[Ffmpeg-cvslog] r8517 - trunk/libavcodec/lzw.c
michael
subversion
Sun Mar 25 17:43:46 CEST 2007
Author: michael
Date: Sun Mar 25 17:43:46 2007
New Revision: 8517
Modified:
trunk/libavcodec/lzw.c
Log:
move eob_reached logic into ff_lzw_decode_tail() which simplifies the code, avoids some checks in the innermost loop and also gets rid of the controversal break while hopefully retaining the last byte in a valid bytestream, invalid bytestreams still can have very significant overread
Modified: trunk/libavcodec/lzw.c
==============================================================================
--- trunk/libavcodec/lzw.c (original)
+++ trunk/libavcodec/lzw.c Sun Mar 25 17:43:46 2007
@@ -42,7 +42,6 @@ static const uint16_t mask[17] =
};
struct LZWState {
- int eob_reached;
uint8_t *pbuf, *ebuf;
int bbits;
unsigned int bbuf;
@@ -74,10 +73,6 @@ static int lzw_get_code(struct LZWState
while (s->bbits < s->cursize) {
if (!s->bs) {
s->bs = *s->pbuf++;
- if(!s->bs) {
- s->eob_reached = 1;
- break;
- }
}
s->bbuf |= (*s->pbuf++) << s->bbits;
s->bbits += 8;
@@ -87,9 +82,6 @@ static int lzw_get_code(struct LZWState
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->bbits += 8;
}
@@ -107,8 +99,14 @@ uint8_t* ff_lzw_cur_ptr(LZWState *p)
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->pbuf < s->ebuf && s->bs>0){
+ s->pbuf += s->bs;
+ s->bs = *s->pbuf++;
+ }
+ }else
+ s->pbuf= s->ebuf;
}
void ff_lzw_decode_open(LZWState **p)
@@ -136,7 +134,6 @@ int ff_lzw_decode_init(LZWState *p, int
if(csize < 1 || csize > LZW_MAXBITS)
return -1;
/* read buffer */
- s->eob_reached = 0;
s->pbuf = buf;
s->ebuf = s->pbuf + buf_size;
s->bbuf = 0;
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