libavformat/crc.c

   1 /*
   2  * CRC decoder (for codec/format testing)
   3  * Copyright (c) 2002 Fabrice Bellard.
   4  *
   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.
   9  *
  10  * This library is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * Lesser General Public License for more details.
  14  *
  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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  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
  36 unsigned long update_adler32(unsigned long adler, const uint8_t *buf, unsigned int len)
  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 #ifdef CONFIG_MUXERS
  60
  61 typedef struct CRCState {
  62     uint32_t crcval;
  63 } CRCState;
  64
  65 static int crc_write_header(struct AVFormatContext *s)
  66 {
  67     CRCState *crc = s->priv_data;
  68
  69     /* init CRC */
  70     crc->crcval = update_adler32(0, NULL, 0);
  71
  72     return 0;
  73 }
  74
  75 static int crc_write_packet(struct AVFormatContext *s, AVPacket *pkt)
  76 {
  77     CRCState *crc = s->priv_data;
  78     crc->crcval = update_adler32(crc->crcval, pkt->data, pkt->size);
  79     return 0;
  80 }
  81
  82 static int crc_write_trailer(struct AVFormatContext *s)
  83 {
  84     CRCState *crc = s->priv_data;
  85     char buf[64];
  86
  87     snprintf(buf, sizeof(buf), "CRC=0x%08x\n", crc->crcval);
  88     put_buffer(&s->pb, buf, strlen(buf));
  89     put_flush_packet(&s->pb);
  90     return 0;
  91 }
  92
  93 static int framecrc_write_packet(struct AVFormatContext *s, AVPacket *pkt)
  94 {
  95     uint32_t crc = update_adler32(0, pkt->data, pkt->size);
  96     char buf[256];
  97
  98     snprintf(buf, sizeof(buf), "%d, %"PRId64", %d, 0x%08x\n", pkt->stream_index, pkt->dts, pkt->size, crc);
  99     put_buffer(&s->pb, buf, strlen(buf));
 100     put_flush_packet(&s->pb);
 101     return 0;
 102 }
 103
 104 static AVOutputFormat crc_format = {
 105     "crc",
 106     "crc testing format",
 107     NULL,
 108     "",
 109     sizeof(CRCState),
 110     CODEC_ID_PCM_S16LE,
 111     CODEC_ID_RAWVIDEO,
 112     crc_write_header,
 113     crc_write_packet,
 114     crc_write_trailer,
 115 };
 116
 117 static AVOutputFormat framecrc_format = {
 118     "framecrc",
 119     "framecrc testing format",
 120     NULL,
 121     "",
 122     0,
 123     CODEC_ID_PCM_S16LE,
 124     CODEC_ID_RAWVIDEO,
 125     NULL,
 126     framecrc_write_packet,
 127     NULL,
 128 };
 129
 130 int crc_init(void)
 131 {
 132     av_register_output_format(&crc_format);
 133     av_register_output_format(&framecrc_format);
 134     return 0;
 135 }
 136 #endif /* CONFIG_MUXERS */