💿🐜 Antkeeper source code
https://antkeeper.com
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
96 lines
2.4 KiB
96 lines
2.4 KiB
/*
|
|
* Copyright (C) 2020 Christopher J. Howard
|
|
*
|
|
* This file is part of Antkeeper source code.
|
|
*
|
|
* Antkeeper source code is free software: you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License as published by
|
|
* the Free Software Foundation, either version 3 of the License, or
|
|
* (at your option) any later version.
|
|
*
|
|
* Antkeeper source code is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
* GNU General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License
|
|
* along with Antkeeper source code. If not, see <http://www.gnu.org/licenses/>.
|
|
*/
|
|
|
|
#ifndef ANTKEEPER_BIT_MATH_HPP
|
|
#define ANTKEEPER_BIT_MATH_HPP
|
|
|
|
namespace dna
|
|
{
|
|
|
|
/**
|
|
* Reads bits from the least significant bits of a value and returns them in the positions marked by a mask.
|
|
*
|
|
* @param x Value from which bits should be read.
|
|
* @param mask Bit mask indicating where bits should be deposited.
|
|
* @return Bits from the least significant bits of @p x in the positions marked by @p mask.
|
|
*/
|
|
template <class T>
|
|
constexpr T bit_deposit(T x, T mask) noexcept;
|
|
|
|
/**
|
|
* Reads bits from a value in the positions marked by a mask and returns them in the least significant bits.
|
|
*
|
|
* @param x Value from which bits should be read.
|
|
* @param mask Bit mask indicating which bits to extract.
|
|
* @return Bits of @p x from the positions marked by @p mask in the least significant bits.
|
|
*/
|
|
template <class T>
|
|
constexpr T bit_extract(T x, T mask) noexcept;
|
|
|
|
/**
|
|
* Returns the number of set bits in a value, known as a *population count* or *Hamming weight*.
|
|
*
|
|
* @param x Value to count.
|
|
* @return Number of set bits in @p x.
|
|
*/
|
|
template <typename T>
|
|
constexpr int popcount(T x) noexcept;
|
|
|
|
template <class T>
|
|
constexpr T bit_deposit(T x, T mask) noexcept
|
|
{
|
|
T result = 0;
|
|
|
|
for (T i = 1; mask; i <<= 1)
|
|
{
|
|
if (x & i)
|
|
result |= mask & -mask;
|
|
mask &= mask - 1;
|
|
}
|
|
|
|
return result;
|
|
}
|
|
|
|
template <class T>
|
|
constexpr T bit_extract(T x, T mask) noexcept
|
|
{
|
|
T result = 0;
|
|
|
|
for (T i = 1; mask; i <<= 1)
|
|
{
|
|
if (x & mask & -mask)
|
|
result |= i;
|
|
mask &= mask - 1;
|
|
}
|
|
|
|
return result;
|
|
}
|
|
|
|
template <typename T>
|
|
constexpr int popcount(T x) noexcept
|
|
{
|
|
int n = 0;
|
|
for (; x; ++n)
|
|
x &= x - 1;
|
|
return n;
|
|
}
|
|
|
|
} // namespace dna
|
|
|
|
#endif // ANTKEEPER_BIT_MATH_HPP
|