audio_core: Add initial code for keeping track of audout state.

src/audio_core/audio_out.h

@@ -0,0 +1,44 @@
+// Copyright 2018 yuzu Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <memory>
+#include <vector>
+
+#include "audio_core/buffer.h"
+#include "audio_core/stream.h"
+#include "common/common_types.h"
+
+namespace AudioCore {
+
+using StreamPtr = std::shared_ptr<Stream>;
+
+/**
+ * Represents an audio playback interface, used to open and play audio streams
+ */
+class AudioOut {
+public:
+    /// Opens a new audio stream
+    StreamPtr OpenStream(int sample_rate, int num_channels,
+                         Stream::ReleaseCallback&& release_callback);
+
+    /// Returns a vector of recently released buffers specified by tag for the specified stream
+    std::vector<u64> GetTagsAndReleaseBuffers(StreamPtr stream, size_t max_count);
+
+    /// Starts an audio stream for playback
+    void StartStream(StreamPtr stream);
+
+    /// Stops an audio stream that is currently playing
+    void StopStream(StreamPtr stream);
+
+    /// Queues a buffer into the specified audio stream, returns true on success
+    bool QueueBuffer(StreamPtr stream, Buffer::Tag tag, std::vector<u8>&& data);
+
+private:
+    /// Active audio streams on the interface
+    std::vector<StreamPtr> streams;
+};
+
+} // namespace AudioCore