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
__ledf2(fp_t a,fp_t b)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
__gedf2(fp_t a,fp_t b)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
__unorddf2(fp_t a,fp_t b)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
__eqdf2(fp_t a,fp_t b)117 enum LE_RESULT __eqdf2(fp_t a, fp_t b) {
118 return __ledf2(a, b);
119 }
120
__ltdf2(fp_t a,fp_t b)121 enum LE_RESULT __ltdf2(fp_t a, fp_t b) {
122 return __ledf2(a, b);
123 }
124
__nedf2(fp_t a,fp_t b)125 enum LE_RESULT __nedf2(fp_t a, fp_t b) {
126 return __ledf2(a, b);
127 }
128
__gtdf2(fp_t a,fp_t b)129 enum GE_RESULT __gtdf2(fp_t a, fp_t b) {
130 return __gedf2(a, b);
131 }
132
133