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#include <fitz.h>
/* TODO: rewrite!
* make it non-optimal or something,
* just not this horrid mess...
*/
#define noDEBUG
typedef struct fz_rle_s fz_rle;
struct fz_rle_s
{
fz_filter super;
int reclen;
int curlen;
int state;
int run;
unsigned char buf[128];
};
enum {
ZERO,
ONE,
DIFF,
SAME,
END
};
fz_error *
fz_newrle(fz_filter **fp, fz_obj *params)
{
FZ_NEWFILTER(fz_rle, enc, rle);
if (params)
enc->reclen = fz_toint(params);
else
enc->reclen = 0;
enc->curlen = 0;
enc->state = ZERO;
enc->run = 0;
return nil;
}
void
fz_droprle(fz_filter *enc)
{
}
static fz_error *
putone(fz_rle *enc, fz_buffer *in, fz_buffer *out)
{
if (out->wp + 2 >= out->ep)
return fz_ioneedout;
#ifdef DEBUG
fprintf(stderr, "one '%c'\n", enc->buf[0]);
#endif
*out->wp++ = 0;
*out->wp++ = enc->buf[0];
return nil;
}
static fz_error *
putsame(fz_rle *enc, fz_buffer *in, fz_buffer *out)
{
if (out->wp + enc->run >= out->ep)
return fz_ioneedout;
#ifdef DEBUG
fprintf(stderr, "same %d x '%c'\n", enc->run, enc->buf[0]);
#endif
*out->wp++ = 257 - enc->run;
*out->wp++ = enc->buf[0];
return nil;
}
static fz_error *
putdiff(fz_rle *enc, fz_buffer *in, fz_buffer *out)
{
int i;
if (out->wp + enc->run >= out->ep)
return fz_ioneedout;
#ifdef DEBUG
fprintf(stderr, "diff %d\n", enc->run);
#endif
*out->wp++ = enc->run - 1;
for (i = 0; i < enc->run; i++)
*out->wp++ = enc->buf[i];
return nil;
}
static fz_error *
puteod(fz_rle *enc, fz_buffer *in, fz_buffer *out)
{
if (out->wp + 1 >= out->ep)
return fz_ioneedout;
#ifdef DEBUG
fprintf(stderr, "eod\n");
#endif
*out->wp++ = 128;
return nil;
}
static fz_error *
savebuf(fz_rle *enc, fz_buffer *in, fz_buffer *out)
{
switch (enc->state)
{
case ZERO: return nil;
case ONE: return putone(enc, in, out);
case SAME: return putsame(enc, in, out);
case DIFF: return putdiff(enc, in, out);
case END: return puteod(enc, in, out);
default: assert(!"invalid state in rle"); return nil;
}
}
fz_error *
fz_processrle(fz_filter *filter, fz_buffer *in, fz_buffer *out)
{
fz_rle *enc = (fz_rle*)filter;
fz_error *err;
unsigned char c;
while (1)
{
if (enc->reclen && enc->curlen == enc->reclen) {
err = savebuf(enc, in, out);
if (err) return err;
#ifdef DEBUG
fprintf(stderr, "--record--\n");
#endif
enc->state = ZERO;
enc->curlen = 0;
}
if (in->rp == in->wp) {
if (in->eof) {
if (enc->state != END) {
err = savebuf(enc, in, out);
if (err) return err;
}
enc->state = END;
}
else
return fz_ioneedin;
}
c = *in->rp;
switch (enc->state)
{
case ZERO:
enc->state = ONE;
enc->run = 1;
enc->buf[0] = c;
break;
case ONE:
enc->state = DIFF;
enc->run = 2;
enc->buf[1] = c;
break;
case DIFF:
/* out of space */
if (enc->run == 128) {
err = putdiff(enc, in, out);
if (err) return err;
enc->state = ONE;
enc->run = 1;
enc->buf[0] = c;
}
/* run of three that are the same */
else if ((enc->run > 1) &&
(c == enc->buf[enc->run - 1]) &&
(c == enc->buf[enc->run - 2]))
{
if (enc->run >= 3) {
enc->run -= 2; /* skip prev two for diff run */
err = putdiff(enc, in, out);
if (err) return err;
}
enc->state = SAME;
enc->run = 3;
enc->buf[0] = c;
}
/* keep on collecting */
else {
enc->buf[enc->run++] = c;
}
break;
case SAME:
if (enc->run == 128 || c != enc->buf[0]) {
err = putsame(enc, in, out);
if (err) return err;
enc->state = ONE;
enc->run = 1;
enc->buf[0] = c;
}
else {
enc->run ++;
}
break;
case END:
err = puteod(enc, in, out);
if (err) return err;
out->eof = 1;
return fz_iodone;
}
in->rp ++;
enc->curlen ++;
}
}
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