xref: /third_party/ffmpeg/libavcodec/bitstream.c (revision cabdff1a) 
1/*
2 * Common bit i/o utils
3 * Copyright (c) 2000, 2001 Fabrice Bellard
4 * Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at>
5 * Copyright (c) 2010 Loren Merritt
6 *
7 * alternative bitstream reader & writer by Michael Niedermayer <michaelni@gmx.at>
8 *
9 * This file is part of FFmpeg.
10 *
11 * FFmpeg is free software; you can redistribute it and/or
12 * modify it under the terms of the GNU Lesser General Public
13 * License as published by the Free Software Foundation; either
14 * version 2.1 of the License, or (at your option) any later version.
15 *
16 * FFmpeg is distributed in the hope that it will be useful,
17 * but WITHOUT ANY WARRANTY; without even the implied warranty of
18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
19 * Lesser General Public License for more details.
20 *
21 * You should have received a copy of the GNU Lesser General Public
22 * License along with FFmpeg; if not, write to the Free Software
23 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
24 */
25
26/**
27 * @file
28 * bitstream api.
29 */
30
31#include <stdint.h>
32#include <string.h>
33
34#include "config.h"
35#include "libavutil/avassert.h"
36#include "libavutil/intreadwrite.h"
37#include "put_bits.h"
38
39void ff_put_string(PutBitContext *pb, const char *string, int terminate_string)
40{
41    while (*string) {
42        put_bits(pb, 8, *string);
43        string++;
44    }
45    if (terminate_string)
46        put_bits(pb, 8, 0);
47}
48
49void ff_copy_bits(PutBitContext *pb, const uint8_t *src, int length)
50{
51    int words = length >> 4;
52    int bits  = length & 15;
53    int i;
54
55    if (length == 0)
56        return;
57
58    av_assert0(length <= put_bits_left(pb));
59
60    if (CONFIG_SMALL || words < 16 || put_bits_count(pb) & 7) {
61        for (i = 0; i < words; i++)
62            put_bits(pb, 16, AV_RB16(src + 2 * i));
63    } else {
64        for (i = 0; put_bits_count(pb) & 31; i++)
65            put_bits(pb, 8, src[i]);
66        flush_put_bits(pb);
67        memcpy(put_bits_ptr(pb), src + i, 2 * words - i);
68        skip_put_bytes(pb, 2 * words - i);
69    }
70
71    put_bits(pb, bits, AV_RB16(src + 2 * words) >> (16 - bits));
72}
73