1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
2 * vim: set ts=8 sts=4 et sw=4 tw=99:
3 * This Source Code Form is subject to the terms of the Mozilla Public
4 * License, v. 2.0. If a copy of the MPL was not distributed with this
5 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
6
7 #ifndef jslibmath_h
8 #define jslibmath_h
9
10 #include "mozilla/FloatingPoint.h"
11
12 #include <math.h>
13
14 #include "jsnum.h"
15
16 #include "vm/JSContext.h"
17
18 /*
19 * Use system provided math routines.
20 */
21
22 /* The right copysign function is not always named the same thing. */
23 #ifdef __GNUC__
24 #define js_copysign __builtin_copysign
25 #elif defined _WIN32
26 #define js_copysign _copysign
27 #else
28 #define js_copysign copysign
29 #endif
30
31 /* Consistency wrapper for platform deviations in fmod() */
js_fmod(double d,double d2)32 static inline double js_fmod(double d, double d2) {
33 #ifdef XP_WIN
34 /*
35 * Workaround MS fmod bug where 42 % (1/0) => NaN, not 42.
36 * Workaround MS fmod bug where -0 % -N => 0, not -0.
37 */
38 if ((mozilla::IsFinite(d) && mozilla::IsInfinite(d2)) ||
39 (d == 0 && mozilla::IsFinite(d2))) {
40 return d;
41 }
42 #endif
43 return fmod(d, d2);
44 }
45
46 namespace js {
47
NumberDiv(double a,double b)48 inline double NumberDiv(double a, double b) {
49 AutoUnsafeCallWithABI unsafe;
50 if (b == 0) {
51 if (a == 0 || mozilla::IsNaN(a)
52 #ifdef XP_WIN
53 || mozilla::IsNaN(b) /* XXX MSVC miscompiles such that (NaN == 0) */
54 #endif
55 )
56 return JS::GenericNaN();
57
58 if (mozilla::IsNegative(a) != mozilla::IsNegative(b))
59 return mozilla::NegativeInfinity<double>();
60 return mozilla::PositiveInfinity<double>();
61 }
62
63 return a / b;
64 }
65
NumberMod(double a,double b)66 inline double NumberMod(double a, double b) {
67 AutoUnsafeCallWithABI unsafe;
68 if (b == 0) return JS::GenericNaN();
69 double r = fmod(a, b);
70 #if defined(XP_WIN)
71 // Some versions of Windows (Win 10 v1803, v1809) miscompute the sign of zero
72 // results from fmod. The sign should match the sign of the LHS. This bug
73 // only affects 64-bit builds. See bug 1527007.
74 if (mozilla::IsPositiveZero(r) && mozilla::IsNegative(a)) {
75 return -0.0;
76 }
77 #endif
78 return r;
79 }
80
81 } // namespace js
82
83 #endif /* jslibmath_h */
84