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