92 lines
2.5 KiB
C++
92 lines
2.5 KiB
C++
/*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/.
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*
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* Copyright 2011-2019 Danny Robson <danny@nerdcruft.net>
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*/
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#pragma once
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#include <type_traits>
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#include <cstddef>
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#include <cstdint>
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namespace cruft::align {
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///////////////////////////////////////////////////////////////////////////
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/// round the pointer upwards to satisfy the provided alignment
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constexpr inline uintptr_t
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up (uintptr_t ptr, size_t alignment)
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{
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// we perform this as two steps to avoid unnecessarily incrementing when
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// remainder is zero.
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if (auto mod = ptr % alignment; mod)
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ptr += alignment - mod;
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return ptr;
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}
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///////////////////////////////////////////////////////////////////////////
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/// round the pointer upwards to satisfy the provided alignment
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template <typename T>
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constexpr T*
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up (T *ptr, size_t alignment)
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{
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// we perform this as two steps to avoid unnecessarily incrementing when
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// remainder is zero.
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return reinterpret_cast<T*>(
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up (reinterpret_cast<uintptr_t> (ptr), alignment)
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);
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}
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//-------------------------------------------------------------------------
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template <typename T>
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constexpr T*
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up (T *ptr, std::align_val_t _alignment)
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{
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auto alignment = std::underlying_type_t<decltype(_alignment)> (_alignment);
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return up (ptr, alignment);
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}
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///------------------------------------------------------------------------
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/// round the pointer upwards to the nearest valid alignment for T
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template <typename T>
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constexpr auto
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up (T *t)
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{
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return up (t, alignof (T));
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}
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///------------------------------------------------------------------------
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/// round the pointer upwards to the nearest valid alignment for T
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template <typename T>
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constexpr auto
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up (uintptr_t ptr)
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{
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return up (ptr, alignof (T));
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}
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///////////////////////////////////////////////////////////////////////////
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constexpr inline uintptr_t
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down (uintptr_t ptr, size_t alignment)
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{
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return ptr - ptr % alignment;
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}
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//-------------------------------------------------------------------------
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template <typename T>
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constexpr T*
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down (T *ptr, size_t alignment)
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{
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return reinterpret_cast<T*> (
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down (reinterpret_cast<uintptr_t> (ptr), alignment)
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);
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}
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}
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