js/src/jslibmath.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
   2  * vim: set ts=8 sts=2 et sw=2 tw=80:
   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 "js/Value.h"
  15 #include "vm/JSContext.h"
  16
  17 namespace js {
  18
  19 inline double NumberDiv(double a, double b) {
  20   AutoUnsafeCallWithABI unsafe;
  21   if (b == 0) {
  22     if (a == 0 || std::isnan(a)) {
  23       return JS::GenericNaN();
  24     }
  25     if (mozilla::IsNegative(a) != mozilla::IsNegative(b)) {
  26       return mozilla::NegativeInfinity<double>();
  27     }
  28     return mozilla::PositiveInfinity<double>();
  29   }
  30
  31   return a / b;
  32 }
  33
  34 inline double NumberMod(double a, double b) {
  35   AutoUnsafeCallWithABI unsafe;
  36   if (b == 0) {
  37     return JS::GenericNaN();
  38   }
  39   double r = fmod(a, b);
  40 #if defined(XP_WIN)
  41   // Some versions of Windows (Win 10 v1803, v1809) miscompute the sign of zero
  42   // results from fmod. The sign should match the sign of the LHS. This bug
  43   // only affects 64-bit builds. See bug 1527007.
  44   if (mozilla::IsPositiveZero(r) && mozilla::IsNegative(a)) {
  45     return -0.0;
  46   }
  47 #endif
  48   return r;
  49 }
  50
  51 }  // namespace js
  52
  53 #endif /* jslibmath_h */