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       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 nsMathUtils_h__
       8             : #define nsMathUtils_h__
       9             : 
      10             : #include "nscore.h"
      11             : #include <cmath>
      12             : #include <float.h>
      13             : 
      14             : #if defined(XP_SOLARIS)
      15             : #include <ieeefp.h>
      16             : #endif
      17             : 
      18             : /*
      19             :  * round
      20             :  */
      21             : inline double
      22        2152 : NS_round(double aNum)
      23             : {
      24        2152 :   return aNum >= 0.0 ? floor(aNum + 0.5) : ceil(aNum - 0.5);
      25             : }
      26             : inline float
      27           3 : NS_roundf(float aNum)
      28             : {
      29           3 :   return aNum >= 0.0f ? floorf(aNum + 0.5f) : ceilf(aNum - 0.5f);
      30             : }
      31             : inline int32_t
      32        1656 : NS_lround(double aNum)
      33             : {
      34        1656 :   return aNum >= 0.0 ? int32_t(aNum + 0.5) : int32_t(aNum - 0.5);
      35             : }
      36             : 
      37             : /* NS_roundup30 rounds towards infinity for positive and       */
      38             : /* negative numbers.                                           */
      39             : 
      40             : #if defined(XP_WIN32) && defined(_M_IX86) && !defined(__GNUC__) && !defined(__clang__)
      41             : inline int32_t NS_lroundup30(float x)
      42             : {
      43             :   /* Code derived from Laurent de Soras' paper at             */
      44             :   /* http://ldesoras.free.fr/doc/articles/rounding_en.pdf     */
      45             : 
      46             :   /* Rounding up on Windows is expensive using the float to   */
      47             :   /* int conversion and the floor function. A faster          */
      48             :   /* approach is to use f87 rounding while assuming the       */
      49             :   /* default rounding mode of rounding to the nearest         */
      50             :   /* integer. This rounding mode, however, actually rounds    */
      51             :   /* to the nearest integer so we add the floating point      */
      52             :   /* number to itself and add our rounding factor before      */
      53             :   /* doing the conversion to an integer. We then do a right   */
      54             :   /* shift of one bit on the integer to divide by two.        */
      55             : 
      56             :   /* This routine doesn't handle numbers larger in magnitude  */
      57             :   /* than 2^30 but this is fine for NSToCoordRound because    */
      58             :   /* Coords are limited to 2^30 in magnitude.                 */
      59             : 
      60             :   static const double round_to_nearest = 0.5f;
      61             :   int i;
      62             : 
      63             :   __asm {
      64             :     fld     x                   ; load fp argument
      65             :     fadd    st, st(0)           ; double it
      66             :     fadd    round_to_nearest    ; add the rounding factor
      67             :     fistp   dword ptr i         ; convert the result to int
      68             :   }
      69             :   return i >> 1;                /* divide by 2 */
      70             : }
      71             : #endif /* XP_WIN32 && _M_IX86 && !__GNUC__ */
      72             : 
      73             : inline int32_t
      74        1142 : NS_lroundf(float aNum)
      75             : {
      76        1142 :   return aNum >= 0.0f ? int32_t(aNum + 0.5f) : int32_t(aNum - 0.5f);
      77             : }
      78             : 
      79             : /*
      80             :  * hypot.  We don't need a super accurate version of this, if a platform
      81             :  * turns up with none of the possibilities below it would be okay to fall
      82             :  * back to sqrt(x*x + y*y).
      83             :  */
      84             : inline double
      85          52 : NS_hypot(double aNum1, double aNum2)
      86             : {
      87             : #ifdef __GNUC__
      88          52 :   return __builtin_hypot(aNum1, aNum2);
      89             : #elif defined _WIN32
      90             :   return _hypot(aNum1, aNum2);
      91             : #else
      92             :   return hypot(aNum1, aNum2);
      93             : #endif
      94             : }
      95             : 
      96             : /**
      97             :  * Check whether a floating point number is finite (not +/-infinity and not a
      98             :  * NaN value).
      99             :  */
     100             : inline bool
     101             : NS_finite(double aNum)
     102             : {
     103             : #ifdef WIN32
     104             :   // NOTE: '!!' casts an int to bool without spamming MSVC warning C4800.
     105             :   return !!_finite(aNum);
     106             : #elif defined(XP_DARWIN)
     107             :   // Darwin has deprecated |finite| and recommends |isfinite|. The former is
     108             :   // not present in the iOS SDK.
     109             :   return std::isfinite(aNum);
     110             : #else
     111             :   return finite(aNum);
     112             : #endif
     113             : }
     114             : 
     115             : /**
     116             :  * Returns the result of the modulo of x by y using a floored division.
     117             :  * fmod(x, y) is using a truncated division.
     118             :  * The main difference is that the result of this method will have the sign of
     119             :  * y while the result of fmod(x, y) will have the sign of x.
     120             :  */
     121             : inline double
     122             : NS_floorModulo(double aNum1, double aNum2)
     123             : {
     124             :   return (aNum1 - aNum2 * floor(aNum1 / aNum2));
     125             : }
     126             : 
     127             : #endif