1 /*
2 * RLE encoder
3 * Copyright (c) 2007 Bobby Bingham
4 *
5 * This file is part of FFmpeg.
6 *
7 * FFmpeg is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
11 *
12 * FFmpeg is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
16 *
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 */
21
22 #include <string.h>
23
25
27
29 {
31 int count = 1;
32
33 for (
pos = start + bpp; count <
FFMIN(127,
len);
pos += bpp, count++) {
34 if (same != !memcmp(
pos - bpp,
pos, bpp)) {
35 if (!same) {
36 /* if bpp == 1, then 0 1 1 0 is more efficiently encoded as a
37 * single raw block of pixels. For larger bpp, RLE is as good
38 * or better */
40 continue;
41
42 /* if RLE can encode the next block better than as a raw block,
43 * back up and leave _all_ the identical pixels for RLE */
44 count--;
45 }
46 break;
47 }
48 }
49
50 return count;
51 }
52
54 int w,
int add_rep,
int xor_rep,
int add_raw,
int xor_raw)
55 {
56 int count, x;
57 uint8_t *
out = outbuf;
58
59 for (x = 0; x <
w; x += count) {
60 /* see if we can encode the next set of pixels with RLE */
63 return -1;
64
65 *
out++ = (count ^ xor_rep) + add_rep;
66 memcpy(
out, ptr, bpp);
68 } else {
69 /* fall back on uncompressed */
72 return -1;
73
74 *
out++ = (count ^ xor_raw) + add_raw;
75 memcpy(
out, ptr, bpp * count);
77 }
78
79 ptr += count * bpp;
80 }
81
83 }