diff options
Diffstat (limited to 'fitz/filt_lzwd.c')
| -rw-r--r-- | fitz/filt_lzwd.c | 39 |
1 files changed, 21 insertions, 18 deletions
diff --git a/fitz/filt_lzwd.c b/fitz/filt_lzwd.c index 5ec8093f..e55a8c28 100644 --- a/fitz/filt_lzwd.c +++ b/fitz/filt_lzwd.c @@ -41,9 +41,8 @@ struct fz_lzwd_s int nextcode; /* next free entry */ lzw_code table[NUMCODES]; - unsigned char output[MAXLENGTH]; - int outlen; - int remain; + unsigned char bp[MAXLENGTH]; + unsigned char *rp, *wp; }; static inline void eatbits(fz_lzwd *lzw, int nbits) @@ -77,12 +76,14 @@ readlzwd(fz_stream *stm, unsigned char *buf, int len) { fz_lzwd *lzw = stm->state; unsigned char *p = buf; + unsigned char *ep = buf + len; unsigned char *s; + int codelen; - while (lzw->remain > 0 && p < buf + len) - *p++ = lzw->output[lzw->outlen - lzw->remain--]; + while (lzw->rp < lzw->wp && p < ep) + *p++ = *lzw->rp++; - while (p < buf + len) + while (p < ep) { if (lzw->eod) return 0; @@ -150,28 +151,30 @@ output: /* code maps to a string, copy to output (in reverse...) */ if (lzw->code > 255) { - assert(lzw->table[lzw->code].length < MAXLENGTH); + codelen = lzw->table[lzw->code].length; + lzw->rp = lzw->bp; + lzw->wp = lzw->bp + codelen; - lzw->outlen = lzw->table[lzw->code].length; - lzw->remain = lzw->outlen; - s = lzw->output + lzw->remain; + assert(codelen < MAXLENGTH); + + s = lzw->wp; do { *(--s) = lzw->table[lzw->code].value; lzw->code = lzw->table[lzw->code].prev; - } while (lzw->code >= 0 && s > lzw->output); + } while (lzw->code >= 0 && s > lzw->bp); } /* ... or just a single character */ else { - lzw->output[0] = lzw->code; - lzw->outlen = 1; - lzw->remain = 1; + lzw->bp[0] = lzw->code; + lzw->rp = lzw->bp; + lzw->wp = lzw->bp + 1; } /* copy to output */ - while (lzw->remain > 0 && p < buf + len) - *p++ = lzw->output[lzw->outlen - lzw->remain--]; + while (lzw->rp < lzw->wp && p < ep) + *p++ = *lzw->rp++; } return p - buf; @@ -224,8 +227,8 @@ fz_openlzwd(fz_stream *chain, fz_obj *params) lzw->code = -1; lzw->nextcode = LZW_FIRST; lzw->oldcode = -1; - lzw->remain = 0; - lzw->outlen = 0; + lzw->rp = lzw->bp; + lzw->wp = lzw->bp; return fz_newstream(lzw, readlzwd, closelzwd); } |