WebAssembly

Yayu Wang included in category Programming_languages

2023-05-29 2023-06-08 158 words One minute

Contents

Wasm

WebAssembly (abbreviated Wasm) is a binary instruction format for a stack-based virtual machine. Wasm is designed as a portable compilation target for programming languages, enabling deployment on the web for client and server applications.

Use WebAssembly in JavaScript

compile c/c++/rust code

source code

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int add(int a, int b) {
    return a + b;
}

emcc

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emcc src/add.c -s STANDALONE_WASM=1 -o add.wasm

fetch

use fetch to load the wasm file

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fetch('add.wasm')
    .then((response) => response.arrayBuffer())
    .then((bytes) => WebAssembly.instantiate(bytes, importObject))
    .then((results) => {
        // Do something with the compiled results!
    });

initiate

call WebAssembly.instantiate
new api: WebAssembly.compileStream (not supported in nodejs 12.x)

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function fetchAndInstantiate(url, importObject) {
    return fetch(url)
        .then((response) => response.arrayBuffer())
        .then((bytes) => WebAssembly.instantiate(bytes, importObject))
        .then((results) => results.instance);
}

execute

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fetchAndInstantiate('add.wasm', importObject).then(function (instance) {
    instance.exports.exported_func();

    var i32 = new Uint32Array(instance.exports.memory.buffer);

    var table = instance.exports.table;
    console.log(table.get(0)());
});