1/////////////////////////////////////////////////////////////////////////// 2// 3// Copyright (c) 2006, Industrial Light & Magic, a division of Lucas 4// Digital Ltd. LLC 5// 6// All rights reserved. 7// 8// Redistribution and use in source and binary forms, with or without 9// modification, are permitted provided that the following conditions are 10// met: 11// * Redistributions of source code must retain the above copyright 12// notice, this list of conditions and the following disclaimer. 13// * Redistributions in binary form must reproduce the above 14// copyright notice, this list of conditions and the following disclaimer 15// in the documentation and/or other materials provided with the 16// distribution. 17// * Neither the name of Industrial Light & Magic nor the names of 18// its contributors may be used to endorse or promote products derived 19// from this software without specific prior written permission. 20// 21// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 22// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 23// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 24// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 25// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 26// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 27// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 28// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 29// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 30// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 31// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 32// 33/////////////////////////////////////////////////////////////////////////// 34 35//----------------------------------------------------------------------------- 36// 37// Rational numbers 38// 39// The double-to-Rational conversion code below 40// was contributed to OpenEXR by Greg Ward. 41// 42//----------------------------------------------------------------------------- 43 44#include <ImfRational.h> 45#include <cmath> 46 47using namespace std; 48 49namespace Imf { 50namespace { 51 52double 53frac (double x, double e) 54{ 55 return x - floor (x + e); 56} 57 58 59double 60square (double x) 61{ 62 return x * x; 63} 64 65 66double 67denom (double x, double e) 68{ 69 if (e > frac (x, e)) 70 { 71 return 1; 72 } 73 else 74 { 75 double r = frac (1 / x, e); 76 77 if (e > r) 78 { 79 return floor (1 / x + e); 80 } 81 else 82 { 83 return denom (frac (1 / r, e), e / square (x * r)) + 84 floor (1 / x + e) * denom (frac (1 / x, e), e / square (x)); 85 } 86 } 87} 88 89} // namespace 90 91 92Rational::Rational (double x) 93{ 94 int sign; 95 96 if (x >= 0) 97 { 98 sign = 1; // positive 99 } 100 else if (x < 0) 101 { 102 sign = -1; // negative 103 x = -x; 104 } 105 else 106 { 107 n = 0; // NaN 108 d = 0; 109 return; 110 } 111 112 if (x >= (1U << 31) - 0.5) 113 { 114 n = sign; // infinity 115 d = 0; 116 return; 117 } 118 119 double e = (x < 1? 1: x) / (1U << 30); 120 d = (unsigned int) denom (x, e); 121 n = sign * (int) floor (x * d + 0.5); 122} 123 124 125} // namespace Imf 126