nerdcruft/libcruft-util
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pointer: add some comments...

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Danny Robson 2017-08-30 15:38:13 +10:00
parent 5126bb486c
commit 885b0b4669
1 changed files with 35 additions and 9 deletions
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44
pointer.hpp
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@ -11,11 +11,11 @@
* See the License for the specific language governing permissions and * See the License for the specific language governing permissions and
* limitations under the License. * limitations under the License.
* *
* Copyright 2011 Danny Robson <danny@nerdcruft.net> * Copyright 2011-2017 Danny Robson <danny@nerdcruft.net>
*/ */
#ifndef __POINTER_HPP #ifndef CRUFT_UTIL_POINTER_HPP
#define __POINTER_HPP #define CRUFT_UTIL_POINTER_HPP
#include <cstddef> #include <cstddef>
#include <cstdint> #include <cstdint>
@ -23,10 +23,13 @@
namespace util { namespace util {
/////////////////////////////////////////////////////////////////////////// ///////////////////////////////////////////////////////////////////////////
/// round the pointer upwards to satisfy the provided alignment
template <typename T> template <typename T>
T* constexpr T*
align (T *_ptr, size_t alignment) align (T *_ptr, size_t alignment)
{ {
// we perform this as two steps to avoid unnecessarily incrementing when
// remainder is zero.
auto ptr = reinterpret_cast<uintptr_t> (_ptr); auto ptr = reinterpret_cast<uintptr_t> (_ptr);
if (ptr % alignment) if (ptr % alignment)
ptr += alignment - ptr % alignment; ptr += alignment - ptr % alignment;
@ -34,13 +37,36 @@ namespace util {
} }
//------------------------------------------------------------------------- ///------------------------------------------------------------------------
inline uintptr_t /// round the pointer upwards to satisfy the provided alignment
constexpr inline uintptr_t
align (uintptr_t ptr, size_t alignment) align (uintptr_t ptr, size_t alignment)
{ {
return reinterpret_cast<uintptr_t> ( // we perform this as two steps to avoid unnecessarily incrementing when
align (reinterpret_cast<void*> (ptr), alignment) // 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));
} }
} }