added dummy crc output format for easy codec testing
[libav.git] / libav / crc.c
CommitLineData
1c098b2f
FB
1/*
2 * CRC decoder (for codec/format testing)
3 * Copyright (c) 2002 Gerard Lantau.
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation; either version 2 of the License, or
8 * (at your option) any later version.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
18 */
19#include "avformat.h"
20
21/* adler32.c -- compute the Adler-32 checksum of a data stream
22 * Copyright (C) 1995 Mark Adler
23 * For conditions of distribution and use, see copyright notice in zlib.h
24 */
25
26#define BASE 65521L /* largest prime smaller than 65536 */
27#define NMAX 5552
28/* NMAX is the largest n such that 255n(n+1)/2 + (n+1)(BASE-1) <= 2^32-1 */
29
30#define DO1(buf) {s1 += *buf++; s2 += s1;}
31#define DO2(buf) DO1(buf); DO1(buf);
32#define DO4(buf) DO2(buf); DO2(buf);
33#define DO8(buf) DO4(buf); DO4(buf);
34#define DO16(buf) DO8(buf); DO8(buf);
35
36static UINT32 adler32(UINT32 adler, UINT8 *buf, unsigned int len)
37{
38 unsigned long s1 = adler & 0xffff;
39 unsigned long s2 = (adler >> 16) & 0xffff;
40 int k;
41
42 if (buf == NULL) return 1L;
43
44 while (len > 0) {
45 k = len < NMAX ? len : NMAX;
46 len -= k;
47 while (k >= 16) {
48 DO16(buf);
49 k -= 16;
50 }
51 if (k != 0) do {
52 DO1(buf);
53 } while (--k);
54 s1 %= BASE;
55 s2 %= BASE;
56 }
57 return (s2 << 16) | s1;
58}
59
60typedef struct CRCState {
61 UINT32 crcval;
62} CRCState;
63
64/* simple formats */
65static int crc_write_header(struct AVFormatContext *s)
66{
67 CRCState *crc;
68 crc = av_malloc(sizeof(CRCState));
69 if (!crc)
70 return -1;
71 s->priv_data = crc;
72
73 /* init CRC */
74 crc->crcval = adler32(0, NULL, 0);
75
76 return 0;
77}
78
79static int crc_write_packet(struct AVFormatContext *s,
80 int stream_index,
81 unsigned char *buf, int size, int force_pts)
82{
83 CRCState *crc = s->priv_data;
84 crc->crcval = adler32(crc->crcval, buf, size);
85 return 0;
86}
87
88static int crc_write_trailer(struct AVFormatContext *s)
89{
90 CRCState *crc = s->priv_data;
91 char buf[64];
92
93 snprintf(buf, sizeof(buf), "CRC=%08x\n", crc->crcval);
94 put_buffer(&s->pb, buf, strlen(buf));
95 put_flush_packet(&s->pb);
96 return 0;
97}
98
99AVFormat crc_format = {
100 "crc",
101 "crc testing format",
102 NULL,
103 "",
104 CODEC_ID_PCM_S16LE,
105 CODEC_ID_RAWVIDEO,
106 crc_write_header,
107 crc_write_packet,
108 crc_write_trailer,
109};