Memory

WebAssembly memory constructor.

Usage

var Memory = require( '@stdlib/wasm/memory' );

Memory( descriptor )

Returns a new WebAssembly memory instance.

var mem = new Memory({
    'initial': 0
});
// returns <Memory>

The descriptor argument is an object which supports the following properties:

initial: (required) initial memory size in units of WebAssembly pages (i.e., 64KiB).
maximum: maximum memory size in units of WebAssembly pages (i.e., 64KiB).
shared: boolean indicating whether the memory is shared. Default: false.

Memory.prototype.buffer

Read-only property which returns the ArrayBuffer (or SharedArrayBuffer) referenced by memory instance.

var mem = new Memory({
    'initial': 0
});

var buf = mem.buffer;
// returns <ArrayBuffer>

Methods

Memory.prototype.grow( delta )

Increases the size of the memory instance by a specified number of WebAssembly pages (i.e., 64KiB).

var mem = new Memory({
    'initial': 0
});

// ...

var prevSize = mem.grow( 1 );

The method returns the size of the previous ArrayBuffer (or SharedArrayBuffer).

Notes

Upon increasing the size, the previous ArrayBuffer is detached, thus invalidating any typed arrays which were views over the previous ArrayBuffer.
Detachment means that the previous ArrayBuffer byte length becomes zero, and it no longer has bytes accessible to JavaScript.
When calling grow, ArrayBuffer detachment applies even when delta is zero.
Detachment only applies for non-shared memory instances. For a shared memory instance, the initial buffer (which is a SharedArrayBuffer) will not become detached and, instead, its length will not be updated.
Accesses to the buffer property after growing a SharedArrayBuffer will yield a larger SharedArrayBuffer which may access a larger span of memory than the buffer before growing memory.
Every SharedArrayBuffer accessed via the buffer property will always refer to the start of the same memory address range and thus manipulate the same data.

Examples

var hasWebAssemblySupport = require( '@stdlib/assert/has-wasm-support' );
var DataView = require( '@stdlib/array/dataview' );
var Memory = require( '@stdlib/wasm/memory' );

function main() {
    var view;
    var mem;
    var v;
    if ( !hasWebAssemblySupport() ) {
        console.error( 'Environment does not support WebAssembly.' );
        return;
    }
    mem = new Memory({
        'initial': 1
    });
    view = new DataView( mem.buffer );

    view.setFloat64( 0, 3.14 );

    // ...

    v = view.getFloat64( 0 );
    console.log( v );
    // => 3.14
}

main();