1 //===-- lib/comparedf2.c - Double-precision comparisons -----------*- C -*-===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is dual licensed under the MIT and the University of Illinois Open 6 // Source Licenses. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // // This file implements the following soft-float comparison routines: 11 // 12 // __eqdf2 __gedf2 __unorddf2 13 // __ledf2 __gtdf2 14 // __ltdf2 15 // __nedf2 16 // 17 // The semantics of the routines grouped in each column are identical, so there 18 // is a single implementation for each, and wrappers to provide the other names. 19 // 20 // The main routines behave as follows: 21 // 22 // __ledf2(a,b) returns -1 if a < b 23 // 0 if a == b 24 // 1 if a > b 25 // 1 if either a or b is NaN 26 // 27 // __gedf2(a,b) returns -1 if a < b 28 // 0 if a == b 29 // 1 if a > b 30 // -1 if either a or b is NaN 31 // 32 // __unorddf2(a,b) returns 0 if both a and b are numbers 33 // 1 if either a or b is NaN 34 // 35 // Note that __ledf2( ) and __gedf2( ) are identical except in their handling of 36 // NaN values. 37 // 38 //===----------------------------------------------------------------------===// 39 40 #define DOUBLE_PRECISION 41 #include "fp_lib.h" 42 43 enum LE_RESULT { 44 LE_LESS = -1, 45 LE_EQUAL = 0, 46 LE_GREATER = 1, 47 LE_UNORDERED = 1 48 }; 49 50 enum LE_RESULT __ledf2(fp_t a, fp_t b) { 51 52 const srep_t aInt = toRep(a); 53 const srep_t bInt = toRep(b); 54 const rep_t aAbs = aInt & absMask; 55 const rep_t bAbs = bInt & absMask; 56 57 // If either a or b is NaN, they are unordered. 58 if (aAbs > infRep || bAbs > infRep) return LE_UNORDERED; 59 60 // If a and b are both zeros, they are equal. 61 if ((aAbs | bAbs) == 0) return LE_EQUAL; 62 63 // If at least one of a and b is positive, we get the same result comparing 64 // a and b as signed integers as we would with a floating-point compare. 65 if ((aInt & bInt) >= 0) { 66 if (aInt < bInt) return LE_LESS; 67 else if (aInt == bInt) return LE_EQUAL; 68 else return LE_GREATER; 69 } 70 71 // Otherwise, both are negative, so we need to flip the sense of the 72 // comparison to get the correct result. (This assumes a twos- or ones- 73 // complement integer representation; if integers are represented in a 74 // sign-magnitude representation, then this flip is incorrect). 75 else { 76 if (aInt > bInt) return LE_LESS; 77 else if (aInt == bInt) return LE_EQUAL; 78 else return LE_GREATER; 79 } 80 } 81 82 enum GE_RESULT { 83 GE_LESS = -1, 84 GE_EQUAL = 0, 85 GE_GREATER = 1, 86 GE_UNORDERED = -1 // Note: different from LE_UNORDERED 87 }; 88 89 enum GE_RESULT __gedf2(fp_t a, fp_t b) { 90 91 const srep_t aInt = toRep(a); 92 const srep_t bInt = toRep(b); 93 const rep_t aAbs = aInt & absMask; 94 const rep_t bAbs = bInt & absMask; 95 96 if (aAbs > infRep || bAbs > infRep) return GE_UNORDERED; 97 if ((aAbs | bAbs) == 0) return GE_EQUAL; 98 if ((aInt & bInt) >= 0) { 99 if (aInt < bInt) return GE_LESS; 100 else if (aInt == bInt) return GE_EQUAL; 101 else return GE_GREATER; 102 } else { 103 if (aInt > bInt) return GE_LESS; 104 else if (aInt == bInt) return GE_EQUAL; 105 else return GE_GREATER; 106 } 107 } 108 109 int __unorddf2(fp_t a, fp_t b) { 110 const rep_t aAbs = toRep(a) & absMask; 111 const rep_t bAbs = toRep(b) & absMask; 112 return aAbs > infRep || bAbs > infRep; 113 } 114 115 // The following are alternative names for the preceeding routines. 116 117 enum LE_RESULT __eqdf2(fp_t a, fp_t b) { 118 return __ledf2(a, b); 119 } 120 121 enum LE_RESULT __ltdf2(fp_t a, fp_t b) { 122 return __ledf2(a, b); 123 } 124 125 enum LE_RESULT __nedf2(fp_t a, fp_t b) { 126 return __ledf2(a, b); 127 } 128 129 enum GE_RESULT __gtdf2(fp_t a, fp_t b) { 130 return __gedf2(a, b); 131 } 132 133
