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|
/*
* BriefLZ - small fast Lempel-Ziv
*
* C depacker
*
* Copyright (c) 2002-2018 Joergen Ibsen
*
* 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.
*/
#include "brieflz.h"
/* Internal data structure */
struct blz_state {
const unsigned char *src;
unsigned char *dst;
unsigned int tag;
int bits_left;
};
#if !defined(BLZ_NO_LUT)
static const unsigned char blz_gamma_lookup[256][2] = {
/* 00xxxxxx = 2 */
{ 2, 2},
{ 2, 2},
{ 2, 2},
{ 2, 2},
{ 2, 2},
{ 2, 2},
{ 2, 2},
{ 2, 2},
{ 2, 2},
{ 2, 2},
{ 2, 2},
{ 2, 2},
{ 2, 2},
{ 2, 2},
{ 2, 2},
{ 2, 2},
{ 2, 2},
{ 2, 2},
{ 2, 2},
{ 2, 2},
{ 2, 2},
{ 2, 2},
{ 2, 2},
{ 2, 2},
{ 2, 2},
{ 2, 2},
{ 2, 2},
{ 2, 2},
{ 2, 2},
{ 2, 2},
{ 2, 2},
{ 2, 2},
{ 2, 2},
{ 2, 2},
{ 2, 2},
{ 2, 2},
{ 2, 2},
{ 2, 2},
{ 2, 2},
{ 2, 2},
{ 2, 2},
{ 2, 2},
{ 2, 2},
{ 2, 2},
{ 2, 2},
{ 2, 2},
{ 2, 2},
{ 2, 2},
{ 2, 2},
{ 2, 2},
{ 2, 2},
{ 2, 2},
{ 2, 2},
{ 2, 2},
{ 2, 2},
{ 2, 2},
{ 2, 2},
{ 2, 2},
{ 2, 2},
{ 2, 2},
{ 2, 2},
{ 2, 2},
{ 2, 2},
{ 2, 2},
/* 0100xxxx = 4 */
{ 4, 4},
{ 4, 4},
{ 4, 4},
{ 4, 4},
{ 4, 4},
{ 4, 4},
{ 4, 4},
{ 4, 4},
{ 4, 4},
{ 4, 4},
{ 4, 4},
{ 4, 4},
{ 4, 4},
{ 4, 4},
{ 4, 4},
{ 4, 4},
/* 010100xx = 8 */
{ 8, 6},
{ 8, 6},
{ 8, 6},
{ 8, 6},
/* 01010100 = 16 01010101 = 16+ 01010110 = 17 01010111 = 17+ */
{16, 8},
{16, 0},
{17, 8},
{17, 0},
/* 010110xx = 9 */
{ 9, 6},
{ 9, 6},
{ 9, 6},
{ 9, 6},
/* 01011100 = 18 01011101 = 18+ 01011110 = 19 01011111 = 19+ */
{18, 8},
{18, 0},
{19, 8},
{19, 0},
/* 0110xxxx = 5 */
{ 5, 4},
{ 5, 4},
{ 5, 4},
{ 5, 4},
{ 5, 4},
{ 5, 4},
{ 5, 4},
{ 5, 4},
{ 5, 4},
{ 5, 4},
{ 5, 4},
{ 5, 4},
{ 5, 4},
{ 5, 4},
{ 5, 4},
{ 5, 4},
/* 011100xx = 10 */
{10, 6},
{10, 6},
{10, 6},
{10, 6},
/* 01110100 = 20 01110101 = 20+ 01110110 = 21 01110111 = 21+ */
{20, 8},
{20, 0},
{21, 8},
{21, 0},
/* 011110xx = 11 */
{11, 6},
{11, 6},
{11, 6},
{11, 6},
/* 01111100 = 22 01111101 = 22+ 01111110 = 23 01111111 = 23+ */
{22, 8},
{22, 0},
{23, 8},
{23, 0},
/* 10xxxxxx = 3 */
{ 3, 2},
{ 3, 2},
{ 3, 2},
{ 3, 2},
{ 3, 2},
{ 3, 2},
{ 3, 2},
{ 3, 2},
{ 3, 2},
{ 3, 2},
{ 3, 2},
{ 3, 2},
{ 3, 2},
{ 3, 2},
{ 3, 2},
{ 3, 2},
{ 3, 2},
{ 3, 2},
{ 3, 2},
{ 3, 2},
{ 3, 2},
{ 3, 2},
{ 3, 2},
{ 3, 2},
{ 3, 2},
{ 3, 2},
{ 3, 2},
{ 3, 2},
{ 3, 2},
{ 3, 2},
{ 3, 2},
{ 3, 2},
{ 3, 2},
{ 3, 2},
{ 3, 2},
{ 3, 2},
{ 3, 2},
{ 3, 2},
{ 3, 2},
{ 3, 2},
{ 3, 2},
{ 3, 2},
{ 3, 2},
{ 3, 2},
{ 3, 2},
{ 3, 2},
{ 3, 2},
{ 3, 2},
{ 3, 2},
{ 3, 2},
{ 3, 2},
{ 3, 2},
{ 3, 2},
{ 3, 2},
{ 3, 2},
{ 3, 2},
{ 3, 2},
{ 3, 2},
{ 3, 2},
{ 3, 2},
{ 3, 2},
{ 3, 2},
{ 3, 2},
{ 3, 2},
/* 1100xxxx = 6 */
{ 6, 4},
{ 6, 4},
{ 6, 4},
{ 6, 4},
{ 6, 4},
{ 6, 4},
{ 6, 4},
{ 6, 4},
{ 6, 4},
{ 6, 4},
{ 6, 4},
{ 6, 4},
{ 6, 4},
{ 6, 4},
{ 6, 4},
{ 6, 4},
/* 110100xx = 12 */
{12, 6},
{12, 6},
{12, 6},
{12, 6},
/* 11010100 = 24 11010101 = 24+ 11010110 = 25 11010111 = 25+ */
{24, 8},
{24, 0},
{25, 8},
{25, 0},
/* 110110xx = 13 */
{13, 6},
{13, 6},
{13, 6},
{13, 6},
/* 11011100 = 26 11011101 = 26+ 11011110 = 27 11011111 = 27+ */
{26, 8},
{26, 0},
{27, 8},
{27, 0},
/* 1110xxxx = 7 */
{ 7, 4},
{ 7, 4},
{ 7, 4},
{ 7, 4},
{ 7, 4},
{ 7, 4},
{ 7, 4},
{ 7, 4},
{ 7, 4},
{ 7, 4},
{ 7, 4},
{ 7, 4},
{ 7, 4},
{ 7, 4},
{ 7, 4},
{ 7, 4},
/* 111100xx = 14 */
{14, 6},
{14, 6},
{14, 6},
{14, 6},
/* 11110100 = 28 11110101 = 28+ 11110110 = 29 11110111 = 29+ */
{28, 8},
{28, 0},
{29, 8},
{29, 0},
/* 111110xx = 15 */
{15, 6},
{15, 6},
{15, 6},
{15, 6},
/* 11111100 = 30 11111101 = 30+ 11111110 = 31 11111111 = 31+ */
{30, 8},
{30, 0},
{31, 8},
{31, 0}
};
#endif
static unsigned int blz_getbit(struct blz_state *bs) {
unsigned int bit;
/* Check if tag is empty */
if (!bs->bits_left--) {
/* Load next tag */
bs->tag = (unsigned int)bs->src[0] | ((unsigned int)bs->src[1] << 8);
bs->src += 2;
bs->bits_left = 15;
}
/* Shift bit out of tag */
bit = (bs->tag & 0x8000) ? 1 : 0;
bs->tag <<= 1;
return bit;
}
static unsigned long blz_getgamma(struct blz_state *bs) {
unsigned long result = 1;
#if !defined(BLZ_NO_LUT)
/* Decode up to 8 bits of gamma2 code using lookup if possible */
if (bs->bits_left >= 8) {
unsigned int top8 = (bs->tag >> 8) & 0x00FF;
int shift;
result = blz_gamma_lookup[top8][0];
shift = (int)blz_gamma_lookup[top8][1];
if (shift) {
bs->tag <<= shift;
bs->bits_left -= shift;
return result;
}
bs->tag <<= 8;
bs->bits_left -= 8;
}
#endif
/* Input gamma2-encoded bits */
do {
result = (result << 1) + blz_getbit(bs);
} while (blz_getbit(bs));
return result;
}
unsigned long blz_depack(const void *src, void *dst, unsigned long depacked_size) {
struct blz_state bs;
unsigned long dst_size = 0;
bs.src = (const unsigned char *)src;
bs.dst = (unsigned char *)dst;
/* Initialise to one bit left in tag; that bit is zero (a literal) */
bs.bits_left = 1;
bs.tag = 0x4000;
/* Main decompression loop */
while (dst_size < depacked_size) {
if (blz_getbit(&bs)) {
/* Input match length and offset */
unsigned long len = blz_getgamma(&bs) + 2;
unsigned long off = blz_getgamma(&bs) - 2;
off = (off << 8) + (unsigned long)*bs.src++ + 1;
/* Copy match */
{
const unsigned char *p = bs.dst - off;
unsigned long i;
for (i = len; i > 0; --i) {
*bs.dst++ = *p++;
}
}
dst_size += len;
} else {
/* Copy literal */
*bs.dst++ = *bs.src++;
dst_size++;
}
}
/* Return decompressed size */
return dst_size;
}
unsigned long blz_depack_srcsize(const void *src, void *dst, unsigned long src_size) {
struct blz_state bs;
unsigned long dst_size = 0;
const unsigned char *src_end = src + src_size;
bs.src = (const unsigned char *)src;
bs.dst = (unsigned char *)dst;
/* Initialise to one bit left in tag; that bit is zero (a literal) */
bs.bits_left = 1;
bs.tag = 0x4000;
/* Main decompression loop */
while (bs.src < src_end) {
if (blz_getbit(&bs)) {
/* Input match length and offset */
unsigned long len = blz_getgamma(&bs) + 2;
unsigned long off = blz_getgamma(&bs) - 2;
off = (off << 8) + (unsigned long)*bs.src++ + 1;
/* Copy match */
{
const unsigned char *p = bs.dst - off;
unsigned long i;
for (i = len; i > 0; --i) {
*bs.dst++ = *p++;
}
}
dst_size += len;
} else {
/* Copy literal */
*bs.dst++ = *bs.src++;
dst_size++;
}
}
/* Return decompressed size */
return dst_size;
}
|
