include/ntfs-3g/support.h

   1 /*
   2  * support.h - Useful definitions and macros. Originated from the Linux-NTFS project.
   3  *
   4  * Copyright (c) 2000-2004 Anton Altaparmakov
   5  *
   6  * This program/include file is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License as published
   8  * by the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program/include file is distributed in the hope that it will be
  12  * useful, but WITHOUT ANY WARRANTY; without even the implied warranty
  13  * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program (in the main directory of the NTFS-3G
  18  * distribution in the file COPYING); if not, write to the Free Software
  19  * Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  20  */
  21
  22 #ifndef _NTFS_SUPPORT_H
  23 #define _NTFS_SUPPORT_H
  24
  25 #ifdef HAVE_CONFIG_H
  26 #include "config.h"
  27 #endif
  28
  29 #ifdef HAVE_STDDEF_H
  30 #include <stddef.h>
  31 #endif
  32
  33 /*
  34  * Our mailing list. Use this define to prevent typos in email address.
  35  */
  36 #define NTFS_DEV_LIST   "ntfs-3g-devel@lists.sf.net"
  37
  38 /*
  39  * Generic macro to convert pointers to values for comparison purposes.
  40  */
  41 #ifndef p2n
  42 #define p2n(p)          ((ptrdiff_t)((ptrdiff_t*)(p)))
  43 #endif
  44
  45 /*
  46  * The classic min and max macros.
  47  */
  48 #ifndef min
  49 #define min(a,b)        ((a) <= (b) ? (a) : (b))
  50 #endif
  51
  52 #ifndef max
  53 #define max(a,b)        ((a) >= (b) ? (a) : (b))
  54 #endif
  55
  56 /*
  57  * Useful macro for determining the offset of a struct member.
  58  */
  59 #ifndef offsetof
  60 #define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
  61 #endif
  62
  63 /*
  64  * Simple bit operation macros. NOTE: These are NOT atomic.
  65  */
  66 #define test_bit(bit, var)            ((var) & (1 << (bit)))
  67 #define set_bit(bit, var)             (var) |= 1 << (bit)
  68 #define clear_bit(bit, var)           (var) &= ~(1 << (bit))
  69
  70 #define test_and_set_bit(bit, var)                      \
  71 ({                                                      \
  72         const BOOL old_state = test_bit(bit, var);      \
  73         set_bit(bit, var);                              \
  74         old_state;                                      \
  75 })
  76
  77 #define test_and_clear_bit(bit, var)                    \
  78 ({                                                      \
  79         const BOOL old_state = test_bit(bit, var);      \
  80         clear_bit(bit, var);                            \
  81         old_state;                                      \
  82 })
  83
  84 #endif /* defined _NTFS_SUPPORT_H */
  85