1 files changed, 11 insertions, 0 deletions
diff --git a/signal.c b/signal.c
index 4906e9162a..e2d9d84e4d 100644
--- a/signal.c
+++ b/signal.c
@@ -25,6 +25,17 @@ typedef LONG rb_atomic_t;
 # define ATOMIC_INC(var) InterlockedIncrement(&(var))
 # define ATOMIC_DEC(var) InterlockedDecrement(&(var))
 
+#elsif __GNUC__ >= 4
+/* @shyouhei hack to support atomic operations in case of gcc. Gcc
+ * has its own pseudo-insns to support them.  See info, or
+ * http://gcc.gnu.org/onlinedocs/gcc/Atomic-Builtins.html */
+
+typedef unsigned char rb_atomic_t; /* Anything OK */
+# define ATOMIC_TEST(var) __sync_lock_test_and_set(&(var), 0)
+# define ATOMIC_SET(var, val)  __sync_lock_test_and_set(&(var), (val))
+# define ATOMIC_INC(var) __sync_fetch_and_add(&(var), 1)
+# define ATOMIC_DEC(var) __sync_fetch_and_sub(&(var), 1)
+
 #else
 typedef int rb_atomic_t;