};
struct LZWState {
- int eob_reached;
- uint8_t *pbuf, *ebuf;
+ const uint8_t *pbuf, *ebuf;
int bbits;
unsigned int bbuf;
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;
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->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)
+const uint8_t* ff_lzw_cur_ptr(LZWState *p)
{
return ((struct LZWState*)p)->pbuf;
}
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)
* @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)
return -1;
/* read buffer */
- s->eob_reached = 0;
s->pbuf = buf;
s->ebuf = s->pbuf + buf_size;
s->bbuf = 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;
}
}
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;