michael@0: /* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 4 -*-
michael@0:  * This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: #ifndef nsMathUtils_h__
michael@0: #define nsMathUtils_h__
michael@0: 
michael@0: #define _USE_MATH_DEFINES /* needed for M_ constants on Win32 */
michael@0: 
michael@0: #include "nscore.h"
michael@0: #include <cmath>
michael@0: #include <float.h>
michael@0: 
michael@0: #ifdef SOLARIS
michael@0: #include <ieeefp.h>
michael@0: #endif
michael@0: 
michael@0: /*
michael@0:  * round
michael@0:  */
michael@0: inline NS_HIDDEN_(double) NS_round(double x)
michael@0: {
michael@0:     return x >= 0.0 ? floor(x + 0.5) : ceil(x - 0.5);
michael@0: }
michael@0: inline NS_HIDDEN_(float) NS_roundf(float x)
michael@0: {
michael@0:     return x >= 0.0f ? floorf(x + 0.5f) : ceilf(x - 0.5f);
michael@0: }
michael@0: inline NS_HIDDEN_(int32_t) NS_lround(double x)
michael@0: {
michael@0:     return x >= 0.0 ? int32_t(x + 0.5) : int32_t(x - 0.5);
michael@0: }
michael@0: 
michael@0: /* NS_roundup30 rounds towards infinity for positive and       */
michael@0: /* negative numbers.                                           */
michael@0: 
michael@0: #if defined(XP_WIN32) && defined(_M_IX86) && !defined(__GNUC__)
michael@0: inline NS_HIDDEN_(int32_t) NS_lroundup30(float x)
michael@0: {
michael@0:     /* Code derived from Laurent de Soras' paper at             */
michael@0:     /* http://ldesoras.free.fr/doc/articles/rounding_en.pdf     */
michael@0: 
michael@0:     /* Rounding up on Windows is expensive using the float to   */
michael@0:     /* int conversion and the floor function. A faster          */
michael@0:     /* approach is to use f87 rounding while assuming the       */
michael@0:     /* default rounding mode of rounding to the nearest         */
michael@0:     /* integer. This rounding mode, however, actually rounds    */
michael@0:     /* to the nearest integer so we add the floating point      */
michael@0:     /* number to itself and add our rounding factor before      */
michael@0:     /* doing the conversion to an integer. We then do a right   */
michael@0:     /* shift of one bit on the integer to divide by two.        */
michael@0: 
michael@0:     /* This routine doesn't handle numbers larger in magnitude  */
michael@0:     /* than 2^30 but this is fine for NSToCoordRound because    */
michael@0:     /* Coords are limited to 2^30 in magnitude.                 */
michael@0: 
michael@0:     static const double round_to_nearest = 0.5f;
michael@0:     int i;
michael@0: 
michael@0:     __asm {
michael@0:       fld     x                   ; load fp argument
michael@0:       fadd    st, st(0)           ; double it
michael@0:       fadd    round_to_nearest    ; add the rounding factor
michael@0:       fistp   dword ptr i         ; convert the result to int
michael@0:     }
michael@0:     return i >> 1;                /* divide by 2 */
michael@0: }
michael@0: #endif /* XP_WIN32 && _M_IX86 && !__GNUC__ */
michael@0: 
michael@0: inline NS_HIDDEN_(int32_t) NS_lroundf(float x)
michael@0: {
michael@0:     return x >= 0.0f ? int32_t(x + 0.5f) : int32_t(x - 0.5f);
michael@0: }
michael@0: 
michael@0: /*
michael@0:  * hypot.  We don't need a super accurate version of this, if a platform
michael@0:  * turns up with none of the possibilities below it would be okay to fall
michael@0:  * back to sqrt(x*x + y*y).
michael@0:  */
michael@0: inline NS_HIDDEN_(double) NS_hypot(double x, double y)
michael@0: {
michael@0: #ifdef __GNUC__
michael@0:     return __builtin_hypot(x, y);
michael@0: #elif defined _WIN32
michael@0:     return _hypot(x, y);
michael@0: #else
michael@0:     return hypot(x, y);
michael@0: #endif
michael@0: }
michael@0: 
michael@0: /**
michael@0:  * Check whether a floating point number is finite (not +/-infinity and not a
michael@0:  * NaN value).
michael@0:  */
michael@0: inline NS_HIDDEN_(bool) NS_finite(double d)
michael@0: {
michael@0: #ifdef WIN32
michael@0:     // NOTE: '!!' casts an int to bool without spamming MSVC warning C4800.
michael@0:     return !!_finite(d);
michael@0: #elif defined(XP_DARWIN)
michael@0:     // Darwin has deprecated |finite| and recommends |isfinite|. The former is
michael@0:     // not present in the iOS SDK.
michael@0:     return std::isfinite(d);
michael@0: #else
michael@0:     return finite(d);
michael@0: #endif
michael@0: }
michael@0: 
michael@0: /**
michael@0:  * Returns the result of the modulo of x by y using a floored division.
michael@0:  * fmod(x, y) is using a truncated division.
michael@0:  * The main difference is that the result of this method will have the sign of
michael@0:  * y while the result of fmod(x, y) will have the sign of x.
michael@0:  */
michael@0: inline NS_HIDDEN_(double) NS_floorModulo(double x, double y)
michael@0: {
michael@0:   return (x - y * floor(x / y));
michael@0: }
michael@0: 
michael@0: #endif