ovs-atomic: Add native Clang implementation.

With this implementation I get warnings with Clang on GNU/Linux when the
previous patch is not applied.  This ought to make it easier to avoid
introducing new problems in the future even without building on FreeBSD.

Signed-off-by: Ben Pfaff <blp@nicira.com>
Acked-by: Jarno Rajahalme <jrajahalme@nicira.com>

1 files changed, 52 insertions, 0 deletions

diff --git a/lib/ovs-atomic-flag-gcc4.7+.h b/lib/ovs-atomic-flag-gcc4.7+.h
new file mode 100644
index 000000000..c42c7cad8
--- /dev/null
+++ b/lib/ovs-atomic-flag-gcc4.7+.h
@@ -0,0 +1,52 @@
+/*
+ * Copyright (c) 2013 Nicira, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/* This header implements atomic_flag on Clang and on GCC 4.7 and later. */
+#ifndef IN_OVS_ATOMIC_H
+#error "This header should only be included indirectly via ovs-atomic.h."
+#endif
+
+/* atomic_flag */
+
+typedef struct {
+    unsigned char b;
+} atomic_flag;
+#define ATOMIC_FLAG_INIT { .b = false }
+
+static inline bool
+atomic_flag_test_and_set_explicit(volatile atomic_flag *object,
+                                  memory_order order)
+{
+    return __atomic_test_and_set(&object->b, order);
+}
+
+static inline bool
+atomic_flag_test_and_set(volatile atomic_flag *object)
+{
+    return atomic_flag_test_and_set_explicit(object, memory_order_seq_cst);
+}
+
+static inline void
+atomic_flag_clear_explicit(volatile atomic_flag *object, memory_order order)
+{
+    __atomic_clear(object, order);
+}
+
+static inline void
+atomic_flag_clear(volatile atomic_flag *object)
+{
+    atomic_flag_clear_explicit(object, memory_order_seq_cst);
+}