* ruby_atomic.h (ATOMIC_CAS): added.

* signal.c (ruby_atomic_compare_and_swap): ATOMIC_CAS implementation
  for non-VC/gcc platform.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_9_3@44950 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 11 insertions, 0 deletions

diff --git a/signal.c b/signal.c
index cda61d3d80..d4954fb21b 100644
--- a/signal.c
+++ b/signal.c
@@ -29,6 +29,17 @@ ruby_atomic_exchange(rb_atomic_t *ptr, rb_atomic_t val)
     *ptr = val;
     return old;
 }
+
+rb_atomic_t
+ruby_atomic_compare_and_swap(rb_atomic_t *ptr, rb_atomic_t cmp,
+			     rb_atomic_t newval)
+{
+    rb_atomic_t old = *ptr;
+    if (old == cmp) {
+	*ptr = newval;
+    }
+    return old;
+}
 #endif
 
 #if defined(__BEOS__) || defined(__HAIKU__)