endian.hpp

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// -------------------------------------------------------//
//
// SHAMROCK code for hydrodynamics
// Copyright (c) 2021-2026 Timothée David--Cléris <tim.shamrock@proton.me>
// SPDX-License-Identifier: CeCILL Free Software License Agreement v2.1
// Shamrock is licensed under the CeCILL 2.1 License, see LICENSE for more information
//
// -------------------------------------------------------//
 
#pragma once

 
#include "shambase/aliases_int.hpp"
#include "shambase/integer.hpp"
#include <bit>
 
namespace shambase {

    constexpr bool is_little_endian() noexcept {
        return std::endian::native == std::endian::little;
    }

    template<class T>
    inline void endian_swap(T &a) {
 
        constexpr i32 sz = sizeof(a);
 
        // Compute the number of byte swaps to perform, which is half of the size
        // of the type if it is even, or (size - 1) / 2 if it is odd
        auto constexpr lambd = []() {
            if constexpr (sz % 2 == 0) {
                return sz / 2;
            } else {
                return (sz - 1) / 2;
            }
        };
 
        constexpr i32 steps = lambd();
 
        u8 *bytes = (u8 *) &a;
 
        // Perform byte swaps
        for (i32 i = 0; i < steps; i++) {
            xor_swap(bytes[i], bytes[sz - 1 - i]);
        }
    }

    template<class T>
    inline T get_endian_swap(T a) {
        T ret = a;
        endian_swap(ret);
        return ret;
    }
 
} // namespace shambase