js/src/jslibmath.h

   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 /*
  17  * Use system provided math routines.
  18  */
  19
  20 /* The right copysign function is not always named the same thing. */
  21 #ifdef __GNUC__
  22 #define js_copysign __builtin_copysign
  23 #elif defined _WIN32
  24 #define js_copysign _copysign
  25 #else
  26 #define js_copysign copysign
  27 #endif
  28
  29 /* Consistency wrapper for platform deviations in fmod() */
  30 static inline double
  31 js_fmod(double d, double d2)
  32 {
  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
  48 inline double
  49 NumberDiv(double a, double b)
  50 {
  51     if (b == 0) {
  52         if (a == 0 || mozilla::IsNaN(a)
  53 #ifdef XP_WIN
  54             || mozilla::IsNaN(b) /* XXX MSVC miscompiles such that (NaN == 0) */
  55 #endif
  56         )
  57             return JS::GenericNaN();
  58
  59         if (mozilla::IsNegative(a) != mozilla::IsNegative(b))
  60             return mozilla::NegativeInfinity<double>();
  61         return mozilla::PositiveInfinity<double>();
  62     }
  63
  64     return a / b;
  65 }
  66
  67 inline double
  68 NumberMod(double a, double b) {
  69     if (b == 0)
  70         return JS::GenericNaN();
  71     return js_fmod(a, b);
  72 }
  73
  74 }
  75
  76 #endif /* jslibmath_h */