Add a comment that explains why this header lacks multiple inclusion guards.
[libav.git] / libavutil / mathematics.h
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1/*
2 * copyright (c) 2005 Michael Niedermayer <michaelni@gmx.at>
3 *
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4 * This file is part of FFmpeg.
5 *
6 * FFmpeg is free software; you can redistribute it and/or
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7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
b78e7197 9 * version 2.1 of the License, or (at your option) any later version.
04d7f601 10 *
b78e7197 11 * FFmpeg is distributed in the hope that it will be useful,
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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
b78e7197 17 * License along with FFmpeg; if not, write to the Free Software
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18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19 */
20
c11c2bc2
AS
21#ifndef MATHEMATICS_H
22#define MATHEMATICS_H
23
24#include "rational.h"
25
26enum AVRounding {
27 AV_ROUND_ZERO = 0, ///< round toward zero
28 AV_ROUND_INF = 1, ///< round away from zero
29 AV_ROUND_DOWN = 2, ///< round toward -infinity
30 AV_ROUND_UP = 3, ///< round toward +infinity
31 AV_ROUND_NEAR_INF = 5, ///< round to nearest and halfway cases away from zero
32};
33
34/**
35 * rescale a 64bit integer with rounding to nearest.
36 * a simple a*b/c isn't possible as it can overflow
37 */
38int64_t av_rescale(int64_t a, int64_t b, int64_t c);
39
40/**
41 * rescale a 64bit integer with specified rounding.
42 * a simple a*b/c isn't possible as it can overflow
43 */
44int64_t av_rescale_rnd(int64_t a, int64_t b, int64_t c, enum AVRounding);
45
46/**
47 * rescale a 64bit integer by 2 rational numbers.
48 */
49int64_t av_rescale_q(int64_t a, AVRational bq, AVRational cq);
50
51#endif /* MATHEMATICS_H */