libaaudio: implement callback

Use AudioTrack and AudioRecord TRANSFER_CALLBACK.
Add FixedBlockAdapter to provide fixed size callbacks.

Bug: 36489240
Test: CTS test_aaudio.cpp
Change-Id: Id2034dd640f878dd27fee6b43ad80a01c627dfd6
Signed-off-by: Phil Burk <philburk@google.com>
diff --git a/media/libaaudio/src/utility/FixedBlockAdapter.cpp b/media/libaaudio/src/utility/FixedBlockAdapter.cpp
new file mode 100644
index 0000000..f4666af
--- /dev/null
+++ b/media/libaaudio/src/utility/FixedBlockAdapter.cpp
@@ -0,0 +1,40 @@
+/*
+ * Copyright (C) 2017 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.
+ */
+
+#include <stdint.h>
+
+#include "FixedBlockAdapter.h"
+
+FixedBlockAdapter::~FixedBlockAdapter() {
+    close();
+}
+
+int32_t FixedBlockAdapter::open(int32_t bytesPerFixedBlock)
+{
+    mSize = bytesPerFixedBlock;
+    mStorage = new uint8_t[bytesPerFixedBlock]; // TODO use std::nothrow
+    mPosition = 0;
+    return 0;
+}
+
+int32_t FixedBlockAdapter::close()
+{
+    delete[] mStorage;
+    mStorage = nullptr;
+    mSize = 0;
+    mPosition = 0;
+    return 0;
+}