FFmpeg
startcode.c
Go to the documentation of this file.
1 /*
2  * Copyright (c) 2003-2010 Michael Niedermayer <michaelni@gmx.at>
3  *
4  * This file is part of FFmpeg.
5  *
6  * FFmpeg is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU Lesser General Public
8  * License as published by the Free Software Foundation; either
9  * version 2.1 of the License, or (at your option) any later version.
10  *
11  * FFmpeg is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14  * Lesser General Public License for more details.
15  *
16  * You should have received a copy of the GNU Lesser General Public
17  * License along with FFmpeg; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19  */
20 
21 /**
22  * @file
23  * Accelerated start code search function for start codes common to
24  * MPEG-1/2/4 video, VC-1, H.264/5
25  * @author Michael Niedermayer <michaelni@gmx.at>
26  */
27 
28 #include "libavutil/intreadwrite.h"
29 #include "startcode.h"
30 #include "config.h"
31 
32 int ff_startcode_find_candidate_c(const uint8_t *buf, int size)
33 {
34  int i = 0;
35 #if HAVE_FAST_UNALIGNED
36  /* we check i < size instead of i + 3 / 7 because it is
37  * simpler and there must be AV_INPUT_BUFFER_PADDING_SIZE
38  * bytes at the end.
39  */
40 #if HAVE_FAST_64BIT
41  while (i < size &&
42  !((~AV_RN64(buf + i) &
43  (AV_RN64(buf + i) - 0x0101010101010101ULL)) &
44  0x8080808080808080ULL))
45  i += 8;
46 #else
47  while (i < size &&
48  !((~AV_RN32(buf + i) &
49  (AV_RN32(buf + i) - 0x01010101U)) &
50  0x80808080U))
51  i += 4;
52 #endif
53 #endif
54  for (; i < size; i++)
55  if (!buf[i])
56  break;
57  return i;
58 }
AV_RN64
#define AV_RN64(p)
Definition: intreadwrite.h:362
ff_startcode_find_candidate_c
int ff_startcode_find_candidate_c(const uint8_t *buf, int size)
Definition: startcode.c:32
intreadwrite.h
AV_RN32
#define AV_RN32(p)
Definition: intreadwrite.h:358
startcode.h
size
int size
Definition: twinvq_data.h:10344
i
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:256