detail.hxx

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/*
 * Copyright (C) 2024-2026 David C. Manuelda (StormBytePP)
 *
 * This file is part of StormByte.
 *
 * StormByte is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License version 3
 * or later, as published by the Free Software Foundation.
 *
 * StormByte 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with StormByte. If not, see
 * <https://www.gnu.org/licenses/lgpl-3.0.html>.
 */
 
#pragma once
 
// TriviallyCopyable / Integral: swap_endian's requires-clause and dispatch.
#include <StormByte/type_traits/categories.hxx>
#include <StormByte/type_traits/object_semantics.hxx>
 
#include <array>
#include <bit>
#include <cstddef>
 
namespace StormByte {
    namespace Type {
        namespace Detail {
            template<typename U>
            requires TriviallyCopyable<U> && (sizeof(U) > 0)
            constexpr U swap_endian(U val) noexcept {
                if constexpr (sizeof(U) == 1) {
                    return val;
                } else if constexpr (Integral<U>) {
                    return std::byteswap(val);
                } else {
                    auto bytes = std::bit_cast<std::array<std::byte, sizeof(U)>>(val);
                    for (std::size_t i = 0, j = sizeof(U); i < j; ++i) {
                        --j;
                        const std::byte tmp = bytes[i];
                        bytes[i] = bytes[j];
                        bytes[j] = tmp;
                    }
                    return std::bit_cast<U>(bytes);
                }
            }
        }
    }
}