1 /* Determine alignment of types.
2 Copyright (C) 2003-2004, 2006, 2009 Free Software Foundation, Inc.
4 This program is free software; you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation; either version 2, or (at your option)
9 This program is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU General Public License for more details.
14 You should have received a copy of the GNU General Public License
15 along with this program; if not, write to the Free Software Foundation,
16 Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
23 /* Determine the alignment of a structure slot (field) of a given type,
24 at compile time. Note that the result depends on the ABI. */
25 #if defined __cplusplus
26 template <class type> struct alignof_helper { char __slot1; type __slot2; };
27 # define alignof_slot(type) offsetof (alignof_helper<type>, __slot2)
29 # define alignof_slot(type) offsetof (struct { char __slot1; type __slot2; }, __slot2)
32 /* Determine the good alignment of a object of the given type at compile time.
33 Note that this is not necessarily the same as alignof_slot(type).
34 For example, with GNU C on x86 platforms: alignof_type(double) = 8, but
35 - when -malign-double is not specified: alignof_slot(double) = 4,
36 - when -malign-double is specified: alignof_slot(double) = 8. */
38 # define alignof_type __alignof__
40 # define alignof_type alignof_slot
43 /* alignof is an alias for alignof_slot semantics, since that's what most
45 Note: The result cannot be used as a value for an 'enum' constant, */
46 #define alignof alignof_slot
48 #endif /* _ALIGNOF_H */