/* * Copyright (C) 2003, 2006 Apple Computer, Inc. * * This library is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2 of the License, or (at your option) any later version. * * This library is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with this library; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, * USA. * */ #include "config.h" namespace KJS { // This file exists because JavaScriptCore needs to define the NaN and Inf globals in a way // that does not use a static initializer so we don't have a framework initialization routine. // The trick is to define the NaN and Inf globals with a different type than the declaration. // This trick works because the mangled name of the globals does not include the type, although // I'm not sure that's guaranteed. There could be alignment issues with this, since arrays of // characters don't necessarily need the same alignment doubles do, but for now it seems to work. // It would be good to figure out a 100% clean way that still avoids code that runs at init time. #if PLATFORM(DARWIN) #if PLATFORM(BIG_ENDIAN) extern const unsigned char NaN[sizeof(double)] = { 0x7f, 0xf8, 0, 0, 0, 0, 0, 0 }; extern const unsigned char Inf[sizeof(double)] = { 0x7f, 0xf0, 0, 0, 0, 0, 0, 0 }; #elif PLATFORM(MIDDLE_ENDIAN) extern const unsigned char NaN[] = { 0, 0, 0xf8, 0x7f, 0, 0, 0, 0 }; extern const unsigned char Inf[] = { 0, 0, 0xf0, 0x7f, 0, 0, 0, 0 }; #else extern const unsigned char NaN[sizeof(double)] = { 0, 0, 0, 0, 0, 0, 0xf8, 0x7f }; extern const unsigned char Inf[sizeof(double)] = { 0, 0, 0, 0, 0, 0, 0xf0, 0x7f }; #endif // PLATFORM(MIDDLE_ENDIAN) #else // !PLATFORM(DARWIN) // Note, we have to use union to ensure alignment. Otherwise, NaN_Bytes can start anywhere, // while NaN_double has to be 4-byte aligned for 32-bits. // With -fstrict-aliasing enabled, unions are the only safe way to do type masquerading. static const union { struct { unsigned char NaN_Bytes[8]; unsigned char Inf_Bytes[8]; } bytes; struct { double NaN_Double; double Inf_Double; } doubles; } NaNInf = { { #if PLATFORM(BIG_ENDIAN) { 0x7f, 0xf8, 0, 0, 0, 0, 0, 0 }, { 0x7f, 0xf0, 0, 0, 0, 0, 0, 0 } #elif PLATFORM(MIDDLE_ENDIAN) { 0, 0, 0xf8, 0x7f, 0, 0, 0, 0 }, { 0, 0, 0xf0, 0x7f, 0, 0, 0, 0 } #else { 0, 0, 0, 0, 0, 0, 0xf8, 0x7f }, { 0, 0, 0, 0, 0, 0, 0xf0, 0x7f } #endif } } ; extern const double NaN = NaNInf.doubles.NaN_Double; extern const double Inf = NaNInf.doubles.Inf_Double; #endif // !PLATFORM(DARWIN) } // namespace KJS