| 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 | } |