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// Copyright (c) 2011 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
// This is a legacy file from old Chromium base, some repos still depend on it.
#include <limits.h> // So we can set the bounds of our types
#include <stddef.h> // For size_t
#include <string.h> // for memcpy
#include "base/macros.h"
#if defined(STARBOARD)
#include "starboard/types.h"
#endif // defined(STARBOARD)
// stdint.h is part of C99 but MSVC doesn't have it.
#include <stdint.h> // For intptr_t.
typedef signed char schar;
typedef signed char int8;
typedef short int16;
#if defined(STARBOARD)
typedef int32_t int32;
typedef int int32;
#endif // defined(STARBOARD)
#if defined(STARBOARD)
typedef int64_t int64;
// The NSPR system headers define 64-bit as |long| when possible, except on
// Mac OS X. In order to not have typedef mismatches, we do the same on LP64.
// On Mac OS X, |long long| is used for 64-bit types for compatibility with
// <inttypes.h> format macros even in the LP64 model.
#if defined(__LP64__) && !defined(OS_MACOSX) && !defined(OS_OPENBSD)
typedef long int64;
typedef long long int64;
#endif // defined(STARBOARD)
// NOTE: unsigned types are DANGEROUS in loops and other arithmetical
// places. Use the signed types unless your variable represents a bit
// pattern (eg a hash value) or you really need the extra bit. Do NOT
// use 'unsigned' to express "this value should always be positive";
// use assertions for this.
#if defined(STARBOARD)
typedef uint8_t uint8;
typedef uint16_t uint16;
typedef uint32_t uint32;
typedef unsigned char uint8;
typedef unsigned short uint16;
typedef unsigned int uint32;
#endif // defined(STARBOARD)
#if defined(STARBOARD)
typedef uint64_t uint64;
// See the comment above about NSPR and 64-bit.
#if defined(__LP64__) && !defined(OS_MACOSX) && !defined(OS_OPENBSD)
typedef unsigned long uint64;
typedef unsigned long long uint64;
#endif // defined(STARBOARD)
// A type to represent a Unicode code-point value. As of Unicode 4.0,
// such values require up to 21 bits.
// (For type-checking on pointers, make this explicitly signed,
// and it should always be the signed version of whatever int32 is.)
#if defined(STARBOARD)
typedef int32_t char32;
typedef signed int char32;
#endif // defined(STARBOARD)
#if defined(COBALT_WIN)
#pragma warning(push)
#pragma warning(disable : 4310) // Cast truncates constant value.
const uint8 kuint8max = ((uint8)0xFF);
const uint16 kuint16max = ((uint16)0xFFFF);
const uint32 kuint32max = ((uint32)0xFFFFFFFF);
// const uint64 kuint64max = ((uint64) GG_LONGLONG(0xFFFFFFFFFFFFFFFF));
const int8 kint8min = ((int8)0x80);
const int8 kint8max = ((int8)0x7F);
const int16 kint16min = ((int16)0x8000);
const int16 kint16max = ((int16)0x7FFF);
const int32 kint32min = ((int32)0x80000000);
const int32 kint32max = ((int32)0x7FFFFFFF);
// const int64 kint64min = (( int64) GG_LONGLONG(0x8000000000000000));
// const int64 kint64max = (( int64) GG_LONGLONG(0x7FFFFFFFFFFFFFFF));
#if defined(COBALT_WIN)
#pragma warning(pop)
// An older, deprecated, politically incorrect name for the above.
// NOTE: The usage of this macro was baned from our code base, but some
// third_party libraries are yet using it.
// TODO(tfarina): Figure out how to fix the usage of this macro in the
// third_party libraries and get rid of it.
// The arraysize(arr) macro returns the # of elements in an array arr.
// The expression is a compile-time constant, and therefore can be
// used in defining new arrays, for example. If you use arraysize on
// a pointer by mistake, you will get a compile-time error.
// One caveat is that arraysize() doesn't accept any array of an
// anonymous type or a type defined inside a function. In these rare
// cases, you have to use the unsafe ARRAYSIZE_UNSAFE() macro below. This is
// due to a limitation in C++'s template system. The limitation might
// eventually be removed, but it hasn't happened yet.
// This template function declaration is used in defining arraysize.
// Note that the function doesn't need an implementation, as we only
// use its type.
template <typename T, size_t N>
char (&ArraySizeHelper(T (&array)[N]))[N];
// That gcc wants both of these prototypes seems mysterious. VC, for
// its part, can't decide which to use (another mystery). Matching of
// template overloads: the final frontier.
#ifndef _MSC_VER
template <typename T, size_t N>
char (&ArraySizeHelper(const T (&array)[N]))[N];
#if defined(COMPILER_GHS)
// GHS does not support local types as template arguments, so we must fall back
// to the unsafe version
#define arraysize ARRAYSIZE_UNSAFE
#define arraysize(array) (sizeof(ArraySizeHelper(array)))
// ARRAYSIZE_UNSAFE performs essentially the same calculation as arraysize,
// but can be used on anonymous types or types defined inside
// functions. It's less safe than arraysize as it accepts some
// (although not all) pointers. Therefore, you should use arraysize
// whenever possible.
// The expression ARRAYSIZE_UNSAFE(a) is a compile-time constant of type
// size_t.
// ARRAYSIZE_UNSAFE catches a few type errors. If you see a compiler error
// "warning: division by zero in ..."
// when using ARRAYSIZE_UNSAFE, you are (wrongfully) giving it a pointer.
// You should only use ARRAYSIZE_UNSAFE on statically allocated arrays.
// The following comments are on the implementation details, and can
// be ignored by the users.
// ARRAYSIZE_UNSAFE(arr) works by inspecting sizeof(arr) (the # of bytes in
// the array) and sizeof(*(arr)) (the # of bytes in one array
// element). If the former is divisible by the latter, perhaps arr is
// indeed an array, in which case the division result is the # of
// elements in the array. Otherwise, arr cannot possibly be an array,
// and we generate a compiler error to prevent the code from
// compiling.
// Since the size of bool is implementation-defined, we need to cast
// !(sizeof(a) & sizeof(*(a))) to size_t in order to ensure the final
// result has type size_t.
// This macro is not perfect as it wrongfully accepts certain
// pointers, namely where the pointer size is divisible by the pointee
// size. Since all our code has to go through a 32-bit compiler,
// where a pointer is 4 bytes, this means all pointers to a type whose
// size is 3 or greater than 4 will be (righteously) rejected.
((sizeof(a) / sizeof(*(a))) / \
static_cast<size_t>(!(sizeof(a) % sizeof(*(a)))))
// Use implicit_cast as a safe version of static_cast or const_cast
// for upcasting in the type hierarchy (i.e. casting a pointer to Foo
// to a pointer to SuperclassOfFoo or casting a pointer to Foo to
// a const pointer to Foo).
// When you use implicit_cast, the compiler checks that the cast is safe.
// Such explicit implicit_casts are necessary in surprisingly many
// situations where C++ demands an exact type match instead of an
// argument type convertable to a target type.
// The From type can be inferred, so the preferred syntax for using
// implicit_cast is the same as for static_cast etc.:
// implicit_cast<ToType>(expr)
// implicit_cast would have been part of the C++ standard library,
// but the proposal was submitted too late. It will probably make
// its way into the language in the future.
template <typename To, typename From>
inline To implicit_cast(From const& f) {
return f;
// The COMPILE_ASSERT macro can be used to verify that a compile time
// expression is true. For example, you could use it to verify the
// size of a static array:
// content_type_names_incorrect_size);
// or to make sure a struct is smaller than a certain size:
// COMPILE_ASSERT(sizeof(foo) < 128, foo_too_large);
// The second argument to the macro is the name of the variable. If
// the expression is false, most compilers will issue a warning/error
// containing the name of the variable.
template <bool>
struct CompileAssert {};
#define COMPILE_ASSERT(expr, msg) \
typedef CompileAssert<(bool(expr))> msg[bool(expr) ? 1 : -1]
// Implementation details of COMPILE_ASSERT:
// - COMPILE_ASSERT works by defining an array type that has -1
// elements (and thus is invalid) when the expression is false.
// - The simpler definition
// #define COMPILE_ASSERT(expr, msg) typedef char msg[(expr) ? 1 : -1]
// does not work, as gcc supports variable-length arrays whose sizes
// are determined at run-time (this is gcc's extension and not part
// of the C++ standard). As a result, gcc fails to reject the
// following code with the simple definition:
// int foo;
// COMPILE_ASSERT(foo, msg); // not supposed to compile as foo is
// // not a compile-time constant.
// - By using the type CompileAssert<(bool(expr))>, we ensures that
// expr is a compile-time constant. (Template arguments must be
// determined at compile-time.)
// - The outer parentheses in CompileAssert<(bool(expr))> are necessary
// to work around a bug in gcc 3.4.4 and 4.0.1. If we had written
// CompileAssert<bool(expr)>
// instead, these compilers will refuse to compile
// COMPILE_ASSERT(5 > 0, some_message);
// (They seem to think the ">" in "5 > 0" marks the end of the
// template argument list.)
// - The array size is (bool(expr) ? 1 : -1), instead of simply
// ((expr) ? 1 : -1).
// This is to avoid running into a bug in MS VC 7.1, which
// causes ((0.0) ? 1 : -1) to incorrectly evaluate to 1.
// bit_cast<Dest,Source> is a template function that implements the
// equivalent of "*reinterpret_cast<Dest*>(&source)". We need this in
// very low-level functions like the protobuf library and fast math
// support.
// float f = 3.14159265358979;
// int i = bit_cast<int32>(f);
// // i = 0x40490fdb
// The classical address-casting method is:
// // WRONG
// float f = 3.14159265358979; // WRONG
// int i = * reinterpret_cast<int*>(&f); // WRONG
// The address-casting method actually produces undefined behavior
// according to ISO C++ specification section 3.10 -15 -. Roughly, this
// section says: if an object in memory has one type, and a program
// accesses it with a different type, then the result is undefined
// behavior for most values of "different type".
// This is true for any cast syntax, either *(int*)&f or
// *reinterpret_cast<int*>(&f). And it is particularly true for
// conversions betweeen integral lvalues and floating-point lvalues.
// The purpose of 3.10 -15- is to allow optimizing compilers to assume
// that expressions with different types refer to different memory. gcc
// 4.0.1 has an optimizer that takes advantage of this. So a
// non-conforming program quietly produces wildly incorrect output.
// The problem is not the use of reinterpret_cast. The problem is type
// punning: holding an object in memory of one type and reading its bits
// back using a different type.
// The C++ standard is more subtle and complex than this, but that
// is the basic idea.
// Anyways ...
// bit_cast<> calls memcpy() which is blessed by the standard,
// especially by the example in section 3.9 . Also, of course,
// bit_cast<> wraps up the nasty logic in one place.
// Fortunately memcpy() is very fast. In optimized mode, with a
// constant size, gcc 2.95.3, gcc 4.0.1, and msvc 7.1 produce inline
// code with the minimal amount of data movement. On a 32-bit system,
// memcpy(d,s,4) compiles to one load and one store, and memcpy(d,s,8)
// compiles to two loads and two stores.
// I tested this code with gcc 2.95.3, gcc 4.0.1, icc 8.1, and msvc 7.1.
// WARNING: if Dest or Source is a non-POD type, the result of the memcpy
// is likely to surprise you.
template <class Dest, class Source>
inline Dest bit_cast(const Source& source) {
// Compile time assertion: sizeof(Dest) == sizeof(Source)
// A compile error here means your Dest and Source have different sizes.
typedef char VerifySizesAreEqual[sizeof(Dest) == sizeof(Source) ? 1 : -1];
Dest dest;
memcpy(&dest, &source, sizeof(dest));
return dest;
// The following enum should be used only as a constructor argument to indicate
// that the variable has static storage class, and that the constructor should
// do nothing to its state. It indicates to the reader that it is legal to
// declare a static instance of the class, provided the constructor is given
// the base::LINKER_INITIALIZED argument. Normally, it is unsafe to declare a
// static variable that has a constructor or a destructor because invocation
// order is undefined. However, IF the type can be initialized by filling with
// zeroes (which the loader does for static variables), AND the destructor also
// does nothing to the storage, AND there are no virtual methods, then a
// constructor declared as
// explicit MyClass(base::LinkerInitialized x) {}
// and invoked as
// static MyClass my_variable_name(base::LINKER_INITIALIZED);
namespace base {
enum LinkerInitialized { LINKER_INITIALIZED };
// Use these to declare and define a static local variable (static T;) so that
// it is leaked so that its destructors are not called at exit. If you need
// thread-safe initialization, use base/lazy_instance.h instead.
#define CR_DEFINE_STATIC_LOCAL(type, name, arguments) \
static type& name = *new type arguments
} // namespace base