/*
- * Rational numbers
+ * rational numbers
* Copyright (c) 2003 Michael Niedermayer <michaelni@gmx.at>
*
- * This file is part of FFmpeg.
+ * This file is part of Libav.
*
- * FFmpeg is free software; you can redistribute it and/or
+ * 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.
*
- * FFmpeg is distributed in the hope that it will be useful,
+ * 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 FFmpeg; if not, write to the Free Software
+ * 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.c
- * Rational numbers
+ * @file
+ * rational numbers
* @author Michael Niedermayer <michaelni@gmx.at>
*/
+#include "avassert.h"
//#include <math.h>
#include <limits.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));
+int av_reduce(int *dst_num, int *dst_den,
+ int64_t num, int64_t den, int64_t max)
+{
+ AVRational a0 = { 0, 1 }, a1 = { 1, 0 };
+ int sign = (num < 0) ^ (den < 0);
+ int64_t gcd = av_gcd(FFABS(num), FFABS(den));
- nom = FFABS(nom)/gcd;
- den = FFABS(den)/gcd;
- if(nom<=max && den<=max){
- a1= (AVRational){nom, den};
- den=0;
+ if (gcd) {
+ num = FFABS(num) / gcd;
+ den = FFABS(den) / gcd;
+ }
+ if (num <= max && den <= max) {
+ a1 = (AVRational) { num, 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;
+ while (den) {
+ uint64_t x = num / den;
+ int64_t next_den = num - 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 (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};
+ if (den * (2 * x * a1.den + a0.den) > num * 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;
+ a0 = a1;
+ a1 = (AVRational) { a2n, a2d };
+ num = den;
+ den = next_den;
}
- assert(ff_gcd(a1.num, a1.den) == 1);
+ av_assert2(av_gcd(a1.num, a1.den) <= 1U);
- *dst_nom = sign ? -a1.num : a1.num;
+ *dst_num = sign ? -a1.num : a1.num;
*dst_den = a1.den;
- return den==0;
+ return den == 0;
}
-/**
- * returns b*c.
- */
-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);
+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;
}
-/**
- * returns b/c.
- */
-AVRational av_div_q(AVRational b, AVRational c){
- return av_mul_q(b, (AVRational){c.den, c.num});
+AVRational av_div_q(AVRational b, AVRational c)
+{
+ return av_mul_q(b, (AVRational) { c.den, c.num });
}
-/**
- * returns b+c.
- */
-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);
+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;
}
-/**
- * returns b-c.
- */
-AVRational av_sub_q(AVRational b, AVRational c){
- return av_add_q(b, (AVRational){-c.num, c.den});
+AVRational av_sub_q(AVRational b, AVRational c)
+{
+ return av_add_q(b, (AVRational) { -c.num, c.den });
}
-/**
- * Converts a double precission floating point number to a AVRational.
- * @param max the maximum allowed numerator and denominator
- */
-AVRational av_d2q(double d, int max){
+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);
+ int exponent;
+ int64_t den;
+ if (isnan(d))
+ return (AVRational) { 0,0 };
+ if (isinf(d))
+ return (AVRational) { d < 0 ? -1 : 1, 0 };
+ exponent = FFMAX( (int)(log(fabs(d) + 1e-20)/LOG2), 0);
+ den = 1LL << (61 - exponent);
av_reduce(&a.num, &a.den, (int64_t)(d * den + 0.5), den, max);
return a;
}
+
+int av_nearer_q(AVRational q, AVRational q1, AVRational q2)
+{
+ /* n/d is q, a/b is the median between q1 and q2 */
+ int64_t a = q1.num * (int64_t)q2.den + q2.num * (int64_t)q1.den;
+ int64_t b = 2 * (int64_t)q1.den * q2.den;
+
+ /* rnd_up(a*d/b) > n => a*d/b > n */
+ int64_t x_up = av_rescale_rnd(a, q.den, b, AV_ROUND_UP);
+
+ /* rnd_down(a*d/b) < n => a*d/b < n */
+ int64_t x_down = av_rescale_rnd(a, q.den, b, AV_ROUND_DOWN);
+
+ return ((x_up > q.num) - (x_down < q.num)) * av_cmp_q(q2, q1);
+}
+
+int av_find_nearest_q_idx(AVRational q, const AVRational* q_list)
+{
+ int i, nearest_q_idx = 0;
+ for (i = 0; q_list[i].den; i++)
+ if (av_nearer_q(q, q_list[i], q_list[nearest_q_idx]) > 0)
+ nearest_q_idx = i;
+
+ return nearest_q_idx;
+}
projects / ffmpeg / blobdiff