auto import from //depot/cupcake/@135843

1 files changed, 48 insertions, 0 deletions

diff --git a/vm/Atomic.h b/vm/Atomic.h
new file mode 100644
index 000000000..bc0203c10
--- /dev/null
+++ b/vm/Atomic.h
@@ -0,0 +1,48 @@
+/*
+ * Copyright (C) 2008 The Android Open Source Project
+ *
+ * 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.
+ */
+/*
+ * Atomic operations
+ */
+#ifndef _DALVIK_ATOMIC
+#define _DALVIK_ATOMIC
+
+#include <utils/Atomic.h>       /* use common Android atomic ops */
+
+/*
+ * Memory barrier.  Guarantee that register-resident variables
+ * are flushed to memory, and guarantee that instructions before
+ * the barrier do not get reordered to appear past it.
+ *
+ * 'asm volatile ("":::"memory")' is probably overkill, but it's correct.
+ * There may be a way to do it that doesn't flush every single register.
+ *
+ * TODO: look into the wmb() family on Linux and equivalents on other systems.
+ */
+#define MEM_BARRIER()   do { asm volatile ("":::"memory"); } while (0)
+
+/*
+ * Atomic compare-and-swap macro.
+ *
+ * If *_addr equals "_old", replace it with "_new" and return 1.  Otherwise
+ * return 0.  (e.g. x86 "cmpxchgl" instruction.)
+ *
+ * Underlying function is currently declared:
+ * int android_atomic_cmpxchg(int32_t old, int32_t new, volatile int32_t* addr)
+ */
+#define ATOMIC_CMP_SWAP(_addr, _old, _new) \
+            (android_atomic_cmpxchg((_old), (_new), (_addr)) == 0)
+
+#endif /*_DALVIK_ATOMIC*/