layout.hpp

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// Copyright (c) 2024 Contributors to the Eclipse Foundation
//
// See the NOTICE file(s) distributed with this work for additional
// information regarding copyright ownership.
//
// This program and the accompanying materials are made available under the
// terms of the Apache Software License 2.0 which is available at
// https://www.apache.org/licenses/LICENSE-2.0, or the MIT license
// which is available at https://opensource.org/licenses/MIT.
//
// SPDX-License-Identifier: Apache-2.0 OR MIT
 
#ifndef IOX2_BB_LAYOUT_HPP
#define IOX2_BB_LAYOUT_HPP
 
#include "iox2/bb/expected.hpp"
#include <cstdint>
#include <type_traits>
 
namespace iox2 {
namespace bb {
 
enum class LayoutCreationError : uint8_t {
    InvalidAlignment
};
 
class Layout {
  public:
    template <typename T>
    static auto from() -> std::enable_if_t<!std::is_same<T, void>::value, Layout>;
 
    template <typename T>
    static auto from() -> std::enable_if_t<std::is_same<T, void>::value, Layout>;
 
    static auto create(uint64_t size, uint64_t align) -> iox2::bb::Expected<Layout, LayoutCreationError>;
 
    auto size() const -> uint64_t;
 
    auto alignment() const -> uint64_t;
 
  private:
    static auto is_power_of_two(uint64_t value) -> bool;
 
    static auto round_up_to(uint64_t value, uint64_t multiple) -> uint64_t;
 
    Layout(uint64_t size, uint64_t align);
 
    uint64_t m_size;
    uint64_t m_align;
};
 
 
template <typename T>
inline auto Layout::from() -> std::enable_if_t<!std::is_same<T, void>::value, Layout> {
    return Layout { sizeof(T), alignof(T) };
}
 
template <typename T>
inline auto Layout::from() -> std::enable_if_t<std::is_same<T, void>::value, Layout> {
    return Layout { 0, 1 };
}
 
inline auto Layout::create(const uint64_t size, const uint64_t align)
    -> iox2::bb::Expected<Layout, LayoutCreationError> {
    if (!is_power_of_two(align)) {
        return iox2::bb::err(LayoutCreationError::InvalidAlignment);
    }
 
    return Layout(round_up_to(size, align), align);
}
 
inline auto Layout::size() const -> uint64_t {
    return m_size;
}
 
inline auto Layout::alignment() const -> uint64_t {
    return m_align;
}
 
inline auto Layout::is_power_of_two(const uint64_t value) -> bool {
    return (value != 0) && ((value & (value - 1)) == 0);
}
 
inline auto Layout::round_up_to(const uint64_t value, const uint64_t multiple) -> uint64_t {
    return (value % multiple == 0) ? value : multiple * ((value / multiple) + 1);
}
 
// NOLINTNEXTLINE(bugprone-easily-swappable-parameters) private ctor, only used internally
inline Layout::Layout(const uint64_t size, const uint64_t align)
    : m_size { size }
    , m_align { align } {
}
 
} // namespace bb
} // namespace iox2
 
#endif // IOX2_BB_LAYOUT_HPP