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/*
* 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);
av_free(crc);
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,
};
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