Attempts to bring audio to the Apple II.

By factoring the audio toggle out from the MSX.

Components/AudioToggle/AudioToggle.cpp

@@ -0,0 +1,38 @@
+//
+//  AudioToggle.cpp
+//  Clock Signal
+//
+//  Created by Thomas Harte on 17/04/2018.
+//  Copyright © 2018 Thomas Harte. All rights reserved.
+//
+
+#include "AudioToggle.hpp"
+
+using namespace Audio;
+
+Audio::Toggle::Toggle(Concurrency::DeferringAsyncTaskQueue &audio_queue) :
+	audio_queue_(audio_queue) {}
+
+void Toggle::get_samples(std::size_t number_of_samples, std::int16_t *target) {
+	for(std::size_t sample = 0; sample < number_of_samples; ++sample) {
+		target[sample] = level_;
+	}
+}
+
+void Toggle::set_sample_volume_range(std::int16_t range) {
+	volume_ = range;
+}
+
+void Toggle::skip_samples(const std::size_t number_of_samples) {}
+
+void Toggle::set_output(bool enabled) {
+	if(is_enabled_ == enabled) return;
+	is_enabled_ = enabled;
+	audio_queue_.defer([=] {
+		level_ = enabled ? volume_ : 0;
+	});
+}
+
+bool Toggle::get_output() {
+	return is_enabled_;
+}

Components/AudioToggle/AudioToggle.hpp

@@ -0,0 +1,39 @@
+//
+//  AudioToggle.hpp
+//  Clock Signal
+//
+//  Created by Thomas Harte on 17/04/2018.
+//  Copyright © 2018 Thomas Harte. All rights reserved.
+//
+
+#ifndef AudioToggle_hpp
+#define AudioToggle_hpp
+
+#include "../../Outputs/Speaker/Implementation/SampleSource.hpp"
+#include "../../Concurrency/AsyncTaskQueue.hpp"
+
+namespace Audio {
+
+/*!
+	Provides a sample source that can programmatically be set to one of two values.
+*/
+class Toggle: public Outputs::Speaker::SampleSource {
+	public:
+		Toggle(Concurrency::DeferringAsyncTaskQueue &audio_queue);
+
+		void get_samples(std::size_t number_of_samples, std::int16_t *target);
+		void set_sample_volume_range(std::int16_t range);
+		void skip_samples(const std::size_t number_of_samples);
+
+		void set_output(bool enabled);
+		bool get_output();
+
+	private:
+		bool is_enabled_ = false;
+		int16_t level_ = 0, volume_ = 0;
+		Concurrency::DeferringAsyncTaskQueue &audio_queue_;
+};
+
+}
+
+#endif /* AudioToggle_hpp */