mirror of
https://git.ffmpeg.org/ffmpeg.git
synced 2024-12-29 19:02:21 +00:00
156 lines
3.8 KiB
C
156 lines
3.8 KiB
C
/*
|
|
* 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;
|
|
|
|
/**
|
|
* Invert a rational.
|
|
* @param q value
|
|
* @return 1 / q
|
|
*/
|
|
static av_always_inline AVRational av_inv_q(AVRational q)
|
|
{
|
|
AVRational r = { q.den, q.num };
|
|
return r;
|
|
}
|
|
|
|
/**
|
|
* 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 */
|