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
31int 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}
58