@stdlib/buffer-from-arraybuffer
v0.2.2
Published
Allocate a buffer from an ArrayBuffer.
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arraybuffer2buffer
Allocate a buffer from an ArrayBuffer.
Installation
npm install @stdlib/buffer-from-arraybuffer
Usage
var arraybuffer2buffer = require( '@stdlib/buffer-from-arraybuffer' );
arraybuffer2buffer( buf[, byteOffset[, length]] )
Allocates a buffer from an ArrayBuffer
.
var ArrayBuffer = require( '@stdlib/array-buffer' );
var ab = new ArrayBuffer( 10 );
var buf = arraybuffer2buffer( ab );
// returns <Buffer>
By default, the function allocates a buffer starting from the first byte of the provided ArrayBuffer
. To specify an alternative starting index, provide a byteOffset
.
var ArrayBuffer = require( '@stdlib/array-buffer' );
var ab = new ArrayBuffer( 10 );
var buf = arraybuffer2buffer( ab, 2 );
// returns <Buffer>
var len = buf.length;
// returns 8
By default, the function allocates a buffer until the end of the provided ArrayBuffer
. To allocate a specified number of ArrayBuffer
bytes, provide a length
.
var ArrayBuffer = require( '@stdlib/array-buffer' );
var ab = new ArrayBuffer( 10 );
var buf = arraybuffer2buffer( ab, 2, 4 );
// returns <Buffer>
var len = buf.length;
// returns 4
Notes
The behavior of this function varies across Node.js versions due to changes in the underlying Node.js APIs:
<3.0.0
: the function copiesArrayBuffer
bytes to a newBuffer
instance.>=3.0.0
and<5.10.0
: if provided abyteOffset
, the function copiesArrayBuffer
bytes to a newBuffer
instance; otherwise, the function returns a view of anArrayBuffer
without copying the underlying memory.<6.0.0
: if provided an emptyArrayBuffer
, the function returns an emptyBuffer
which is not anArrayBuffer
view.>=6.0.0
: the function returns a view of anArrayBuffer
without copying the underlying memory.
Examples
var ArrayBuffer = require( '@stdlib/array-buffer' );
var Float64Array = require( '@stdlib/array-float64' );
var randu = require( '@stdlib/random-base-randu' );
var IS_LITTLE_ENDIAN = require( '@stdlib/assert-is-little-endian' );
var arraybuffer2buffer = require( '@stdlib/buffer-from-arraybuffer' );
var high;
var view;
var low;
var buf;
var ab;
var i;
// Allocate an ArrayBuffer:
ab = new ArrayBuffer( 64 );
// Create a Float64 view and set random values:
view = new Float64Array( ab );
for ( i = 0; i < view.length; i++ ) {
view[ i ] = randu();
}
// Create a new buffer from the ArrayBuffer:
buf = arraybuffer2buffer( ab );
// Read the high and low words for each double:
for ( i = 0; i < view.length; i++ ) {
if ( IS_LITTLE_ENDIAN ) {
high = buf.readUInt32LE( (8*i)+4 );
low = buf.readUInt32LE( 8*i );
} else {
high = buf.readUInt32BE( 8*i );
low = buf.readUInt32BE( (8*i)+4 );
}
console.log( 'Value: %d. High: %d. Low: %d.', view[ i ], high, low );
}
See Also
@stdlib/buffer-ctor
: Buffer.@stdlib/buffer-from-array
: allocate a buffer using an octet array.@stdlib/buffer-from-buffer
: copy buffer data to a new Buffer instance.@stdlib/buffer-from-string
: allocate a buffer containing a provided string.
Notice
This package is part of stdlib, a standard library for JavaScript and Node.js, with an emphasis on numerical and scientific computing. The library provides a collection of robust, high performance libraries for mathematics, statistics, streams, utilities, and more.
For more information on the project, filing bug reports and feature requests, and guidance on how to develop stdlib, see the main project repository.
Community
License
See LICENSE.
Copyright
Copyright © 2016-2024. The Stdlib Authors.