1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/xpcom/ds/nsMathUtils.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,121 @@
1.4 +/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 4 -*-
1.5 + * This Source Code Form is subject to the terms of the Mozilla Public
1.6 + * License, v. 2.0. If a copy of the MPL was not distributed with this
1.7 + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
1.8 +
1.9 +#ifndef nsMathUtils_h__
1.10 +#define nsMathUtils_h__
1.11 +
1.12 +#define _USE_MATH_DEFINES /* needed for M_ constants on Win32 */
1.13 +
1.14 +#include "nscore.h"
1.15 +#include <cmath>
1.16 +#include <float.h>
1.17 +
1.18 +#ifdef SOLARIS
1.19 +#include <ieeefp.h>
1.20 +#endif
1.21 +
1.22 +/*
1.23 + * round
1.24 + */
1.25 +inline NS_HIDDEN_(double) NS_round(double x)
1.26 +{
1.27 + return x >= 0.0 ? floor(x + 0.5) : ceil(x - 0.5);
1.28 +}
1.29 +inline NS_HIDDEN_(float) NS_roundf(float x)
1.30 +{
1.31 + return x >= 0.0f ? floorf(x + 0.5f) : ceilf(x - 0.5f);
1.32 +}
1.33 +inline NS_HIDDEN_(int32_t) NS_lround(double x)
1.34 +{
1.35 + return x >= 0.0 ? int32_t(x + 0.5) : int32_t(x - 0.5);
1.36 +}
1.37 +
1.38 +/* NS_roundup30 rounds towards infinity for positive and */
1.39 +/* negative numbers. */
1.40 +
1.41 +#if defined(XP_WIN32) && defined(_M_IX86) && !defined(__GNUC__)
1.42 +inline NS_HIDDEN_(int32_t) NS_lroundup30(float x)
1.43 +{
1.44 + /* Code derived from Laurent de Soras' paper at */
1.45 + /* http://ldesoras.free.fr/doc/articles/rounding_en.pdf */
1.46 +
1.47 + /* Rounding up on Windows is expensive using the float to */
1.48 + /* int conversion and the floor function. A faster */
1.49 + /* approach is to use f87 rounding while assuming the */
1.50 + /* default rounding mode of rounding to the nearest */
1.51 + /* integer. This rounding mode, however, actually rounds */
1.52 + /* to the nearest integer so we add the floating point */
1.53 + /* number to itself and add our rounding factor before */
1.54 + /* doing the conversion to an integer. We then do a right */
1.55 + /* shift of one bit on the integer to divide by two. */
1.56 +
1.57 + /* This routine doesn't handle numbers larger in magnitude */
1.58 + /* than 2^30 but this is fine for NSToCoordRound because */
1.59 + /* Coords are limited to 2^30 in magnitude. */
1.60 +
1.61 + static const double round_to_nearest = 0.5f;
1.62 + int i;
1.63 +
1.64 + __asm {
1.65 + fld x ; load fp argument
1.66 + fadd st, st(0) ; double it
1.67 + fadd round_to_nearest ; add the rounding factor
1.68 + fistp dword ptr i ; convert the result to int
1.69 + }
1.70 + return i >> 1; /* divide by 2 */
1.71 +}
1.72 +#endif /* XP_WIN32 && _M_IX86 && !__GNUC__ */
1.73 +
1.74 +inline NS_HIDDEN_(int32_t) NS_lroundf(float x)
1.75 +{
1.76 + return x >= 0.0f ? int32_t(x + 0.5f) : int32_t(x - 0.5f);
1.77 +}
1.78 +
1.79 +/*
1.80 + * hypot. We don't need a super accurate version of this, if a platform
1.81 + * turns up with none of the possibilities below it would be okay to fall
1.82 + * back to sqrt(x*x + y*y).
1.83 + */
1.84 +inline NS_HIDDEN_(double) NS_hypot(double x, double y)
1.85 +{
1.86 +#ifdef __GNUC__
1.87 + return __builtin_hypot(x, y);
1.88 +#elif defined _WIN32
1.89 + return _hypot(x, y);
1.90 +#else
1.91 + return hypot(x, y);
1.92 +#endif
1.93 +}
1.94 +
1.95 +/**
1.96 + * Check whether a floating point number is finite (not +/-infinity and not a
1.97 + * NaN value).
1.98 + */
1.99 +inline NS_HIDDEN_(bool) NS_finite(double d)
1.100 +{
1.101 +#ifdef WIN32
1.102 + // NOTE: '!!' casts an int to bool without spamming MSVC warning C4800.
1.103 + return !!_finite(d);
1.104 +#elif defined(XP_DARWIN)
1.105 + // Darwin has deprecated |finite| and recommends |isfinite|. The former is
1.106 + // not present in the iOS SDK.
1.107 + return std::isfinite(d);
1.108 +#else
1.109 + return finite(d);
1.110 +#endif
1.111 +}
1.112 +
1.113 +/**
1.114 + * Returns the result of the modulo of x by y using a floored division.
1.115 + * fmod(x, y) is using a truncated division.
1.116 + * The main difference is that the result of this method will have the sign of
1.117 + * y while the result of fmod(x, y) will have the sign of x.
1.118 + */
1.119 +inline NS_HIDDEN_(double) NS_floorModulo(double x, double y)
1.120 +{
1.121 + return (x - y * floor(x / y));
1.122 +}
1.123 +
1.124 +#endif
