1/*
2 * Copyright (C) 2008 Apple Inc. All Rights Reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
14 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
16 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
17 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
18 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
19 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
20 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
21 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
23 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26#ifndef WTF_StdLibExtras_h
27#define WTF_StdLibExtras_h
28
29#include <wtf/Platform.h>
30#include <wtf/Assertions.h>
31
32// Use these to declare and define a static local variable (static T;) so that
33// it is leaked so that its destructors are not called at exit. Using this
34// macro also allows workarounds a compiler bug present in Apple's version of GCC 4.0.1.
35#ifndef DEFINE_STATIC_LOCAL
36#if COMPILER(GCC) && defined(__APPLE_CC__) && __GNUC__ == 4 && __GNUC_MINOR__ == 0 && __GNUC_PATCHLEVEL__ == 1
37#define DEFINE_STATIC_LOCAL(type, name, arguments) \
38 static type* name##Ptr = new type arguments; \
39 type& name = *name##Ptr
40#else
41#define DEFINE_STATIC_LOCAL(type, name, arguments) \
42 static type& name = *new type arguments
43#endif
44#endif
45
46// OBJECT_OFFSETOF: Like the C++ offsetof macro, but you can use it with classes.
47// The magic number 0x4000 is insignificant. We use it to avoid using NULL, since
48// NULL can cause compiler problems, especially in cases of multiple inheritance.
49#define OBJECT_OFFSETOF(class, field) (reinterpret_cast<std::ptrdiff_t>(&(reinterpret_cast<class*>(0x4000)->field)) - 0x4000)
50
51// STRINGIZE: Can convert any value to quoted string, even expandable macros
52#define STRINGIZE(exp) #exp
53#define STRINGIZE_VALUE_OF(exp) STRINGIZE(exp)
54
55namespace WTF {
56
57 /*
58 * C++'s idea of a reinterpret_cast lacks sufficient cojones.
59 */
60 template<typename TO, typename FROM>
61 TO bitwise_cast(FROM from)
62 {
63 COMPILE_ASSERT(sizeof(TO) == sizeof(FROM), WTF_bitwise_cast_sizeof_casted_types_is_equal);
64 union {
65 FROM from;
66 TO to;
67 } u;
68 u.from = from;
69 return u.to;
70 }
71
72 // Returns a count of the number of bits set in 'bits'.
73 inline size_t bitCount(unsigned bits)
74 {
75 bits = bits - ((bits >> 1) & 0x55555555);
76 bits = (bits & 0x33333333) + ((bits >> 2) & 0x33333333);
77 return (((bits + (bits >> 4)) & 0xF0F0F0F) * 0x1010101) >> 24;
78 }
79
80} // namespace WTF
81
82#endif
83

source code of qtscript/src/3rdparty/javascriptcore/JavaScriptCore/wtf/StdLibExtras.h