/*
* LZW decoder
- * Copyright (c) 2003 Fabrice Bellard.
- * Copyright (c) 2006 Konstantin Shishkov.
+ * Copyright (c) 2003 Fabrice Bellard
+ * Copyright (c) 2006 Konstantin Shishkov
*
- * This file is part of FFmpeg.
+ * This file is part of Libav.
*
- * FFmpeg is free software; you can redistribute it and/or
+ * Libav is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
- * FFmpeg is distributed in the hope that it will be useful,
+ * Libav is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
- * License along with FFmpeg; if not, write to the Free Software
+ * License along with Libav; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
- * @file lzw.c
+ * @file
* @brief LZW decoding routines
* @author Fabrice Bellard
- * Modified for use in TIFF by Konstantin Shishkov
+ * @author modified for use in TIFF by Konstantin Shishkov
*/
#include "avcodec.h"
+#include "bytestream.h"
#include "lzw.h"
+#include "libavutil/mem.h"
#define LZW_MAXBITS 12
#define LZW_SIZTABLE (1<<LZW_MAXBITS)
};
struct LZWState {
- int eob_reached;
- uint8_t *pbuf, *ebuf;
+ GetByteContext gb;
int bbits;
unsigned int bbuf;
/* get one code from stream */
static int lzw_get_code(struct LZWState * s)
{
- int c, sizbuf;
+ int c;
if(s->mode == FF_LZW_GIF) {
while (s->bbits < s->cursize) {
if (!s->bs) {
- sizbuf = *s->pbuf++;
- s->bs = sizbuf;
- if(!sizbuf) {
- s->eob_reached = 1;
- break;
- }
+ s->bs = bytestream2_get_byte(&s->gb);
}
- s->bbuf |= (*s->pbuf++) << s->bbits;
+ s->bbuf |= bytestream2_get_byte(&s->gb) << s->bbits;
s->bbits += 8;
s->bs--;
}
- c = s->bbuf & s->curmask;
+ c = s->bbuf;
s->bbuf >>= s->cursize;
} else { // TIFF
while (s->bbits < s->cursize) {
- if (s->pbuf >= s->ebuf) {
- s->eob_reached = 1;
- }
- s->bbuf = (s->bbuf << 8) | (*s->pbuf++);
+ s->bbuf = (s->bbuf << 8) | bytestream2_get_byte(&s->gb);
s->bbits += 8;
}
- c = (s->bbuf >> (s->bbits - s->cursize)) & s->curmask;
+ c = s->bbuf >> (s->bbits - s->cursize);
}
s->bbits -= s->cursize;
- return c;
+ return c & s->curmask;
}
-uint8_t* ff_lzw_cur_ptr(LZWState *p)
+int ff_lzw_size_read(LZWState *p)
{
- return ((struct LZWState*)p)->pbuf;
+ struct LZWState *s = p;
+ return bytestream2_tell(&s->gb);
}
void ff_lzw_decode_tail(LZWState *p)
{
struct LZWState *s = (struct LZWState *)p;
- while(!s->eob_reached)
- lzw_get_code(s);
+
+ if(s->mode == FF_LZW_GIF) {
+ while (s->bs > 0 && bytestream2_get_bytes_left(&s->gb)) {
+ bytestream2_skip(&s->gb, s->bs);
+ s->bs = bytestream2_get_byte(&s->gb);
+ }
+ }else
+ bytestream2_skip(&s->gb, bytestream2_get_bytes_left(&s->gb));
}
-void ff_lzw_decode_open(LZWState **p)
+av_cold void ff_lzw_decode_open(LZWState **p)
{
*p = av_mallocz(sizeof(struct LZWState));
}
-void ff_lzw_decode_close(LZWState **p)
+av_cold void ff_lzw_decode_close(LZWState **p)
{
av_freep(p);
}
/**
* Initialize LZW decoder
- * @param s LZW context
+ * @param p LZW context
* @param csize initial code size in bits
* @param buf input data
* @param buf_size input data size
* @param mode decoder working mode - either GIF or TIFF
*/
-int ff_lzw_decode_init(LZWState *p, int csize, uint8_t *buf, int buf_size, int mode)
+int ff_lzw_decode_init(LZWState *p, int csize, const uint8_t *buf, int buf_size, int mode)
{
struct LZWState *s = (struct LZWState *)p;
- if(csize < 1 || csize > LZW_MAXBITS)
+ if(csize < 1 || csize >= LZW_MAXBITS)
return -1;
/* read buffer */
- s->eob_reached = 0;
- s->pbuf = buf;
- s->ebuf = s->pbuf + buf_size;
+ bytestream2_init(&s->gb, buf, buf_size);
s->bbuf = 0;
s->bbits = 0;
s->bs = 0;
s->clear_code = 1 << s->codesize;
s->end_code = s->clear_code + 1;
s->slot = s->newcodes = s->clear_code + 2;
- s->oc = s->fc = 0;
+ s->oc = s->fc = -1;
s->sp = s->stack;
s->mode = mode;
- switch(s->mode){
- case FF_LZW_GIF:
- s->extra_slot= 0;
- break;
- case FF_LZW_TIFF:
- s->extra_slot= 1;
- break;
- default:
- return -1;
- }
+ s->extra_slot = s->mode == FF_LZW_TIFF;
return 0;
}
* NOTE: the algorithm here is inspired from the LZW GIF decoder
* written by Steven A. Bennett in 1987.
*
- * @param s LZW context
+ * @param p LZW context
* @param buf output buffer
* @param len number of bytes to decode
* @return number of bytes decoded
}
c = lzw_get_code(s);
if (c == s->end_code) {
- s->end_code = -1;
break;
} else if (c == s->clear_code) {
s->cursize = s->codesize + 1;
s->curmask = mask[s->cursize];
s->slot = s->newcodes;
s->top_slot = 1 << s->cursize;
- while ((c = lzw_get_code(s)) == s->clear_code);
- if (c == s->end_code) {
- s->end_code = -1;
- break;
- }
- /* test error */
- if (c >= s->slot)
- c = 0;
- fc = oc = c;
- *buf++ = c;
- if ((--l) == 0)
- break;
+ fc= oc= -1;
} else {
code = c;
- if (code >= s->slot) {
+ if (code == s->slot && fc>=0) {
*sp++ = fc;
code = oc;
- }
+ }else if(code >= s->slot)
+ break;
while (code >= s->newcodes) {
*sp++ = s->suffix[code];
code = s->prefix[code];
}
*sp++ = code;
- if (s->slot < s->top_slot) {
- s->suffix[s->slot] = fc = code;
+ if (s->slot < s->top_slot && oc>=0) {
+ s->suffix[s->slot] = code;
s->prefix[s->slot++] = oc;
- oc = c;
}
+ fc = code;
+ oc = c;
if (s->slot >= s->top_slot - s->extra_slot) {
if (s->cursize < LZW_MAXBITS) {
s->top_slot <<= 1;
}
}
}
+ s->end_code = -1;
the_end:
s->sp = sp;
s->oc = oc;