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

src/audio_core/stream.h

@@ -0,0 +1,89 @@
+// Copyright 2018 yuzu Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <functional>
+#include <memory>
+#include <vector>
+#include <queue>
+
+#include "audio_core/buffer.h"
+#include "common/assert.h"
+#include "common/common_types.h"
+#include "core/core_timing.h"
+
+namespace AudioCore {
+
+using BufferPtr = std::shared_ptr<Buffer>;
+
+/**
+ * Represents an audio stream, which is a sequence of queued buffers, to be outputed by AudioOut
+ */
+class Stream {
+public:
+    /// Audio format of the stream
+    enum class Format {
+        Mono16,
+        Stereo16,
+        Multi51Channel16,
+    };
+
+    /// Callback function type, used to change guest state on a buffer being released
+    using ReleaseCallback = std::function<void()>;
+
+    Stream(int sample_rate, Format format, ReleaseCallback&& release_callback);
+
+    /// Plays the audio stream
+    void Play();
+
+    /// Stops the audio stream
+    void Stop();
+
+    /// Queues a buffer into the audio stream, returns true on success
+    bool QueueBuffer(BufferPtr&& buffer);
+
+    /// Returns true if the audio stream contains a buffer with the specified tag
+    bool ContainsBuffer(Buffer::Tag tag) const;
+
+    /// Returns a vector of recently released buffers specified by tag
+    std::vector<Buffer::Tag> GetTagsAndReleaseBuffers(size_t max_count);
+
+    /// Returns true if the stream is currently playing
+    bool IsPlaying() const {
+        return state == State::Playing;
+    }
+
+    /// Returns the number of queued buffers
+    size_t GetQueueSize() const {
+        return queued_buffers.size();
+    }
+
+private:
+    /// Current state of the stream
+    enum class State {
+        Stopped,
+        Playing,
+    };
+
+    /// Plays the next queued buffer in the audio stream, starting playback if necessary
+    void PlayNextBuffer();
+
+    /// Releases the actively playing buffer, signalling that it has been completed
+    void ReleaseActiveBuffer();
+
+    /// Gets the number of core cycles when the specified buffer will be released
+    s64 GetBufferReleaseCycles(const Buffer& buffer) const;
+
+    int sample_rate;                        ///< Sample rate of the stream
+    Format format;                          ///< Format of the stream
+    ReleaseCallback release_callback;       ///< Buffer release callback for the stream
+    State state{State::Stopped};            ///< Playback state of the stream
+    CoreTiming::EventType* release_event{}; ///< Core timing release event for the stream
+    BufferPtr active_buffer;                ///< Actively playing buffer in the stream
+    std::queue<BufferPtr> queued_buffers;   ///< Buffers queued to be played in the stream
+    std::queue<BufferPtr> released_buffers; ///< Buffers recently released from the stream
+};
+
+} // namespace AudioCore