mathematics.h 3.5 KB
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/*
 * copyright (c) 2005 Michael Niedermayer <michaelni@gmx.at>
 *
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 * This file is part of Libav.
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 *
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 * Libav is free software; you can redistribute it and/or
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 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
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 * version 2.1 of the License, or (at your option) any later version.
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 *
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 * Libav is distributed in the hope that it will be useful,
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 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
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 * License along with Libav; if not, write to the Free Software
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 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

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#ifndef AVUTIL_MATHEMATICS_H
#define AVUTIL_MATHEMATICS_H
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#include <stdint.h>
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#include <math.h>
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#include "attributes.h"
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#include "rational.h"

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#ifndef M_E
#define M_E            2.7182818284590452354   /* e */
#endif
#ifndef M_LN2
#define M_LN2          0.69314718055994530942  /* log_e 2 */
#endif
#ifndef M_LN10
#define M_LN10         2.30258509299404568402  /* log_e 10 */
#endif
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#ifndef M_LOG2_10
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#define M_LOG2_10      3.32192809488736234787  /* log_2 10 */
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#endif
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#ifndef M_PHI
#define M_PHI          1.61803398874989484820   /* phi / golden ratio */
#endif
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#ifndef M_PI
#define M_PI           3.14159265358979323846  /* pi */
#endif
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#ifndef M_SQRT1_2
#define M_SQRT1_2      0.70710678118654752440  /* 1/sqrt(2) */
#endif
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#ifndef M_SQRT2
#define M_SQRT2        1.41421356237309504880  /* sqrt(2) */
#endif
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#ifndef NAN
#define NAN            (0.0/0.0)
#endif
#ifndef INFINITY
#define INFINITY       (1.0/0.0)
#endif
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enum AVRounding {
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    AV_ROUND_ZERO     = 0, ///< Round toward zero.
    AV_ROUND_INF      = 1, ///< Round away from zero.
    AV_ROUND_DOWN     = 2, ///< Round toward -infinity.
    AV_ROUND_UP       = 3, ///< Round toward +infinity.
    AV_ROUND_NEAR_INF = 5, ///< Round to nearest and halfway cases away from zero.
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};

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/**
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 * Return the greatest common divisor of a and b.
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 * If both a and b are 0 or either or both are <0 then behavior is
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 * undefined.
 */
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int64_t av_const av_gcd(int64_t a, int64_t b);

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/**
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 * Rescale a 64-bit integer with rounding to nearest.
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 * A simple a*b/c isn't possible as it can overflow.
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 */
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int64_t av_rescale(int64_t a, int64_t b, int64_t c) av_const;
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/**
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 * Rescale a 64-bit integer with specified rounding.
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 * A simple a*b/c isn't possible as it can overflow.
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 */
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int64_t av_rescale_rnd(int64_t a, int64_t b, int64_t c, enum AVRounding) av_const;
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/**
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 * Rescale a 64-bit integer by 2 rational numbers.
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 */
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int64_t av_rescale_q(int64_t a, AVRational bq, AVRational cq) av_const;
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/**
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 * Compare 2 timestamps each in its own timebases.
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 * The result of the function is undefined if one of the timestamps
 * is outside the int64_t range when represented in the others timebase.
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 * @return -1 if ts_a is before ts_b, 1 if ts_a is after ts_b or 0 if they represent the same position
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 */
int av_compare_ts(int64_t ts_a, AVRational tb_a, int64_t ts_b, AVRational tb_b);

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/**
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 * Compare 2 integers modulo mod.
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 * That is we compare integers a and b for which only the least
 * significant log2(mod) bits are known.
 *
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 * @param mod must be a power of 2
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 * @return a negative value if a is smaller than b
 *         a positive value if a is greater than b
 *         0                if a equals          b
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 */
int64_t av_compare_mod(uint64_t a, uint64_t b, uint64_t mod);
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#endif /* AVUTIL_MATHEMATICS_H */