yading@11: /*
yading@11:  * rational numbers
yading@11:  * Copyright (c) 2003 Michael Niedermayer <michaelni@gmx.at>
yading@11:  *
yading@11:  * This file is part of FFmpeg.
yading@11:  *
yading@11:  * FFmpeg is free software; you can redistribute it and/or
yading@11:  * modify it under the terms of the GNU Lesser General Public
yading@11:  * License as published by the Free Software Foundation; either
yading@11:  * version 2.1 of the License, or (at your option) any later version.
yading@11:  *
yading@11:  * FFmpeg is distributed in the hope that it will be useful,
yading@11:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
yading@11:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
yading@11:  * Lesser General Public License for more details.
yading@11:  *
yading@11:  * You should have received a copy of the GNU Lesser General Public
yading@11:  * License along with FFmpeg; if not, write to the Free Software
yading@11:  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
yading@11:  */
yading@11: 
yading@11: /**
yading@11:  * @file
yading@11:  * rational numbers
yading@11:  * @author Michael Niedermayer <michaelni@gmx.at>
yading@11:  */
yading@11: 
yading@11: #ifndef AVUTIL_RATIONAL_H
yading@11: #define AVUTIL_RATIONAL_H
yading@11: 
yading@11: #include <stdint.h>
yading@11: #include <limits.h>
yading@11: #include "attributes.h"
yading@11: 
yading@11: /**
yading@11:  * @addtogroup lavu_math
yading@11:  * @{
yading@11:  */
yading@11: 
yading@11: /**
yading@11:  * rational number numerator/denominator
yading@11:  */
yading@11: typedef struct AVRational{
yading@11:     int num; ///< numerator
yading@11:     int den; ///< denominator
yading@11: } AVRational;
yading@11: 
yading@11: /**
yading@11:  * Compare two rationals.
yading@11:  * @param a first rational
yading@11:  * @param b second rational
yading@11:  * @return 0 if a==b, 1 if a>b, -1 if a<b, and INT_MIN if one of the
yading@11:  * values is of the form 0/0
yading@11:  */
yading@11: static inline int av_cmp_q(AVRational a, AVRational b){
yading@11:     const int64_t tmp= a.num * (int64_t)b.den - b.num * (int64_t)a.den;
yading@11: 
yading@11:     if(tmp) return ((tmp ^ a.den ^ b.den)>>63)|1;
yading@11:     else if(b.den && a.den) return 0;
yading@11:     else if(a.num && b.num) return (a.num>>31) - (b.num>>31);
yading@11:     else                    return INT_MIN;
yading@11: }
yading@11: 
yading@11: /**
yading@11:  * Convert rational to double.
yading@11:  * @param a rational to convert
yading@11:  * @return (double) a
yading@11:  */
yading@11: static inline double av_q2d(AVRational a){
yading@11:     return a.num / (double) a.den;
yading@11: }
yading@11: 
yading@11: /**
yading@11:  * Reduce a fraction.
yading@11:  * This is useful for framerate calculations.
yading@11:  * @param dst_num destination numerator
yading@11:  * @param dst_den destination denominator
yading@11:  * @param num source numerator
yading@11:  * @param den source denominator
yading@11:  * @param max the maximum allowed for dst_num & dst_den
yading@11:  * @return 1 if exact, 0 otherwise
yading@11:  */
yading@11: int av_reduce(int *dst_num, int *dst_den, int64_t num, int64_t den, int64_t max);
yading@11: 
yading@11: /**
yading@11:  * Multiply two rationals.
yading@11:  * @param b first rational
yading@11:  * @param c second rational
yading@11:  * @return b*c
yading@11:  */
yading@11: AVRational av_mul_q(AVRational b, AVRational c) av_const;
yading@11: 
yading@11: /**
yading@11:  * Divide one rational by another.
yading@11:  * @param b first rational
yading@11:  * @param c second rational
yading@11:  * @return b/c
yading@11:  */
yading@11: AVRational av_div_q(AVRational b, AVRational c) av_const;
yading@11: 
yading@11: /**
yading@11:  * Add two rationals.
yading@11:  * @param b first rational
yading@11:  * @param c second rational
yading@11:  * @return b+c
yading@11:  */
yading@11: AVRational av_add_q(AVRational b, AVRational c) av_const;
yading@11: 
yading@11: /**
yading@11:  * Subtract one rational from another.
yading@11:  * @param b first rational
yading@11:  * @param c second rational
yading@11:  * @return b-c
yading@11:  */
yading@11: AVRational av_sub_q(AVRational b, AVRational c) av_const;
yading@11: 
yading@11: /**
yading@11:  * Invert a rational.
yading@11:  * @param q value
yading@11:  * @return 1 / q
yading@11:  */
yading@11: static av_always_inline AVRational av_inv_q(AVRational q)
yading@11: {
yading@11:     AVRational r = { q.den, q.num };
yading@11:     return r;
yading@11: }
yading@11: 
yading@11: /**
yading@11:  * Convert a double precision floating point number to a rational.
yading@11:  * inf is expressed as {1,0} or {-1,0} depending on the sign.
yading@11:  *
yading@11:  * @param d double to convert
yading@11:  * @param max the maximum allowed numerator and denominator
yading@11:  * @return (AVRational) d
yading@11:  */
yading@11: AVRational av_d2q(double d, int max) av_const;
yading@11: 
yading@11: /**
yading@11:  * @return 1 if q1 is nearer to q than q2, -1 if q2 is nearer
yading@11:  * than q1, 0 if they have the same distance.
yading@11:  */
yading@11: int av_nearer_q(AVRational q, AVRational q1, AVRational q2);
yading@11: 
yading@11: /**
yading@11:  * Find the nearest value in q_list to q.
yading@11:  * @param q_list an array of rationals terminated by {0, 0}
yading@11:  * @return the index of the nearest value found in the array
yading@11:  */
yading@11: int av_find_nearest_q_idx(AVRational q, const AVRational* q_list);
yading@11: 
yading@11: /**
yading@11:  * @}
yading@11:  */
yading@11: 
yading@11: #endif /* AVUTIL_RATIONAL_H */