root/ROOT/RAlignmentUtils.hxx

0001 // @(#)root/foundation:
0002 // Author: Philippe Canal, April 2026
0003
0004 /*************************************************************************
0005  * Copyright (C) 1995-2026, Rene Brun and Fons Rademakers.               *
0006  * All rights reserved.                                                  *
0007  *                                                                       *
0008  * For the licensing terms see $ROOTSYS/LICENSE.                         *
0009  * For the list of contributors see $ROOTSYS/README/CREDITS.             *
0010  *************************************************************************/
0011
0012 #ifndef ROOT_RAlignmentUtils
0013 #define ROOT_RAlignmentUtils
0014
0015 #include <cassert>
0016 #include <cstddef>
0017
0018 namespace ROOT {
0019 namespace Internal {
0020
0021 /// Return true if \p align is a valid C++ alignment value: strictly positive
0022 /// and a power of two.  This is the set of values accepted by
0023 /// `::operator new[](n, std::align_val_t(align))`.
0024 inline constexpr bool IsValidAlignment(std::size_t align) noexcept
0025 {
0026    return align > 0 && (align & (align - 1)) == 0;
0027 }
0028
0029 /// Round \p value up to the next multiple of \p align.
0030 /// \p align must be a power of two (asserted at runtime in debug builds).
0031 template <typename T>
0032 inline constexpr T AlignUp(T value, T align) noexcept
0033 {
0034    assert(IsValidAlignment(static_cast<std::size_t>(align))); // must be a power of two
0035    return (value + align - 1) & ~(align - 1);
0036 }
0037
0038 } // namespace Internal
0039 } // namespace ROOT
0040
0041 #endif // ROOT_RAlignmentUtils