aaudio: add simple flowgraph system

Implement a simple data flow model that can be used to
chain various processing modules including:
    data format conversion
    volume ramping
    channel conversion

Bug: 65067568
Test: test_flowgraph.cpp
Change-Id: I81a5655406cfa8c1c7d7cef4d933879f823939a5
diff --git a/media/libaaudio/src/flowgraph/SinkFloat.cpp b/media/libaaudio/src/flowgraph/SinkFloat.cpp
new file mode 100644
index 0000000..fb3dcbc
--- /dev/null
+++ b/media/libaaudio/src/flowgraph/SinkFloat.cpp
@@ -0,0 +1,46 @@
+/*
+ * Copyright 2018 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 <algorithm>
+#include <unistd.h>
+#include "AudioProcessorBase.h"
+#include "SinkFloat.h"
+
+using namespace flowgraph;
+
+SinkFloat::SinkFloat(int32_t channelCount)
+        : AudioSink(channelCount) {
+}
+
+int32_t SinkFloat::read(void *data, int32_t numFrames) {
+    float *floatData = (float *) data;
+    int32_t channelCount = input.getSamplesPerFrame();
+
+    int32_t framesLeft = numFrames;
+    while (framesLeft > 0) {
+        // Run the graph and pull data through the input port.
+        int32_t framesRead = pull(framesLeft);
+        if (framesRead <= 0) {
+            break;
+        }
+        const float *signal = input.getBlock();
+        int32_t numSamples = framesRead * channelCount;
+        memcpy(floatData, signal, numSamples * sizeof(float));
+        floatData += numSamples;
+        framesLeft -= framesRead;
+    }
+    return numFrames - framesLeft;
+}