kjs/fpconst.cpp

   1 /*
   2  *  Copyright (C) 2003, 2006 Apple Computer, Inc.
   3  *
   4  *  This library is free software; you can redistribute it and/or
   5  *  modify it under the terms of the GNU Lesser General Public
   6  *  License as published by the Free Software Foundation; either
   7  *  version 2 of the License, or (at your option) any later version.
   8  *
   9  *  This library is distributed in the hope that it will be useful,
  10  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  *  Lesser General Public License for more details.
  13  *
  14  *  You should have received a copy of the GNU Lesser General Public
  15  *  License along with this library; if not, write to the Free Software
  16  *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
  17  *  USA.
  18  *
  19  */
  20
  21 #include <math.h>
  22 #include "global.h"
  23
  24 namespace KJS {
  25
  26 // This file exists because JavaScriptCore needs to define the NaN and Inf globals in a way
  27 // that does not use a static initializer so we don't have a framework initialization routine.
  28
  29 // The trick is to define the NaN and Inf globals with a different type than the declaration.
  30 // This trick works because the mangled name of the globals does not include the type, although
  31 // I'm not sure that's guaranteed. There could be alignment issues with this, since arrays of
  32 // characters don't necessarily need the same alignment doubles do, but for now it seems to work.
  33 // It would be good to figure out a 100% clean way that still avoids code that runs at init time.
  34
  35 #if (defined(AVOID_STATIC_CONSTRUCTORS) && !AVOID_STATIC_CONSTRUCTORS)
  36     extern const double NaN = NAN;
  37     extern const double Inf = INFINITY;
  38 #elif PLATFORM(DARWIN)
  39
  40 #if PLATFORM(BIG_ENDIAN)
  41     extern const unsigned char NaN[sizeof(double)] = { 0x7f, 0xf8, 0, 0, 0, 0, 0, 0 };
  42     extern const unsigned char Inf[sizeof(double)] = { 0x7f, 0xf0, 0, 0, 0, 0, 0, 0 };
  43 #elif PLATFORM(MIDDLE_ENDIAN)
  44     extern const unsigned char NaN[] = { 0, 0, 0xf8, 0x7f, 0, 0, 0, 0 };
  45     extern const unsigned char Inf[] = { 0, 0, 0xf0, 0x7f, 0, 0, 0, 0 };
  46 #else
  47     extern const unsigned char NaN[sizeof(double)] = { 0, 0, 0, 0, 0, 0, 0xf8, 0x7f };
  48     extern const unsigned char Inf[sizeof(double)] = { 0, 0, 0, 0, 0, 0, 0xf0, 0x7f };
  49 #endif // PLATFORM(MIDDLE_ENDIAN)
  50
  51 #else // !PLATFORM(DARWIN)
  52
  53 #if PLATFORM(BIG_ENDIAN)
  54     const unsigned char NaN_Bytes[] = { 0x7f, 0xf8, 0, 0, 0, 0, 0, 0 };
  55     const unsigned char Inf_Bytes[] = { 0x7f, 0xf0, 0, 0, 0, 0, 0, 0 };
  56 #elif PLATFORM(MIDDLE_ENDIAN)
  57     const unsigned char NaN_Bytes[] = { 0, 0, 0xf8, 0x7f, 0, 0, 0, 0 };
  58     const unsigned char Inf_Bytes[] = { 0, 0, 0xf0, 0x7f, 0, 0, 0, 0 };
  59 #else
  60     const unsigned char NaN_Bytes[] = { 0, 0, 0, 0, 0, 0, 0xf8, 0x7f };
  61     const unsigned char Inf_Bytes[] = { 0, 0, 0, 0, 0, 0, 0xf0, 0x7f };
  62 #endif
  63     extern const double NaN = *(const double*) NaN_Bytes;
  64     extern const double Inf = *(const double*) Inf_Bytes;
  65
  66 #endif // !PLATFORM(DARWIN)
  67
  68
  69 } // namespace KJS