xpcom/ds/nsMathUtils.h

   1 /* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 4 -*-
   2  * ***** BEGIN LICENSE BLOCK *****
   3  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
   4  *
   5  * The contents of this file are subject to the Mozilla Public License Version
   6  * 1.1 (the "License"); you may not use this file except in compliance with
   7  * the License. You may obtain a copy of the License at
   8  * http://www.mozilla.org/MPL/
   9  *
  10  * Software distributed under the License is distributed on an "AS IS" basis,
  11  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
  12  * for the specific language governing rights and limitations under the
  13  * License.
  14  *
  15  * The Original Code is Mozilla Foundation code.
  16  *
  17  * The Initial Developer of the Original Code is Mozilla Foundation.
  18  * Portions created by the Initial Developer are Copyright (C) 2007
  19  * the Initial Developer. All Rights Reserved.
  20  *
  21  * Contributor(s):
  22  *   Stuart Parmenter <stuart@mozilla.com>
  23  *
  24  * Alternatively, the contents of this file may be used under the terms of
  25  * either the GNU General Public License Version 2 or later (the "GPL"), or
  26  * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
  27  * in which case the provisions of the GPL or the LGPL are applicable instead
  28  * of those above. If you wish to allow use of your version of this file only
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  33  * the provisions above, a recipient may use your version of this file under
  34  * the terms of any one of the MPL, the GPL or the LGPL.
  35  *
  36  * ***** END LICENSE BLOCK ***** */
  37
  38 #ifndef nsMathUtils_h__
  39 #define nsMathUtils_h__
  40
  41 #define _USE_MATH_DEFINES /* needed for M_ constants on Win32 */
  42
  43 #include "nscore.h"
  44 #include <math.h>
  45 #include <float.h>
  46
  47 /*
  48  * The M_ constants are not defined by the WinCE/WinMo SDKs even with
  49  * _USE_MATH_DEFINES.  Provide a fallback.  We assume that the entire
  50  * set is not available if M_E isn't.  Values taken from GNU libc,
  51  * providing just enough precision for IEEE double.
  52  */
  53
  54 #ifndef M_E
  55 # define M_E            2.7182818284590452354   /* e */
  56 # define M_LOG2E        1.4426950408889634074   /* log_2 e */
  57 # define M_LOG10E       0.43429448190325182765  /* log_10 e */
  58 # define M_LN2          0.69314718055994530942  /* log_e 2 */
  59 # define M_LN10         2.30258509299404568402  /* log_e 10 */
  60 # define M_PI           3.14159265358979323846  /* pi */
  61 # define M_PI_2         1.57079632679489661923  /* pi/2 */
  62 # define M_PI_4         0.78539816339744830962  /* pi/4 */
  63 # define M_1_PI         0.31830988618379067154  /* 1/pi */
  64 # define M_2_PI         0.63661977236758134308  /* 2/pi */
  65 # define M_2_SQRTPI     1.12837916709551257390  /* 2/sqrt(pi) */
  66 # define M_SQRT2        1.41421356237309504880  /* sqrt(2) */
  67 # define M_SQRT1_2      0.70710678118654752440  /* 1/sqrt(2) */
  68 #endif
  69
  70 /*
  71  * round
  72  */
  73 inline NS_HIDDEN_(double) NS_round(double x)
  74 {
  75     return x >= 0.0 ? floor(x + 0.5) : ceil(x - 0.5);
  76 }
  77 inline NS_HIDDEN_(float) NS_roundf(float x)
  78 {
  79     return x >= 0.0f ? floorf(x + 0.5f) : ceilf(x - 0.5f);
  80 }
  81 inline NS_HIDDEN_(PRInt32) NS_lround(double x)
  82 {
  83     return x >= 0.0 ? PRInt32(x + 0.5) : PRInt32(x - 0.5);
  84 }
  85
  86 /* NS_roundup30 rounds towards infinity for positive and       */
  87 /* negative numbers.                                           */
  88
  89 #if defined(XP_WIN32) && defined(_M_IX86) && !defined(__GNUC__)
  90 inline NS_HIDDEN_(PRInt32) NS_lroundup30(float x)
  91 {
  92     /* Code derived from Laurent de Soras' paper at             */
  93     /* http://ldesoras.free.fr/doc/articles/rounding_en.pdf     */
  94
  95     /* Rounding up on Windows is expensive using the float to   */
  96     /* int conversion and the floor function. A faster          */
  97     /* approach is to use f87 rounding while assuming the       */
  98     /* default rounding mode of rounding to the nearest         */
  99     /* integer. This rounding mode, however, actually rounds    */
 100     /* to the nearest integer so we add the floating point      */
 101     /* number to itself and add our rounding factor before      */
 102     /* doing the conversion to an integer. We then do a right   */
 103     /* shift of one bit on the integer to divide by two.        */
 104
 105     /* This routine doesn't handle numbers larger in magnitude  */
 106     /* than 2^30 but this is fine for NSToCoordRound because    */
 107     /* Coords are limited to 2^30 in magnitude.                 */
 108
 109     static const double round_to_nearest = 0.5f;
 110     int i;
 111
 112     __asm {
 113       fld     x                   ; load fp argument
 114       fadd    st, st(0)           ; double it
 115       fadd    round_to_nearest    ; add the rounding factor
 116       fistp   dword ptr i         ; convert the result to int
 117     }
 118     return i >> 1;                /* divide by 2 */
 119 }
 120 #endif /* XP_WIN32 && _M_IX86 && !__GNUC__ */
 121
 122 inline NS_HIDDEN_(PRInt32) NS_lroundf(float x)
 123 {
 124     return x >= 0.0f ? PRInt32(x + 0.5f) : PRInt32(x - 0.5f);
 125 }
 126
 127 /*
 128  * ceil
 129  */
 130 inline NS_HIDDEN_(double) NS_ceil(double x)
 131 {
 132     return ceil(x);
 133 }
 134 inline NS_HIDDEN_(float) NS_ceilf(float x)
 135 {
 136     return ceilf(x);
 137 }
 138
 139 /*
 140  * floor
 141  */
 142 inline NS_HIDDEN_(double) NS_floor(double x)
 143 {
 144     return floor(x);
 145 }
 146 inline NS_HIDDEN_(float) NS_floorf(float x)
 147 {
 148     return floorf(x);
 149 }
 150
 151 /*
 152  * hypot.  We don't need a super accurate version of this, if a platform
 153  * turns up with none of the possibilities below it would be okay to fall
 154  * back to sqrt(x*x + y*y).
 155  */
 156 inline NS_HIDDEN_(double) NS_hypot(double x, double y)
 157 {
 158 #if __GNUC__ >= 4
 159     return __builtin_hypot(x, y);
 160 #elif defined _WIN32
 161     return _hypot(x, y);
 162 #else
 163     return hypot(x, y);
 164 #endif
 165 }
 166
 167 #endif