/* * Rational numbers * Copyright (c) 2003 Michael Niedermayer <michaelni@gmx.at> * * This file is part of FFmpeg. * * FFmpeg 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. * * FFmpeg 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 FFmpeg; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ /** * @file rational.c * Rational numbers * @author Michael Niedermayer <michaelni@gmx.at> */ //#include <math.h> #include <limits.h> #include "common.h" #include "mathematics.h" #include "rational.h" int av_reduce(int *dst_nom, int *dst_den, int64_t nom, int64_t den, int64_t max){ AVRational a0={0,1}, a1={1,0}; int sign= (nom<0) ^ (den<0); int64_t gcd= ff_gcd(FFABS(nom), FFABS(den)); if(gcd){ nom = FFABS(nom)/gcd; den = FFABS(den)/gcd; } if(nom<=max && den<=max){ a1= (AVRational){nom, den}; den=0; } while(den){ uint64_t x = nom / den; int64_t next_den= nom - den*x; int64_t a2n= x*a1.num + a0.num; int64_t a2d= x*a1.den + a0.den; if(a2n > max || a2d > max){ if(a1.num) x= (max - a0.num) / a1.num; if(a1.den) x= FFMIN(x, (max - a0.den) / a1.den); if (den*(2*x*a1.den + a0.den) > nom*a1.den) a1 = (AVRational){x*a1.num + a0.num, x*a1.den + a0.den}; break; } a0= a1; a1= (AVRational){a2n, a2d}; nom= den; den= next_den; } assert(ff_gcd(a1.num, a1.den) <= 1U); *dst_nom = sign ? -a1.num : a1.num; *dst_den = a1.den; return den==0; } AVRational av_mul_q(AVRational b, AVRational c){ av_reduce(&b.num, &b.den, b.num * (int64_t)c.num, b.den * (int64_t)c.den, INT_MAX); return b; } AVRational av_div_q(AVRational b, AVRational c){ return av_mul_q(b, (AVRational){c.den, c.num}); } AVRational av_add_q(AVRational b, AVRational c){ 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); return b; } AVRational av_sub_q(AVRational b, AVRational c){ return av_add_q(b, (AVRational){-c.num, c.den}); } AVRational av_d2q(double d, int max){ AVRational a; #define LOG2 0.69314718055994530941723212145817656807550013436025 int exponent= FFMAX( (int)(log(fabs(d) + 1e-20)/LOG2), 0); int64_t den= 1LL << (61 - exponent); av_reduce(&a.num, &a.den, (int64_t)(d * den + 0.5), den, max); return a; }