Emulate PC speaker beep sounds

Makefile

@@ -79,7 +79,7 @@ CORE_FILES=const.js config.js io.js main.js lib.js fpu.js ide.js pci.js floppy.j
 	   elf.js
 LIB_FILES=9p.js filesystem.js jor1k.js marshall.js utf8.js
 BROWSER_FILES=screen.js \
-	      keyboard.js mouse.js serial.js \
+	      keyboard.js mouse.js speaker.js serial.js \
 	      network.js lib.js starter.js worker_bus.js dummy_screen.js
 
 CORE_FILES:=$(addprefix src/,$(CORE_FILES))

loader.js

@@ -10,7 +10,7 @@
         "memory.js dma.js pit.js vga.js ps2.js pic.js rtc.js uart.js acpi.js apic.js ioapic.js hpet.js " +
         "ne2k.js state.js virtio.js bus.js elf.js";
 
-    var BROWSER_FILES = "main.js screen.js keyboard.js mouse.js serial.js lib.js network.js starter.js worker_bus.js";
+    var BROWSER_FILES = "main.js screen.js keyboard.js mouse.js speaker.js serial.js lib.js network.js starter.js worker_bus.js";
     //var LIB_FILES = "esprima.js walk.js";
     var LIB_FILES = "";
 

src/browser/speaker.js

@@ -0,0 +1,67 @@
+"use strict";
+
+/**
+ * @constructor
+ * @param {BusConnector} bus
+ * @suppress {deprecated}
+ */
+function SpeakerAdapter(bus)
+{
+    if (typeof window === "undefined")
+    {
+        return;
+    }
+
+    /** @const @type {BusConnector} */
+    this.bus = bus;
+
+    this.audio_context = new (window.AudioContext || window.webkitAudioContext)();
+
+    this.beep_gain = this.audio_context.createGain();
+    this.beep_gain.gain.value = 0;
+    this.beep_gain.connect(this.audio_context.destination);
+
+    this.beep_oscillator = this.audio_context.createOscillator();
+    this.beep_oscillator.type = 'square';
+    this.beep_oscillator.frequency.value = 440;
+    this.beep_oscillator.connect(this.beep_gain);
+    this.beep_oscillator.start();
+
+    this.beep_playing = false;
+    this.beep_enable = false;
+    this.beep_frequency = 440;
+    this.pit_enabled = false;
+
+    bus.register("pcspeaker-enable", function(yesplease)
+    {
+        this.beep_enable = yesplease;
+        this.beep_update();
+    }, this);
+
+    bus.register("pcspeaker-update", function(pit)
+    {
+        this.pit_enabled = pit.counter_mode[2] == 3;
+        this.beep_frequency = OSCILLATOR_FREQ * 1000 / pit.counter_reload[2];
+        this.beep_update();
+    }, this);
+}
+
+SpeakerAdapter.prototype.beep_update = function()
+{
+    var current_time = this.audio_context.currentTime;
+
+    if(this.pit_enabled && this.beep_enable)
+    {
+        this.beep_oscillator.frequency.setValueAtTime(this.beep_frequency, current_time);
+        if(!this.beep_playing)
+        {
+            this.beep_gain.gain.setValueAtTime(1, current_time);
+            this.beep_playing = true;
+        }
+    }
+    else if(this.beep_playing)
+    {
+        this.beep_gain.gain.setValueAtTime(0, current_time);
+        this.beep_playing = false;
+    }
+}

src/browser/starter.js

@@ -151,6 +151,11 @@ function V86Starter(options)
         this.serial_adapter = new SerialAdapter(options["serial_container"], adapter_bus);
     }
 
+    if(!options["disable_speaker"])
+    {
+        this.speaker_adapter = new SpeakerAdapter(adapter_bus);
+    }
+
     // ugly, but required for closure compiler compilation
     function put_on_settings(name, buffer)
     {

src/cpu.js

@@ -736,7 +736,7 @@ CPU.prototype.init = function(settings, device_bus)
             this.devices.hdb = new IDEDevice(this, settings.hdb, false, ide_device_count++, device_bus);
         }
 
-        this.devices.pit = new PIT(this);
+        this.devices.pit = new PIT(this, device_bus);
 
         if(settings.enable_ne2k)
         {

src/pit.js

@@ -11,11 +11,13 @@ var OSCILLATOR_FREQ = 1193.1816666; // 1.193182 MHz
  *
  * Programmable Interval Timer
  */
-function PIT(cpu)
+function PIT(cpu, bus)
 {
     /** @const @type {CPU} */
     this.cpu = cpu;
 
+    this.bus = bus;
+
     this.counter_start_time = new Float64Array(3);
     this.counter_start_value = new Uint16Array(3);
 
@@ -42,6 +44,10 @@ function PIT(cpu)
 
         return ref_toggle << 4 | counter2_out << 5;
     });
+    cpu.io.register_write(0x61, this, function(data)
+    {
+        this.bus.send("pcspeaker-enable", data & 1);
+    });
 
     cpu.io.register_read(0x40, this, function() { return this.counter_read(0); });
     cpu.io.register_read(0x41, this, function() { return this.counter_read(1); });
@@ -228,6 +234,8 @@ PIT.prototype.counter_write = function(i, value)
     {
         this.counter_next_low[i] ^= 1;
     }
+
+    this.bus.send("pcspeaker-update", this);
 };
 
 PIT.prototype.port43_write = function(reg_byte)
@@ -303,4 +311,6 @@ PIT.prototype.port43_write = function(reg_byte)
 
     this.counter_mode[i] = mode;
     this.counter_read_mode[i] = read_mode;
+
+    this.bus.send("pcspeaker-update", this);
 };