/* * Copyright © 2011 Ryan Lortie * * This library is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version. * * This library is distributed in the hope that it will be useful, but * WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with this library; if not, see <http://www.gnu.org/licenses/>. * * Author: Ryan Lortie <desrt@desrt.ca> */ #ifndef __G_ATOMIC_H__ #define __G_ATOMIC_H__ #if !defined (__GLIB_H_INSIDE__) && !defined (GLIB_COMPILATION) #error "Only <glib.h> can be included directly." #endif #include <glib/gtypes.h> #if defined(glib_typeof_2_68) && GLIB_VERSION_MIN_REQUIRED >= GLIB_VERSION_2_68 /* for glib_typeof */ #include <type_traits> #endif G_BEGIN_DECLS GLIB_AVAILABLE_IN_ALL gint g_atomic_int_get (const volatile gint *atomic); GLIB_AVAILABLE_IN_ALL void g_atomic_int_set (volatile gint *atomic, gint newval); GLIB_AVAILABLE_IN_ALL void g_atomic_int_inc (volatile gint *atomic); GLIB_AVAILABLE_IN_ALL gboolean g_atomic_int_dec_and_test (volatile gint *atomic); GLIB_AVAILABLE_IN_ALL gboolean g_atomic_int_compare_and_exchange (volatile gint *atomic, gint oldval, gint newval); GLIB_AVAILABLE_IN_ALL gint g_atomic_int_add (volatile gint *atomic, gint val); GLIB_AVAILABLE_IN_2_30 guint g_atomic_int_and (volatile guint *atomic, guint val); GLIB_AVAILABLE_IN_2_30 guint g_atomic_int_or (volatile guint *atomic, guint val); GLIB_AVAILABLE_IN_ALL guint g_atomic_int_xor (volatile guint *atomic, guint val); GLIB_AVAILABLE_IN_ALL gpointer g_atomic_pointer_get (const volatile void *atomic); GLIB_AVAILABLE_IN_ALL void g_atomic_pointer_set (volatile void *atomic, gpointer newval); GLIB_AVAILABLE_IN_ALL gboolean g_atomic_pointer_compare_and_exchange (volatile void *atomic, gpointer oldval, gpointer newval); GLIB_AVAILABLE_IN_ALL gssize g_atomic_pointer_add (volatile void *atomic, gssize val); GLIB_AVAILABLE_IN_2_30 gsize g_atomic_pointer_and (volatile void *atomic, gsize val); GLIB_AVAILABLE_IN_2_30 gsize g_atomic_pointer_or (volatile void *atomic, gsize val); GLIB_AVAILABLE_IN_ALL gsize g_atomic_pointer_xor (volatile void *atomic, gsize val); GLIB_DEPRECATED_IN_2_30_FOR(g_atomic_int_add) gint g_atomic_int_exchange_and_add (volatile gint *atomic, gint val); G_END_DECLS #if defined(G_ATOMIC_LOCK_FREE) && defined(__GCC_HAVE_SYNC_COMPARE_AND_SWAP_4) /* We prefer the new C11-style atomic extension of GCC if available */ #if defined(__ATOMIC_SEQ_CST) #define g_atomic_int_get(atomic) \ (G_GNUC_EXTENSION ({ \ G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gint)); \ gint gaig_temp; \ (void) (0 ? *(atomic) ^ *(atomic) : 1); \ __atomic_load ((gint *)(atomic), &gaig_temp, __ATOMIC_SEQ_CST); \ (gint) gaig_temp; \ })) #define g_atomic_int_set(atomic, newval) \ (G_GNUC_EXTENSION ({ \ G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gint)); \ gint gais_temp = (gint) (newval); \ (void) (0 ? *(atomic) ^ (newval) : 1); \ __atomic_store ((gint *)(atomic), &gais_temp, __ATOMIC_SEQ_CST); \ })) #if defined(glib_typeof) && (!defined(glib_typeof_2_68) || GLIB_VERSION_MIN_REQUIRED >= GLIB_VERSION_2_68) #define g_atomic_pointer_get(atomic) \ (G_GNUC_EXTENSION ({ \ G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gpointer)); \ glib_typeof (*(atomic)) gapg_temp_newval; \ glib_typeof ((atomic)) gapg_temp_atomic = (atomic); \ __atomic_load (gapg_temp_atomic, &gapg_temp_newval, __ATOMIC_SEQ_CST); \ gapg_temp_newval; \ })) #define g_atomic_pointer_set(atomic, newval) \ (G_GNUC_EXTENSION ({ \ G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gpointer)); \ glib_typeof ((atomic)) gaps_temp_atomic = (atomic); \ glib_typeof (*(atomic)) gaps_temp_newval = (newval); \ (void) (0 ? (gpointer) * (atomic) : NULL); \ __atomic_store (gaps_temp_atomic, &gaps_temp_newval, __ATOMIC_SEQ_CST); \ })) #else /* if !(defined(glib_typeof) && (!defined(glib_typeof_2_68) || GLIB_VERSION_MIN_REQUIRED >= GLIB_VERSION_2_68)) */ #define g_atomic_pointer_get(atomic) \ (G_GNUC_EXTENSION ({ \ G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gpointer)); \ gpointer gapg_temp_newval; \ gpointer *gapg_temp_atomic = (gpointer *)(atomic); \ __atomic_load (gapg_temp_atomic, &gapg_temp_newval, __ATOMIC_SEQ_CST); \ gapg_temp_newval; \ })) #define g_atomic_pointer_set(atomic, newval) \ (G_GNUC_EXTENSION ({ \ G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gpointer)); \ gpointer *gaps_temp_atomic = (gpointer *)(atomic); \ gpointer gaps_temp_newval = (gpointer)(newval); \ (void) (0 ? (gpointer) *(atomic) : NULL); \ __atomic_store (gaps_temp_atomic, &gaps_temp_newval, __ATOMIC_SEQ_CST); \ })) #endif /* if defined(glib_typeof) && (!defined(glib_typeof_2_68) || GLIB_VERSION_MIN_REQUIRED >= GLIB_VERSION_2_68) */ #define g_atomic_int_inc(atomic) \ (G_GNUC_EXTENSION ({ \ G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gint)); \ (void) (0 ? *(atomic) ^ *(atomic) : 1); \ (void) __atomic_fetch_add ((atomic), 1, __ATOMIC_SEQ_CST); \ })) #define g_atomic_int_dec_and_test(atomic) \ (G_GNUC_EXTENSION ({ \ G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gint)); \ (void) (0 ? *(atomic) ^ *(atomic) : 1); \ __atomic_fetch_sub ((atomic), 1, __ATOMIC_SEQ_CST) == 1; \ })) #define g_atomic_int_compare_and_exchange(atomic, oldval, newval) \ (G_GNUC_EXTENSION ({ \ gint gaicae_oldval = (oldval); \ G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gint)); \ (void) (0 ? *(atomic) ^ (newval) ^ (oldval) : 1); \ __atomic_compare_exchange_n ((atomic), &gaicae_oldval, (newval), FALSE, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST) ? TRUE : FALSE; \ })) #define g_atomic_int_add(atomic, val) \ (G_GNUC_EXTENSION ({ \ G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gint)); \ (void) (0 ? *(atomic) ^ (val) : 1); \ (gint) __atomic_fetch_add ((atomic), (val), __ATOMIC_SEQ_CST); \ })) #define g_atomic_int_and(atomic, val) \ (G_GNUC_EXTENSION ({ \ G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gint)); \ (void) (0 ? *(atomic) ^ (val) : 1); \ (guint) __atomic_fetch_and ((atomic), (val), __ATOMIC_SEQ_CST); \ })) #define g_atomic_int_or(atomic, val) \ (G_GNUC_EXTENSION ({ \ G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gint)); \ (void) (0 ? *(atomic) ^ (val) : 1); \ (guint) __atomic_fetch_or ((atomic), (val), __ATOMIC_SEQ_CST); \ })) #define g_atomic_int_xor(atomic, val) \ (G_GNUC_EXTENSION ({ \ G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gint)); \ (void) (0 ? *(atomic) ^ (val) : 1); \ (guint) __atomic_fetch_xor ((atomic), (val), __ATOMIC_SEQ_CST); \ })) #if defined(glib_typeof) && defined(__cplusplus) && __cplusplus >= 201103L /* This is typesafe because we check we can assign oldval to the type of * (*atomic). Unfortunately it can only be done in C++ because gcc/clang warn * when atomic is volatile and not oldval, or when atomic is gsize* and oldval * is NULL. Note that clang++ force us to be typesafe because it is an error if the 2nd * argument of __atomic_compare_exchange_n() has a different type than the * first. * https://gitlab.gnome.org/GNOME/glib/-/merge_requests/1919 * https://gitlab.gnome.org/GNOME/glib/-/merge_requests/1715#note_1024120. */ #define g_atomic_pointer_compare_and_exchange(atomic, oldval, newval) \ (G_GNUC_EXTENSION ({ \ G_STATIC_ASSERT (sizeof (oldval) == sizeof (gpointer)); \ glib_typeof (*(atomic)) gapcae_oldval = (oldval); \ G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gpointer)); \ (void) (0 ? (gpointer) *(atomic) : NULL); \ __atomic_compare_exchange_n ((atomic), &gapcae_oldval, (newval), FALSE, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST) ? TRUE : FALSE; \ })) #else /* if !(defined(glib_typeof) && defined(__cplusplus) && __cplusplus >= 201103L) */ #define g_atomic_pointer_compare_and_exchange(atomic, oldval, newval) \ (G_GNUC_EXTENSION ({ \ G_STATIC_ASSERT (sizeof (oldval) == sizeof (gpointer)); \ gpointer gapcae_oldval = (gpointer)(oldval); \ G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gpointer)); \ (void) (0 ? (gpointer) *(atomic) : NULL); \ __atomic_compare_exchange_n ((atomic), &gapcae_oldval, (newval), FALSE, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST) ? TRUE : FALSE; \ })) #endif /* defined(glib_typeof) */ #define g_atomic_pointer_add(atomic, val) \ (G_GNUC_EXTENSION ({ \ G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gpointer)); \ (void) (0 ? (gpointer) *(atomic) : NULL); \ (void) (0 ? (val) ^ (val) : 1); \ (gssize) __atomic_fetch_add ((atomic), (val), __ATOMIC_SEQ_CST); \ })) #define g_atomic_pointer_and(atomic, val) \ (G_GNUC_EXTENSION ({ \ gsize *gapa_atomic = (gsize *) (atomic); \ G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gpointer)); \ G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gsize)); \ (void) (0 ? (gpointer) *(atomic) : NULL); \ (void) (0 ? (val) ^ (val) : 1); \ (gsize) __atomic_fetch_and (gapa_atomic, (val), __ATOMIC_SEQ_CST); \ })) #define g_atomic_pointer_or(atomic, val) \ (G_GNUC_EXTENSION ({ \ gsize *gapo_atomic = (gsize *) (atomic); \ G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gpointer)); \ G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gsize)); \ (void) (0 ? (gpointer) *(atomic) : NULL); \ (void) (0 ? (val) ^ (val) : 1); \ (gsize) __atomic_fetch_or (gapo_atomic, (val), __ATOMIC_SEQ_CST); \ })) #define g_atomic_pointer_xor(atomic, val) \ (G_GNUC_EXTENSION ({ \ gsize *gapx_atomic = (gsize *) (atomic); \ G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gpointer)); \ G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gsize)); \ (void) (0 ? (gpointer) *(atomic) : NULL); \ (void) (0 ? (val) ^ (val) : 1); \ (gsize) __atomic_fetch_xor (gapx_atomic, (val), __ATOMIC_SEQ_CST); \ })) #else /* defined(__ATOMIC_SEQ_CST) */ /* We want to achieve __ATOMIC_SEQ_CST semantics here. See * https://en.cppreference.com/w/c/atomic/memory_order#Constants. For load * operations, that means performing an *acquire*: * > A load operation with this memory order performs the acquire operation on * > the affected memory location: no reads or writes in the current thread can * > be reordered before this load. All writes in other threads that release * > the same atomic variable are visible in the current thread. * * “no reads or writes in the current thread can be reordered before this load” * is implemented using a compiler barrier (a no-op `__asm__` section) to * prevent instruction reordering. Writes in other threads are synchronised * using `__sync_synchronize()`. It’s unclear from the GCC documentation whether * `__sync_synchronize()` acts as a compiler barrier, hence our explicit use of * one. * * For store operations, `__ATOMIC_SEQ_CST` means performing a *release*: * > A store operation with this memory order performs the release operation: * > no reads or writes in the current thread can be reordered after this store. * > All writes in the current thread are visible in other threads that acquire * > the same atomic variable (see Release-Acquire ordering below) and writes * > that carry a dependency into the atomic variable become visible in other * > threads that consume the same atomic (see Release-Consume ordering below). * * “no reads or writes in the current thread can be reordered after this store” * is implemented using a compiler barrier to prevent instruction reordering. * “All writes in the current thread are visible in other threads” is implemented * using `__sync_synchronize()`; similarly for “writes that carry a dependency”. */ #define g_atomic_int_get(atomic) \ (G_GNUC_EXTENSION ({ \ gint gaig_result; \ G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gint)); \ (void) (0 ? *(atomic) ^ *(atomic) : 1); \ gaig_result = (gint) *(atomic); \ __sync_synchronize (); \ __asm__ __volatile__ ("" : : : "memory"); \ gaig_result; \ })) #define g_atomic_int_set(atomic, newval) \ (G_GNUC_EXTENSION ({ \ G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gint)); \ (void) (0 ? *(atomic) ^ (newval) : 1); \ __sync_synchronize (); \ __asm__ __volatile__ ("" : : : "memory"); \ *(atomic) = (newval); \ })) #define g_atomic_pointer_get(atomic) \ (G_GNUC_EXTENSION ({ \ gpointer gapg_result; \ G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gpointer)); \ gapg_result = (gpointer) *(atomic); \ __sync_synchronize (); \ __asm__ __volatile__ ("" : : : "memory"); \ gapg_result; \ })) #if defined(glib_typeof) && (!defined(glib_typeof_2_68) || GLIB_VERSION_MIN_REQUIRED >= GLIB_VERSION_2_68) #define g_atomic_pointer_set(atomic, newval) \ (G_GNUC_EXTENSION ({ \ G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gpointer)); \ (void) (0 ? (gpointer) *(atomic) : NULL); \ __sync_synchronize (); \ __asm__ __volatile__ ("" : : : "memory"); \ *(atomic) = (glib_typeof (*(atomic))) (gsize) (newval); \ })) #else /* if !(defined(glib_typeof) && (!defined(glib_typeof_2_68) || GLIB_VERSION_MIN_REQUIRED >= GLIB_VERSION_2_68)) */ #define g_atomic_pointer_set(atomic, newval) \ (G_GNUC_EXTENSION ({ \ G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gpointer)); \ (void) (0 ? (gpointer) *(atomic) : NULL); \ __sync_synchronize (); \ __asm__ __volatile__ ("" : : : "memory"); \ *(atomic) = (gpointer) (gsize) (newval); \ })) #endif /* if defined(glib_typeof) && (!defined(glib_typeof_2_68) || GLIB_VERSION_MIN_REQUIRED >= GLIB_VERSION_2_68) */ #define g_atomic_int_inc(atomic) \ (G_GNUC_EXTENSION ({ \ G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gint)); \ (void) (0 ? *(atomic) ^ *(atomic) : 1); \ (void) __sync_fetch_and_add ((atomic), 1); \ })) #define g_atomic_int_dec_and_test(atomic) \ (G_GNUC_EXTENSION ({ \ G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gint)); \ (void) (0 ? *(atomic) ^ *(atomic) : 1); \ __sync_fetch_and_sub ((atomic), 1) == 1; \ })) #define g_atomic_int_compare_and_exchange(atomic, oldval, newval) \ (G_GNUC_EXTENSION ({ \ G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gint)); \ (void) (0 ? *(atomic) ^ (newval) ^ (oldval) : 1); \ __sync_bool_compare_and_swap ((atomic), (oldval), (newval)) ? TRUE : FALSE; \ })) #define g_atomic_int_add(atomic, val) \ (G_GNUC_EXTENSION ({ \ G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gint)); \ (void) (0 ? *(atomic) ^ (val) : 1); \ (gint) __sync_fetch_and_add ((atomic), (val)); \ })) #define g_atomic_int_and(atomic, val) \ (G_GNUC_EXTENSION ({ \ G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gint)); \ (void) (0 ? *(atomic) ^ (val) : 1); \ (guint) __sync_fetch_and_and ((atomic), (val)); \ })) #define g_atomic_int_or(atomic, val) \ (G_GNUC_EXTENSION ({ \ G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gint)); \ (void) (0 ? *(atomic) ^ (val) : 1); \ (guint) __sync_fetch_and_or ((atomic), (val)); \ })) #define g_atomic_int_xor(atomic, val) \ (G_GNUC_EXTENSION ({ \ G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gint)); \ (void) (0 ? *(atomic) ^ (val) : 1); \ (guint) __sync_fetch_and_xor ((atomic), (val)); \ })) #define g_atomic_pointer_compare_and_exchange(atomic, oldval, newval) \ (G_GNUC_EXTENSION ({ \ G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gpointer)); \ (void) (0 ? (gpointer) *(atomic) : NULL); \ __sync_bool_compare_and_swap ((atomic), (oldval), (newval)) ? TRUE : FALSE; \ })) #define g_atomic_pointer_add(atomic, val) \ (G_GNUC_EXTENSION ({ \ G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gpointer)); \ (void) (0 ? (gpointer) *(atomic) : NULL); \ (void) (0 ? (val) ^ (val) : 1); \ (gssize) __sync_fetch_and_add ((atomic), (val)); \ })) #define g_atomic_pointer_and(atomic, val) \ (G_GNUC_EXTENSION ({ \ G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gpointer)); \ (void) (0 ? (gpointer) *(atomic) : NULL); \ (void) (0 ? (val) ^ (val) : 1); \ (gsize) __sync_fetch_and_and ((atomic), (val)); \ })) #define g_atomic_pointer_or(atomic, val) \ (G_GNUC_EXTENSION ({ \ G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gpointer)); \ (void) (0 ? (gpointer) *(atomic) : NULL); \ (void) (0 ? (val) ^ (val) : 1); \ (gsize) __sync_fetch_and_or ((atomic), (val)); \ })) #define g_atomic_pointer_xor(atomic, val) \ (G_GNUC_EXTENSION ({ \ G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gpointer)); \ (void) (0 ? (gpointer) *(atomic) : NULL); \ (void) (0 ? (val) ^ (val) : 1); \ (gsize) __sync_fetch_and_xor ((atomic), (val)); \ })) #endif /* !defined(__ATOMIC_SEQ_CST) */ #else /* defined(G_ATOMIC_LOCK_FREE) && defined(__GCC_HAVE_SYNC_COMPARE_AND_SWAP_4) */ #define g_atomic_int_get(atomic) \ (g_atomic_int_get ((gint *) (atomic))) #define g_atomic_int_set(atomic, newval) \ (g_atomic_int_set ((gint *) (atomic), (gint) (newval))) #define g_atomic_int_compare_and_exchange(atomic, oldval, newval) \ (g_atomic_int_compare_and_exchange ((gint *) (atomic), (oldval), (newval))) #define g_atomic_int_add(atomic, val) \ (g_atomic_int_add ((gint *) (atomic), (val))) #define g_atomic_int_and(atomic, val) \ (g_atomic_int_and ((guint *) (atomic), (val))) #define g_atomic_int_or(atomic, val) \ (g_atomic_int_or ((guint *) (atomic), (val))) #define g_atomic_int_xor(atomic, val) \ (g_atomic_int_xor ((guint *) (atomic), (val))) #define g_atomic_int_inc(atomic) \ (g_atomic_int_inc ((gint *) (atomic))) #define g_atomic_int_dec_and_test(atomic) \ (g_atomic_int_dec_and_test ((gint *) (atomic))) #if defined(glib_typeof) && (!defined(glib_typeof_2_68) || GLIB_VERSION_MIN_REQUIRED >= GLIB_VERSION_2_68) /* The (void *) cast in the middle *looks* redundant, because * g_atomic_pointer_get returns void * already, but it's to silence * -Werror=bad-function-cast when we're doing something like: * guintptr a, b; ...; a = g_atomic_pointer_get (&b); * which would otherwise be assigning the void * result of * g_atomic_pointer_get directly to the pointer-sized but * non-pointer-typed result. */ #define g_atomic_pointer_get(atomic) \ (glib_typeof (*(atomic))) (void *) ((g_atomic_pointer_get) ((void *) atomic)) #else /* !(defined(glib_typeof) && (!defined(glib_typeof_2_68) || GLIB_VERSION_MIN_REQUIRED >= GLIB_VERSION_2_68)) */ #define g_atomic_pointer_get(atomic) \ (g_atomic_pointer_get (atomic)) #endif #define g_atomic_pointer_set(atomic, newval) \ (g_atomic_pointer_set ((atomic), (gpointer) (newval))) #define g_atomic_pointer_compare_and_exchange(atomic, oldval, newval) \ (g_atomic_pointer_compare_and_exchange ((atomic), (gpointer) (oldval), (gpointer) (newval))) #define g_atomic_pointer_add(atomic, val) \ (g_atomic_pointer_add ((atomic), (gssize) (val))) #define g_atomic_pointer_and(atomic, val) \ (g_atomic_pointer_and ((atomic), (gsize) (val))) #define g_atomic_pointer_or(atomic, val) \ (g_atomic_pointer_or ((atomic), (gsize) (val))) #define g_atomic_pointer_xor(atomic, val) \ (g_atomic_pointer_xor ((atomic), (gsize) (val))) #endif /* defined(G_ATOMIC_LOCK_FREE) && defined(__GCC_HAVE_SYNC_COMPARE_AND_SWAP_4) */ #endif /* __G_ATOMIC_H__ */