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feat(examples): add example demonstrating wasm playback in browser

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João Faria 2024-04-08 17:01:39 +01:00 committed by GitHub
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4 changed files with 67 additions and 1 deletions
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@ -32,4 +32,5 @@ actual_output/
*.exe
*.dll
**/testdata/fuzz/
**/testdata/fuzz/
.DS_Store

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examples/code/wasm/README.md Normal file
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Requirements: sointu binaries, `wabt`
To generate the .wasm file:
```
sointu-compile -o . -arch=wasm tests/test_chords.yml
wat2wasm --enable-bulk-memory test_chords.wat
```
To run the example:
```
npx serve examples/code/wasm
```

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examples/code/wasm/index.html Normal file
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<!DOCTYPE html>
<html>
<head>
<title>sointu WASM example</title>
</head>
<body>
<script type="module">
// button to start audio context
const button = document.createElement("button");
button.innerHTML = "start";
document.body.appendChild(button);
button.onclick = () => {
document.body.removeChild(button);
fetch("test_chords.wasm")
.then((response) => response.arrayBuffer())
.then((bytes) => WebAssembly.instantiate(bytes, { m: Math }))
.then(({ instance }) => {
const context = new AudioContext({ sampleRate: 44100 });
let frames = instance.exports.t.value
? instance.exports.l.value / 4
: instance.exports.l.value / 8;
let wasmBuffer = new Float32Array(
instance.exports.m.buffer,
instance.exports.s.value,
frames * 2
);
const buffer = context.createBuffer(2, frames, context.sampleRate);
// convert wasm buffer to audio buffer
for (let channel = 0; channel < 2; channel++) {
const buffering = buffer.getChannelData(channel);
for (let i = 0; i < frames; i++) {
buffering[i] = wasmBuffer[i * 2 + channel];
}
}
// connect to output and start playing
const src = context.createBufferSource();
src.buffer = buffer;
src.connect(context.destination);
src.start();
});
};
</script>
</body>
</html>

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