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/*
* Copyright (c) 2001, 2003-2005 The Regents of The University of Michigan
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met: redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer;
* 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;
* neither the name of the copyright holders nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "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 THE COPYRIGHT
* OWNER 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 __BASE_INTMATH_HH__
#define __BASE_INTMATH_HH__
#include <cassert>
#include <cstdint>
#include <type_traits>
#include "base/logging.hh"
#include "base/types.hh"
/**
* @ingroup api_base_utils
*/
inline uint64_t
power(uint32_t n, uint32_t e)
{
uint64_t result = 1;
uint64_t component = n;
while (e) {
uint64_t last = result;
if (e & 0x1)
result *= component;
warn_if(result < last, "power() overflowed!");
e >>= 1;
component *= component;
}
return result;
}
/**
* @ingroup api_base_utils
*/
template <class T>
inline typename std::enable_if<std::is_integral<T>::value, int>::type
floorLog2(T x)
{
assert(x > 0);
// A guaranteed unsigned version of x.
uint64_t ux = (typename std::make_unsigned<T>::type)x;
int y = 0;
constexpr auto ts = sizeof(T);
if (ts >= 8 && (ux & ULL(0xffffffff00000000))) { y += 32; ux >>= 32; }
if (ts >= 4 && (ux & ULL(0x00000000ffff0000))) { y += 16; ux >>= 16; }
if (ts >= 2 && (ux & ULL(0x000000000000ff00))) { y += 8; ux >>= 8; }
if (ux & ULL(0x00000000000000f0)) { y += 4; ux >>= 4; }
if (ux & ULL(0x000000000000000c)) { y += 2; ux >>= 2; }
if (ux & ULL(0x0000000000000002)) { y += 1; }
return y;
}
/**
* @ingroup api_base_utils
*/
template <class T>
inline int
ceilLog2(const T& n)
{
assert(n > 0);
if (n == 1)
return 0;
return floorLog2(n - (T)1) + 1;
}
/**
* @ingroup api_base_utils
*/
template <class T>
inline bool
isPowerOf2(const T& n)
{
// If n is non-zero, and subtracting one borrows all the way to the MSB
// and flips all bits, then this is a power of 2.
return n && !(n & (n - 1));
}
/**
* @ingroup api_base_utils
*/
template <class T, class U>
inline T
divCeil(const T& a, const U& b)
{
return (a + b - 1) / b;
}
/**
* This function is used to align addresses in memory.
*
* @param val is the address to be aligned.
* @param align is the alignment. Can only be a power of 2.
* @return The aligned address. The smallest number divisible
* by @param align which is greater than or equal to @param val.
*
* @ingroup api_base_utils
*/
template <class T, class U>
inline T
roundUp(const T& val, const U& align)
{
assert(isPowerOf2(align));
T mask = (T)align - 1;
return (val + mask) & ~mask;
}
/**
* This function is used to align addresses in memory.
*
* @param val is the address to be aligned.
* @param align is the alignment. Can only be a power of 2.
* @return The aligned address. The biggest number divisible
* by @param align which is less than or equal to @param val.
*
* @ingroup api_base_utils
*/
template <class T, class U>
inline T
roundDown(const T& val, const U& align)
{
assert(isPowerOf2(align));
T mask = (T)align - 1;
return val & ~mask;
}
#endif // __BASE_INTMATH_HH__