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Algorithm.h
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Algorithm.h
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/*
* Copyright (C) 2014 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef Algorithm_h
#define Algorithm_h
#include "BAssert.h"
#include <algorithm>
#include <cstdint>
#include <cstddef>
#include <limits>
#include <type_traits>
#include <chrono>
namespace bmalloc {
// Versions of min and max that are compatible with compile-time constants.
template<typename T> inline constexpr T max(T a, T b)
{
return a > b ? a : b;
}
template<typename T> inline constexpr T min(T a, T b)
{
return a < b ? a : b;
}
template<typename T> inline constexpr T mask(T value, uintptr_t mask)
{
static_assert(sizeof(T) == sizeof(uintptr_t), "sizeof(T) must be equal to sizeof(uintptr_t).");
return static_cast<T>(static_cast<uintptr_t>(value) & mask);
}
template<typename T> inline T* mask(T* value, uintptr_t mask)
{
return reinterpret_cast<T*>(reinterpret_cast<uintptr_t>(value) & mask);
}
template<typename T> inline constexpr bool test(T value, uintptr_t mask)
{
return !!(reinterpret_cast<uintptr_t>(value) & mask);
}
inline constexpr bool isPowerOfTwo(size_t size)
{
return size && !(size & (size - 1));
}
template<typename T> inline T roundUpToMultipleOf(size_t divisor, T x)
{
BASSERT(isPowerOfTwo(divisor));
static_assert(sizeof(T) == sizeof(uintptr_t), "sizeof(T) must be equal to sizeof(uintptr_t).");
return static_cast<T>((static_cast<uintptr_t>(x) + (divisor - 1)) & ~(divisor - 1));
}
template<size_t divisor, typename T> inline T roundUpToMultipleOf(T x)
{
static_assert(isPowerOfTwo(divisor), "'divisor' must be a power of two.");
return roundUpToMultipleOf(divisor, x);
}
template<typename T> inline T* roundUpToMultipleOf(size_t divisor, T* x)
{
BASSERT(isPowerOfTwo(divisor));
return reinterpret_cast<T*>((reinterpret_cast<uintptr_t>(x) + (divisor - 1)) & ~(divisor - 1));
}
template<size_t divisor, typename T> inline T* roundUpToMultipleOf(T* x)
{
static_assert(isPowerOfTwo(divisor), "'divisor' must be a power of two.");
return roundUpToMultipleOf(divisor, x);
}
template<typename T> inline T roundDownToMultipleOf(size_t divisor, T x)
{
BASSERT(isPowerOfTwo(divisor));
return reinterpret_cast<T>(mask(reinterpret_cast<uintptr_t>(x), ~(divisor - 1ul)));
}
template<size_t divisor, typename T> inline constexpr T roundDownToMultipleOf(T x)
{
static_assert(isPowerOfTwo(divisor), "'divisor' must be a power of two.");
return roundDownToMultipleOf(divisor, x);
}
template<typename T> inline void divideRoundingUp(T numerator, T denominator, T& quotient, T& remainder)
{
// We expect the compiler to emit a single divide instruction to extract both the quotient and the remainder.
quotient = numerator / denominator;
remainder = numerator % denominator;
if (remainder)
quotient += 1;
}
template<typename T> inline T divideRoundingUp(T numerator, T denominator)
{
return (numerator + denominator - 1) / denominator;
}
template<typename T> inline T roundUpToMultipleOfNonPowerOfTwo(size_t divisor, T x)
{
return divideRoundingUp(x, divisor) * divisor;
}
// Version of sizeof that returns 0 for empty classes.
template<typename T> inline constexpr size_t sizeOf()
{
return std::is_empty<T>::value ? 0 : sizeof(T);
}
template<typename T> inline constexpr size_t bitCount()
{
return sizeof(T) * 8;
}
#if BOS(WINDOWS)
template<int depth> __forceinline constexpr unsigned long clzl(unsigned long value)
{
return value & (1UL << (bitCount<unsigned long>() - 1)) ? 0 : 1 + clzl<depth - 1>(value << 1);
}
template<> __forceinline constexpr unsigned long clzl<1>(unsigned long value)
{
return 0;
}
__forceinline constexpr unsigned long __builtin_clzl(unsigned long value)
{
return value == 0 ? 32 : clzl<bitCount<unsigned long>()>(value);
}
#endif
inline constexpr unsigned long log2(unsigned long value)
{
return bitCount<unsigned long>() - 1 - __builtin_clzl(value);
}
} // namespace bmalloc
#endif // Algorithm_h