 loader
======================
A convenient loader for AssemblyScript modules. Demangles module exports to a friendly object structure compatible with WebIDL and TypeScript definitions and provides some useful utility to read/write data from/to memory.
Usage
-----
```js
const loader = require("@assemblyscript/loader");
...
```
API
---
* **instantiate**<`T`>(module: `WebAssembly.Module`, imports?: `WasmImports`): `ASUtil & T`
Instantiates an AssemblyScript module using the specified imports.
* **instantiateBuffer**<`T`>(buffer: `Uint8Array`, imports?: `WasmImports`): `ASUtil & T`
Instantiates an AssemblyScript module from a buffer using the specified imports.
* **instantiateStreaming**<`T`>(response: `Response`, imports?: `WasmImports`): `Promise`
Instantiates an AssemblyScript module from a response using the specified imports.
* **demangle**<`T`>(exports: `WasmExports`, baseModule?: `Object`): `T`
Demangles an AssemblyScript module's exports to a friendly object structure. You usually don't have to call this manually as instantiation does this implicitly.
**Note:** `T` above can either be omitted if the structure of the module is unknown, or can reference a `.d.ts` (i.e. `typeof MyModule`) as produced by the compiler with the `-d` option.
Instances are automatically populated with useful utility:
* **I8**: `Int8Array`
An 8-bit signed integer view on the memory.
* **U8**: `Uint8Array`
An 8-bit unsigned integer view on the memory.
* **I16**: `Int16Array`
A 16-bit signed integer view on the memory.
* **U16**: `Uint16Array`
A 16-bit unsigned integer view on the memory.
* **I32**: `Int32Array`
A 32-bit signed integer view on the memory.
* **U32**: `Uint32Array`
A 32-bit unsigned integer view on the memory.
* **I64**: `BigInt64Array`
A 64-bit signed integer view on the memory1.
* **U64**: `BigUint64Array`
A 64-bit unsigned integer view on the memory1.
* **F32**: `Float32Array`
A 32-bit float view on the memory.
* **F64**: `Float64Array`
A 64-bit float view on the memory.
* **newString**(str: `string`): `number`
Allocates a new string in the module's memory and returns its retained pointer. When done with the string, make sure to `Module#__release` it.
* **getString**(ptr: `number`): `string`
Reads a string from the module's memory by its pointer.
* **newArray**(id: `number`, values: `number[]`): `number`
Allocates a new array in the module's memory and returns its retained pointer.
The `id` is the unique runtime id of the respective array class. If you are using `Int32Array` for example, the best way to know the relevant value is an `export const INT32ARRAY_ID = idof()`. When done with the array, make sure to `Module#__release` it.
* **getArray**(ptr: `number`): `number[]`
Gets the values of an array in the module's memory by its pointer.
1 This feature has not yet landed in any VM as of this writing.
Examples
--------
### Instantiating a module
```js
// From a module provided as a buffer, i.e. as returned by fs.readFileSync
const myModule = loader.instantiateBuffer(fs.readFileSync("myModule.wasm"), myImports);
// From a response object, i.e. as returned by window.fetch
const myModule = await loader.instantiateStreaming(fetch("myModule.wasm"), myImports);
```
### Reading/writing basic values to/from memory
```js
var ptrToInt8 = ...;
var value = myModule.I8[ptrToInt8]; // alignment of log2(1)=0
var ptrToInt16 = ...;
var value = myModule.I16[ptrToInt16 >>> 1]; // alignment of log2(2)=1
var ptrToInt32 = ...;
var value = myModule.I32[ptrToInt32 >>> 2]; // alignment of log2(4)=2
var ptrToInt64 = ...;
var value = myModule.I64[ptrToInt64 >>> 3]; // alignment of log2(8)=3
var ptrToFloat32 = ...;
var value = myModule.F32[ptrToFloat32 >>> 2]; // alignment of log2(4)=2
var ptrToFloat64 = ...;
var value = myModule.F64[ptrToFloat64 >>> 3]; // alignment of log2(8)=3
// Likewise, for writing
myModule.I8[ptrToInt8] = newValue;
myModule.I16[ptrToInt16 >>> 1] = newValue;
myModule.I32[ptrToInt32 >>> 2] = newValue;
myModule.I64[ptrToInt64 >>> 3] = newValue;
myModule.F32[ptrToFloat32 >>> 2] = newValue;
myModule.F64[ptrToFloat64 >>> 3] = newValue;
```
**Note:** Make sure to reference the views as shown above as these will automatically be updated when the module's memory grows.
### Working with strings and arrays
Strings and arrays cannot yet flow in and out of WebAssembly naturally, hence it is necessary to create them in the module's memory using the `newString` and `newArray` helpers. Afterwards, instead of passing the string or array directly, the resulting reference (pointer) is provided instead:
```js
var str = "Hello world!";
var ptr = module.newString(str);
// do something with ptr, i.e. call a WebAssembly export
...
// when done, allow the runtime to collect it
module.__release(ptr);
```
Similarly, when a string or array is returned from a WebAssembly function, a reference (pointer) is received on the JS side and the `getString` and `getArray` helpers can be used to obtain their values:
```js
var ptrToString = ...;
var str = module.getString(ptrToString);
// ... do something with str ...
```
### Usage with TypeScript definitions produced by the compiler
```ts
import MyModule from "myModule"; // pointing at the d.ts
const myModule = loader.instatiateBuffer(fs.readFileSync("myModule.wasm"), myImports);
```