1 /* PSPP - a program for statistical analysis.
2 Copyright (C) 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 3 of the License, or
7 (at your option) any later version.
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, see <http://www.gnu.org/licenses/>. */
17 #ifndef LIBPSPP_CAST_H
18 #define LIBPSPP_CAST_H 1
22 /* Given expressions A and B, both of which have pointer type,
23 expands to a void expression that causes a compiler warning if
24 A and B are not pointers to qualified or unqualified versions
25 of compatible types. */
26 #define CHECK_POINTER_COMPATIBILITY(A, B) ((void) sizeof ((A) == (B)))
28 /* Given POINTER, a pointer to the given MEMBER within structure
29 STRUCT, returns the address of the STRUCT. */
30 #define UP_CAST(POINTER, STRUCT, MEMBER) \
31 (CHECK_POINTER_COMPATIBILITY (&((STRUCT *) 0)->MEMBER, POINTER), \
32 (STRUCT *) ((char *) (POINTER) - offsetof (STRUCT, MEMBER)))
34 #endif /* libpspp/cast.h */