gecko-dev/xpcom/ds/nsMathUtils.h
2008-04-01 21:21:31 -07:00

127 lines
4.2 KiB
C

/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 4 -*-
* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is Mozilla Foundation code.
*
* The Initial Developer of the Original Code is Mozilla Foundation.
* Portions created by the Initial Developer are Copyright (C) 2007
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* Stuart Parmenter <stuart@mozilla.com>
*
* Alternatively, the contents of this file may be used under the terms of
* either the GNU General Public License Version 2 or later (the "GPL"), or
* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
#ifndef nsMathUtils_h__
#define nsMathUtils_h__
#include "nscore.h"
#include <math.h>
#include <float.h>
/*
* round
*/
inline NS_HIDDEN_(double) NS_round(double x)
{
return x >= 0.0 ? floor(x + 0.5) : ceil(x - 0.5);
}
inline NS_HIDDEN_(float) NS_roundf(float x)
{
return x >= 0.0f ? floorf(x + 0.5f) : ceilf(x - 0.5f);
}
inline NS_HIDDEN_(PRInt32) NS_lround(double x)
{
return x >= 0.0 ? PRInt32(x + 0.5) : PRInt32(x - 0.5);
}
/* NS_roundup30 rounds towards infinity for positive and */
/* negative numbers. */
#if defined(XP_WIN32) && defined(_M_IX86) && !defined(__GNUC__)
inline NS_HIDDEN_(PRInt32) NS_lroundup30(float x)
{
/* Code derived from Laurent de Soras' paper at */
/* http://ldesoras.free.fr/doc/articles/rounding_en.pdf */
/* Rounding up on Windows is expensive using the float to */
/* int conversion and the floor function. A faster */
/* approach is to use f87 rounding while assuming the */
/* default rounding mode of rounding to the nearest */
/* integer. This rounding mode, however, actually rounds */
/* to the nearest integer so we add the floating point */
/* number to itself and add our rounding factor before */
/* doing the conversion to an integer. We then do a right */
/* shift of one bit on the integer to divide by two. */
/* This routine doesn't handle numbers larger in magnitude */
/* than 2^30 but this is fine for NSToCoordRound because */
/* Coords are limited to 2^30 in magnitude. */
static const double round_to_nearest = 0.5f;
int i;
__asm {
fld x ; load fp argument
fadd st, st(0) ; double it
fadd round_to_nearest ; add the rounding factor
fistp dword ptr i ; convert the result to int
}
return i >> 1; /* divide by 2 */
}
#endif /* XP_WIN32 && _M_IX86 && !__GNUC__ */
inline NS_HIDDEN_(PRInt32) NS_lroundf(float x)
{
return x >= 0.0f ? PRInt32(x + 0.5f) : PRInt32(x - 0.5f);
}
/*
* ceil
*/
inline NS_HIDDEN_(double) NS_ceil(double x)
{
return ceil(x);
}
inline NS_HIDDEN_(float) NS_ceilf(float x)
{
return ceilf(x);
}
/*
* floor
*/
inline NS_HIDDEN_(double) NS_floor(double x)
{
return floor(x);
}
inline NS_HIDDEN_(float) NS_floorf(float x)
{
return floorf(x);
}
#endif