3 * Copyright (c) 2003 Michael Niedermayer <michaelni@gmx.at>
5 * This library is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU Lesser General Public
7 * License as published by the Free Software Foundation; either
8 * version 2 of the License, or (at your option) any later version.
10 * This library is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * Lesser General Public License for more details.
15 * You should have received a copy of the GNU Lesser General Public
16 * License along with this library; if not, write to the Free Software
17 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
24 * @author Michael Niedermayer <michaelni@gmx.at>
31 #include "mathematics.h"
34 int av_reduce(int *dst_nom, int *dst_den, int64_t nom, int64_t den, int64_t max){
35 AVRational a0={0,1}, a1={1,0};
36 int sign= (nom<0) ^ (den<0);
37 int64_t gcd= ff_gcd(ABS(nom), ABS(den));
41 if(nom<=max && den<=max){
42 a1= (AVRational){nom, den};
47 int64_t x = nom / den;
48 int64_t next_den= nom - den*x;
49 int64_t a2n= x*a1.num + a0.num;
50 int64_t a2d= x*a1.den + a0.den;
52 if(a2n > max || a2d > max) break;
55 a1= (AVRational){a2n, a2d};
59 assert(ff_gcd(a1.num, a1.den) == 1);
61 *dst_nom = sign ? -a1.num : a1.num;
70 AVRational av_mul_q(AVRational b, AVRational c){
71 av_reduce(&b.num, &b.den, b.num * (int64_t)c.num, b.den * (int64_t)c.den, INT_MAX);
78 AVRational av_div_q(AVRational b, AVRational c){
79 av_reduce(&b.num, &b.den, b.num * (int64_t)c.den, b.den * (int64_t)c.num, INT_MAX);
86 AVRational av_add_q(AVRational b, AVRational c){
87 av_reduce(&b.num, &b.den, b.num * (int64_t)c.den + c.num * (int64_t)b.den, b.den * (int64_t)c.den, INT_MAX);
94 AVRational av_sub_q(AVRational b, AVRational c){
95 av_reduce(&b.num, &b.den, b.num * (int64_t)c.den - c.num * (int64_t)b.den, b.den * (int64_t)c.den, INT_MAX);
100 * Converts a double precission floating point number to a AVRational.
101 * @param max the maximum allowed numerator and denominator
103 AVRational av_d2q(double d, int max){
105 int exponent= FFMAX( (int)(log(ABS(d) + 1e-20)/log(2)), 0);
106 int64_t den= 1LL << (61 - exponent);
107 av_reduce(&a.num, &a.den, (int64_t)(d * den + 0.5), den, max);