mirror of
https://git.ffmpeg.org/ffmpeg.git
synced 2024-12-26 17:32:06 +00:00
110 lines
2.8 KiB
C
110 lines
2.8 KiB
C
/*
|
|
* CRC decoder (for codec/format testing)
|
|
* Copyright (c) 2002 Gerard Lantau.
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License as published by
|
|
* the Free Software Foundation; either version 2 of the License, or
|
|
* (at your option) any later version.
|
|
*
|
|
* This program is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
* GNU General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License
|
|
* along with this program; if not, write to the Free Software
|
|
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
|
|
*/
|
|
#include "avformat.h"
|
|
|
|
/* adler32.c -- compute the Adler-32 checksum of a data stream
|
|
* Copyright (C) 1995 Mark Adler
|
|
* For conditions of distribution and use, see copyright notice in zlib.h
|
|
*/
|
|
|
|
#define BASE 65521L /* largest prime smaller than 65536 */
|
|
#define NMAX 5552
|
|
/* NMAX is the largest n such that 255n(n+1)/2 + (n+1)(BASE-1) <= 2^32-1 */
|
|
|
|
#define DO1(buf) {s1 += *buf++; s2 += s1;}
|
|
#define DO2(buf) DO1(buf); DO1(buf);
|
|
#define DO4(buf) DO2(buf); DO2(buf);
|
|
#define DO8(buf) DO4(buf); DO4(buf);
|
|
#define DO16(buf) DO8(buf); DO8(buf);
|
|
|
|
static UINT32 adler32(UINT32 adler, UINT8 *buf, unsigned int len)
|
|
{
|
|
unsigned long s1 = adler & 0xffff;
|
|
unsigned long s2 = (adler >> 16) & 0xffff;
|
|
int k;
|
|
|
|
if (buf == NULL) return 1L;
|
|
|
|
while (len > 0) {
|
|
k = len < NMAX ? len : NMAX;
|
|
len -= k;
|
|
while (k >= 16) {
|
|
DO16(buf);
|
|
k -= 16;
|
|
}
|
|
if (k != 0) do {
|
|
DO1(buf);
|
|
} while (--k);
|
|
s1 %= BASE;
|
|
s2 %= BASE;
|
|
}
|
|
return (s2 << 16) | s1;
|
|
}
|
|
|
|
typedef struct CRCState {
|
|
UINT32 crcval;
|
|
} CRCState;
|
|
|
|
/* simple formats */
|
|
static int crc_write_header(struct AVFormatContext *s)
|
|
{
|
|
CRCState *crc;
|
|
crc = av_malloc(sizeof(CRCState));
|
|
if (!crc)
|
|
return -1;
|
|
s->priv_data = crc;
|
|
|
|
/* init CRC */
|
|
crc->crcval = adler32(0, NULL, 0);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int crc_write_packet(struct AVFormatContext *s,
|
|
int stream_index,
|
|
unsigned char *buf, int size, int force_pts)
|
|
{
|
|
CRCState *crc = s->priv_data;
|
|
crc->crcval = adler32(crc->crcval, buf, size);
|
|
return 0;
|
|
}
|
|
|
|
static int crc_write_trailer(struct AVFormatContext *s)
|
|
{
|
|
CRCState *crc = s->priv_data;
|
|
char buf[64];
|
|
|
|
snprintf(buf, sizeof(buf), "CRC=%08x\n", crc->crcval);
|
|
put_buffer(&s->pb, buf, strlen(buf));
|
|
put_flush_packet(&s->pb);
|
|
return 0;
|
|
}
|
|
|
|
AVFormat crc_format = {
|
|
"crc",
|
|
"crc testing format",
|
|
NULL,
|
|
"",
|
|
CODEC_ID_PCM_S16LE,
|
|
CODEC_ID_RAWVIDEO,
|
|
crc_write_header,
|
|
crc_write_packet,
|
|
crc_write_trailer,
|
|
};
|