int ff_lzw_decode(LZWState *p, uint8_t *buf, int len){ int l, c, code, oc, fc; uint8_t *sp; struct LZWState *s = (struct LZWState *)p; if (s->end_code < 0) return 0; l = len; sp = s->sp; oc = s->oc; fc = s->fc; for (;;) { while (sp > s->stack) { *buf++ = *(--sp); if ((--l) == 0) goto the_end; } 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; fc= oc= -1; } else { code = c; if (code >= s->slot) { *sp++ = fc; code = oc; } while (code >= s->newcodes) { *sp++ = s->suffix[code]; code = s->prefix[code]; } *sp++ = code; if (s->slot < s->top_slot && oc>=0) { s->suffix[s->slot] = code; s->prefix[s->slot++] = oc; } fc = code; oc = c; if (s->slot >= s->top_slot - s->extra_slot) { if (s->cursize < LZW_MAXBITS) { s->top_slot <<= 1; s->curmask = mask[++s->cursize]; } } } } the_end: s->sp = sp; s->oc = oc; s->fc = fc; return len - l; }
int ff_lzw_decode(LZWState *p, uint8_t *buf, int len){ int l, c, code, oc, fc; uint8_t *sp; struct LZWState *s = (struct LZWState *)p; if (s->end_code < 0) return 0; l = len; sp = s->sp; oc = s->oc; fc = s->fc; for (;;) { while (sp > s->stack) { *buf++ = *(--sp); if ((--l) == 0) goto the_end; } 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; fc= oc= -1; } else { code = c; if (code >= s->slot) { *sp++ = fc; code = oc; } while (code >= s->newcodes) { *sp++ = s->suffix[code]; code = s->prefix[code]; } *sp++ = code; if (s->slot < s->top_slot && oc>=0) { s->suffix[s->slot] = code; s->prefix[s->slot++] = oc; } fc = code; oc = c; if (s->slot >= s->top_slot - s->extra_slot) { if (s->cursize < LZW_MAXBITS) { s->top_slot <<= 1; s->curmask = mask[++s->cursize]; } } } } the_end: s->sp = sp; s->oc = oc; s->fc = fc; return len - l; }