCopyEndDst = pCurOutData + nMaxFast;
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do {
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memcpy(pCopyDst, pCopySrc, 16);
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pCopySrc += 16;
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pCopyDst += 16;
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} while (pCopyDst < pCopyEndDst);
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pCurOutData += nMaxFast;
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pSrc += nMaxFast;
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nMatchLen -= nMaxFast;
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}
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while (nMatchLen >= 4) {
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*pCurOutData++ = *pSrc++;
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*pCurOutData++ = *pSrc++;
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*pCurOutData++ = *pSrc++;
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*pCurOutData++ = *pSrc++;
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nMatchLen -= 4;
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}
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while (nMatchLen > 0) {
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*pCurOutData++ = *pSrc++;
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nMatchLen--;
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}
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}
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*ppInBlock = pInBlock;
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*ppCurOutData = pCurOutData;
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return 0;
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}
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/**
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* Decompress one data block
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*
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* @param pInBlock pointer to compressed data
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* @param nInBlockSize size of compressed data, in bytes
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* @param pOutData pointer to output decompression buffer (previously decompressed bytes + room for decompressing this block)
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* @param nOutDataOffset starting index of where to store decompressed bytes in output buffer (and size of previously decompressed bytes)
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* @param nBlockMaxSize total size of output decompression buffer, in bytes
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*
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* @return size of decompressed data in bytes, or -1 for error
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*/
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int lzsa_expand_block(const unsigned char *pInBlock, int nBlockSize, unsigned char *pOutData, int nOutDataOffset, int nBlockMaxSize) {
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const unsigned char *pInBlockEnd = pInBlock + nBlockSize;
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const unsigned char *pInBlockFastEnd = pInBlock + nBlockSize - 16;
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unsigned char *pCurOutData = pOutData + nOutDataOffset;
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const unsigned char *pOutDataEnd = pCurOutData + nBlockMaxSize;
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const unsigned char *pOutDataFastEnd = pOutDataEnd - 16;
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/* Fast loop */
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while (pInBlock < pInBlockFastEnd && pCurOutData < pOutDataFastEnd) {
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const unsigned char token = *pInBlock++;
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int nLiterals = (int)((unsigned int)((token & 0x70) >> 4));
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if (nLiterals < LITERALS_RUN_LEN) {
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memcpy(pCurOutData, pInBlock, 8);
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pInBlock += nLiterals;
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pCurOutData += nLiterals;
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}
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else {
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if (lzsa_expand_literals_slow(&pInBlock, pInBlockEnd, nLiterals, &pCurOutData, pOutDataEnd))
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return -1;
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}
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if ((pInBlock + 2) <= pInBlockEnd) { /* The last token in the block does not include match information */
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int nMatchOffset;
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nMatchOffset = ((unsigned int)*pInBlock++);
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if (token & 0x80)
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nMatchOffset |= (((unsigned int)*pInBlock++) << 8);
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nMatchOffset++;
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const unsigned char *pSrc = pCurOutData - nMatchOffset;
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if (pSrc < pOutData)
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return -1;
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int nMatchLen = (int)((unsigned int)(token & 0x0f));
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if (nMatchLen < (16 - MIN_MATCH_SIZE + 1) && (pSrc + MIN_MATCH_SIZE + nMatchLen) < pCurOutData) {
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memcpy(pCurOutData, pSrc, 16);
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pCurOutData += (MIN_MATCH_SIZE + nMatchLen);
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}
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else {
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if (lzsa_expand_match_slow(&pInBlock, pInBlockEnd, pSrc, nMatchLen, &pCurOutData, pOutDataEnd, pOutDataFastEnd))
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return -1;
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}
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}
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}
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/* Slow loop for the remainder of the buffer */
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while (pInBlock < pInBlockEnd) {
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const unsigned char token = *pInBlock++;
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int nLiterals = (int)((unsigned int)((token & 0x70) >> 4));
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if (lzsa_expand_literals_slow(&pInBlock, pInBlockEnd, nLiterals, &pCurOutData, pOutDataEnd))
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return -1;
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if ((pInBlock + 2) <= pInBlockEnd) { /* The last token in the block does not include match information */
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int nMatchOffset;
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nMatchOffset = ((unsigned int)*pInBlock++);
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if (token & 0x80)
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nMatchOffset |= (((unsigned int)*pInBlock++) << 8);
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nMatchOffset++;
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const unsigned char *pSrc = pCurOutData - nMatchOffset;
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if (pSrc < pOutData)
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return -1;
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int nMatchLen = (int)((unsigned int)(token & 0x0f));
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if (lzsa_expand_match_slow(&pInBlock, pInBlockEnd, pSrc, nMatchLen, &pCurOutData, pOutDataEnd, pOutDataFastEnd))
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return -1;
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}
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}
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return (int)(pCurOutData - (pOutData + nOutDataOffset));
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}
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