time-to-botec

4d_accessors.js (5564B)

---

 /**
 * @license Apache-2.0
 *
 * Copyright (c) 2021 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.
 */
 
 'use strict';
 
 // MAIN //
 
 /**
 * Applies a unary callback to elements in a four-dimensional input ndarray and assigns results to elements in an equivalently shaped output ndarray.
 *
 * @private
 * @param {Object} x - object containing input ndarray meta data
 * @param {string} x.dtype - data type
 * @param {Collection} x.data - data buffer
 * @param {NonNegativeIntegerArray} x.shape - dimensions
 * @param {IntegerArray} x.strides - stride lengths
 * @param {NonNegativeInteger} x.offset - index offset
 * @param {string} x.order - specifies whether `x` is row-major (C-style) or column-major (Fortran-style)
 * @param {Function} x.getter - callback for accessing `x` data buffer elements
 * @param {Object} y - object containing output ndarray meta data
 * @param {string} y.dtype - data type
 * @param {Collection} y.data - data buffer
 * @param {NonNegativeIntegerArray} y.shape - dimensions
 * @param {IntegerArray} y.strides - stride lengths
 * @param {NonNegativeInteger} y.offset - index offset
 * @param {string} y.order - specifies whether `y` is row-major (C-style) or column-major (Fortran-style)
 * @param {Function} y.setter - callback for setting `y` data buffer elements
 * @param {Callback} fcn - unary callback
 * @returns {void}
 *
 * @example
 * var Complex64Array = require( '@stdlib/array/complex64' );
 * var Complex64 = require( '@stdlib/complex/float32' );
 * var real = require( '@stdlib/complex/real' );
 * var imag = require( '@stdlib/complex/imag' );
 *
 * function scale( z ) {
 *     return new Complex64( real(z)*10.0, imag(z)*10.0 );
 * }
 *
 * // Create data buffers:
 * var xbuf = new Complex64Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0 ] );
 * var ybuf = new Complex64Array( 4 );
 *
 * // Define the shape of the input and output arrays:
 * var shape = [ 1, 1, 2, 2 ];
 *
 * // Define the array strides:
 * var sx = [ 2, 2, 2, 1 ];
 * var sy = [ 2, 2, 2, 1 ];
 *
 * // Define the index offsets:
 * var ox = 0;
 * var oy = 0;
 *
 * // Define getters and setters:
 * function getter( buf, idx ) {
 *     return buf.get( idx );
 * }
 *
 * function setter( buf, idx, value ) {
 *     buf.set( value, idx );
 * }
 *
 * // Create the input and output ndarray-like objects:
 * var x = {
 *     'dtype': 'complex64',
 *     'data': xbuf,
 *     'shape': shape,
 *     'strides': sx,
 *     'offset': ox,
 *     'order': 'row-major',
 *     'getter': getter
 * };
 * var y = {
 *     'dtype': 'complex64',
 *     'data': ybuf,
 *     'shape': shape,
 *     'strides': sy,
 *     'offset': oy,
 *     'order': 'row-major',
 *     'setter': setter
 * };
 *
 * // Apply the unary function:
 * unary4d( x, y, scale );
 *
 * var v = y.data.get( 0 );
 *
 * var re = real( v );
 * // returns 10.0
 *
 * var im = imag( v );
 * // returns 20.0
 */
 function unary4d( x, y, fcn ) {
 	var xbuf;
 	var ybuf;
 	var get;
 	var set;
 	var dx0;
 	var dx1;
 	var dx2;
 	var dx3;
 	var dy0;
 	var dy1;
 	var dy2;
 	var dy3;
 	var sh;
 	var S0;
 	var S1;
 	var S2;
 	var S3;
 	var sx;
 	var sy;
 	var ix;
 	var iy;
 	var i0;
 	var i1;
 	var i2;
 	var i3;
 
 	// Note on variable naming convention: S#, dx#, dy#, i# where # corresponds to the loop number, with `0` being the innermost loop...
 
 	// Extract loop variables for purposes of loop interchange: dimensions and loop offset (pointer) increments...
 	sh = x.shape;
 	sx = x.strides;
 	sy = y.strides;
 	if ( x.order === 'row-major' ) {
 		// For row-major ndarrays, the last dimensions have the fastest changing indices...
 		S0 = sh[ 3 ];
 		S1 = sh[ 2 ];
 		S2 = sh[ 1 ];
 		S3 = sh[ 0 ];
 		dx0 = sx[ 3 ];                // offset increment for innermost loop
 		dx1 = sx[ 2 ] - ( S0*sx[3] );
 		dx2 = sx[ 1 ] - ( S1*sx[2] );
 		dx3 = sx[ 0 ] - ( S2*sx[1] ); // offset increment for outermost loop
 		dy0 = sy[ 3 ];
 		dy1 = sy[ 2 ] - ( S0*sy[3] );
 		dy2 = sy[ 1 ] - ( S1*sy[2] );
 		dy3 = sy[ 0 ] - ( S2*sy[1] );
 	} else { // order === 'column-major'
 		// For column-major ndarrays, the first dimensions have the fastest changing indices...
 		S0 = sh[ 0 ];
 		S1 = sh[ 1 ];
 		S2 = sh[ 2 ];
 		S3 = sh[ 3 ];
 		dx0 = sx[ 0 ];                // offset increment for innermost loop
 		dx1 = sx[ 1 ] - ( S0*sx[0] );
 		dx2 = sx[ 2 ] - ( S1*sx[1] );
 		dx3 = sx[ 3 ] - ( S2*sx[2] ); // offset increment for outermost loop
 		dy0 = sy[ 0 ];
 		dy1 = sy[ 1 ] - ( S0*sy[0] );
 		dy2 = sy[ 2 ] - ( S1*sy[1] );
 		dy3 = sy[ 3 ] - ( S2*sy[2] );
 	}
 	// Set the pointers to the first indexed elements in the respective ndarrays...
 	ix = x.offset;
 	iy = y.offset;
 
 	// Cache references to the input and output ndarray buffers...
 	xbuf = x.data;
 	ybuf = y.data;
 
 	// Cache accessors:
 	get = x.getter;
 	set = y.setter;
 
 	// Iterate over the ndarray dimensions...
 	for ( i3 = 0; i3 < S3; i3++ ) {
 		for ( i2 = 0; i2 < S2; i2++ ) {
 			for ( i1 = 0; i1 < S1; i1++ ) {
 				for ( i0 = 0; i0 < S0; i0++ ) {
 					set( ybuf, iy, fcn( get( xbuf, ix ) ) );
 					ix += dx0;
 					iy += dy0;
 				}
 				ix += dx1;
 				iy += dy1;
 			}
 			ix += dx2;
 			iy += dy2;
 		}
 		ix += dx3;
 		iy += dy3;
 	}
 }
 
 
 // EXPORTS //
 
 module.exports = unary4d;