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comparison: xpcom/ds/nsMathUtils.h
xpcom/ds/nsMathUtils.h
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- TOR_BUG_3246
- changeset 7
- 129ffea94266
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| -1:000000000000 | 0:7607e8ee4f60 |
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| 1 /* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 4 -*- | |
| 2 * This Source Code Form is subject to the terms of the Mozilla Public | |
| 3 * License, v. 2.0. If a copy of the MPL was not distributed with this | |
| 4 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ | |
| 5 | |
| 6 #ifndef nsMathUtils_h__ | |
| 7 #define nsMathUtils_h__ | |
| 8 | |
| 9 #define _USE_MATH_DEFINES /* needed for M_ constants on Win32 */ | |
| 10 | |
| 11 #include "nscore.h" | |
| 12 #include <cmath> | |
| 13 #include <float.h> | |
| 14 | |
| 15 #ifdef SOLARIS | |
| 16 #include <ieeefp.h> | |
| 17 #endif | |
| 18 | |
| 19 /* | |
| 20 * round | |
| 21 */ | |
| 22 inline NS_HIDDEN_(double) NS_round(double x) | |
| 23 { | |
| 24 return x >= 0.0 ? floor(x + 0.5) : ceil(x - 0.5); | |
| 25 } | |
| 26 inline NS_HIDDEN_(float) NS_roundf(float x) | |
| 27 { | |
| 28 return x >= 0.0f ? floorf(x + 0.5f) : ceilf(x - 0.5f); | |
| 29 } | |
| 30 inline NS_HIDDEN_(int32_t) NS_lround(double x) | |
| 31 { | |
| 32 return x >= 0.0 ? int32_t(x + 0.5) : int32_t(x - 0.5); | |
| 33 } | |
| 34 | |
| 35 /* NS_roundup30 rounds towards infinity for positive and */ | |
| 36 /* negative numbers. */ | |
| 37 | |
| 38 #if defined(XP_WIN32) && defined(_M_IX86) && !defined(__GNUC__) | |
| 39 inline NS_HIDDEN_(int32_t) NS_lroundup30(float x) | |
| 40 { | |
| 41 /* Code derived from Laurent de Soras' paper at */ | |
| 42 /* http://ldesoras.free.fr/doc/articles/rounding_en.pdf */ | |
| 43 | |
| 44 /* Rounding up on Windows is expensive using the float to */ | |
| 45 /* int conversion and the floor function. A faster */ | |
| 46 /* approach is to use f87 rounding while assuming the */ | |
| 47 /* default rounding mode of rounding to the nearest */ | |
| 48 /* integer. This rounding mode, however, actually rounds */ | |
| 49 /* to the nearest integer so we add the floating point */ | |
| 50 /* number to itself and add our rounding factor before */ | |
| 51 /* doing the conversion to an integer. We then do a right */ | |
| 52 /* shift of one bit on the integer to divide by two. */ | |
| 53 | |
| 54 /* This routine doesn't handle numbers larger in magnitude */ | |
| 55 /* than 2^30 but this is fine for NSToCoordRound because */ | |
| 56 /* Coords are limited to 2^30 in magnitude. */ | |
| 57 | |
| 58 static const double round_to_nearest = 0.5f; | |
| 59 int i; | |
| 60 | |
| 61 __asm { | |
| 62 fld x ; load fp argument | |
| 63 fadd st, st(0) ; double it | |
| 64 fadd round_to_nearest ; add the rounding factor | |
| 65 fistp dword ptr i ; convert the result to int | |
| 66 } | |
| 67 return i >> 1; /* divide by 2 */ | |
| 68 } | |
| 69 #endif /* XP_WIN32 && _M_IX86 && !__GNUC__ */ | |
| 70 | |
| 71 inline NS_HIDDEN_(int32_t) NS_lroundf(float x) | |
| 72 { | |
| 73 return x >= 0.0f ? int32_t(x + 0.5f) : int32_t(x - 0.5f); | |
| 74 } | |
| 75 | |
| 76 /* | |
| 77 * hypot. We don't need a super accurate version of this, if a platform | |
| 78 * turns up with none of the possibilities below it would be okay to fall | |
| 79 * back to sqrt(x*x + y*y). | |
| 80 */ | |
| 81 inline NS_HIDDEN_(double) NS_hypot(double x, double y) | |
| 82 { | |
| 83 #ifdef __GNUC__ | |
| 84 return __builtin_hypot(x, y); | |
| 85 #elif defined _WIN32 | |
| 86 return _hypot(x, y); | |
| 87 #else | |
| 88 return hypot(x, y); | |
| 89 #endif | |
| 90 } | |
| 91 | |
| 92 /** | |
| 93 * Check whether a floating point number is finite (not +/-infinity and not a | |
| 94 * NaN value). | |
| 95 */ | |
| 96 inline NS_HIDDEN_(bool) NS_finite(double d) | |
| 97 { | |
| 98 #ifdef WIN32 | |
| 99 // NOTE: '!!' casts an int to bool without spamming MSVC warning C4800. | |
| 100 return !!_finite(d); | |
| 101 #elif defined(XP_DARWIN) | |
| 102 // Darwin has deprecated |finite| and recommends |isfinite|. The former is | |
| 103 // not present in the iOS SDK. | |
| 104 return std::isfinite(d); | |
| 105 #else | |
| 106 return finite(d); | |
| 107 #endif | |
| 108 } | |
| 109 | |
| 110 /** | |
| 111 * Returns the result of the modulo of x by y using a floored division. | |
| 112 * fmod(x, y) is using a truncated division. | |
| 113 * The main difference is that the result of this method will have the sign of | |
| 114 * y while the result of fmod(x, y) will have the sign of x. | |
| 115 */ | |
| 116 inline NS_HIDDEN_(double) NS_floorModulo(double x, double y) | |
| 117 { | |
| 118 return (x - y * floor(x / y)); | |
| 119 } | |
| 120 | |
| 121 #endif |
