@stdlib/strided
Version:
Strided.
282 lines (253 loc) • 9.12 kB
JavaScript
/**
* @license Apache-2.0
*
* Copyright (c) 2024 The Stdlib Authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/* eslint-disable max-len */
;
// MODULES //
var isComplex128Array = require( '@stdlib/array/base/assert/is-complex128array' );
var isComplex64Array = require( '@stdlib/array/base/assert/is-complex64array' );
var isBooleanArray = require( '@stdlib/array/base/assert/is-booleanarray' );
var arraylike2object = require( '@stdlib/array/base/arraylike2object' );
var reinterpret128 = require( './../../../base/reinterpret-complex128' );
var reinterpret64 = require( './../../../base/reinterpret-complex64' );
var reinterpretBoolean = require( './../../../base/reinterpret-boolean' );
var bytesPerElement = require( '@stdlib/ndarray/base/bytes-per-element' );
// VARIABLES //
var METHOD_TABLE = {
'float64': 'getFloat64',
'float32': 'getFloat32',
'float16': 'getFloat16',
'int64': 'getBigInt64',
'int32': 'getInt32',
'int16': 'getInt16',
'int8': 'getInt8',
'uint64': 'getBigUint64',
'uint32': 'getUint32',
'uint16': 'getUint16',
'uint8': 'getUint8'
};
// FUNCTIONS //
/**
* Copies elements from an input strided DataView to elements in a strided indexed array.
*
* @private
* @param {string} dtype - output array data type
* @param {NonNegativeInteger} N - number of indexed elements
* @param {DataView} view - input DataView
* @param {integer} strideView - `view` stride length (in bytes)
* @param {NonNegativeInteger} offsetView - starting `view` index (in bytes)
* @param {Object} out - output array object
* @param {integer} strideOut - `out` stride length
* @param {NonNegativeInteger} offsetOut - starting `out` index
* @param {boolean} littleEndian - boolean indicating whether the data is stored in little-endian format
* @returns {void}
*
* @example
* var Float64Array = require( '@stdlib/array/float64' );
* var DataView = require( '@stdlib/array/dataview' );
* var arraylike2object = require( '@stdlib/array/base/arraylike2object' );
*
* var x = new Float64Array( [ 1.0, 2.0, 3.0, 4.0 ] );
* var view = new DataView( x.buffer );
*
* var y = new Float64Array( x.length );
*
* indexed( 'float64', x.length, view, 8, 0, arraylike2object( y ), 1, 0, true );
* // e.g., y => <Float64Array>[ 1.0, 2.0, 3.0, 4.0 ]
*/
function indexed( dtype, N, view, strideView, offsetView, out, strideOut, offsetOut, littleEndian ) {
var data;
var io;
var iv;
var m;
var i;
m = METHOD_TABLE[ dtype ];
data = out.data;
io = offsetOut;
iv = offsetView;
for ( i = 0; i < N; i++ ) {
data[ io ] = view[ m ]( iv, littleEndian );
io += strideOut;
iv += strideView;
}
}
/**
* Copies elements from an input strided DataView to elements in a strided complex array.
*
* @private
* @param {string} dtype - output array data type
* @param {NonNegativeInteger} N - number of indexed elements
* @param {DataView} view - input DataView
* @param {integer} strideView - `view` stride length (in bytes)
* @param {NonNegativeInteger} offsetView - starting `view` index (in bytes)
* @param {Collection} out - output array object
* @param {integer} strideOut - `out` stride length
* @param {NonNegativeInteger} offsetOut - starting `out` index
* @param {boolean} littleEndian - boolean indicating whether the data is stored in little-endian format
* @returns {void}
*
* @example
* var Float64Array = require( '@stdlib/array/float64' );
* var DataView = require( '@stdlib/array/dataview' );
* var arraylike2object = require( '@stdlib/array/base/arraylike2object' );
*
* var x = new Float64Array( [ 1.0, 2.0, 3.0, 4.0 ] );
* var view = new DataView( x.buffer );
*
* var y = new Float64Array( x.length );
*
* complex( 'float64', 2, view, 8, 0, arraylike2object( y ), 1, 0, true );
* // e.g., y => <Float64Array>[ 1.0, 2.0, 3.0, 4.0 ]
*/
function complex( dtype, N, view, strideView, offsetView, out, strideOut, offsetOut, littleEndian ) {
var nbytes;
var data;
var io;
var iv;
var m;
var i;
m = METHOD_TABLE[ dtype ];
nbytes = bytesPerElement( dtype );
data = out.data;
// Adjust meta data to account for interleaved real and imaginary components:
strideOut *= 2;
offsetOut *= 2;
io = offsetOut;
iv = offsetView;
for ( i = 0; i < N; i++ ) {
data[ io ] = view[ m ]( iv, littleEndian );
data[ io+1 ] = view[ m ]( iv+nbytes, littleEndian );
io += strideOut;
iv += strideView;
}
}
/**
* Copies elements from an input strided DataView to elements in a strided accessor array.
*
* @private
* @param {string} dtype - output array data type
* @param {NonNegativeInteger} N - number of indexed elements
* @param {DataView} view - input DataView
* @param {integer} strideView - `view` stride length (in bytes)
* @param {NonNegativeInteger} offsetView - starting `view` index (in bytes)
* @param {Object} out - output array object
* @param {integer} strideOut - `out` stride length
* @param {NonNegativeInteger} offsetOut - starting `out` index
* @param {boolean} littleEndian - boolean indicating whether the data is stored in little-endian format
* @returns {void}
*
* @example
* var toAccessorArray = require( '@stdlib/array/base/to-accessor-array' );
* var arraylike2object = require( '@stdlib/array/base/arraylike2object' );
* var Float64Array = require( '@stdlib/array/float64' );
* var DataView = require( '@stdlib/array/dataview' );
*
* var x = new Float64Array( [ 1.0, 2.0, 3.0, 4.0 ] );
* var view = new DataView( x.buffer );
*
* var y = new Float64Array( x.length );
*
* accessors( 'float64', x.length, view, 8, 0, arraylike2object( toAccessorArray( y ) ), 1, 0, true );
* // e.g., y => <Float64Array>[ 1.0, 2.0, 3.0, 4.0 ]
*/
function accessors( dtype, N, view, strideView, offsetView, out, strideOut, offsetOut, littleEndian ) {
var data;
var set;
var io;
var iv;
var m;
var i;
m = METHOD_TABLE[ dtype ];
data = out.data;
set = out.accessors[ 1 ];
io = offsetOut;
iv = offsetView;
for ( i = 0; i < N; i++ ) {
set( data, io, view[ m ]( iv, littleEndian ) );
io += strideOut;
iv += strideView;
}
return view;
}
// MAIN //
/**
* Copies elements from an input strided DataView to elements in an output strided array.
*
* @param {NonNegativeInteger} N - number of indexed elements
* @param {DataView} view - input DataView
* @param {integer} strideView - `view` stride length (in bytes)
* @param {NonNegativeInteger} offsetView - starting `view` index (in bytes)
* @param {Collection} out - output array
* @param {integer} strideOut - `out` stride length
* @param {NonNegativeInteger} offsetOut - starting `out` index
* @param {boolean} littleEndian - boolean indicating whether the data is stored in little-endian format
* @returns {Collection} output array
*
* @example
* var Float64Array = require( '@stdlib/array/float64' );
* var DataView = require( '@stdlib/array/dataview' );
*
* var x = new Float64Array( [ 1.0, 2.0, 3.0, 4.0 ] );
* var view = new DataView( x.buffer );
*
* var y = new Float64Array( x.length );
* var out = readDataView( x.length, view, 8, 0, y, 1, 0, true );
* // e.g., returns <Float64Array>[ 1.0, 2.0, 3.0, 4.0 ]
*
* var bool = ( out === y );
* // returns true
*/
function readDataView( N, view, strideView, offsetView, out, strideOut, offsetOut, littleEndian ) {
var obj;
var dt;
if ( N <= 0 ) {
return out;
}
obj = arraylike2object( out );
if ( obj.accessorProtocol ) {
// If provided a complex number array, reinterpret as a real typed array of interleaved real and imaginary components...
if ( isComplex128Array( out ) ) {
obj.data = reinterpret128( out, 0 );
complex( 'float64', N, view, strideView, offsetView, obj, strideOut, offsetOut, littleEndian );
return out;
}
if ( isComplex64Array( out ) ) {
obj.data = reinterpret64( out, 0 );
complex( 'float32', N, view, strideView, offsetView, obj, strideOut, offsetOut, littleEndian );
return out;
}
// If provided a boolean array, reinterpret as typed array of integers...
if ( isBooleanArray( out ) ) {
obj.data = reinterpretBoolean( out, 0 );
indexed( 'uint8', N, view, strideView, offsetView, obj, strideOut, offsetOut, littleEndian );
return out;
}
// If provided a "generic" accessor array, assume double-precision floating-point numbers...
accessors( 'float64', N, view, strideView, offsetView, obj, strideOut, offsetOut, littleEndian );
return out;
}
if ( obj.dtype === null || obj.dtype === 'generic' ) {
// If provided a "generic" array, assume double-precision floating-point numbers...
dt = 'float64';
} else {
dt = obj.dtype;
}
indexed( dt, N, view, strideView, offsetView, obj, strideOut, offsetOut, littleEndian );
return out;
}
// EXPORTS //
module.exports = readDataView;