forked from KolibriOS/kolibrios
ffmpeg-2.1.1: move directory
git-svn-id: svn://kolibrios.org@6148 a494cfbc-eb01-0410-851d-a64ba20cac60
This commit is contained in:
Sergey Semyonov (Serge)
234
contrib/sdk/sources/ffmpeg/ffmpeg-2.1/libavcodec/lzw.c
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234
contrib/sdk/sources/ffmpeg/ffmpeg-2.1/libavcodec/lzw.c
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/*
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* LZW decoder
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* Copyright (c) 2003 Fabrice Bellard
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* Copyright (c) 2006 Konstantin Shishkov
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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/**
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* @file
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* @brief LZW decoding routines
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* @author Fabrice Bellard
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* @author modified for use in TIFF by Konstantin Shishkov
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*/
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#include "avcodec.h"
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#include "lzw.h"
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#include "libavutil/mem.h"
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#define LZW_MAXBITS 12
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#define LZW_SIZTABLE (1<<LZW_MAXBITS)
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static const uint16_t mask[17] =
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{
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0x0000, 0x0001, 0x0003, 0x0007,
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0x000F, 0x001F, 0x003F, 0x007F,
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0x00FF, 0x01FF, 0x03FF, 0x07FF,
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0x0FFF, 0x1FFF, 0x3FFF, 0x7FFF, 0xFFFF
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};
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struct LZWState {
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const uint8_t *pbuf, *ebuf;
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int bbits;
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unsigned int bbuf;
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int mode; ///< Decoder mode
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int cursize; ///< The current code size
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int curmask;
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int codesize;
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int clear_code;
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int end_code;
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int newcodes; ///< First available code
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int top_slot; ///< Highest code for current size
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int extra_slot;
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int slot; ///< Last read code
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int fc, oc;
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uint8_t *sp;
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uint8_t stack[LZW_SIZTABLE];
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uint8_t suffix[LZW_SIZTABLE];
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uint16_t prefix[LZW_SIZTABLE];
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int bs; ///< current buffer size for GIF
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};
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/* get one code from stream */
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static int lzw_get_code(struct LZWState * s)
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{
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int c;
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if(s->mode == FF_LZW_GIF) {
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while (s->bbits < s->cursize) {
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if (!s->bs) {
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s->bs = *s->pbuf++;
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}
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s->bbuf |= (*s->pbuf++) << s->bbits;
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s->bbits += 8;
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s->bs--;
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}
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c = s->bbuf;
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s->bbuf >>= s->cursize;
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} else { // TIFF
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while (s->bbits < s->cursize) {
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s->bbuf = (s->bbuf << 8) | (*s->pbuf++);
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s->bbits += 8;
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}
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c = s->bbuf >> (s->bbits - s->cursize);
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}
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s->bbits -= s->cursize;
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return c & s->curmask;
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}
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void ff_lzw_decode_tail(LZWState *p)
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{
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struct LZWState *s = (struct LZWState *)p;
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if(s->mode == FF_LZW_GIF) {
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while (s->bs > 0) {
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if (s->bs >= s->ebuf - s->pbuf) {
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s->pbuf = s->ebuf;
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break;
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} else {
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s->pbuf += s->bs;
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s->bs = *s->pbuf++;
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}
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}
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}else
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s->pbuf= s->ebuf;
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}
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av_cold void ff_lzw_decode_open(LZWState **p)
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{
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*p = av_mallocz(sizeof(struct LZWState));
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}
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av_cold void ff_lzw_decode_close(LZWState **p)
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{
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av_freep(p);
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}
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/**
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* Initialize LZW decoder
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* @param p LZW context
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* @param csize initial code size in bits
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* @param buf input data
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* @param buf_size input data size
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* @param mode decoder working mode - either GIF or TIFF
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*/
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int ff_lzw_decode_init(LZWState *p, int csize, const uint8_t *buf, int buf_size, int mode)
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{
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struct LZWState *s = (struct LZWState *)p;
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if(csize < 1 || csize >= LZW_MAXBITS)
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return -1;
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/* read buffer */
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s->pbuf = buf;
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s->ebuf = s->pbuf + buf_size;
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s->bbuf = 0;
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s->bbits = 0;
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s->bs = 0;
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/* decoder */
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s->codesize = csize;
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s->cursize = s->codesize + 1;
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s->curmask = mask[s->cursize];
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s->top_slot = 1 << s->cursize;
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s->clear_code = 1 << s->codesize;
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s->end_code = s->clear_code + 1;
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s->slot = s->newcodes = s->clear_code + 2;
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s->oc = s->fc = -1;
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s->sp = s->stack;
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s->mode = mode;
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s->extra_slot = s->mode == FF_LZW_TIFF;
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return 0;
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}
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/**
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* Decode given number of bytes
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* NOTE: the algorithm here is inspired from the LZW GIF decoder
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* written by Steven A. Bennett in 1987.
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*
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* @param p LZW context
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* @param buf output buffer
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* @param len number of bytes to decode
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* @return number of bytes decoded
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*/
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int ff_lzw_decode(LZWState *p, uint8_t *buf, int len){
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int l, c, code, oc, fc;
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uint8_t *sp;
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struct LZWState *s = (struct LZWState *)p;
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if (s->end_code < 0)
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return 0;
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l = len;
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sp = s->sp;
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oc = s->oc;
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fc = s->fc;
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for (;;) {
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while (sp > s->stack) {
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*buf++ = *(--sp);
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if ((--l) == 0)
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goto the_end;
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}
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if (s->ebuf < s->pbuf) {
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av_log(NULL, AV_LOG_ERROR, "lzw overread\n");
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goto the_end;
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}
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c = lzw_get_code(s);
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if (c == s->end_code) {
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break;
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} else if (c == s->clear_code) {
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s->cursize = s->codesize + 1;
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s->curmask = mask[s->cursize];
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s->slot = s->newcodes;
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s->top_slot = 1 << s->cursize;
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fc= oc= -1;
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} else {
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code = c;
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if (code == s->slot && fc>=0) {
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*sp++ = fc;
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code = oc;
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}else if(code >= s->slot)
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break;
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while (code >= s->newcodes) {
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*sp++ = s->suffix[code];
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code = s->prefix[code];
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}
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*sp++ = code;
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if (s->slot < s->top_slot && oc>=0) {
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s->suffix[s->slot] = code;
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s->prefix[s->slot++] = oc;
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}
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fc = code;
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oc = c;
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if (s->slot >= s->top_slot - s->extra_slot) {
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if (s->cursize < LZW_MAXBITS) {
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s->top_slot <<= 1;
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s->curmask = mask[++s->cursize];
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}
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}
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}
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}
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s->end_code = -1;
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the_end:
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s->sp = sp;
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s->oc = oc;
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s->fc = fc;
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return len - l;
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}
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