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DmitrySoshnikov/wasm-binary-example.html

Last active July 6, 2017 15:38
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wasm-binary-example.html
<!DOCTYPE html>
<html>
<head>
<title>Wasm</title>
</head>
<body>
<script>
(async () => {
/**
* Binary code for the following WASM program in s-expression format:
*
* (module
* (export "sqrt" (func $sqrt))
* (func $sqrt
* (param $num f32)
* (result f32)
*
* (f32.sqrt (get_local $num))
* )
* )
*
* Can also assemble a binary from the s-expression format, and then
* load it as:
*
* const wasm = await fetch('./test.wasm');
* const bytes = await wasm.arrayBuffer();
*
* Initial byte sequence `0x00, 0x61, 0x73, 0x6d` is the
* `\0asm` WebAssembly magic number.
*/
const bytes = new Int8Array([
0x00, 0x61, 0x73, 0x6d, 0x01, 0x00, 0x00, 0x00, 0x01, 0x86,
0x80, 0x80, 0x80, 0x00, 0x01, 0x60, 0x01, 0x7d, 0x01, 0x7d,
0x03, 0x82, 0x80, 0x80, 0x80, 0x00, 0x01, 0x00, 0x06, 0x81,
0x80, 0x80, 0x80, 0x00, 0x00, 0x07, 0x88, 0x80, 0x80, 0x80,
0x00, 0x01, 0x04, 0x73, 0x71, 0x72, 0x74, 0x00, 0x00, 0x0a,
0x8b, 0x80, 0x80, 0x80, 0x00, 0x01, 0x85, 0x80, 0x80, 0x80,
0x00, 0x00, 0x20, 0x00, 0x91, 0x0b
]);
const module = await WebAssembly.compile(bytes);
const instance = await WebAssembly.instantiate(module);
const {sqrt} = instance.exports;
console.log('Hello from WASM binary! sqrt(4) =', sqrt(4)); // 2
})();
</script>
</body>
</html>
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