Create initial emulator and hello world demo

.gitignore

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+*.wasm

LICENSE.md

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+# Komorebi License
+
+Version 2.0.0
+
+## Acceptance
+
+In order to get any license under these terms, you must agree
+to them as both strict obligations and conditions to all
+your licenses.
+
+## Copyright License
+
+The licensor grants you a copyright license for the software
+to do everything you might do with the software that would
+otherwise infringe the licensor's copyright in it for any
+permitted purpose. However, you may only distribute the source
+code of the software according to the [Distribution License](
+#distribution-license), you may only make changes according
+to the [Changes License](#changes-license), and you may not
+otherwise distribute the software or new works based on the
+software.
+
+## Distribution License
+
+The licensor grants you an additional copyright license to
+distribute copies of the source code of the software. Your
+license to distribute covers distributing the source code of
+the software with changes permitted by the [Changes License](
+#changes-license).
+
+## Changes License
+
+The licensor grants you an additional copyright license to
+make changes for any permitted purpose.
+
+## Patent License
+
+The licensor grants you a patent license for the software that
+covers patent claims the licensor can license, or becomes able
+to license, that you would infringe by using the software.
+
+## Personal Uses
+
+Personal use for research, experiment, and testing for
+the benefit of public knowledge, personal study, private
+entertainment, hobby projects, amateur pursuits, or religious
+observance, without any anticipated commercial application,
+is use for a permitted purpose.
+
+## Fair Use
+
+You may have "fair use" rights for the software under the
+law. These terms do not limit them.
+
+## No Other Rights
+
+These terms do not allow you to sublicense or transfer any of
+your licenses to anyone else, or prevent the licensor from
+granting licenses to anyone else.  These terms do not imply
+any other licenses.
+
+## Patent Defense
+
+If you make any written claim that the software infringes or
+contributes to infringement of any patent, your patent license
+for the software granted under these terms ends immediately. If
+your company makes such a claim, your patent license ends
+immediately for work on behalf of your company.
+
+## Violations
+
+The first time you are notified in writing that you have
+violated any of these terms, or done anything with the software
+not covered by your licenses, your licenses can nonetheless
+continue if you come into full compliance with these terms,
+and take practical steps to correct past violations, within
+32 days of receiving notice.  Otherwise, all your licenses
+end immediately.
+
+## No Liability
+
+***As far as the law allows, the software comes as is, without
+any warranty or condition, and the licensor will not be liable
+to you for any damages arising out of these terms or the use
+or nature of the software, under any kind of legal claim.***
+
+## Definitions
+
+The **licensor** is the individual or entity offering these
+terms, and the **software** is the software the licensor makes
+available under these terms.
+
+**You** refers to the individual or entity agreeing to these
+terms.
+
+**Your company** is any legal entity, sole proprietorship,
+or other kind of organization that you work for, plus all
+organizations that have control over, are under the control of,
+or are under common control with that organization.  **Control**
+means ownership of substantially all the assets of an entity,
+or the power to direct its management and policies by vote,
+contract, or otherwise.  Control can be direct or indirect.
+
+**Your licenses** are all the licenses granted to you for the
+software under these terms.
+
+**Use** means anything you do with the software requiring one
+of your licenses.

README.md

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+# Wipforth
+
+## Building and Running
+
+To run, first compile the WebAssembly module:
+
+```
+wat2wasm --enable-threads wipforth.wat
+```
+
+Then run the server:
+
+```
+python3 server.py
+```
+
+You should then be able to open <http://localhost:8080> in a browser
+and use the system from there.
+
+**NOTE**: The server is just a very simple instantiation of Python's
+built-in `http.server` that sets the cross-origin headers required for
+`SharedMemoryBuffer` use.  You could use any HTTP server that sets
+these headers.
+
+## Peripherals
+
+# Serial
+
+| Name   | Offset | Size / B | Access       |
+|--------|--------|----------|--------------|
+| TXBUF  | 0      | 32       | write        |
+| RXBUF  | 32     | 32       | read         |
+| TXDATA | 64     | 1        | atomic write |
+| TXHEAD | 65     | 1        | atomic read  |
+| TXTAIL | 66     | 1        | atomic write |
+| RXDATA | 67     | 1        | atomic read  |
+| RXHEAD | 68     | 1        | atomic write |
+| RXTAIL | 69     | 1        | atomic read  |
+
+For both sending (`TX`) and receiving (`RX`), there are four
+registers: `xBUF`, `xDATA`, `xHEAD` and `xTAIL`:
+
+- `xBUF` registers are 32-byte FIFO ring buffers used for data
+- The `xDATA` registers indicate whether data is available (0 for
+  data, FFh for no data)
+- The `xHEAD` and `xTAIL` registers specify the start and end of
+  data in the FIFO, `xHEAD` being the offset of the first byte of
+  data, and `xTAIL` being the offset of the first byte after the
+  data.

boot.js

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+self.onmessage = async (e) => {
+	const exports = { emu: { mem: e.data } };
+	const mod = await WebAssembly.instantiateStreaming(
+		fetch('wipforth.wasm'), exports)
+	mod.instance.exports.reset();
+};

emu.js

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+const TXBUF = 0;
+const RXBUF = 32;
+const TXDATA = 64;
+const TXHEAD = 65;
+const TXTAIL = 66;
+const RXDATA = 67;
+const RXHEAD = 68;
+const RXTAIL = 69;
+
+const TXBUF_SIZE = 32;
+const RXBUF_SIZE = 32;
+const PERIPHS_SIZE = 70;
+
+const POLL_INTERVAL_MS = 20;
+
+class Emulator {
+	constructor() {
+		this.mem = new WebAssembly.Memory({
+			initial: 1,
+			maximum: 1,
+			shared: true
+		});
+		this.mem_u8 = new Uint8Array(this.mem.buffer);
+		for (let i = 0; i < PERIPHS_SIZE; ++i)
+			this.mem_u8[i] = 0;
+
+		this.decoder = new TextDecoder('utf-8');
+
+		this.output = document.getElementById('output');
+		this.input = document.getElementById('input');
+
+		this.timer = setInterval(() => this.poll(), POLL_INTERVAL_MS);
+
+		this.worker = new Worker('boot.js');
+		this.worker.postMessage(this.mem);
+	}
+
+	poll() {
+		const txdata = Atomics.load(this.mem_u8, TXDATA);
+		if (txdata !== 0)
+			this.handle_txdata();
+	}
+
+	handle_txdata() {
+		const head = Atomics.load(this.mem_u8, TXHEAD);
+		const tail = Atomics.load(this.mem_u8, TXTAIL);
+
+		const data = [];
+		let i = head;
+		do {
+			data.push(this.mem_u8[TXBUF + i]);
+			i = (i + 1) % TXBUF_SIZE;
+		} while (i !== tail);
+
+		Atomics.store(this.mem_u8, TXHEAD, tail);
+
+		// More data could have been added -- only clear TXDATA if
+		// tail is unchanged.
+		if (tail === Atomics.load(this.mem_u8, TXTAIL))
+			Atomics.store(this.mem_u8, TXDATA, 0);
+
+		const str = this.decoder.decode(new Uint8Array(data));
+		this.output.innerText += str;
+	}
+}
+
+window.addEventListener('DOMContentLoaded', () => {
+	window.emu = new Emulator();
+});

index.html

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+<!DOCTYPE html>
+<html>
+  <head>
+	<title>Wipforth</title>
+	<link rel="stylesheet" type="text/css" href="styles.css"/>
+  </head>
+  <body>
+	<script type="text/javascript" src="emu.js"></script>
+	<div id="output"></div>
+	<input id="input" type="text" autofocus></input>
+  </body>
+</html>

server.py

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+from http.server import HTTPServer, SimpleHTTPRequestHandler
+import sys
+
+class CORSRequestHandler(SimpleHTTPRequestHandler):
+	def end_headers(self):
+		self.send_header(
+			'Cross-Origin-Opener-Policy', 'same-origin')
+		self.send_header(
+			'Cross-Origin-Embedder-Policy', 'require-corp')
+		self.send_header(
+			'Cache-Control', 'no-store, no-cache, must-revalidate')
+		super().end_headers()
+
+if __name__ == '__main__':
+	server = HTTPServer(('localhost', 8080), CORSRequestHandler)
+	server.serve_forever()

styles.css

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+body {
+	line-height: 1.4em;
+	font-family: 'Courier 10 Pitch', monospace;
+	font-size: 12pt;
+	background-color: black;
+	color: white;
+}
+
+#output {
+	margin: 1.4em auto;
+	width: 80em;
+	height: 48em;
+}
+
+#input {
+	display: none;
+}

wipforth.wat

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+(module
+ (import "emu" "mem" (memory 1 1 shared))
+
+ (func (export "reset")
+	   ;; Write message into TXBUF
+	   (i32.store8 (i32.const 0x0) (i32.const 0x48)) ;; H
+	   (i32.store8 (i32.const 0x1) (i32.const 0x65)) ;; e
+	   (i32.store8 (i32.const 0x2) (i32.const 0x6c)) ;; l
+	   (i32.store8 (i32.const 0x3) (i32.const 0x6c)) ;; l
+	   (i32.store8 (i32.const 0x4) (i32.const 0x6f)) ;; o
+	   (i32.store8 (i32.const 0x5) (i32.const 0x2c)) ;; ,
+	   (i32.store8 (i32.const 0x6) (i32.const 0x20)) ;; <space>
+	   (i32.store8 (i32.const 0x7) (i32.const 0x77)) ;; w
+	   (i32.store8 (i32.const 0x8) (i32.const 0x6f)) ;; o
+	   (i32.store8 (i32.const 0x9) (i32.const 0x72)) ;; r
+	   (i32.store8 (i32.const 0xa) (i32.const 0x6c)) ;; l
+	   (i32.store8 (i32.const 0xb) (i32.const 0x64)) ;; d
+	   (i32.store8 (i32.const 0xc) (i32.const 0x21)) ;; !
+
+	   ;; Update TXTAIL and set TXDATA
+	   (i32.atomic.store8 (i32.const 0x42) (i32.const 0xd))
+	   (i32.atomic.store8 (i32.const 0x40) (i32.const 0xff))))