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<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 55 namespace 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
