intrinsic.hpp

Go to the documentation of this file.

/* Copyright 2025 Luca Venerando Greco, René Widera
 * SPDX-License-Identifier: MPL-2.0
 */
 
#pragma once
 
#include "alpaka/api/api.hpp"
#include "alpaka/api/intrinsic.hpp"
#include "alpaka/api/trait.hpp"
#include "internal/intrinsic.hpp"
 
#include <climits>
 
namespace alpaka
{
    /** Returns the number of bits set to 1. */
    constexpr int32_t popcount(auto const& arg)
        requires(sizeof(ALPAKA_TYPEOF(arg)) == 4u || sizeof(ALPAKA_TYPEOF(arg)) == 8u)
    {
        constexpr auto intrinsicImpl = trait::getIntrinsicImpl(thisApi());
        return internal::intrinsic::Popcount::Op<ALPAKA_TYPEOF(intrinsicImpl), ALPAKA_TYPEOF(arg)>{}(
            intrinsicImpl,
            arg);
    }
 
    /* Position of the least significant bit set to 1.
     *
     * @return 1-based position of the first set bit, zero for input value 0.
     */
    constexpr int32_t ffs(auto const& arg)
        requires(sizeof(ALPAKA_TYPEOF(arg)) == 4u || sizeof(ALPAKA_TYPEOF(arg)) == 8u)
    {
        constexpr auto intrinsicImpl = trait::getIntrinsicImpl(thisApi());
        return internal::intrinsic::Ffs::Op<ALPAKA_TYPEOF(intrinsicImpl), ALPAKA_TYPEOF(arg)>{}(intrinsicImpl, arg);
    }
 
    /* Return the number of most significant zero bits
     *
     * @return number consecutive most significant zero bits, zero for input value 0.
     */
    constexpr int32_t clz(auto const& arg)
        requires(sizeof(ALPAKA_TYPEOF(arg)) == 4u || sizeof(ALPAKA_TYPEOF(arg)) == 8u)
    {
        constexpr auto intrinsicImpl = alpaka::trait::getIntrinsicImpl(thisApi());
        return internal::intrinsic::Clz::Op<ALPAKA_TYPEOF(intrinsicImpl), ALPAKA_TYPEOF(arg)>{}(intrinsicImpl, arg);
    }
} // namespace alpaka