writeDataView

Usage

var writeDataView = require( '@stdlib/strided/base/write-dataview' );

writeDataView( N, x, strideX, view, strideView, littleEndian )

Copies elements from an input strided array to elements in a strided DataView.

var ArrayBuffer = require( '@stdlib/array/buffer' );
var DataView = require( '@stdlib/array/dataview' );

var x = [ 1.0, 2.0, 3.0, 4.0 ];

var buf = new ArrayBuffer( 32 );
var view = new DataView( buf );

var out = writeDataView( 4, x, 1, view, 8, true );
// returns <DataView>

var bool = ( out === view );
// returns true

var v = view.getFloat64( 0, true );
// returns 1.0

v = view.getFloat64( 8, true );
// returns 2.0

The function accepts the following arguments:

• N: number of indexed elements.
• x: input strided array.
• strideX: index increment for x.
• view: output DataView.
• strideView: index increment (in bytes) for view.
• littleEndian: boolean indicating whether to store values in little-endian format.

The N and stride parameters determine which elements in x and view are accessed at runtime. For example, to index every other value in x and to index the first N elements of view in reverse order,

var ArrayBuffer = require( '@stdlib/array/buffer' );
var DataView = require( '@stdlib/array/dataview' );

var x = [ 1.0, 0.0, 2.0, 0.0, 3.0, 0.0, 4.0, 0.0 ];

var buf = new ArrayBuffer( 64 );
var view = new DataView( buf );

var out = writeDataView( 4, x, 2, view, -8, true );
// returns <DataView>

var bool = ( out === view );
// returns true

var v = view.getFloat64( 0, true );
// returns 4.0

v = view.getFloat64( 8, true );
// returns 3.0

Note that indexing is relative to the first index. To introduce an offset, use typed array views.

var ArrayBuffer = require( '@stdlib/array/buffer' );
var DataView = require( '@stdlib/array/dataview' );
var Float32Array = require( '@stdlib/array/float32' );

// Initial array:
var x0 = new Float32Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 ] );

// Create an offset view:
var x1 = new Float32Array( x0.buffer, x0.BYTES_PER_ELEMENT*1 ); // start at 2nd element

// Create an output DataView:
var buf = new ArrayBuffer( 64 );
var view = new DataView( buf );

var out = writeDataView( 4, x1, 1, view, 8, true );
// returns <DataView>

var bool = ( out === view );
// returns true

var v = view.getFloat32( 0, true );
// returns 2.0

v = view.getFloat32( 8, true );
// returns 3.0

writeDataView.ndarray( N, x, strideX, offsetX, view, strideView, offsetView, littleEndian )

Copies elements from an input strided array to elements in a strided DataView using alternative indexing semantics.

var ArrayBuffer = require( '@stdlib/array/buffer' );
var DataView = require( '@stdlib/array/dataview' );

var x = [ 1.0, 2.0, 3.0, 4.0 ];

var buf = new ArrayBuffer( 32 );
var view = new DataView( buf );

var out = writeDataView.ndarray( 4, x, 1, 0, view, 8, 0, true );
// returns <DataView>

var bool = ( out === view );
// returns true

var v = view.getFloat64( 0, true );
// returns 1.0

The function accepts the following additional arguments:

• offsetX: starting index for x.
• offsetView: starting index (in bytes) for view.

While typed array views mandate a view offset based on the underlying buffer, the offset parameters support indexing semantics based on starting indices. For example, to index every other value in x starting from the second value and to index the last N elements in view in reverse order,

var ArrayBuffer = require( '@stdlib/array/buffer' );
var DataView = require( '@stdlib/array/dataview' );

var x = [ 0.0, 1.0, 0.0, 2.0, 0.0, 3.0, 0.0, 4.0 ];

var buf = new ArrayBuffer( 64 );
var view = new DataView( buf );

var out = writeDataView.ndarray( 4, x, 2, 1, view, -8, 56, true );
// returns <DataView>

var bool = ( out === view );
// returns true

var v = view.getFloat64( 32, true );
// returns 4.0

v = view.getFloat64( 40, true );
// returns 3.0