utils/bits/operators.hpp

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#ifndef GENESIS_UTILS_BITS_OPERATORS_H_
#define GENESIS_UTILS_BITS_OPERATORS_H_
 
/*
    Genesis - A toolkit for working with phylogenetic data.
    Copyright (C) 2014-2024 Lucas Czech
 
    This program 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.
 
    This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
 
    Contact:
    Lucas Czech <lucas.czech@sund.ku.dk>
    University of Copenhagen, Globe Institute, Section for GeoGenetics
    Oster Voldgade 5-7, 1350 Copenhagen K, Denmark
*/
 
#if ((defined(_MSVC_LANG) && _MSVC_LANG >= 201703L) || __cplusplus >= 201703L)
 
#include "genesis/utils/core/info.hpp"
 
#include <cstdint>
#include <immintrin.h>  // _pext_u64
 
#ifdef __BMI2__
#    define GENSIS_HAS_COMPILETIME_BMI2 1
#else
#    define GENSIS_HAS_COMPILETIME_BMI2 0
#endif
 
namespace genesis {
namespace utils {
 
// ================================================================================================
//     Bit Extract
// ================================================================================================
 
template <typename Integral>
inline constexpr Integral extract_bits( Integral source, Integral mask )
{
    Integral res = 0;
    Integral bb = 1;
    do {
        Integral lsb = mask & -mask;
        mask &= ~lsb;
        bool isset = source & lsb;
        res |= isset ? bb : 0;
        bb += bb;
    } while (mask);
 
    return res;
}
 
inline uint64_t bit_extract( uint64_t source, uint64_t mask )
{
    return _pext_u64( source, mask );
 
    // static const bool has_pext_support = info_get_hardware().HW_BMI2;
    // if( GENSIS_HAS_COMPILETIME_BMI2 && has_pext_support ) {
    //     return _pext_u64( source, mask );
    // } else {
    //
    // }
}
 
// ================================================================================================
//     Pop Count
// ================================================================================================
 
template< class T >
inline constexpr size_t pop_count( T x )
{
    (void) x;
    // https://en.cppreference.com/w/cpp/numeric/popcount
    // https://en.cppreference.com/w/cpp/header/bit
    return 0;
}
 
} // namespace utils
} // namespace genesis
 
#endif // ((defined(_MSVC_LANG) && _MSVC_LANG >= 201703L) || __cplusplus >= 201703L)
#endif // include guard