misc/wasm/wasm_exec.js - go - Git at Google

 // 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);
 		});
 	}
 })();
	// 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);
	});
	}
	})();