ffmpeg / libavformat / crc.c @ 5509bffa
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/*
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* CRC decoder (for codec/format testing)
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* Copyright (c) 2002 Fabrice Bellard.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library 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 GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 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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unsigned long update_adler32(unsigned long adler, const uint8_t *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_t crcval; |
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} CRCState; |
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static int crc_write_header(struct AVFormatContext *s) |
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{ |
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CRCState *crc = s->priv_data; |
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/* init CRC */
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crc->crcval = update_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, AVPacket *pkt) |
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{ |
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CRCState *crc = s->priv_data; |
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crc->crcval = update_adler32(crc->crcval, pkt->data, pkt->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=0x%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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static int framecrc_write_packet(struct AVFormatContext *s, AVPacket *pkt) |
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{ |
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uint32_t crc = update_adler32(0, pkt->data, pkt->size);
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char buf[256]; |
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snprintf(buf, sizeof(buf), "%d, %"PRId64", %d, 0x%08x\n", pkt->stream_index, pkt->dts, pkt->size, crc); |
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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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static AVOutputFormat 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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sizeof(CRCState),
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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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static AVOutputFormat framecrc_format = {
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"framecrc",
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"framecrc testing format",
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NULL,
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"",
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0,
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CODEC_ID_PCM_S16LE, |
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CODEC_ID_RAWVIDEO, |
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NULL,
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framecrc_write_packet, |
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NULL,
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}; |
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int crc_init(void) |
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{ |
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av_register_output_format(&crc_format); |
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av_register_output_format(&framecrc_format); |
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return 0; |
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} |