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/* Determine alignment of types.
Copyright (C) 2003-2004, 2006, 2009-2010 Free Software Foundation, Inc.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3, or (at your option)
any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software Foundation,
Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
#ifndef _ALIGNOF_H
#define _ALIGNOF_H
#include <stddef.h>
/* Determine the alignment of a structure slot (field) of a given type,
at compile time. Note that the result depends on the ABI.
Note: The result cannot be used as a value for an 'enum' constant,
due to bugs in HP-UX 10.20 cc and AIX 3.2.5 xlc. */
#if defined __cplusplus
template <class type> struct alignof_helper { char __slot1; type __slot2; };
# define alignof_slot(type) offsetof (alignof_helper<type>, __slot2)
#else
# define alignof_slot(type) offsetof (struct { char __slot1; type __slot2; }, __slot2)
#endif
/* Determine the good alignment of a object of the given type at compile time.
Note that this is not necessarily the same as alignof_slot(type).
For example, with GNU C on x86 platforms: alignof_type(double) = 8, but
- when -malign-double is not specified: alignof_slot(double) = 4,
- when -malign-double is specified: alignof_slot(double) = 8.
Note: The result cannot be used as a value for an 'enum' constant,
due to bugs in HP-UX 10.20 cc and AIX 3.2.5 xlc. */
#if defined __GNUC__
# define alignof_type __alignof__
#else
# define alignof_type alignof_slot
#endif
/* alignof is an alias for alignof_slot semantics, since that's what most
callers need.
Note: The result cannot be used as a value for an 'enum' constant,
due to bugs in HP-UX 10.20 cc and AIX 3.2.5 xlc. */
#define alignof alignof_slot
#endif /* _ALIGNOF_H */
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