9b090603a0
With this commit, `interpreter.runPythonAsync(code)` can now be used to run Python code that uses `await` at the top level. That will yield up to JavaScript and produce a thenable, which the JavaScript runtime can then resume. Also implemented is the ability for Python code to await on JavaScript promises/thenables. For example, outer JavaScript code can await on `runPythonAsync(code)` which then runs Python code that does `await js.fetch(url)`. The entire chain of calls will be suspended until the fetch completes. Signed-off-by: Damien George <damien@micropython.org>
MicroPython WebAssembly
MicroPython for WebAssembly.
Dependencies
Building webassembly port bears the same requirements as the standard MicroPython ports with the addition of Emscripten (and uglify-js for the minified file).
The output includes micropython.js (a JavaScript wrapper for the
MicroPython runtime) and firmware.wasm (actual MicroPython compiled to
WASM).
Build instructions
In order to build micropython.js, run:
$ make
To generate the minified file micropython.min.js, run:
$ make min
Running with Node.js
Access the repl with:
$ node build/micropython.js
Stack size may be modified using:
$ node build/micropython.js -X stack=64K
Where stack size may be represented in Bytes, KiB or MiB.
MicroPython scripts may be executed using:
$ node build/micropython.js hello.py
Alternatively micropython.js may by accessed by other javascript programs in node using the require command and the general API outlined below. For example:
var mp_js = require('./build/micropython.js');
mp_js_init(64 * 1024);
await mp_js_do_str("print('hello world')\n");
Running with HTML
The prerequisite for browser operation of micropython.js is to listen to the
micropython-print event, which is passed data when MicroPython code prints
something to stdout. The following code demonstrates basic functionality:
<!doctype html>
<html>
<head>
<script src="build/micropython.js"></script>
</head>
<body>
<pre id="micropython-stdout"></pre>
<script>
document.addEventListener("micropython-print", function(e) {
let output = document.getElementById("micropython-stdout");
output.innerText += new TextDecoder().decode(e.detail);
}, false);
var mp_js_startup = Module["onRuntimeInitialized"];
Module["onRuntimeInitialized"] = async function() {
mp_js_startup();
mp_js_init(64 * 1024);
await mp_js_do_str("print('hello world')");
};
</script>
</body>
</html>
MicroPython code execution will suspend the browser so be sure to atomize usage within this environment. Unfortunately interrupts have not been implemented for the browser.
Testing
Run the test suite using:
$ make test
API
The following functions have been exposed to javascript.
mp_js_init(stack_size)
Initialize MicroPython with the given stack size in bytes. This must be called before attempting to interact with MicroPython.
await mp_js_do_str(code)
Execute the input code. code must be a string.
mp_js_init_repl()
Initialize MicroPython repl. Must be called before entering characters into the repl.
await mp_js_process_char(char)
Input character into MicroPython repl. char must be of type number. This
will execute MicroPython code when necessary.