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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 FF_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 | } |