The Tor Browser: xpcom/ds/nsMathUtils.h@6474c204b198

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

     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/. */

     6 #ifndef nsMathUtils_h__

     7 #define nsMathUtils_h__

     9 #define _USE_MATH_DEFINES /* needed for M_ constants on Win32 */

    11 #include "nscore.h"

    12 #include <cmath>

    13 #include <float.h>

    15 #ifdef SOLARIS

    16 #include <ieeefp.h>

    17 #endif

    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 }

    35 /* NS_roundup30 rounds towards infinity for positive and       */

    36 /* negative numbers.                                           */

    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     */

    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.        */

    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.                 */

    58     static const double round_to_nearest = 0.5f;

    59     int i;

    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__ */

    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 }

    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 }

    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 }

   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 }

   121 #endif

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