WIP Game Settings Window, WASM Fixes, Sound FX

* Add sound effect and music support to Doodle.
* Fix WASM build to use the 'null' sound driver for now.
* Add a Settings button to the main menu; UI for it is WIP.

pkg/main_scene.go

@@ -112,6 +112,10 @@ func (s *MainScene) Setup(d *Doodle) error {
 			Name: "Edit a Level",
 			Func: d.GotoLoadMenu,
 		},
+		{
+			Name: "Settings",
+			Func: d.GotoSettingsMenu,
+		},
 	}
 	for _, button := range buttons {
 		button := button

pkg/menu_scene.go

@@ -72,6 +72,15 @@ func (d *Doodle) GotoPlayMenu() {
 	d.Goto(scene)
 }
 
+// GotoSettingsMenu loads the settings screen.
+func (d *Doodle) GotoSettingsMenu() {
+	log.Info("Loading the MenuScene to the Settings Menu")
+	scene := &MenuScene{
+		StartupMenu: "settings",
+	}
+	d.Goto(scene)
+}
+
 // Setup the scene.
 func (s *MenuScene) Setup(d *Doodle) error {
 	s.Supervisor = ui.NewSupervisor()
@@ -98,6 +107,10 @@ func (s *MenuScene) Setup(d *Doodle) error {
 		if err := s.setupLoadWindow(d); err != nil {
 			return err
 		}
+	case "settings":
+		if err := s.setupSettingsWindow(d); err != nil {
+			return err
+		}
 	default:
 		d.Flash("No Valid StartupMenu Given to MenuScene")
 	}
@@ -171,6 +184,17 @@ func (s *MenuScene) setupLoadWindow(d *Doodle) error {
 	return nil
 }
 
+// setupLoadWindow sets up the UI for the "New" window.
+func (s *MenuScene) setupSettingsWindow(d *Doodle) error {
+	window := windows.NewSettingsWindow(windows.Settings{
+		Supervisor: s.Supervisor,
+		Engine:     d.Engine,
+	})
+	window.SetButtons(0)
+	s.window = window
+	return nil
+}
+
 // Loop the editor scene.
 func (s *MenuScene) Loop(d *Doodle, ev *event.State) error {
 	s.Supervisor.Loop(ev)

pkg/sound/sound.go

@@ -1,16 +1,9 @@
-// Package sound provides audio functions for Doodle.
+// Package sound manages music and sound effects.
 package sound
 
-import (
+import "path/filepath"
-	"path/filepath"
-	"sync"
 
-	"git.kirsle.net/apps/doodle/pkg/log"
+// Package globals.
-	"git.kirsle.net/go/audio/sdl"
-	"github.com/veandco/go-sdl2/mix"
-)
-
-// Globals.
 var (
 	// If enabled is false, all sound functions are no-ops.
 	Enabled bool
@@ -18,97 +11,4 @@ var (
 	// Root folder on disk where sound and music files should live.
 	SoundRoot = filepath.Join("rtp", "sfx")
 	MusicRoot = filepath.Join("rtp", "music")
-
-	// Cache of loaded music and sound effects.
-	music  = map[string]*sdl.Track{}
-	sounds = map[string]*sdl.Track{}
-	mu     sync.RWMutex
-
-	engine *sdl.Engine
 )
-
-// Initialize SDL2 Audio at startup.
-func init() {
-	eng, err := sdl.New(mix.INIT_MP3 | mix.INIT_OGG)
-	if err != nil {
-		log.Error("sound.init(): error initializing SDL2 audio: %s", err)
-		return
-	}
-
-	err = eng.Setup()
-	if err != nil {
-		log.Error("sound.init(): error setting up SDL2 audio: %s", err)
-		return
-	}
-
-	engine = eng
-	Enabled = true
-}
-
-// LoadMusic loads filename from the MusicRoot into the global music cache.
-// If the music is already loaded, does nothing.
-func LoadMusic(filename string) *sdl.Track {
-	if engine == nil || !Enabled {
-		return nil
-	}
-
-	// Check if the music is already loaded.
-	mu.RLock()
-	mus, ok := music[filename]
-	mu.RUnlock()
-	if ok {
-		return mus
-	}
-
-	// Load the music in.
-	track, err := engine.LoadMusic(filepath.Join(MusicRoot, filename))
-	if err != nil {
-		log.Error("sound.LoadMusic: failed to load file %s: %s", filename, err)
-		return nil
-	}
-
-	mu.Lock()
-	music[filename] = &track
-	mu.Unlock()
-
-	return &track
-}
-
-// LoadSound loads filename from the SoundRoot into the global SFX cache.
-// If the sound is already loaded, does nothing.
-func LoadSound(filename string) *sdl.Track {
-	if engine == nil || !Enabled {
-		return nil
-	}
-
-	// Check if the music is already loaded.
-	mu.RLock()
-	sfx, ok := sounds[filename]
-	mu.RUnlock()
-	if ok {
-		return sfx
-	}
-
-	// Load the sound in.
-	log.Info("Loading sound: %s", filename)
-	track, err := engine.LoadSound(filepath.Join(SoundRoot, filename))
-	if err != nil {
-		log.Error("sound.LoadSound: failed to load file %s: %s", filename, err)
-		return nil
-	}
-
-	mu.Lock()
-	sounds[filename] = &track
-	mu.Unlock()
-
-	return &track
-}
-
-// PlaySound plays the named sound.
-func PlaySound(filename string) {
-	log.Debug("Play sound: %s", filename)
-	sound := LoadSound(filename)
-	if sound != nil {
-		sound.Play(1)
-	}
-}

pkg/sound/sound_sdl.go

@@ -0,0 +1,109 @@
+//+build !js,!wasm
+
+package sound
+
+import (
+	"path/filepath"
+	"sync"
+
+	"git.kirsle.net/apps/doodle/pkg/log"
+	"git.kirsle.net/go/audio"
+	"git.kirsle.net/go/audio/sdl"
+	"github.com/veandco/go-sdl2/mix"
+)
+
+// SDL engine globals.
+var (
+	engine *sdl.Engine
+
+	// Cache of loaded music and sound effects.
+	music  = map[string]*sdl.Track{}
+	sounds = map[string]*sdl.Track{}
+	mu     sync.RWMutex
+)
+
+// Initialize SDL2 Audio at startup.
+func init() {
+	eng, err := sdl.New(mix.INIT_MP3 | mix.INIT_OGG)
+	if err != nil {
+		log.Error("sound.init(): error initializing SDL2 audio: %s", err)
+		return
+	}
+
+	err = eng.Setup()
+	if err != nil {
+		log.Error("sound.init(): error setting up SDL2 audio: %s", err)
+		return
+	}
+
+	engine = eng
+	Enabled = true
+}
+
+// LoadMusic loads filename from the MusicRoot into the global music cache.
+// If the music is already loaded, does nothing.
+func LoadMusic(filename string) audio.Playable {
+	if engine == nil || !Enabled {
+		return nil
+	}
+
+	// Check if the music is already loaded.
+	mu.RLock()
+	mus, ok := music[filename]
+	mu.RUnlock()
+	if ok {
+		return mus
+	}
+
+	// Load the music in.
+	track, err := engine.LoadMusic(filepath.Join(MusicRoot, filename))
+	if err != nil {
+		log.Error("sound.LoadMusic: failed to load file %s: %s", filename, err)
+		return nil
+	}
+
+	mu.Lock()
+	music[filename] = &track
+	mu.Unlock()
+
+	return &track
+}
+
+// LoadSound loads filename from the SoundRoot into the global SFX cache.
+// If the sound is already loaded, does nothing.
+func LoadSound(filename string) audio.Playable {
+	if engine == nil || !Enabled {
+		return nil
+	}
+
+	// Check if the music is already loaded.
+	mu.RLock()
+	sfx, ok := sounds[filename]
+	mu.RUnlock()
+	if ok {
+		return sfx
+	}
+
+	// Load the sound in.
+	log.Info("Loading sound: %s", filename)
+	track, err := engine.LoadSound(filepath.Join(SoundRoot, filename))
+	if err != nil {
+		log.Error("sound.LoadSound: failed to load file %s: %s", filename, err)
+		return nil
+	}
+
+	mu.Lock()
+	sounds[filename] = &track
+	mu.Unlock()
+
+	return &track
+}
+
+// PlaySound plays the named sound.
+func PlaySound(filename string) {
+	log.Debug("Play sound: %s", filename)
+	sound := LoadSound(filename)
+	if sound != nil {
+		sound.Play(1)
+	}
+}

pkg/sound/sound_wasm.go

@@ -0,0 +1,32 @@
+//+build js,wasm
+
+package sound
+
+import (
+	"git.kirsle.net/go/audio"
+	"git.kirsle.net/go/audio/null"
+)
+
+// Globals for WASM sound engine.
+var (
+	engine *null.Engine
+)
+
+func init() {
+	engine = null.New()
+}
+
+// LoadMusic loads filename from the MusicRoot into the global music cache.
+// If the music is already loaded, does nothing.
+func LoadMusic(filename string) audio.Playable {
+	return null.Playable{}
+}
+
+// LoadSound loads filename from the SoundRoot into the global SFX cache.
+// If the sound is already loaded, does nothing.
+func LoadSound(filename string) audio.Playable {
+	return null.Playable{}
+}
+
+// PlaySound plays the named sound.
+func PlaySound(filename string) {}

pkg/windows/settings.go

@@ -0,0 +1,94 @@
+package windows
+
+import (
+	"fmt"
+
+	"git.kirsle.net/apps/doodle/pkg/balance"
+	"git.kirsle.net/apps/doodle/pkg/branding"
+	"git.kirsle.net/apps/doodle/pkg/native"
+	"git.kirsle.net/go/render"
+	"git.kirsle.net/go/ui"
+)
+
+// Settings window.
+type Settings struct {
+	// Settings passed in by doodle
+	Supervisor *ui.Supervisor
+	Engine     render.Engine
+}
+
+// NewSettingsWindow initializes the window.
+func NewSettingsWindow(cfg Settings) *ui.Window {
+	window := ui.NewWindow("Game Settings")
+	window.SetButtons(ui.CloseButton)
+	window.Configure(ui.Config{
+		Width:      400,
+		Height:     170,
+		Background: render.Grey,
+	})
+
+	// {
+	// 	row := ui.NewFrame("Theme Frame")
+	// 	label := ui.NewLabel(ui.Label{
+	// 		Text: "Theme:",
+	// 		Font: balance.MenuFont,
+	// 	})
+	// }
+
+	text := ui.NewLabel(ui.Label{
+		Text: fmt.Sprintf("%s is a drawing-based maze game.\n\n"+
+			"Copyright © %s.\nAll rights reserved.\n\n"+
+			"Version %s",
+			branding.AppName,
+			branding.Copyright,
+			branding.Version,
+		),
+	})
+	window.Pack(text, ui.Pack{
+		Side:    ui.N,
+		Padding: 8,
+	})
+
+	frame := ui.NewFrame("Button frame")
+	buttons := []struct {
+		label string
+		f     func()
+	}{
+		{"Website", func() {
+			native.OpenURL(branding.Website)
+		}},
+		{"Open Source Licenses", func() {
+			// TODO: open file
+			native.OpenURL("./Open Source Licenses.md")
+		}},
+	}
+	for _, button := range buttons {
+		button := button
+
+		btn := ui.NewButton(button.label, ui.NewLabel(ui.Label{
+			Text: button.label,
+			Font: balance.MenuFont,
+		}))
+
+		btn.Handle(ui.Click, func(ed ui.EventData) error {
+			button.f()
+			return nil
+		})
+
+		btn.Compute(cfg.Engine)
+		cfg.Supervisor.Add(btn)
+
+		frame.Pack(btn, ui.Pack{
+			Side:   ui.W,
+			PadX:   4,
+			Expand: true,
+			Fill:   true,
+		})
+	}
+	window.Pack(frame, ui.Pack{
+		Side:    ui.N,
+		Padding: 8,
+	})
+
+	return window
+}

wasm/wasm_exec.js

@@ -30,6 +30,12 @@
 		global.fs = require("fs");
 	}
 
+	const enosys = () => {
+		const err = new Error("not implemented");
+		err.code = "ENOSYS";
+		return err;
+	};
+
 	if (!global.fs) {
 		let outputBuf = "";
 		global.fs = {
@@ -45,27 +51,53 @@
 			},
 			write(fd, buf, offset, length, position, callback) {
 				if (offset !== 0 || length !== buf.length || position !== null) {
-					throw new Error("not implemented");
+					callback(enosys());
+					return;
 				}
 				const n = this.writeSync(fd, buf);
 				callback(null, n);
 			},
-			open(path, flags, mode, callback) {
+			chmod(path, mode, callback) { callback(enosys()); },
-				const err = new Error("not implemented");
+			chown(path, uid, gid, callback) { callback(enosys()); },
-				err.code = "ENOSYS";
+			close(fd, callback) { callback(enosys()); },
-				callback(err);
+			fchmod(fd, mode, callback) { callback(enosys()); },
-			},
+			fchown(fd, uid, gid, callback) { callback(enosys()); },
-			read(fd, buffer, offset, length, position, callback) {
+			fstat(fd, callback) { callback(enosys()); },
-				const err = new Error("not implemented");
+			fsync(fd, callback) { callback(null); },
-				err.code = "ENOSYS";
+			ftruncate(fd, length, callback) { callback(enosys()); },
-				callback(err);
+			lchown(path, uid, gid, callback) { callback(enosys()); },
-			},
+			link(path, link, callback) { callback(enosys()); },
-			fsync(fd, callback) {
+			lstat(path, callback) { callback(enosys()); },
-				callback(null);
+			mkdir(path, perm, callback) { callback(enosys()); },
-			},
+			open(path, flags, mode, callback) { callback(enosys()); },
+			read(fd, buffer, offset, length, position, callback) { callback(enosys()); },
+			readdir(path, callback) { callback(enosys()); },
+			readlink(path, callback) { callback(enosys()); },
+			rename(from, to, callback) { callback(enosys()); },
+			rmdir(path, callback) { callback(enosys()); },
+			stat(path, callback) { callback(enosys()); },
+			symlink(path, link, callback) { callback(enosys()); },
+			truncate(path, length, callback) { callback(enosys()); },
+			unlink(path, callback) { callback(enosys()); },
+			utimes(path, atime, mtime, callback) { callback(enosys()); },
 		};
 	}
 
+	if (!global.process) {
+		global.process = {
+			getuid() { return -1; },
+			getgid() { return -1; },
+			geteuid() { return -1; },
+			getegid() { return -1; },
+			getgroups() { throw enosys(); },
+			pid: -1,
+			ppid: -1,
+			umask() { throw enosys(); },
+			cwd() { throw enosys(); },
+			chdir() { throw enosys(); },
+		}
+	}
+
 	if (!global.crypto) {
 		const nodeCrypto = require("crypto");
 		global.crypto = {
@@ -113,24 +145,19 @@
 			this._scheduledTimeouts = new Map();
 			this._nextCallbackTimeoutID = 1;
 
-			const mem = () => {
-				// The buffer may change when requesting more memory.
-				return new DataView(this._inst.exports.mem.buffer);
-			}
-
 			const setInt64 = (addr, v) => {
-				mem().setUint32(addr + 0, v, true);
+				this.mem.setUint32(addr + 0, v, true);
-				mem().setUint32(addr + 4, Math.floor(v / 4294967296), true);
+				this.mem.setUint32(addr + 4, Math.floor(v / 4294967296), true);
 			}
 
 			const getInt64 = (addr) => {
-				const low = mem().getUint32(addr + 0, true);
+				const low = this.mem.getUint32(addr + 0, true);
-				const high = mem().getInt32(addr + 4, true);
+				const high = this.mem.getInt32(addr + 4, true);
 				return low + high * 4294967296;
 			}
 
 			const loadValue = (addr) => {
-				const f = mem().getFloat64(addr, true);
+				const f = this.mem.getFloat64(addr, true);
 				if (f === 0) {
 					return undefined;
 				}
@@ -138,7 +165,7 @@
 					return f;
 				}
 
-				const id = mem().getUint32(addr, true);
+				const id = this.mem.getUint32(addr, true);
 				return this._values[id];
 			}
 
@@ -147,57 +174,62 @@
 
 				if (typeof v === "number") {
 					if (isNaN(v)) {
-						mem().setUint32(addr + 4, nanHead, true);
+						this.mem.setUint32(addr + 4, nanHead, true);
-						mem().setUint32(addr, 0, true);
+						this.mem.setUint32(addr, 0, true);
 						return;
 					}
 					if (v === 0) {
-						mem().setUint32(addr + 4, nanHead, true);
+						this.mem.setUint32(addr + 4, nanHead, true);
-						mem().setUint32(addr, 1, true);
+						this.mem.setUint32(addr, 1, true);
 						return;
 					}
-					mem().setFloat64(addr, v, true);
+					this.mem.setFloat64(addr, v, true);
 					return;
 				}
 
 				switch (v) {
 					case undefined:
-						mem().setFloat64(addr, 0, true);
+						this.mem.setFloat64(addr, 0, true);
 						return;
 					case null:
-						mem().setUint32(addr + 4, nanHead, true);
+						this.mem.setUint32(addr + 4, nanHead, true);
-						mem().setUint32(addr, 2, true);
+						this.mem.setUint32(addr, 2, true);
 						return;
 					case true:
-						mem().setUint32(addr + 4, nanHead, true);
+						this.mem.setUint32(addr + 4, nanHead, true);
-						mem().setUint32(addr, 3, true);
+						this.mem.setUint32(addr, 3, true);
 						return;
 					case false:
-						mem().setUint32(addr + 4, nanHead, true);
+						this.mem.setUint32(addr + 4, nanHead, true);
-						mem().setUint32(addr, 4, true);
+						this.mem.setUint32(addr, 4, true);
 						return;
 				}
 
-				let ref = this._refs.get(v);
+				let id = this._ids.get(v);
-				if (ref === undefined) {
+				if (id === undefined) {
-					ref = this._values.length;
+					id = this._idPool.pop();
-					this._values.push(v);
+					if (id === undefined) {
-					this._refs.set(v, ref);
+						id = this._values.length;
+					}
+					this._values[id] = v;
+					this._goRefCounts[id] = 0;
+					this._ids.set(v, id);
 				}
-				let typeFlag = 0;
+				this._goRefCounts[id]++;
+				let typeFlag = 1;
 				switch (typeof v) {
 					case "string":
-						typeFlag = 1;
-						break;
-					case "symbol":
 						typeFlag = 2;
 						break;
-					case "function":
+					case "symbol":
 						typeFlag = 3;
 						break;
+					case "function":
+						typeFlag = 4;
+						break;
 				}
-				mem().setUint32(addr + 4, nanHead | typeFlag, true);
+				this.mem.setUint32(addr + 4, nanHead | typeFlag, true);
-				mem().setUint32(addr, ref, true);
+				this.mem.setUint32(addr, id, true);
 			}
 
 			const loadSlice = (addr) => {
@@ -232,11 +264,13 @@
 
 					// func wasmExit(code int32)
 					"runtime.wasmExit": (sp) => {
-						const code = mem().getInt32(sp + 8, true);
+						const code = this.mem.getInt32(sp + 8, true);
 						this.exited = true;
 						delete this._inst;
 						delete this._values;
-						delete this._refs;
+						delete this._goRefCounts;
+						delete this._ids;
+						delete this._idPool;
 						this.exit(code);
 					},
 
@@ -244,20 +278,25 @@
 					"runtime.wasmWrite": (sp) => {
 						const fd = getInt64(sp + 8);
 						const p = getInt64(sp + 16);
-						const n = mem().getInt32(sp + 24, true);
+						const n = this.mem.getInt32(sp + 24, true);
 						fs.writeSync(fd, new Uint8Array(this._inst.exports.mem.buffer, p, n));
 					},
 
-					// func nanotime() int64
+					// func resetMemoryDataView()
-					"runtime.nanotime": (sp) => {
+					"runtime.resetMemoryDataView": (sp) => {
+						this.mem = new DataView(this._inst.exports.mem.buffer);
+					},
+
+					// func nanotime1() int64
+					"runtime.nanotime1": (sp) => {
 						setInt64(sp + 8, (timeOrigin + performance.now()) * 1000000);
 					},
 
-					// func walltime() (sec int64, nsec int32)
+					// func walltime1() (sec int64, nsec int32)
-					"runtime.walltime": (sp) => {
+					"runtime.walltime1": (sp) => {
 						const msec = (new Date).getTime();
 						setInt64(sp + 8, msec / 1000);
-						mem().setInt32(sp + 16, (msec % 1000) * 1000000, true);
+						this.mem.setInt32(sp + 16, (msec % 1000) * 1000000, true);
 					},
 
 					// func scheduleTimeoutEvent(delay int64) int32
@@ -276,12 +315,12 @@
 							},
 							getInt64(sp + 8) + 1, // setTimeout has been seen to fire up to 1 millisecond early
 						));
-						mem().setInt32(sp + 16, id, true);
+						this.mem.setInt32(sp + 16, id, true);
 					},
 
 					// func clearTimeoutEvent(id int32)
 					"runtime.clearTimeoutEvent": (sp) => {
-						const id = mem().getInt32(sp + 8, true);
+						const id = this.mem.getInt32(sp + 8, true);
 						clearTimeout(this._scheduledTimeouts.get(id));
 						this._scheduledTimeouts.delete(id);
 					},
@@ -291,6 +330,18 @@
 						crypto.getRandomValues(loadSlice(sp + 8));
 					},
 
+					// func finalizeRef(v ref)
+					"syscall/js.finalizeRef": (sp) => {
+						const id = this.mem.getUint32(sp + 8, true);
+						this._goRefCounts[id]--;
+						if (this._goRefCounts[id] === 0) {
+							const v = this._values[id];
+							this._values[id] = null;
+							this._ids.delete(v);
+							this._idPool.push(id);
+						}
+					},
+
 					// func stringVal(value string) ref
 					"syscall/js.stringVal": (sp) => {
 						storeValue(sp + 24, loadString(sp + 8));
@@ -308,6 +359,11 @@
 						Reflect.set(loadValue(sp + 8), loadString(sp + 16), loadValue(sp + 32));
 					},
 
+					// func valueDelete(v ref, p string)
+					"syscall/js.valueDelete": (sp) => {
+						Reflect.deleteProperty(loadValue(sp + 8), loadString(sp + 16));
+					},
+
 					// func valueIndex(v ref, i int) ref
 					"syscall/js.valueIndex": (sp) => {
 						storeValue(sp + 24, Reflect.get(loadValue(sp + 8), getInt64(sp + 16)));
@@ -327,10 +383,10 @@
 							const result = Reflect.apply(m, v, args);
 							sp = this._inst.exports.getsp(); // see comment above
 							storeValue(sp + 56, result);
-							mem().setUint8(sp + 64, 1);
+							this.mem.setUint8(sp + 64, 1);
 						} catch (err) {
 							storeValue(sp + 56, err);
-							mem().setUint8(sp + 64, 0);
+							this.mem.setUint8(sp + 64, 0);
 						}
 					},
 
@@ -342,10 +398,10 @@
 							const result = Reflect.apply(v, undefined, args);
 							sp = this._inst.exports.getsp(); // see comment above
 							storeValue(sp + 40, result);
-							mem().setUint8(sp + 48, 1);
+							this.mem.setUint8(sp + 48, 1);
 						} catch (err) {
 							storeValue(sp + 40, err);
-							mem().setUint8(sp + 48, 0);
+							this.mem.setUint8(sp + 48, 0);
 						}
 					},
 
@@ -357,10 +413,10 @@
 							const result = Reflect.construct(v, args);
 							sp = this._inst.exports.getsp(); // see comment above
 							storeValue(sp + 40, result);
-							mem().setUint8(sp + 48, 1);
+							this.mem.setUint8(sp + 48, 1);
 						} catch (err) {
 							storeValue(sp + 40, err);
-							mem().setUint8(sp + 48, 0);
+							this.mem.setUint8(sp + 48, 0);
 						}
 					},
 
@@ -384,7 +440,7 @@
 
 					// func valueInstanceOf(v ref, t ref) bool
 					"syscall/js.valueInstanceOf": (sp) => {
-						mem().setUint8(sp + 24, loadValue(sp + 8) instanceof loadValue(sp + 16));
+						this.mem.setUint8(sp + 24, loadValue(sp + 8) instanceof loadValue(sp + 16));
 					},
 
 					// func copyBytesToGo(dst []byte, src ref) (int, bool)
@@ -392,13 +448,13 @@
 						const dst = loadSlice(sp + 8);
 						const src = loadValue(sp + 32);
 						if (!(src instanceof Uint8Array)) {
-							mem().setUint8(sp + 48, 0);
+							this.mem.setUint8(sp + 48, 0);
 							return;
 						}
 						const toCopy = src.subarray(0, dst.length);
 						dst.set(toCopy);
 						setInt64(sp + 40, toCopy.length);
-						mem().setUint8(sp + 48, 1);
+						this.mem.setUint8(sp + 48, 1);
 					},
 
 					// func copyBytesToJS(dst ref, src []byte) (int, bool)
@@ -406,13 +462,13 @@
 						const dst = loadValue(sp + 8);
 						const src = loadSlice(sp + 16);
 						if (!(dst instanceof Uint8Array)) {
-							mem().setUint8(sp + 48, 0);
+							this.mem.setUint8(sp + 48, 0);
 							return;
 						}
 						const toCopy = src.subarray(0, dst.length);
 						dst.set(toCopy);
 						setInt64(sp + 40, toCopy.length);
-						mem().setUint8(sp + 48, 1);
+						this.mem.setUint8(sp + 48, 1);
 					},
 
 					"debug": (value) => {
@@ -424,7 +480,8 @@
 
 		async run(instance) {
 			this._inst = instance;
-			this._values = [ // TODO: garbage collection
+			this.mem = new DataView(this._inst.exports.mem.buffer);
+			this._values = [ // JS values that Go currently has references to, indexed by reference id
 				NaN,
 				0,
 				null,
@@ -433,10 +490,10 @@
 				global,
 				this,
 			];
-			this._refs = new Map();
+			this._goRefCounts = []; // number of references that Go has to a JS value, indexed by reference id
-			this.exited = false;
+			this._ids = new Map();  // mapping from JS values to reference ids
-
+			this._idPool = [];      // unused ids that have been garbage collected
-			const mem = new DataView(this._inst.exports.mem.buffer)
+			this.exited = false;    // whether the Go program has exited
 
 			// Pass command line arguments and environment variables to WebAssembly by writing them to the linear memory.
 			let offset = 4096;
@@ -444,7 +501,7 @@
 			const strPtr = (str) => {
 				const ptr = offset;
 				const bytes = encoder.encode(str + "\0");
-				new Uint8Array(mem.buffer, offset, bytes.length).set(bytes);
+				new Uint8Array(this.mem.buffer, offset, bytes.length).set(bytes);
 				offset += bytes.length;
 				if (offset % 8 !== 0) {
 					offset += 8 - (offset % 8);
@@ -458,17 +515,18 @@
 			this.argv.forEach((arg) => {
 				argvPtrs.push(strPtr(arg));
 			});
+			argvPtrs.push(0);
 
 			const keys = Object.keys(this.env).sort();
-			argvPtrs.push(keys.length);
 			keys.forEach((key) => {
 				argvPtrs.push(strPtr(`${key}=${this.env[key]}`));
 			});
+			argvPtrs.push(0);
 
 			const argv = offset;
 			argvPtrs.forEach((ptr) => {
-				mem.setUint32(offset, ptr, true);
+				this.mem.setUint32(offset, ptr, true);
-				mem.setUint32(offset + 4, 0, true);
+				this.mem.setUint32(offset + 4, 0, true);
 				offset += 8;
 			});