glib/gatomic.h

   1 /* GLIB - Library of useful routines for C programming
   2  * Copyright (C) 1995-1997  Peter Mattis, Spencer Kimball and Josh MacDonald
   3  *
   4  * g_atomic_*: atomic operations.
   5  * Copyright (C) 2003 Sebastian Wilhelmi
   6  *
   7  * This library is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU Lesser General Public
   9  * License as published by the Free Software Foundation; either
  10  * version 2 of the License, or (at your option) any later version.
  11  *
  12  * This library is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * Lesser General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Lesser General Public
  18  * License along with this library; if not, write to the
  19  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  20  * Boston, MA 02111-1307, USA.
  21  */
  22
  23 /*
  24  * Modified by the GLib Team and others 1997-2000.  See the AUTHORS
  25  * file for a list of people on the GLib Team.  See the ChangeLog
  26  * files for a list of changes.  These files are distributed with
  27  * GLib at ftp://ftp.gtk.org/pub/gtk/.
  28  */
  29
  30 #if defined(G_DISABLE_SINGLE_INCLUDES) && !defined (__GLIB_H_INSIDE__) && !defined (GLIB_COMPILATION)
  31 #error "Only <glib.h> can be included directly."
  32 #endif
  33
  34 #ifndef __G_ATOMIC_H__
  35 #define __G_ATOMIC_H__
  36
  37 #include <glib/gtypes.h>
  38
  39 G_BEGIN_DECLS
  40
  41 gint     g_atomic_int_exchange_and_add         (volatile gint G_GNUC_MAY_ALIAS *atomic,
  42                                                 gint               val);
  43 void     g_atomic_int_add                      (volatile gint G_GNUC_MAY_ALIAS *atomic,
  44                                                 gint               val);
  45 gboolean g_atomic_int_compare_and_exchange     (volatile gint G_GNUC_MAY_ALIAS *atomic,
  46                                                 gint               oldval,
  47                                                 gint               newval);
  48 gboolean g_atomic_pointer_compare_and_exchange (volatile gpointer G_GNUC_MAY_ALIAS *atomic,
  49                                                 gpointer           oldval,
  50                                                 gpointer           newval);
  51
  52 gint     g_atomic_int_get                      (volatile gint G_GNUC_MAY_ALIAS *atomic);
  53 void     g_atomic_int_set                      (volatile gint G_GNUC_MAY_ALIAS *atomic,
  54                                                 gint               newval);
  55 gpointer g_atomic_pointer_get                  (volatile gpointer G_GNUC_MAY_ALIAS *atomic);
  56 void     g_atomic_pointer_set                  (volatile gpointer G_GNUC_MAY_ALIAS *atomic,
  57                                                 gpointer           newval);
  58
  59 #if defined(__GNUC__) && defined(G_ATOMIC_OP_USE_GCC_BUILTINS)
  60
  61 #define g_atomic_int_exchange_and_add(atomic,val) \
  62   __sync_fetch_and_add((atomic),(val))
  63
  64 #define g_atomic_int_add(atomic,val) \
  65   __sync_fetch_and_add((atomic),(val))
  66
  67 #define g_atomic_int_compare_and_exchange(atomic,oldval,newval) \
  68   __sync_bool_compare_and_swap((atomic),(oldval),(newval))
  69
  70 #define g_atomic_int_get(atomic) \
  71   __extension__ ({ __sync_synchronize(); *(atomic); })
  72
  73 #define g_atomic_int_set(atomic,newval) \
  74   __extension__ ({ *(atomic) = (newval); __sync_synchronize(); })
  75
  76 #define g_atomic_pointer_compare_and_exchange(atomic,oldval,newval) \
  77   __sync_bool_compare_and_swap((atomic),(oldval),(newval))
  78
  79 #define g_atomic_pointer_get(atomic) \
  80   __extension__ ({ __sync_synchronize(); *(atomic); })
  81
  82 #define g_atomic_pointer_set(atomic,newval) \
  83   __extension__ ({ *(atomic) = (newval); __sync_synchronize(); })
  84
  85 #elif !defined(G_ATOMIC_OP_MEMORY_BARRIER_NEEDED)
  86
  87 # define g_atomic_int_get(atomic)               ((gint)*(atomic))
  88 # define g_atomic_int_set(atomic, newval)       ((void) (*(atomic) = (newval)))
  89 # define g_atomic_pointer_get(atomic)           ((gpointer)*(atomic))
  90 # define g_atomic_pointer_set(atomic, newval)   ((void) (*(atomic) = (newval)))
  91
  92 #else
  93
  94 # define g_atomic_int_get(atomic) \
  95  ((void) sizeof (gchar [sizeof (*(atomic)) == sizeof (gint) ? 1 : -1]), \
  96   (g_atomic_int_get) ((volatile gint G_GNUC_MAY_ALIAS *) (volatile void *) (atomic)))
  97 # define g_atomic_int_set(atomic, newval) \
  98  ((void) sizeof (gchar [sizeof (*(atomic)) == sizeof (gint) ? 1 : -1]), \
  99   (g_atomic_int_set) ((volatile gint G_GNUC_MAY_ALIAS *) (volatile void *) (atomic), (newval)))
 100 # define g_atomic_pointer_get(atomic) \
 101  ((void) sizeof (gchar [sizeof (*(atomic)) == sizeof (gpointer) ? 1 : -1]), \
 102   (g_atomic_pointer_get) ((volatile gpointer G_GNUC_MAY_ALIAS *) (volatile void *) (atomic)))
 103 # define g_atomic_pointer_set(atomic, newval) \
 104  ((void) sizeof (gchar [sizeof (*(atomic)) == sizeof (gpointer) ? 1 : -1]), \
 105   (g_atomic_pointer_set) ((volatile gpointer G_GNUC_MAY_ALIAS *) (volatile void *) (atomic), (newval)))
 106
 107 #endif /* G_ATOMIC_OP_MEMORY_BARRIER_NEEDED */
 108
 109 /**
 110  * g_atomic_int_inc:
 111  * @atomic: a pointer to an integer.
 112  *
 113  * Atomically increments the integer pointed to by @atomic by 1.
 114  *
 115  * Since: 2.4
 116  */
 117 #define g_atomic_int_inc(atomic) (g_atomic_int_add ((atomic), 1))
 118
 119 /**
 120  * g_atomic_int_dec_and_test:
 121  * @atomic: a pointer to an integer
 122  *
 123  * Atomically decrements the integer pointed to by @atomic by 1.
 124  *
 125  * Returns: %TRUE if the integer pointed to by @atomic is 0
 126  *     after decrementing it
 127  *
 128  * Since: 2.4
 129  */
 130 #define g_atomic_int_dec_and_test(atomic) \
 131   (g_atomic_int_exchange_and_add ((atomic), -1) == 1)
 132
 133 G_END_DECLS
 134
 135 #endif /* __G_ATOMIC_H__ */