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1c098b2f FB |
1 | /* |
2 | * CRC decoder (for codec/format testing) | |
19720f15 | 3 | * Copyright (c) 2002 Fabrice Bellard. |
1c098b2f | 4 | * |
19720f15 FB |
5 | * This library is free software; you can redistribute it and/or |
6 | * modify it under the terms of the GNU Lesser General Public | |
7 | * License as published by the Free Software Foundation; either | |
8 | * version 2 of the License, or (at your option) any later version. | |
1c098b2f | 9 | * |
19720f15 | 10 | * This library is distributed in the hope that it will be useful, |
1c098b2f | 11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
19720f15 FB |
12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
13 | * Lesser General Public License for more details. | |
1c098b2f | 14 | * |
19720f15 FB |
15 | * You should have received a copy of the GNU Lesser General Public |
16 | * License along with this library; if not, write to the Free Software | |
17 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA | |
1c098b2f FB |
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 | ||
ee9f36a8 | 36 | unsigned long update_adler32(unsigned long adler, const uint8_t *buf, unsigned int len) |
1c098b2f FB |
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 | ||
60 | typedef struct CRCState { | |
0c1a9eda | 61 | uint32_t crcval; |
1c098b2f FB |
62 | } CRCState; |
63 | ||
1c098b2f FB |
64 | static int crc_write_header(struct AVFormatContext *s) |
65 | { | |
c9a65ca8 FB |
66 | CRCState *crc = s->priv_data; |
67 | ||
1c098b2f | 68 | /* init CRC */ |
ee9f36a8 | 69 | crc->crcval = update_adler32(0, NULL, 0); |
1c098b2f FB |
70 | |
71 | return 0; | |
72 | } | |
73 | ||
e928649b | 74 | static int crc_write_packet(struct AVFormatContext *s, AVPacket *pkt) |
1c098b2f FB |
75 | { |
76 | CRCState *crc = s->priv_data; | |
e928649b | 77 | crc->crcval = update_adler32(crc->crcval, pkt->data, pkt->size); |
1c098b2f FB |
78 | return 0; |
79 | } | |
80 | ||
81 | static int crc_write_trailer(struct AVFormatContext *s) | |
82 | { | |
83 | CRCState *crc = s->priv_data; | |
84 | char buf[64]; | |
85 | ||
86 | snprintf(buf, sizeof(buf), "CRC=%08x\n", crc->crcval); | |
87 | put_buffer(&s->pb, buf, strlen(buf)); | |
88 | put_flush_packet(&s->pb); | |
89 | return 0; | |
90 | } | |
91 | ||
c18a2692 | 92 | static AVOutputFormat crc_format = { |
1c098b2f FB |
93 | "crc", |
94 | "crc testing format", | |
95 | NULL, | |
96 | "", | |
c9a65ca8 | 97 | sizeof(CRCState), |
1c098b2f FB |
98 | CODEC_ID_PCM_S16LE, |
99 | CODEC_ID_RAWVIDEO, | |
100 | crc_write_header, | |
101 | crc_write_packet, | |
102 | crc_write_trailer, | |
103 | }; | |
c9a65ca8 FB |
104 | |
105 | int crc_init(void) | |
106 | { | |
107 | av_register_output_format(&crc_format); | |
108 | return 0; | |
109 | } |