libavutil: Utility code from libavcodec moved to a separate library.

Originally committed as revision 4489 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavutil/rational.h

@@ -0,0 +1,69 @@
+/*
+ * Rational numbers
+ * Copyright (c) 2003 Michael Niedermayer <michaelni@gmx.at>
+ *
+ * This library 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 of the License, or (at your option) any later version.
+ *
+ * This library 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 this library; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ */
+ 
+/**
+ * @file rational.h
+ * Rational numbers.
+ * @author Michael Niedermayer <michaelni@gmx.at>
+ */
+
+#ifndef RATIONAL_H
+#define RATIONAL_H
+
+/**
+ * Rational number num/den.
+ */
+typedef struct AVRational{
+    int num; ///< numerator
+    int den; ///< denominator
+} AVRational;
+
+/**
+ * returns 0 if a==b, 1 if a>b and -1 if a<b.
+ */
+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>>63)|1;
+    else    return 0;
+}
+
+/**
+ * converts the given AVRational to a double.
+ */
+static inline double av_q2d(AVRational a){
+    return a.num / (double) a.den;
+}
+
+/**
+ * reduce a fraction.
+ * this is usefull for framerate calculations
+ * @param max the maximum allowed for dst_nom & dst_den
+ * @return 1 if exact, 0 otherwise
+ */
+int av_reduce(int *dst_nom, int *dst_den, int64_t nom, int64_t den, int64_t max);
+
+AVRational av_mul_q(AVRational b, AVRational c);
+AVRational av_div_q(AVRational b, AVRational c);
+AVRational av_add_q(AVRational b, AVRational c);
+AVRational av_sub_q(AVRational b, AVRational c);
+AVRational av_d2q(double d, int max);
+
+#endif // RATIONAL_H