1 /////////////////////////////////////////////////////////////////////////// 2 // 3 // Copyright (c) 2002, 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 #include "ImathFun.h" 37 38 namespace Imath { 39 40 41 float 42 succf (float f) 43 { 44 union {float f; int i;} u; 45 u.f = f; 46 47 if ((u.i & 0x7f800000) == 0x7f800000) 48 { 49 // Nan or infinity; don't change value. 50 } 51 else if (u.i == 0x00000000 || u.i == 0x80000000) 52 { 53 // Plus or minus zero. 54 55 u.i = 0x00000001; 56 } 57 else if (u.i > 0) 58 { 59 // Positive float, normalized or denormalized. 60 // Incrementing the largest positive float 61 // produces +infinity. 62 63 ++u.i; 64 } 65 else 66 { 67 // Negative normalized or denormalized float. 68 69 --u.i; 70 } 71 72 return u.f; 73 } 74 75 76 float 77 predf (float f) 78 { 79 union {float f; int i;} u; 80 u.f = f; 81 82 if ((u.i & 0x7f800000) == 0x7f800000) 83 { 84 // Nan or infinity; don't change value. 85 } 86 else if (u.i == 0x00000000 || u.i == 0x80000000) 87 { 88 // Plus or minus zero. 89 90 u.i = 0x80000001; 91 } 92 else if (u.i > 0) 93 { 94 // Positive float, normalized or denormalized. 95 96 --u.i; 97 } 98 else 99 { 100 // Negative normalized or denormalized float. 101 // Decrementing the largest negative float 102 // produces -infinity. 103 104 ++u.i; 105 } 106 107 return u.f; 108 } 109 110 111 double 112 succd (double d) 113 { 114 union {double d; Int64 i;} u; 115 u.d = d; 116 117 if ((u.i & 0x7ff0000000000000LL) == 0x7ff0000000000000LL) 118 { 119 // Nan or infinity; don't change value. 120 } 121 else if (u.i == 0x0000000000000000LL || u.i == 0x8000000000000000LL) 122 { 123 // Plus or minus zero. 124 125 u.i = 0x0000000000000001LL; 126 } 127 else if (u.i > 0) 128 { 129 // Positive double, normalized or denormalized. 130 // Incrementing the largest positive double 131 // produces +infinity. 132 133 ++u.i; 134 } 135 else 136 { 137 // Negative normalized or denormalized double. 138 139 --u.i; 140 } 141 142 return u.d; 143 } 144 145 146 double 147 predd (double d) 148 { 149 union {double d; Int64 i;} u; 150 u.d = d; 151 152 if ((u.i & 0x7ff0000000000000LL) == 0x7ff0000000000000LL) 153 { 154 // Nan or infinity; don't change value. 155 } 156 else if (u.i == 0x0000000000000000LL || u.i == 0x8000000000000000LL) 157 { 158 // Plus or minus zero. 159 160 u.i = 0x8000000000000001LL; 161 } 162 else if (u.i > 0) 163 { 164 // Positive double, normalized or denormalized. 165 166 --u.i; 167 } 168 else 169 { 170 // Negative normalized or denormalized double. 171 // Decrementing the largest negative double 172 // produces -infinity. 173 174 ++u.i; 175 } 176 177 return u.d; 178 } 179 180 181 } // namespace Imath 182