diff options
Diffstat (limited to 'filter/rle.c')
| -rw-r--r-- | filter/rle.c | 238 |
1 files changed, 238 insertions, 0 deletions
diff --git a/filter/rle.c b/filter/rle.c new file mode 100644 index 00000000..0e611918 --- /dev/null +++ b/filter/rle.c @@ -0,0 +1,238 @@ +#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_freerle(fz_filter *enc) +{ + fz_free(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 ++; + + } +} + |