Oboe FIFO: general purpose FIFO

Bug: 33347409
Test: test_oboe_api
Change-Id: I764fe372f00b98364e4d36e7841cb00fc8af5695
Signed-off-by: Phil Burk <philburk@google.com>
diff --git a/media/liboboe/src/fifo/FifoControllerIndirect.h b/media/liboboe/src/fifo/FifoControllerIndirect.h
new file mode 100644
index 0000000..1aaf9ea
--- /dev/null
+++ b/media/liboboe/src/fifo/FifoControllerIndirect.h
@@ -0,0 +1,69 @@
+/*
+ * Copyright 2016 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.
+ */
+
+#ifndef FIFO_FIFO_CONTROLLER_INDIRECT_H
+#define FIFO_FIFO_CONTROLLER_INDIRECT_H
+
+#include <stdint.h>
+#include <atomic>
+
+#include "FifoControllerBase.h"
+
+/**
+ * A FifoControllerBase with counters external to the class.
+ *
+ * The actual copunters may be stored in separate regions of shared memory
+ * with different access rights.
+ */
+class FifoControllerIndirect : public FifoControllerBase {
+
+public:
+    FifoControllerIndirect(fifo_frames_t capacity,
+                           fifo_frames_t threshold,
+                           fifo_counter_t * readCounterAddress,
+                           fifo_counter_t * writeCounterAddress)
+        : FifoControllerBase(capacity, threshold)
+        , mReadCounterAddress((std::atomic<fifo_counter_t> *) readCounterAddress)
+        , mWriteCounterAddress((std::atomic<fifo_counter_t> *) writeCounterAddress)
+    {
+        setReadCounter(0);
+        setWriteCounter(0);
+    }
+    virtual ~FifoControllerIndirect() {};
+
+    // TODO review use of memory barriers, probably incorrect
+    virtual fifo_counter_t getReadCounter() override {
+        return mReadCounterAddress->load(std::memory_order_acquire);
+    }
+
+    virtual void setReadCounter(fifo_counter_t count) override {
+        mReadCounterAddress->store(count, std::memory_order_release);
+    }
+
+    virtual fifo_counter_t getWriteCounter() override {
+        return mWriteCounterAddress->load(std::memory_order_acquire);
+    }
+
+    virtual void setWriteCounter(fifo_counter_t count) override {
+        mWriteCounterAddress->store(count, std::memory_order_release);
+    }
+
+private:
+    std::atomic<fifo_counter_t> * mReadCounterAddress;
+    std::atomic<fifo_counter_t> * mWriteCounterAddress;
+};
+
+#endif //FIFO_FIFO_CONTROLLER_INDIRECT_H