Jef
100 lines
3.3 KiB
C++
100 lines
3.3 KiB
C++
/* SPDX-License-Identifier: BSL-1.0 OR BSD-3-Clause */
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#ifndef MPT_BASE_ALIGNED_ARRAY_HPP
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#define MPT_BASE_ALIGNED_ARRAY_HPP
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#include "mpt/base/bit.hpp"
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#include "mpt/base/namespace.hpp"
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#include <array>
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#include <memory>
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#include <new>
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#include <cassert>
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#include <cstddef>
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namespace mpt {
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inline namespace MPT_INLINE_NS {
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template <typename T, std::size_t count, std::align_val_t alignment>
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struct alignas(static_cast<std::size_t>(alignment)) aligned_array
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: std::array<T, count> {
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static_assert(static_cast<std::size_t>(alignment) >= alignof(T));
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static_assert(((count * sizeof(T)) % static_cast<std::size_t>(alignment)) == 0);
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static_assert(sizeof(std::array<T, count>) == (sizeof(T) * count));
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};
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static_assert(sizeof(mpt::aligned_array<float, 4, std::align_val_t{sizeof(float) * 4}>) == sizeof(std::array<float, 4>));
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template <std::size_t alignment_elements, std::size_t expected_elements, typename T, std::size_t N>
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T * align_elements(std::array<T, N> & a) {
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static_assert(mpt::has_single_bit(alignof(T)));
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static_assert(mpt::has_single_bit(sizeof(T)));
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static_assert(mpt::has_single_bit(alignment_elements));
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static_assert((expected_elements + alignment_elements - 1) <= N);
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void * buf = a.data();
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std::size_t size = N * sizeof(T);
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void * result = std::align(alignment_elements * sizeof(T), expected_elements * sizeof(T), buf, size);
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assert(result);
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return reinterpret_cast<T *>(result);
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}
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template <std::size_t alignment_elements, std::size_t expected_elements, typename T, std::size_t N>
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T * align_elements(T (&a)[N]) {
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static_assert(mpt::has_single_bit(alignof(T)));
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static_assert(mpt::has_single_bit(sizeof(T)));
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static_assert(mpt::has_single_bit(alignment_elements));
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static_assert((expected_elements + alignment_elements - 1) <= N);
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void * buf = a;
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std::size_t size = N * sizeof(T);
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void * result = std::align(alignment_elements * sizeof(T), expected_elements * sizeof(T), buf, size);
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assert(result);
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return reinterpret_cast<T *>(result);
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}
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template <std::size_t alignment_bytes, std::size_t expected_elements, typename T, std::size_t N>
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T * align_bytes(std::array<T, N> & a) {
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static_assert(mpt::has_single_bit(alignof(T)));
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static_assert(mpt::has_single_bit(sizeof(T)));
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static_assert(mpt::has_single_bit(alignment_bytes));
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static_assert((alignment_bytes % alignof(T)) == 0);
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static_assert(((expected_elements * sizeof(T)) + alignment_bytes - 1) <= (N * sizeof(T)));
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void * buf = a.data();
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std::size_t size = N * sizeof(T);
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void * result = std::align(alignment_bytes, expected_elements * sizeof(T), buf, size);
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assert(result);
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return reinterpret_cast<T *>(result);
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}
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template <std::size_t alignment_bytes, std::size_t expected_elements, typename T, std::size_t N>
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T * align_bytes(T (&a)[N]) {
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static_assert(mpt::has_single_bit(alignof(T)));
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static_assert(mpt::has_single_bit(sizeof(T)));
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static_assert(mpt::has_single_bit(alignment_bytes));
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static_assert((alignment_bytes % alignof(T)) == 0);
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static_assert(((expected_elements * sizeof(T)) + alignment_bytes - 1) <= (N * sizeof(T)));
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void * buf = a;
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std::size_t size = N * sizeof(T);
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void * result = std::align(alignment_bytes, expected_elements * sizeof(T), buf, size);
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assert(result);
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return reinterpret_cast<T *>(result);
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}
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} // namespace MPT_INLINE_NS
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} // namespace mpt
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#endif // MPT_BASE_ALIGNED_ARRAY_HPP
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