libcruft-util/pointer.hpp

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/*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
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* Copyright 2011-2017 Danny Robson <danny@nerdcruft.net>
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*/
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#ifndef CRUFT_UTIL_POINTER_HPP
#define CRUFT_UTIL_POINTER_HPP
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#include <cstddef>
#include <cstdint>
namespace util {
///////////////////////////////////////////////////////////////////////////
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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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align (T *_ptr, size_t alignment)
{
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// we perform this as two steps to avoid unnecessarily incrementing when
// remainder is zero.
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auto ptr = reinterpret_cast<uintptr_t> (_ptr);
if (ptr % alignment)
ptr += alignment - ptr % alignment;
return reinterpret_cast<T*> (ptr);
}
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///------------------------------------------------------------------------
/// round the pointer upwards to satisfy the provided alignment
constexpr inline uintptr_t
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align (uintptr_t ptr, size_t alignment)
{
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// we perform this as two steps to avoid unnecessarily incrementing when
// remainder is zero.
if (ptr % alignment)
ptr += alignment - ptr % alignment;
return ptr;
}
///------------------------------------------------------------------------
/// round the pointer upwards to the nearest valid alignment for T
template <typename T>
constexpr auto
align (T *t)
{
return align (t, alignof (T));
}
///------------------------------------------------------------------------
/// round the pointer upwards to the nearest valid alignment for T
template <typename T>
constexpr auto
align (uintptr_t ptr)
{
return align (ptr, alignof (T));
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}
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}
#endif