blob: 9efdffe8c6628e2d0e491f8cb641d56ad266c5db
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 "startcode.h" |
29 | #include "config.h" |
30 | |
31 | int ff_startcode_find_candidate_c(const uint8_t *buf, int size) |
32 | { |
33 | int i = 0; |
34 | #if HAVE_FAST_UNALIGNED |
35 | /* we check i < size instead of i + 3 / 7 because it is |
36 | * simpler and there must be AV_INPUT_BUFFER_PADDING_SIZE |
37 | * bytes at the end. |
38 | */ |
39 | #if HAVE_FAST_64BIT |
40 | while (i < size && |
41 | !((~*(const uint64_t *)(buf + i) & |
42 | (*(const uint64_t *)(buf + i) - 0x0101010101010101ULL)) & |
43 | 0x8080808080808080ULL)) |
44 | i += 8; |
45 | #else |
46 | while (i < size && |
47 | !((~*(const uint32_t *)(buf + i) & |
48 | (*(const uint32_t *)(buf + i) - 0x01010101U)) & |
49 | 0x80808080U)) |
50 | i += 4; |
51 | #endif |
52 | #endif |
53 | for (; i < size; i++) |
54 | if (!buf[i]) |
55 | break; |
56 | return i; |
57 | } |
58 |