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 47 using namespace std; 48 49 namespace Imf { 50 namespace { 51 52 double 53 frac (double x, double e) 54 { 55 return x - floor (x + e); 56 } 57 58 59 double 60 square (double x) 61 { 62 return x * x; 63 } 64 65 66 double 67 denom (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 92 Rational::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
