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_;
+}