mirror of https://github.com/FFmpeg/FFmpeg.git
Originally committed as revision 525 to svn://svn.ffmpeg.org/ffmpeg/trunkpull/126/head
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/*
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* CRC decoder (for codec/format testing) |
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* Copyright (c) 2002 Gerard Lantau. |
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* |
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* This program is free software; you can redistribute it and/or modify |
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* it under the terms of the GNU General Public License as published by |
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* the Free Software Foundation; either version 2 of the License, or |
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* (at your option) any later version. |
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* |
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* This program is distributed in the hope that it will be useful, |
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* but WITHOUT ANY WARRANTY; without even the implied warranty of |
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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* GNU General Public License for more details. |
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* |
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* You should have received a copy of the GNU General Public License |
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* along with this program; if not, write to the Free Software |
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. |
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*/ |
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#include "avformat.h" |
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/* adler32.c -- compute the Adler-32 checksum of a data stream
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* Copyright (C) 1995 Mark Adler |
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* For conditions of distribution and use, see copyright notice in zlib.h |
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*/ |
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#define BASE 65521L /* largest prime smaller than 65536 */ |
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#define NMAX 5552 |
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/* NMAX is the largest n such that 255n(n+1)/2 + (n+1)(BASE-1) <= 2^32-1 */ |
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#define DO1(buf) {s1 += *buf++; s2 += s1;} |
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#define DO2(buf) DO1(buf); DO1(buf); |
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#define DO4(buf) DO2(buf); DO2(buf); |
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#define DO8(buf) DO4(buf); DO4(buf); |
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#define DO16(buf) DO8(buf); DO8(buf); |
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static UINT32 adler32(UINT32 adler, UINT8 *buf, unsigned int len) |
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{ |
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unsigned long s1 = adler & 0xffff; |
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unsigned long s2 = (adler >> 16) & 0xffff; |
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int k; |
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if (buf == NULL) return 1L; |
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while (len > 0) { |
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k = len < NMAX ? len : NMAX; |
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len -= k; |
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while (k >= 16) { |
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DO16(buf); |
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k -= 16; |
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} |
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if (k != 0) do { |
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DO1(buf); |
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} while (--k); |
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s1 %= BASE; |
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s2 %= BASE; |
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} |
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return (s2 << 16) | s1; |
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} |
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typedef struct CRCState { |
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UINT32 crcval; |
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} CRCState; |
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/* simple formats */ |
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static int crc_write_header(struct AVFormatContext *s) |
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{ |
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CRCState *crc; |
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crc = av_malloc(sizeof(CRCState)); |
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if (!crc) |
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return -1; |
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s->priv_data = crc; |
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/* init CRC */ |
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crc->crcval = adler32(0, NULL, 0); |
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return 0; |
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} |
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static int crc_write_packet(struct AVFormatContext *s,
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int stream_index, |
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unsigned char *buf, int size, int force_pts) |
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{ |
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CRCState *crc = s->priv_data; |
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crc->crcval = adler32(crc->crcval, buf, size); |
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return 0; |
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} |
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static int crc_write_trailer(struct AVFormatContext *s) |
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{ |
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CRCState *crc = s->priv_data; |
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char buf[64]; |
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snprintf(buf, sizeof(buf), "CRC=%08x\n", crc->crcval); |
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put_buffer(&s->pb, buf, strlen(buf)); |
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put_flush_packet(&s->pb); |
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return 0; |
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} |
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AVFormat crc_format = { |
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"crc", |
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"crc testing format", |
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NULL, |
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"", |
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CODEC_ID_PCM_S16LE, |
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CODEC_ID_RAWVIDEO, |
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crc_write_header, |
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crc_write_packet, |
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crc_write_trailer, |
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}; |
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