gl/alignof.h

   1 /* Determine alignment of types.
   2    Copyright (C) 2003-2004, 2006, 2009 Free Software Foundation, Inc.
   3
   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 3, or (at your option)
   7    any later version.
   8
   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.
  13
  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.  */
  17
  18 #ifndef _ALIGNOF_H
  19 #define _ALIGNOF_H
  20
  21 #include <stddef.h>
  22
  23 /* Determine the alignment of a type at compile time.  */
  24 #if defined __GNUC__
  25 # define alignof __alignof__
  26 #elif defined __cplusplus
  27   template <class type> struct alignof_helper { char __slot1; type __slot2; };
  28 # define alignof(type) offsetof (alignof_helper<type>, __slot2)
  29 #else
  30 # define alignof(type) offsetof (struct { char __slot1; type __slot2; }, __slot2)
  31 #endif
  32
  33 #endif /* _ALIGNOF_H */