/usr/include/libavutil/rational.h is in libavutil-dev 4:0.8.1-0ubuntu1.
This file is owned by root:root, with mode 0o644.
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* rational numbers
* Copyright (c) 2003 Michael Niedermayer <michaelni@gmx.at>
*
* This file is part of Libav.
*
* Libav is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* Libav is distributed in the hope that it will be useful,
* 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
* License along with Libav; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @file
* rational numbers
* @author Michael Niedermayer <michaelni@gmx.at>
*/
#ifndef AVUTIL_RATIONAL_H
#define AVUTIL_RATIONAL_H
#include <stdint.h>
#include <limits.h>
#include "attributes.h"
/**
* @addtogroup lavu_math
* @{
*/
/**
* rational number numerator/denominator
*/
typedef struct AVRational{
int num; ///< numerator
int den; ///< denominator
} AVRational;
/**
* Compare two rationals.
* @param a first rational
* @param b second rational
* @return 0 if a==b, 1 if a>b, -1 if a<b, and INT_MIN if one of the
* values is of the form 0/0
*/
static inline int av_cmp_q(AVRational a, AVRational b){
const int64_t tmp= a.num * (int64_t)b.den - b.num * (int64_t)a.den;
if(tmp) return ((tmp ^ a.den ^ b.den)>>63)|1;
else if(b.den && a.den) return 0;
else if(a.num && b.num) return (a.num>>31) - (b.num>>31);
else return INT_MIN;
}
/**
* Convert rational to double.
* @param a rational to convert
* @return (double) a
*/
static inline double av_q2d(AVRational a){
return a.num / (double) a.den;
}
/**
* Reduce a fraction.
* This is useful for framerate calculations.
* @param dst_num destination numerator
* @param dst_den destination denominator
* @param num source numerator
* @param den source denominator
* @param max the maximum allowed for dst_num & dst_den
* @return 1 if exact, 0 otherwise
*/
int av_reduce(int *dst_num, int *dst_den, int64_t num, int64_t den, int64_t max);
/**
* Multiply two rationals.
* @param b first rational
* @param c second rational
* @return b*c
*/
AVRational av_mul_q(AVRational b, AVRational c) av_const;
/**
* Divide one rational by another.
* @param b first rational
* @param c second rational
* @return b/c
*/
AVRational av_div_q(AVRational b, AVRational c) av_const;
/**
* Add two rationals.
* @param b first rational
* @param c second rational
* @return b+c
*/
AVRational av_add_q(AVRational b, AVRational c) av_const;
/**
* Subtract one rational from another.
* @param b first rational
* @param c second rational
* @return b-c
*/
AVRational av_sub_q(AVRational b, AVRational c) av_const;
/**
* Convert a double precision floating point number to a rational.
* inf is expressed as {1,0} or {-1,0} depending on the sign.
*
* @param d double to convert
* @param max the maximum allowed numerator and denominator
* @return (AVRational) d
*/
AVRational av_d2q(double d, int max) av_const;
/**
* @return 1 if q1 is nearer to q than q2, -1 if q2 is nearer
* than q1, 0 if they have the same distance.
*/
int av_nearer_q(AVRational q, AVRational q1, AVRational q2);
/**
* Find the nearest value in q_list to q.
* @param q_list an array of rationals terminated by {0, 0}
* @return the index of the nearest value found in the array
*/
int av_find_nearest_q_idx(AVRational q, const AVRational* q_list);
/**
* @}
*/
#endif /* AVUTIL_RATIONAL_H */
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