fixedEndianFactory

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fixedEndianFactory

Return a typed array constructor for creating typed arrays having a specified byte order.

In contrast to built-in typed array constructors which store values according to the host platform byte order, the typed array constructors returned by the factory function allow enforcing a specific byte order. Such enforcement can be particularly advantageous when working with memory buffers which do not necessarily follow host platform byte order, such as WebAssembly memory.

Installation

npm install @stdlib/array-fixed-endian-factory

Alternatively,

To load the package in a website via a script tag without installation and bundlers, use the ES Module available on the esm branch (see README).
If you are using Deno, visit the deno branch (see README for usage intructions).
For use in Observable, or in browser/node environments, use the Universal Module Definition (UMD) build available on the umd branch (see README).

The branches.md file summarizes the available branches and displays a diagram illustrating their relationships.

To view installation and usage instructions specific to each branch build, be sure to explicitly navigate to the respective README files on each branch, as linked to above.

Usage

var fixedEndianFactory = require( '@stdlib/array-fixed-endian-factory' );

fixedEndianFactory( dtype )

Returns a typed array constructor for creating typed arrays having a specified data type and byte order.

var Float64ArrayFE = fixedEndianFactory( 'float64' );
// returns <Function>

var Float32ArrayFE = fixedEndianFactory( 'float32' );
// returns <Function>

Typed Array Constructor

TypedArrayFE( endianness )

A typed array constructor which returns a typed array representing values stored in a specified byte order.

var Float64ArrayFE = fixedEndianFactory( 'float64' );

var arr = new Float64ArrayFE( 'little-endian' );
// returns <Float64ArrayFE>

TypedArrayFE( endianness, length )

Returns a typed array having a specified length and byte order.

var Float64ArrayFE = fixedEndianFactory( 'float64' );

var arr = new Float64ArrayFE( 'little-endian', 5 );
// returns <Float64ArrayFE>

TypedArrayFE( endianness, typedarray )

Creates a typed array from another typed array.

var Float32Array = require( '@stdlib/array-float32' );

var Float64ArrayFE = fixedEndianFactory( 'float64' );

var arr1 = new Float32Array( [ 0.5, 0.5, 0.5 ] );
var arr2 = new Float64ArrayFE( 'little-endian', arr1 );
// returns <Float64ArrayFE>

var v = arr2.get( 0 );
// returns 0.5

TypedArrayFE( endianness, obj )

Creates a typed array from an array-like object or iterable.

var Float64ArrayFE = fixedEndianFactory( 'float64' );

var arr = new Float64ArrayFE( 'little-endian', [ 0.5, 0.5, 0.5 ] );
// returns <Float64ArrayFE>

var v = arr.get( 0 );
// returns 0.5

TypedArrayFE( endianness, buffer[, byteOffset[, length]] )

Returns a typed array view of an ArrayBuffer.

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

var Float64ArrayFE = fixedEndianFactory( 'float64' );

var buf = new ArrayBuffer( 32 );
var arr = new Float64ArrayFE( 'little-endian', buf, 0, 4 );
// returns <Float64ArrayFE>

Typed Array Properties

TypedArrayFE.BYTES_PER_ELEMENT

Number of bytes per view element.

var Float64ArrayFE = fixedEndianFactory( 'float64' );

var nbytes = Float64ArrayFE.BYTES_PER_ELEMENT;
// returns 8

TypedArrayFE.name

Typed array constructor name.

var Float64ArrayFE = fixedEndianFactory( 'float64' );

var str = Float64ArrayFE.name;
// returns 'Float64ArrayFE'

TypedArrayFE.prototype.buffer

Read-only property which returns the ArrayBuffer referenced by the typed array.

var Float64ArrayFE = fixedEndianFactory( 'float64' );

var arr = new Float64ArrayFE( 'little-endian', 5 );
var buf = arr.buffer;
// returns <ArrayBuffer>

TypedArrayFE.prototype.byteLength

Read-only property which returns the length (in bytes) of the typed array.

var Float64ArrayFE = fixedEndianFactory( 'float64' );

var arr = new Float64ArrayFE( 'little-endian', 5 );
var byteLength = arr.byteLength;
// returns 40

TypedArrayFE.prototype.byteOffset

Read-only property which returns the offset (in bytes) of the typed array from the start of its ArrayBuffer.

var Float64ArrayFE = fixedEndianFactory( 'float64' );

var arr = new Float64ArrayFE( 'little-endian', 5 );
var byteOffset = arr.byteOffset;
// returns 0

TypedArrayFE.prototype.BYTES_PER_ELEMENT

Number of bytes per view element.

var Float64ArrayFE = fixedEndianFactory( 'float64' );

var arr = new Float64ArrayFE( 'little-endian', 5 );
var nbytes = arr.BYTES_PER_ELEMENT;
// returns 8

TypedArrayFE.prototype.length

Read-only property which returns the number of view elements.

var Float64ArrayFE = fixedEndianFactory( 'float64' );

var arr = new Float64ArrayFE( 'little-endian', 5 );
var len = arr.length;
// returns 5

Typed Array Methods

TypedArrayFE.from( endianness, src[, map[, thisArg]] )

Creates a new typed array from an array-like object or an iterable.

var Float64ArrayFE = fixedEndianFactory( 'float64' );

var arr = Float64ArrayFE.from( 'little-endian', [ 1.0, -1.0 ] );
// returns <Float64ArrayFE>

var v = arr.get( 0 );
// returns 1.0

To invoke a function for each src value, provide a callback function.

function mapFcn( v ) {
    return v * 2.0;
}

var Float64ArrayFE = fixedEndianFactory( 'float64' );

var arr = Float64ArrayFE.from( 'little-endian', [ 1.0, -1.0 ], mapFcn );
// returns <Float64ArrayFE>

var v = arr.get( 0 );
// returns 2.0

A callback function is provided two arguments:

value: source value.
index: source index.

To set the callback execution context, provide a thisArg.

function mapFcn( v ) {
    this.count += 1;
    return v * 2.0;
}

var Float64ArrayFE = fixedEndianFactory( 'float64' );

var ctx = {
    'count': 0
};

var arr = Float64ArrayFE.from( 'little-endian', [ 1.0, -1.0 ], mapFcn, ctx );
// returns <Float64ArrayFE>

var v = arr.get( 0 );
// returns 2.0

var n = ctx.count;
// returns 2

TypedArrayFE.of( endianness, element0[, element1[, ...elementN]] )

Creates a new typed array from a variable number of arguments.

var Float64ArrayFE = fixedEndianFactory( 'float64' );

var arr = Float64ArrayFE.of( 'little-endian', 1.0, -1.0 );
// returns <Float64ArrayFE>

var v = arr.get( 0 );
// returns 1.0

TypedArrayFE.prototype.at( i )

Returns an array element located at integer position (index) i, with support for both nonnegative and negative integer positions.

var Float64ArrayFE = fixedEndianFactory( 'float64' );

var arr = new Float64ArrayFE( 'little-endian', [ 1.0, 2.0, 3.0 ] );
// returns <Float64ArrayFE>

var out = arr.at( 0 );
// returns 1.0

out = arr.at( -1 );
// returns 3.0

If provided an out-of-bounds index, the method returns undefined.

var Float64ArrayFE = fixedEndianFactory( 'float64' );

var arr = new Float64ArrayFE( 'little-endian', [ 1.0, 2.0, 3.0 ] );
// returns <Float64ArrayFE>

var v = arr.at( 100 );
// returns undefined

v = arr.at( -100 );
// returns undefined

TypedArrayFE.prototype.every( predicate[, thisArg] )

Tests whether all the elements in an array pass a test implemented by a predicate function.

function isNegative( v ) {
    return v < 0;
}

var Float64ArrayFE = fixedEndianFactory( 'float64' );

var arr = new Float64ArrayFE( 'little-endian', [ -1.0, -2.0, -3.0, -4.0 ] );
// returns <Float64ArrayFE>

var bool = arr.every( isNegative );
// returns true

The predicate function is provided three arguments:

value: current array element.
index: current array element index.
arr: the array on which this method was called.

To set the function execution context, provide a thisArg.

function isPositive( v, i ) {
    this.count += 1;
    return v > 0;
}

var Float64ArrayFE = fixedEndianFactory( 'float64' );

var arr = new Float64ArrayFE( 'little-endian', [ 1.0, 2.0, -3.0 ] );
// returns <Float64ArrayFE>

var context = {
    'count': 0
};

var bool = arr.every( isPositive, context );
// returns false

var count = context.count;
// returns 3

TypedArrayFE.prototype.forEach( callbackFn[, thisArg] )

Invokes a function once for each array element.

function log( v, i ) {
    console.log( '%s: %s', i.toString(), v.toString() );
}

var Float64ArrayFE = fixedEndianFactory( 'float64' );

var arr = new Float64ArrayFE( 'little-endian', 3 );
// returns <Float64ArrayFE>

arr.set( 1.5, 0 );
arr.set( 2.5, 1 );
arr.set( 3.5, 2 );

arr.forEach( log );
/* =>
    0: 1.5
    1: 2.5
    2: 3.5
*/

The invoked function is provided three arguments:

value: current array element.
index: current array element index.
arr: the array on which this method was called.

To set the function execution context, provide a thisArg.

function fcn( v, i ) {
    this.count += 1;
    console.log( '%s: %s', i.toString(), v.toString() );
}

var Float64ArrayFE = fixedEndianFactory( 'float64' );

var arr = new Float64ArrayFE( 'little-endian', 3 );
// returns <Float64ArrayFE>

var context = {
    'count': 0
};

arr.set( 1.0, 0 );
arr.set( 2.0, 1 );
arr.set( 3.0, 2 );

arr.forEach( fcn, context );

var count = context.count;
// returns 3

TypedArrayFE.prototype.get( i )

Returns an array element located at a nonnegative integer position (index) i.

var Float64ArrayFE = fixedEndianFactory( 'float64' );

var arr = new Float64ArrayFE( 'little-endian', 10 );
// returns <Float64ArrayFE>

// Set the first element:
arr.set( 1.0, 0 );

// Get the first element:
var v = arr.get( 0 );
// returns 1.0

If provided an out-of-bounds index, the method returns undefined.

var Float64ArrayFE = fixedEndianFactory( 'float64' );

var arr = new Float64ArrayFE( 'little-endian', 10 );
// returns <Float64ArrayFE>

var v = arr.get( 100 );
// returns undefined

TypedArrayFE.prototype.set( arr[, offset] )

Sets array elements.

var Float64ArrayFE = fixedEndianFactory( 'float64' );

var arr = new Float64ArrayFE( 'little-endian', [ 1.0, 2.0, 3.0 ] );
// returns <Float64ArrayFE>

var v = arr.get( 0 );
// returns 1.0

v = arr.get( 1 );
// returns 2.0

// Set the first two array elements:
arr.set( [ 4.0, 5.0 ] );

v = arr.get( 0 );
// returns 4.0

v = arr.get( 1 );
// returns 5.0

By default, the method starts writing values at the first array index. To specify an alternative index, provide an index offset.

var Float64ArrayFE = fixedEndianFactory( 'float64' );

var arr = new Float64ArrayFE( 'little-endian', [ 1.0, 2.0, 3.0 ] );
// returns <Float64ArrayFE>

// Set the last two array elements:
arr.set( [ 4.0, 5.0 ], 1 );

var v = arr.get( 1 );
// returns 4.0

v = arr.get( 2 );
// returns 5.0

A few notes:

If i is out-of-bounds, the method throws an error.
If a target array cannot accommodate all values (i.e., the length of source array plus i exceeds the target array length), the method throws an error.
If provided a typed array which shares an ArrayBuffer with the target array, the method will intelligently copy the source range to the destination range.

TypedArrayFE.prototype.some( predicate[, thisArg] )

Tests whether at least one element in an array passes a test implemented by a predicate function.

function isPositive( v ) {
    return v > 0;
}

var Float64ArrayFE = fixedEndianFactory( 'float64' );

var arr = new Float64ArrayFE( 'little-endian', [ -1.0, 2.0, -3.0, -4.0 ] );
// returns <Float64ArrayFE>

var bool = arr.some( isPositive );
// returns true

The predicate function is provided three arguments:

value: current array element.
index: current array element index.
arr: the array on which this method was called.

To set the function execution context, provide a thisArg.

function isPositive( v, i ) {
    this.count += 1;
    return v > 0;
}

var Float64ArrayFE = fixedEndianFactory( 'float64' );

var arr = new Float64ArrayFE( 'little-endian', [ -1.0, -2.0, -3.0 ] );
// returns <Float64ArrayFE>

var context = {
    'count': 0
};

var bool = arr.some( isPositive, context );
// returns false

var count = context.count;
// returns 3

TypedArrayFE.prototype.toString()

Serializes an array as a string.

var Float64ArrayFE = fixedEndianFactory( 'float64' );

var arr = new Float64ArrayFE( 'little-endian', [ 1.0, 2.0, 3.0 ] );
// returns <Float64ArrayFE>

var str = arr.toString();
// returns '1,2,3'

Notes

A returned constructor supports the following byte orders:
- little-endian: store values such that bytes are stored from least-to-most significant bytes. This is the dominant ordering for processor architectures and their associated memory. This is also the ordering for WebAssembly memory.
- big-endian: store values such that bytes are stored from most-to-least significant bytes. This is the dominant ordering in network protocols.
While returned constructors strive to maintain (but do not guarantee) consistency with typed arrays, significant deviations from ECMAScript-defined typed array behavior are as follows:
- Constructors do not require the new operator.
- Accessing array elements using bracket syntax (e.g., X[i]) is not supported. Instead, one must use the .get() method.

Examples

var Float64Array = require( '@stdlib/array-float64' );
var logEach = require( '@stdlib/console-log-each' );
var fixedEndianFactory = require( '@stdlib/array-fixed-endian-factory' );

var Float64ArrayFE = fixedEndianFactory( 'float64' );

// Create a typed array by specifying a length:
var out = new Float64ArrayFE( 'little-endian', 3 );
logEach( '%s', out );

// Create a typed array from an array:
var arr = [ 1.0, -1.0, -3.14, 3.14, 0.5, 0.5 ];
out = new Float64ArrayFE( 'big-endian', arr );
logEach( '%s', out );

// Create a typed array from an array buffer:
arr = new Float64Array( [ 1.0, -1.0, -3.14, 3.14, 0.5, 0.5 ] ); // host byte order
out = new Float64ArrayFE( 'little-endian', arr.buffer );
logEach( '%s', out );

// Create a typed array from an array buffer view:
arr = new Float64Array( [ 1.0, -1.0, -3.14, 3.14, 0.5, 0.5 ] ); // host byte order
out = new Float64ArrayFE( 'big-endian', arr.buffer, 8, 2 );
logEach( '%s', out );

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.

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stdlib-js/array-fixed-endian-factory

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fixedEndianFactory

Installation

Usage

fixedEndianFactory( dtype )

Typed Array Constructor

TypedArrayFE( endianness )

TypedArrayFE( endianness, length )

TypedArrayFE( endianness, typedarray )

TypedArrayFE( endianness, obj )

TypedArrayFE( endianness, buffer[, byteOffset[, length]] )

Typed Array Properties

TypedArrayFE.BYTES_PER_ELEMENT

TypedArrayFE.name

TypedArrayFE.prototype.buffer

TypedArrayFE.prototype.byteLength

TypedArrayFE.prototype.byteOffset

TypedArrayFE.prototype.BYTES_PER_ELEMENT

TypedArrayFE.prototype.length

Typed Array Methods

TypedArrayFE.from( endianness, src[, map[, thisArg]] )

TypedArrayFE.of( endianness, element0[, element1[, ...elementN]] )

TypedArrayFE.prototype.at( i )

TypedArrayFE.prototype.every( predicate[, thisArg] )

TypedArrayFE.prototype.forEach( callbackFn[, thisArg] )

TypedArrayFE.prototype.get( i )

TypedArrayFE.prototype.set( arr[, offset] )

TypedArrayFE.prototype.some( predicate[, thisArg] )

TypedArrayFE.prototype.toString()

Notes

Examples

Notice

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