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