WebAssembly

https://webassembly.org/getting-started/
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WebAssembly is a binary instruction format that enables compiling code from multiple programming...
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### Grow WebAssembly Memory

Source: https://webassembly.org/getting-started/js-api

Increases the size of an existing WebAssembly Memory object by a specified number of WebAssembly pages. Growing beyond the maximum limit will throw a RangeError.

```javascript
memory.grow(1);
```

--------------------------------

### Create WebAssembly Memory in JavaScript

Source: https://webassembly.org/getting-started/js-api

Creates a WebAssembly Memory object with specified initial and maximum page sizes. Pages are fixed at 64KiB. This memory can be used to store data for WebAssembly modules.

```javascript
var memory = new WebAssembly.Memory({ initial: 10, maximum: 100 });
```

--------------------------------

### Fetch, Compile, and Instantiate WebAssembly Module (JavaScript)

Source: https://webassembly.org/getting-started/js-api

Demonstrates the complete process of loading a WebAssembly module from a URL, compiling its bytes, and instantiating it with the necessary imports. It uses the Fetch API and promises to handle the asynchronous operations, finally executing an exported function.

```javascript
fetch('simple.wasm')
  .then((response) => response.arrayBuffer())
  .then((bytes) => instantiate(bytes, importObject))
  .then((instance) => instance.exports.e());

```

--------------------------------

### Instantiate WebAssembly Module from Bytes and Imports (JavaScript)

Source: https://webassembly.org/getting-started/js-api

Combines WebAssembly compilation and instantiation into a single asynchronous operation. It takes raw Wasm bytes and an import object, returning a Promise that resolves to a WebAssembly Instance. This is a common pattern for loading and running Wasm modules.

```javascript
function instantiate(bytes, imports) {
  return WebAssembly.compile(bytes).then(
    (m) => new WebAssembly.Instance(m, imports)
  );
}

```

--------------------------------

### WebAssembly Module Memory Export (Wasm)

Source: https://webassembly.org/getting-started/js-api

A WebAssembly module definition that exports a linear memory named 'mem' and a function 'accumulate'. This allows JavaScript to access and interact with the module's memory.

```wast
(module
  (memory (export "mem") 1)
  (func (export "accumulate") (param $ptr i32) (param $length i32) ...))
```

--------------------------------

### Define Simple WebAssembly Module with Import and Export (WebAssembly Text Format)

Source: https://webassembly.org/getting-started/js-api

A basic WebAssembly module written in the text format. It imports a function 'i' from a namespace 'imports' and exports a function named 'e'. The exported function 'e' calls the imported function 'i' with a constant value.

```webassembly
(module
  (func $i (import "imports" "i") (param i32))
  (func (export "e")
    i32.const 42
    call $i))

```

--------------------------------

### Access and Write to WebAssembly Memory

Source: https://webassembly.org/getting-started/js-api

Accesses the underlying ArrayBuffer of a WebAssembly Memory object and uses a typed array (Uint32Array) to write a value directly into the memory. This allows for direct data manipulation.

```javascript
new Uint32Array(memory.buffer)[0] = 42;
```

--------------------------------

### Populate and Use Exported WebAssembly Memory

Source: https://webassembly.org/getting-started/js-api

Populates the memory exported by a WebAssembly instance with integer data using a Uint32Array and then calls an exported function 'accumulate' to process the data. This demonstrates direct memory interaction from JavaScript.

```javascript
var i32 = new Uint32Array(instance.exports.mem);
for (var i = 0; i < 10; i++) i32[i] = i;
var sum = instance.exports.accumulate(0, 10);
```

--------------------------------

### Create Import Object for WebAssembly Module (JavaScript)

Source: https://webassembly.org/getting-started/js-api

Defines the JavaScript object that will be passed as imports to a WebAssembly module. This object mirrors the two-level namespace defined in the WebAssembly module's import section. In this case, it provides the 'i' function for the 'imports' namespace.

```javascript
var importObject = { imports: { i: (arg) => console.log(arg) } };

```
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