audio_core: Implement OpenAL backend (#6450)

src/audio_core/input.h

@@ -0,0 +1,85 @@
+// Copyright 2023 Citra Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <vector>
+#include "common/common_types.h"
+
+namespace AudioCore {
+
+enum class Signedness : u8 {
+    Signed,
+    Unsigned,
+};
+
+using Samples = std::vector<u8>;
+
+struct InputParameters {
+    Signedness sign;
+    u8 sample_size;
+    bool buffer_loop;
+    u32 sample_rate;
+    u32 buffer_offset;
+    u32 buffer_size;
+};
+
+class Input {
+public:
+    Input() = default;
+
+    virtual ~Input() = default;
+
+    /// Starts the microphone. Called by Core
+    virtual void StartSampling(const InputParameters& params) = 0;
+
+    /// Stops the microphone. Called by Core
+    virtual void StopSampling() = 0;
+
+    /**
+     * Called from the actual event timing at a constant period under a given sample rate.
+     * When sampling is enabled this function is expected to return a buffer of 16 samples in ideal
+     * conditions, but can be lax if the data is coming in from another source like a real mic.
+     */
+    virtual Samples Read() = 0;
+
+    /**
+     * Adjusts the Parameters. Implementations should update the parameters field in addition to
+     * changing the mic to sample according to the new parameters. Called by Core
+     */
+    virtual void AdjustSampleRate(u32 sample_rate) = 0;
+
+    /// Value from 0 - 100 to adjust the mic gain setting. Called by Core
+    virtual void SetGain(u8 mic_gain) {
+        gain = mic_gain;
+    }
+
+    u8 GetGain() const {
+        return gain;
+    }
+
+    void SetPower(bool power) {
+        powered = power;
+    }
+
+    bool GetPower() const {
+        return powered;
+    }
+
+    bool IsSampling() const {
+        return is_sampling;
+    }
+
+    const InputParameters& GetParameters() const {
+        return parameters;
+    }
+
+protected:
+    InputParameters parameters;
+    u8 gain = 0;
+    bool is_sampling = false;
+    bool powered = false;
+};
+
+} // namespace AudioCore