dcopy.js (2172B)
1 /** 2 * @license Apache-2.0 3 * 4 * Copyright (c) 2018 The Stdlib Authors. 5 * 6 * Licensed under the Apache License, Version 2.0 (the "License"); 7 * you may not use this file except in compliance with the License. 8 * You may obtain a copy of the License at 9 * 10 * http://www.apache.org/licenses/LICENSE-2.0 11 * 12 * Unless required by applicable law or agreed to in writing, software 13 * distributed under the License is distributed on an "AS IS" BASIS, 14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 15 * See the License for the specific language governing permissions and 16 * limitations under the License. 17 */ 18 19 'use strict'; 20 21 // VARIABLES // 22 23 var M = 8; 24 25 26 // MAIN // 27 28 /** 29 * Copies values from `x` into `y`. 30 * 31 * @param {PositiveInteger} N - number of values to copy 32 * @param {Float64Array} x - input array 33 * @param {integer} strideX - `x` stride length 34 * @param {Float64Array} y - destination array 35 * @param {integer} strideY - `y` stride length 36 * @returns {Float64Array} `y` 37 * 38 * @example 39 * var Float64Array = require( '@stdlib/array/float64' ); 40 * 41 * var x = new Float64Array( [ 1.0, 2.0, 3.0, 4.0, 5.0 ] ); 42 * var y = new Float64Array( [ 6.0, 7.0, 8.0, 9.0, 10.0 ] ); 43 * 44 * dcopy( x.length, x, 1, y, 1 ); 45 * // y => <Float64Array>[ 1.0, 2.0, 3.0, 4.0, 5.0 ] 46 */ 47 function dcopy( N, x, strideX, y, strideY ) { 48 var ix; 49 var iy; 50 var m; 51 var i; 52 if ( N <= 0 ) { 53 return y; 54 } 55 // Use unrolled loops if both strides are equal to `1`... 56 if ( strideX === 1 && strideY === 1 ) { 57 m = N % M; 58 59 // If we have a remainder, run a clean-up loop... 60 if ( m > 0 ) { 61 for ( i = 0; i < m; i++ ) { 62 y[ i ] = x[ i ]; 63 } 64 } 65 if ( N < M ) { 66 return y; 67 } 68 for ( i = m; i < N; i += M ) { 69 y[ i ] = x[ i ]; 70 y[ i+1 ] = x[ i+1 ]; 71 y[ i+2 ] = x[ i+2 ]; 72 y[ i+3 ] = x[ i+3 ]; 73 y[ i+4 ] = x[ i+4 ]; 74 y[ i+5 ] = x[ i+5 ]; 75 y[ i+6 ] = x[ i+6 ]; 76 y[ i+7 ] = x[ i+7 ]; 77 } 78 return y; 79 } 80 if ( strideX < 0 ) { 81 ix = (1-N) * strideX; 82 } else { 83 ix = 0; 84 } 85 if ( strideY < 0 ) { 86 iy = (1-N) * strideY; 87 } else { 88 iy = 0; 89 } 90 for ( i = 0; i < N; i++ ) { 91 y[ iy ] = x[ ix ]; 92 ix += strideX; 93 iy += strideY; 94 } 95 return y; 96 } 97 98 99 // EXPORTS // 100 101 module.exports = dcopy;