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/
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  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
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  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
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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 #include "nscore.h"
  42 #include <math.h>
  43 #include <float.h>
  44
  45 /*
  46  * round
  47  */
  48 inline NS_HIDDEN_(double) NS_round(double x)
  49 {
  50     return x >= 0.0 ? floor(x + 0.5) : ceil(x - 0.5);
  51 }
  52 inline NS_HIDDEN_(float) NS_roundf(float x)
  53 {
  54     return x >= 0.0f ? floorf(x + 0.5f) : ceilf(x - 0.5f);
  55 }
  56 inline NS_HIDDEN_(PRInt32) NS_lround(double x)
  57 {
  58     return x >= 0.0 ? PRInt32(x + 0.5) : PRInt32(x - 0.5);
  59 }
  60
  61 /* NS_roundup30 rounds towards infinity for positive and       */
  62 /* negative numbers.                                           */
  63
  64 #if defined(XP_WIN32) && defined(_M_IX86) && !defined(__GNUC__)
  65 inline NS_HIDDEN_(PRInt32) NS_lroundup30(float x)
  66 {
  67     /* Code derived from Laurent de Soras' paper at             */
  68     /* http://ldesoras.free.fr/doc/articles/rounding_en.pdf     */
  69
  70     /* Rounding up on Windows is expensive using the float to   */
  71     /* int conversion and the floor function. A faster          */
  72     /* approach is to use f87 rounding while assuming the       */
  73     /* default rounding mode of rounding to the nearest         */
  74     /* integer. This rounding mode, however, actually rounds    */
  75     /* to the nearest integer so we add the floating point      */
  76     /* number to itself and add our rounding factor before      */
  77     /* doing the conversion to an integer. We then do a right   */
  78     /* shift of one bit on the integer to divide by two.        */
  79
  80     /* This routine doesn't handle numbers larger in magnitude  */
  81     /* than 2^30 but this is fine for NSToCoordRound because    */
  82     /* Coords are limited to 2^30 in magnitude.                 */
  83
  84     static const double round_to_nearest = 0.5f;
  85     int i;
  86
  87     __asm {
  88       fld     x                   ; load fp argument
  89       fadd    st, st(0)           ; double it
  90       fadd    round_to_nearest    ; add the rounding factor
  91       fistp   dword ptr i         ; convert the result to int
  92     }
  93     return i >> 1;                /* divide by 2 */
  94 }
  95 #endif /* XP_WIN32 && _M_IX86 && !__GNUC__ */
  96
  97 inline NS_HIDDEN_(PRInt32) NS_lroundf(float x)
  98 {
  99     return x >= 0.0f ? PRInt32(x + 0.5f) : PRInt32(x - 0.5f);
 100 }
 101
 102 /*
 103  * ceil
 104  */
 105 inline NS_HIDDEN_(double) NS_ceil(double x)
 106 {
 107     return ceil(x);
 108 }
 109 inline NS_HIDDEN_(float) NS_ceilf(float x)
 110 {
 111     return ceilf(x);
 112 }
 113
 114 /*
 115  * floor
 116  */
 117 inline NS_HIDDEN_(double) NS_floor(double x)
 118 {
 119     return floor(x);
 120 }
 121 inline NS_HIDDEN_(float) NS_floorf(float x)
 122 {
 123     return floorf(x);
 124 }
 125
 126 #endif