Add WebAssembly Hello World Example

2019-12-22 16:26:33 -08:00 · 2019-12-22 16:26:33 -08:00 · ad9d14bdab
commit ad9d14bdab
parent 6803170675
14 changed files with 981 additions and 5 deletions
--- a/.gitignore
+++ b/.gitignore
@ -0,0 +1 @@
+*.wasm
--- a/canvas/draw.go
+++ b/canvas/draw.go
@ -4,7 +4,7 @@ import (
 	"fmt"
 	"syscall/js"

-	"git.kirsle.net/apps/doodle/lib/render"
+	"git.kirsle.net/go/render"
 )

 // Methods here implement the drawing functions of the render.Engine
--- a/canvas/engine.go
+++ b/canvas/engine.go
@ -4,7 +4,7 @@ import (
 	"syscall/js"
 	"time"

-	"git.kirsle.net/apps/doodle/lib/render/event"
+	"git.kirsle.net/go/render/event"
 )

 // Engine implements a rendering engine targeting an HTML canvas for
--- a/canvas/events.go
+++ b/canvas/events.go
@ -3,7 +3,7 @@ package canvas
 import (
 	"syscall/js"

-	"git.kirsle.net/apps/doodle/lib/render/event"
+	"git.kirsle.net/go/render/event"
 )

 // EventClass to categorize JavaScript events.
--- a/canvas/text.go
+++ b/canvas/text.go
@ -7,7 +7,7 @@ import (
 	"path/filepath"
 	"strings"

-	"git.kirsle.net/apps/doodle/lib/render"
+	"git.kirsle.net/go/render"
 )

 // FontFilenameToName converts a FontFilename to its CSS font name.
--- a/canvas/texture.go
+++ b/canvas/texture.go
@ -8,7 +8,7 @@ import (
 	"image/png"
 	"syscall/js"

-	"git.kirsle.net/apps/doodle/lib/render"
+	"git.kirsle.net/go/render"
 )

 // Texture can hold on to cached image textures.
--- a/examples/hello-wasm/DejaVuSans.ttf
+++ b/examples/hello-wasm/DejaVuSans.ttf
--- a/examples/hello-wasm/Makefile
+++ b/examples/hello-wasm/Makefile
@ -0,0 +1,11 @@
+.PHONY: build
+build:
+	GOOS=js GOARCH=wasm go build -v -o hello.wasm main_wasm.go
+
+.PHONY: serve
+serve: build
+	go run server.go
+
+.PHONY: clean
+clean:
+	rm -f hello.wasm
--- a/examples/hello-wasm/README.md
+++ b/examples/hello-wasm/README.md
@ -0,0 +1,81 @@
+# Hello WASM
+
+This is a port of the "hello-world" example for a WebAssembly target.
+
+Differences compared to the SDL2 version include:
+
+* Import render/canvas instead of render/sdl
+* Load the gopher.png via ajax HTTP request, as the syscall to open a file from
+  disk is not supported in a WASM environment.
+* A call to the `canvas.AddEventListeners()` function to set up DOM event
+  bindings, which enables key and mouse events to be handled in the
+  canvas.Engine.
+
+```diff
+--- ../hello-world/main.go	2019-12-22 15:17:42.186838967 -0800
+++ main_wasm.go	2019-12-22 16:21:58.449699021 -0800
+@@ -1,13 +1,17 @@
+// +build js,wasm
+
+// This is a version of the 'hello-world' example but build for WebAssembly.
+
+ package main
+
+ import (
+ 	"image/png"
+ 	"log"
+-	"os"
+	"net/http"
+ 	"time"
+
+ 	"git.kirsle.net/go/render"
+-	"git.kirsle.net/go/render/sdl"
+	"git.kirsle.net/go/render/canvas"
+ )
+
+ var (
+@@ -30,7 +34,11 @@
+ )
+
+ func main() {
+-	mw := sdl.New("Hello World", 800, 600)
+	mw, _ := canvas.New("canvas")
+ 	setup(mw)
+
+ 	for {
+@@ -61,17 +69,22 @@
+ 	}
+ }
+
+-func setup(e render.Engine) {
+func setup(e *canvas.Engine) {
+ 	if err := e.Setup(); err != nil {
+ 		panic(err)
+ 	}
+
+-	// Load gopher sprite.
+-	fh, err := os.Open("gopher.png")
+	// Bind DOM event handlers.
+	e.AddEventListeners()
+
+	// Load gopher sprite via ajax request.
+	resp, err := http.Get("gopher.png")
+ 	if err != nil {
+ 		log.Fatalf("read gopher.png: %s", err)
+ 	}
+	defer resp.Body.Close()
+
+-	img, _ := png.Decode(fh)
+	img, _ := png.Decode(resp.Body)
+
+ 	gopher, _ = e.StoreTexture("gopher.png", img)
+ 	texSize = gopher.Size()
+```
+
+## Credits
+
+Gopher image was created by Takuya Ueda (https://twitter.com/tenntenn)
+from https://github.com/golang-samples/gopher-vector
+
+This example comes with the DejaVu Sans font. License information
+at https://dejavu-fonts.github.io/License.html
--- a/examples/hello-wasm/gopher.png
+++ b/examples/hello-wasm/gopher.png
--- a/examples/hello-wasm/index.html
+++ b/examples/hello-wasm/index.html
@ -0,0 +1,46 @@
+<!DOCTYPE html>
+<html>
+<head>
+	<title>go/render: hello wasm!</title>
+	<style>
+		#canvas {
+			position: fixed;
+			width: 100%;
+			height: 100%;
+			top: 0;
+			right: 0;
+			left: 0;
+			bottom: 0;
+		}
+
+		@font-face {
+			font-family: "DejaVuSans";
+			src: url("fonts/DejaVuSans.ttf") format("truetype");
+		}
+	</style>
+</head>
+<body>
+
+	<script src="wasm_exec.js"></script>
+	<script>
+		if (!WebAssembly.instantiateStreaming) { // polyfill
+			WebAssembly.instantiateStreaming = async (resp, importObject) => {
+				const source = await (await resp).arrayBuffer();
+				return await WebAssembly.instantiate(source, importObject);
+			};
+		}
+
+		(function() {
+			const go = new Go();
+			WebAssembly.instantiateStreaming(fetch("hello.wasm"), go.importObject).then(result => {
+				console.clear();
+				go.run(result.instance);
+				WebAssembly.instantiate(result.module, go.importObject); // reset instance
+			})
+		})();
+	</script>
+
+	<canvas id="canvas"></canvas>
+
+</body>
+</html>
--- a/examples/hello-wasm/main_wasm.go
+++ b/examples/hello-wasm/main_wasm.go
@ -0,0 +1,177 @@
+// +build js,wasm
+
+// This is a version of the 'hello-world' example but build for WebAssembly.
+
+package main
+
+import (
+	"image/png"
+	"log"
+	"net/http"
+	"time"
+
+	"git.kirsle.net/go/render"
+	"git.kirsle.net/go/render/canvas"
+)
+
+var (
+	// Cap animation speed to 60 FPS
+	targetFPS = 1000 / 60
+
+	// Gopher sprite variables
+	gopher   render.Texturer
+	texSize  render.Rect
+	speed    int32 = 4
+	position       = render.NewPoint(0, 0)
+	velocity       = render.NewPoint(speed, speed)
+
+	// Decorative border variables
+	borderColor       = render.Red
+	borderSize  int32 = 12
+
+	// Background color of the window.
+	bgColor = render.RGBA(255, 255, 128, 255)
+)
+
+func main() {
+	// Parameter to New() is the HTML Canvas ID.
+	mw, err := canvas.New("canvas")
+	if err != nil {
+		panic(err)
+	}
+	setup(mw)
+
+	for {
+		start := time.Now()
+
+		ev, err := mw.Poll()
+		if err != nil {
+			panic(err)
+		}
+
+		if ev.Escape {
+			mw.Teardown()
+			break
+		}
+
+		update(mw)
+		draw(mw)
+		mw.Present()
+
+		// Delay to maintain constant 60 FPS.
+		var delay uint32
+		elapsed := time.Now().Sub(start)
+		tmp := elapsed / time.Millisecond
+		if targetFPS-int(tmp) > 0 {
+			delay = uint32(targetFPS - int(tmp))
+		}
+		mw.Delay(delay)
+	}
+}
+
+func setup(e *canvas.Engine) {
+	if err := e.Setup(); err != nil {
+		panic(err)
+	}
+
+	// Bind DOM event handlers.
+	e.AddEventListeners()
+
+	// Load gopher sprite via ajax request.
+	resp, err := http.Get("gopher.png")
+	if err != nil {
+		log.Fatalf("GET gopher.png: %s", err)
+	}
+	defer resp.Body.Close()
+
+	img, _ := png.Decode(resp.Body)
+
+	gopher, _ = e.StoreTexture("gopher.png", img)
+	texSize = gopher.Size()
+}
+
+func update(e render.Engine) {
+	position.X += velocity.X
+	position.Y += velocity.Y
+
+	// Bounce off the walls.
+	w, h := e.WindowSize()
+
+	if velocity.X > 0 && position.X+texSize.W >= int32(w)-borderSize {
+		velocity.X *= -1
+	} else if velocity.X < 0 && position.X <= borderSize {
+		velocity.X *= -1
+	}
+
+	if velocity.Y > 0 && position.Y+texSize.H >= int32(h)-borderSize {
+		velocity.Y *= -1
+	} else if velocity.Y < 0 && position.Y <= borderSize {
+		velocity.Y *= -1
+	}
+}
+
+func draw(e render.Engine) {
+	w, h := e.WindowSize()
+
+	drawBorder(e, w, h)
+
+	// Draw some text centered along the top of the canvas.
+	text := render.Text{
+		Text:         "Hello, world!",
+		Size:         24,
+		Color:        render.SkyBlue,
+		Shadow:       render.Blue,
+		FontFilename: "DejaVuSans.ttf",
+	}
+	rect, _ := e.ComputeTextRect(text)
+	e.DrawText(text, render.NewPoint(
+		(int32(w)/2)-(rect.W/2),
+		25,
+	))
+
+	e.Copy(gopher, texSize, render.Rect{
+		X: position.X,
+		Y: position.Y,
+		W: texSize.W,
+		H: texSize.H,
+	})
+}
+
+func drawBorder(e render.Engine, w, h int) {
+	// Draw the decorative border. We're going for a "ridged" border
+	// style here. First draw the light and dark edges of the top/left
+	// sides of the border.
+	e.DrawBox(borderColor.Lighten(40), render.Rect{
+		X: 0,
+		Y: 0,
+		W: int32(w),
+		H: int32(h),
+	})
+	e.DrawBox(borderColor.Darken(40), render.Rect{
+		X: borderSize / 2,
+		Y: borderSize / 2,
+		W: int32(w) - (borderSize / 2),
+		H: int32(h) - (borderSize / 2),
+	})
+
+	// Now inset a bit and draw the light/dark edges of the bottom/right.
+	e.DrawBox(borderColor.Darken(40), render.Rect{
+		X: borderSize,
+		Y: borderSize,
+		W: int32(w),
+		H: int32(h),
+	})
+	e.DrawBox(borderColor.Lighten(40), render.Rect{
+		X: borderSize,
+		Y: borderSize,
+		W: int32(w) - borderSize - (borderSize / 2),
+		H: int32(h) - borderSize - (borderSize / 2),
+	})
+
+	e.DrawBox(bgColor, render.Rect{
+		X: borderSize,
+		Y: borderSize,
+		W: int32(w) - (borderSize * 2),
+		H: int32(h) - (borderSize * 2),
+	})
+}
--- a/examples/hello-wasm/server.go
+++ b/examples/hello-wasm/server.go
@ -0,0 +1,127 @@
+// +build disabled
+
+package main
+
+import (
+	"fmt"
+	"io/ioutil"
+	"log"
+	"net/http"
+	"os/exec"
+	"path/filepath"
+
+	"github.com/fsnotify/fsnotify"
+)
+
+func main() {
+	const wasm = "/doodle.wasm"
+
+	// Watch the dev directory for changes.
+	go watchChanges()
+
+	http.Handle("/", http.FileServer(http.Dir(".")))
+	http.HandleFunc(wasm, func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "application/wasm")
+		http.ServeFile(w, r, "."+wasm)
+	})
+
+	fmt.Println("Listening at http://localhost:8080/")
+	log.Fatal(http.ListenAndServe(":8080", nil))
+}
+
+// onChange handler to rebuild the wasm file automatically.
+func onChange() {
+	out, err := exec.Command("make").Output()
+	if err != nil {
+		log.Printf("error: %s", err)
+	}
+	log.Printf("%s", out)
+	log.Printf("Doodle WASM file rebuilt")
+}
+
+// Watch the Doodle source tree for changes to Go files and rebuild
+// the wasm binary automatically.
+func watchChanges() {
+	watcher, err := fsnotify.NewWatcher()
+	if err != nil {
+		log.Printf("error: %s", err)
+		return
+	}
+	defer watcher.Close()
+
+	done := make(chan bool)
+	go func() {
+		log.Println("Starting watch files loop")
+		for {
+			select {
+			case event, ok := <-watcher.Events:
+				if !ok {
+					return
+				}
+
+				log.Printf("event: %s", event)
+				if event.Op&fsnotify.Write == fsnotify.Write {
+					log.Printf("modified file: %s", event.Name)
+					onChange()
+				}
+			case err, ok := <-watcher.Errors:
+				if !ok {
+					return
+				}
+
+				log.Printf("error: %s", err)
+			}
+		}
+	}()
+
+	log.Println("Adding source directory to watcher")
+	dirs := crawlDirectory("../")
+
+	// Watch all these folders.
+	for _, dir := range dirs {
+		err = watcher.Add(dir)
+		if err != nil {
+			log.Printf("error: %s", err)
+		}
+	}
+	<-done
+}
+
+// Crawl the filesystem and return paths with Go files.
+func crawlDirectory(root string) []string {
+	var (
+		ext    = ".go"
+		result []string
+		has    bool
+	)
+
+	files, err := ioutil.ReadDir(root)
+	if err != nil {
+		log.Fatalln(err)
+	}
+
+	for _, file := range files {
+		if file.Name() == ".git" {
+			continue
+		}
+
+		// Recursively scan subdirectories.
+		if file.IsDir() {
+			result = append(result,
+				crawlDirectory(filepath.Join(root, file.Name()))...,
+			)
+			continue
+		}
+
+		// This root has a file we want?
+		if filepath.Ext(file.Name()) == ext {
+			has = true
+		}
+	}
+
+	if has {
+		result = append(result, root)
+	}
+
+	return result
+}
--- a/examples/hello-wasm/wasm_exec.js
+++ b/examples/hello-wasm/wasm_exec.js
@ -0,0 +1,533 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+(() => {
+	// Map multiple JavaScript environments to a single common API,
+	// preferring web standards over Node.js API.
+	//
+	// Environments considered:
+	// - Browsers
+	// - Node.js
+	// - Electron
+	// - Parcel
+
+	if (typeof global !== "undefined") {
+		// global already exists
+	} else if (typeof window !== "undefined") {
+		window.global = window;
+	} else if (typeof self !== "undefined") {
+		self.global = self;
+	} else {
+		throw new Error("cannot export Go (neither global, window nor self is defined)");
+	}
+
+	if (!global.require && typeof require !== "undefined") {
+		global.require = require;
+	}
+
+	if (!global.fs && global.require) {
+		global.fs = require("fs");
+	}
+
+	if (!global.fs) {
+		let outputBuf = "";
+		global.fs = {
+			constants: { O_WRONLY: -1, O_RDWR: -1, O_CREAT: -1, O_TRUNC: -1, O_APPEND: -1, O_EXCL: -1 }, // unused
+			writeSync(fd, buf) {
+				outputBuf += decoder.decode(buf);
+				const nl = outputBuf.lastIndexOf("\n");
+				if (nl != -1) {
+					console.log(outputBuf.substr(0, nl));
+					outputBuf = outputBuf.substr(nl + 1);
+				}
+				return buf.length;
+			},
+			write(fd, buf, offset, length, position, callback) {
+				if (offset !== 0 || length !== buf.length || position !== null) {
+					throw new Error("not implemented");
+				}
+				const n = this.writeSync(fd, buf);
+				callback(null, n);
+			},
+			open(path, flags, mode, callback) {
+				const err = new Error("not implemented");
+				err.code = "ENOSYS";
+				callback(err);
+			},
+			read(fd, buffer, offset, length, position, callback) {
+				const err = new Error("not implemented");
+				err.code = "ENOSYS";
+				callback(err);
+			},
+			fsync(fd, callback) {
+				callback(null);
+			},
+		};
+	}
+
+	if (!global.crypto) {
+		const nodeCrypto = require("crypto");
+		global.crypto = {
+			getRandomValues(b) {
+				nodeCrypto.randomFillSync(b);
+			},
+		};
+	}
+
+	if (!global.performance) {
+		global.performance = {
+			now() {
+				const [sec, nsec] = process.hrtime();
+				return sec * 1000 + nsec / 1000000;
+			},
+		};
+	}
+
+	if (!global.TextEncoder) {
+		global.TextEncoder = require("util").TextEncoder;
+	}
+
+	if (!global.TextDecoder) {
+		global.TextDecoder = require("util").TextDecoder;
+	}
+
+	// End of polyfills for common API.
+
+	const encoder = new TextEncoder("utf-8");
+	const decoder = new TextDecoder("utf-8");
+
+	global.Go = class {
+		constructor() {
+			this.argv = ["js"];
+			this.env = {};
+			this.exit = (code) => {
+				if (code !== 0) {
+					console.warn("exit code:", code);
+				}
+			};
+			this._exitPromise = new Promise((resolve) => {
+				this._resolveExitPromise = resolve;
+			});
+			this._pendingEvent = null;
+			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);
+				mem().setUint32(addr + 4, Math.floor(v / 4294967296), true);
+			}
+
+			const getInt64 = (addr) => {
+				const low = mem().getUint32(addr + 0, true);
+				const high = mem().getInt32(addr + 4, true);
+				return low + high * 4294967296;
+			}
+
+			const loadValue = (addr) => {
+				const f = mem().getFloat64(addr, true);
+				if (f === 0) {
+					return undefined;
+				}
+				if (!isNaN(f)) {
+					return f;
+				}
+
+				const id = mem().getUint32(addr, true);
+				return this._values[id];
+			}
+
+			const storeValue = (addr, v) => {
+				const nanHead = 0x7FF80000;
+
+				if (typeof v === "number") {
+					if (isNaN(v)) {
+						mem().setUint32(addr + 4, nanHead, true);
+						mem().setUint32(addr, 0, true);
+						return;
+					}
+					if (v === 0) {
+						mem().setUint32(addr + 4, nanHead, true);
+						mem().setUint32(addr, 1, true);
+						return;
+					}
+					mem().setFloat64(addr, v, true);
+					return;
+				}
+
+				switch (v) {
+					case undefined:
+						mem().setFloat64(addr, 0, true);
+						return;
+					case null:
+						mem().setUint32(addr + 4, nanHead, true);
+						mem().setUint32(addr, 2, true);
+						return;
+					case true:
+						mem().setUint32(addr + 4, nanHead, true);
+						mem().setUint32(addr, 3, true);
+						return;
+					case false:
+						mem().setUint32(addr + 4, nanHead, true);
+						mem().setUint32(addr, 4, true);
+						return;
+				}
+
+				let ref = this._refs.get(v);
+				if (ref === undefined) {
+					ref = this._values.length;
+					this._values.push(v);
+					this._refs.set(v, ref);
+				}
+				let typeFlag = 0;
+				switch (typeof v) {
+					case "string":
+						typeFlag = 1;
+						break;
+					case "symbol":
+						typeFlag = 2;
+						break;
+					case "function":
+						typeFlag = 3;
+						break;
+				}
+				mem().setUint32(addr + 4, nanHead | typeFlag, true);
+				mem().setUint32(addr, ref, true);
+			}
+
+			const loadSlice = (addr) => {
+				const array = getInt64(addr + 0);
+				const len = getInt64(addr + 8);
+				return new Uint8Array(this._inst.exports.mem.buffer, array, len);
+			}
+
+			const loadSliceOfValues = (addr) => {
+				const array = getInt64(addr + 0);
+				const len = getInt64(addr + 8);
+				const a = new Array(len);
+				for (let i = 0; i < len; i++) {
+					a[i] = loadValue(array + i * 8);
+				}
+				return a;
+			}
+
+			const loadString = (addr) => {
+				const saddr = getInt64(addr + 0);
+				const len = getInt64(addr + 8);
+				return decoder.decode(new DataView(this._inst.exports.mem.buffer, saddr, len));
+			}
+
+			const timeOrigin = Date.now() - performance.now();
+			this.importObject = {
+				go: {
+					// Go's SP does not change as long as no Go code is running. Some operations (e.g. calls, getters and setters)
+					// may synchronously trigger a Go event handler. This makes Go code get executed in the middle of the imported
+					// function. A goroutine can switch to a new stack if the current stack is too small (see morestack function).
+					// This changes the SP, thus we have to update the SP used by the imported function.
+
+					// func wasmExit(code int32)
+					"runtime.wasmExit": (sp) => {
+						const code = mem().getInt32(sp + 8, true);
+						this.exited = true;
+						delete this._inst;
+						delete this._values;
+						delete this._refs;
+						this.exit(code);
+					},
+
+					// func wasmWrite(fd uintptr, p unsafe.Pointer, n int32)
+					"runtime.wasmWrite": (sp) => {
+						const fd = getInt64(sp + 8);
+						const p = getInt64(sp + 16);
+						const n = mem().getInt32(sp + 24, true);
+						fs.writeSync(fd, new Uint8Array(this._inst.exports.mem.buffer, p, n));
+					},
+
+					// func nanotime() int64
+					"runtime.nanotime": (sp) => {
+						setInt64(sp + 8, (timeOrigin + performance.now()) * 1000000);
+					},
+
+					// func walltime() (sec int64, nsec int32)
+					"runtime.walltime": (sp) => {
+						const msec = (new Date).getTime();
+						setInt64(sp + 8, msec / 1000);
+						mem().setInt32(sp + 16, (msec % 1000) * 1000000, true);
+					},
+
+					// func scheduleTimeoutEvent(delay int64) int32
+					"runtime.scheduleTimeoutEvent": (sp) => {
+						const id = this._nextCallbackTimeoutID;
+						this._nextCallbackTimeoutID++;
+						this._scheduledTimeouts.set(id, setTimeout(
+							() => {
+								this._resume();
+								while (this._scheduledTimeouts.has(id)) {
+									// for some reason Go failed to register the timeout event, log and try again
+									// (temporary workaround for https://github.com/golang/go/issues/28975)
+									console.warn("scheduleTimeoutEvent: missed timeout event");
+									this._resume();
+								}
+							},
+							getInt64(sp + 8) + 1, // setTimeout has been seen to fire up to 1 millisecond early
+						));
+						mem().setInt32(sp + 16, id, true);
+					},
+
+					// func clearTimeoutEvent(id int32)
+					"runtime.clearTimeoutEvent": (sp) => {
+						const id = mem().getInt32(sp + 8, true);
+						clearTimeout(this._scheduledTimeouts.get(id));
+						this._scheduledTimeouts.delete(id);
+					},
+
+					// func getRandomData(r []byte)
+					"runtime.getRandomData": (sp) => {
+						crypto.getRandomValues(loadSlice(sp + 8));
+					},
+
+					// func stringVal(value string) ref
+					"syscall/js.stringVal": (sp) => {
+						storeValue(sp + 24, loadString(sp + 8));
+					},
+
+					// func valueGet(v ref, p string) ref
+					"syscall/js.valueGet": (sp) => {
+						const result = Reflect.get(loadValue(sp + 8), loadString(sp + 16));
+						sp = this._inst.exports.getsp(); // see comment above
+						storeValue(sp + 32, result);
+					},
+
+					// func valueSet(v ref, p string, x ref)
+					"syscall/js.valueSet": (sp) => {
+						Reflect.set(loadValue(sp + 8), loadString(sp + 16), loadValue(sp + 32));
+					},
+
+					// func valueIndex(v ref, i int) ref
+					"syscall/js.valueIndex": (sp) => {
+						storeValue(sp + 24, Reflect.get(loadValue(sp + 8), getInt64(sp + 16)));
+					},
+
+					// valueSetIndex(v ref, i int, x ref)
+					"syscall/js.valueSetIndex": (sp) => {
+						Reflect.set(loadValue(sp + 8), getInt64(sp + 16), loadValue(sp + 24));
+					},
+
+					// func valueCall(v ref, m string, args []ref) (ref, bool)
+					"syscall/js.valueCall": (sp) => {
+						try {
+							const v = loadValue(sp + 8);
+							const m = Reflect.get(v, loadString(sp + 16));
+							const args = loadSliceOfValues(sp + 32);
+							const result = Reflect.apply(m, v, args);
+							sp = this._inst.exports.getsp(); // see comment above
+							storeValue(sp + 56, result);
+							mem().setUint8(sp + 64, 1);
+						} catch (err) {
+							storeValue(sp + 56, err);
+							mem().setUint8(sp + 64, 0);
+						}
+					},
+
+					// func valueInvoke(v ref, args []ref) (ref, bool)
+					"syscall/js.valueInvoke": (sp) => {
+						try {
+							const v = loadValue(sp + 8);
+							const args = loadSliceOfValues(sp + 16);
+							const result = Reflect.apply(v, undefined, args);
+							sp = this._inst.exports.getsp(); // see comment above
+							storeValue(sp + 40, result);
+							mem().setUint8(sp + 48, 1);
+						} catch (err) {
+							storeValue(sp + 40, err);
+							mem().setUint8(sp + 48, 0);
+						}
+					},
+
+					// func valueNew(v ref, args []ref) (ref, bool)
+					"syscall/js.valueNew": (sp) => {
+						try {
+							const v = loadValue(sp + 8);
+							const args = loadSliceOfValues(sp + 16);
+							const result = Reflect.construct(v, args);
+							sp = this._inst.exports.getsp(); // see comment above
+							storeValue(sp + 40, result);
+							mem().setUint8(sp + 48, 1);
+						} catch (err) {
+							storeValue(sp + 40, err);
+							mem().setUint8(sp + 48, 0);
+						}
+					},
+
+					// func valueLength(v ref) int
+					"syscall/js.valueLength": (sp) => {
+						setInt64(sp + 16, parseInt(loadValue(sp + 8).length));
+					},
+
+					// valuePrepareString(v ref) (ref, int)
+					"syscall/js.valuePrepareString": (sp) => {
+						const str = encoder.encode(String(loadValue(sp + 8)));
+						storeValue(sp + 16, str);
+						setInt64(sp + 24, str.length);
+					},
+
+					// valueLoadString(v ref, b []byte)
+					"syscall/js.valueLoadString": (sp) => {
+						const str = loadValue(sp + 8);
+						loadSlice(sp + 16).set(str);
+					},
+
+					// func valueInstanceOf(v ref, t ref) bool
+					"syscall/js.valueInstanceOf": (sp) => {
+						mem().setUint8(sp + 24, loadValue(sp + 8) instanceof loadValue(sp + 16));
+					},
+
+					// func copyBytesToGo(dst []byte, src ref) (int, bool)
+					"syscall/js.copyBytesToGo": (sp) => {
+						const dst = loadSlice(sp + 8);
+						const src = loadValue(sp + 32);
+						if (!(src instanceof Uint8Array)) {
+							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);
+					},
+
+					// func copyBytesToJS(dst ref, src []byte) (int, bool)
+					"syscall/js.copyBytesToJS": (sp) => {
+						const dst = loadValue(sp + 8);
+						const src = loadSlice(sp + 16);
+						if (!(dst instanceof Uint8Array)) {
+							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);
+					},
+
+					"debug": (value) => {
+						console.log(value);
+					},
+				}
+			};
+		}
+
+		async run(instance) {
+			this._inst = instance;
+			this._values = [ // TODO: garbage collection
+				NaN,
+				0,
+				null,
+				true,
+				false,
+				global,
+				this,
+			];
+			this._refs = new Map();
+			this.exited = false;
+
+			const mem = new DataView(this._inst.exports.mem.buffer)
+
+			// Pass command line arguments and environment variables to WebAssembly by writing them to the linear memory.
+			let offset = 4096;
+
+			const strPtr = (str) => {
+				const ptr = offset;
+				const bytes = encoder.encode(str + "\0");
+				new Uint8Array(mem.buffer, offset, bytes.length).set(bytes);
+				offset += bytes.length;
+				if (offset % 8 !== 0) {
+					offset += 8 - (offset % 8);
+				}
+				return ptr;
+			};
+
+			const argc = this.argv.length;
+
+			const argvPtrs = [];
+			this.argv.forEach((arg) => {
+				argvPtrs.push(strPtr(arg));
+			});
+
+			const keys = Object.keys(this.env).sort();
+			argvPtrs.push(keys.length);
+			keys.forEach((key) => {
+				argvPtrs.push(strPtr(`${key}=${this.env[key]}`));
+			});
+
+			const argv = offset;
+			argvPtrs.forEach((ptr) => {
+				mem.setUint32(offset, ptr, true);
+				mem.setUint32(offset + 4, 0, true);
+				offset += 8;
+			});
+
+			this._inst.exports.run(argc, argv);
+			if (this.exited) {
+				this._resolveExitPromise();
+			}
+			await this._exitPromise;
+		}
+
+		_resume() {
+			if (this.exited) {
+				throw new Error("Go program has already exited");
+			}
+			this._inst.exports.resume();
+			if (this.exited) {
+				this._resolveExitPromise();
+			}
+		}
+
+		_makeFuncWrapper(id) {
+			const go = this;
+			return function () {
+				const event = { id: id, this: this, args: arguments };
+				go._pendingEvent = event;
+				go._resume();
+				return event.result;
+			};
+		}
+	}
+
+	if (
+		global.require &&
+		global.require.main === module &&
+		global.process &&
+		global.process.versions &&
+		!global.process.versions.electron
+	) {
+		if (process.argv.length < 3) {
+			console.error("usage: go_js_wasm_exec [wasm binary] [arguments]");
+			process.exit(1);
+		}
+
+		const go = new Go();
+		go.argv = process.argv.slice(2);
+		go.env = Object.assign({ TMPDIR: require("os").tmpdir() }, process.env);
+		go.exit = process.exit;
+		WebAssembly.instantiate(fs.readFileSync(process.argv[2]), go.importObject).then((result) => {
+			process.on("exit", (code) => { // Node.js exits if no event handler is pending
+				if (code === 0 && !go.exited) {
+					// deadlock, make Go print error and stack traces
+					go._pendingEvent = { id: 0 };
+					go._resume();
+				}
+			});
+			return go.run(result.instance);
+		}).catch((err) => {
+			console.error(err);
+			process.exit(1);
+		});
+	}
+})();