main.js (2027B)
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 // FUNCTIONS // 22 23 /** 24 * Generates a stride array from an array shape (row-major). 25 * 26 * @private 27 * @param {NonNegativeIntegerArray} shape - array shape 28 * @returns {Array} array strides 29 */ 30 function rowmajor( shape ) { 31 var ndims; 32 var out; 33 var s; 34 var i; 35 36 ndims = shape.length; 37 out = []; 38 for ( i = 0; i < ndims; i++ ) { 39 out.push( 0 ); 40 } 41 s = 1; 42 for ( i = ndims-1; i >= 0; i-- ) { 43 out[ i ] = s; 44 s *= shape[ i ]; 45 } 46 return out; 47 } 48 49 /** 50 * Generates a stride array from an array shape (column-major). 51 * 52 * @private 53 * @param {NonNegativeIntegerArray} shape - array shape 54 * @returns {Array} array strides 55 */ 56 function columnmajor( shape ) { 57 var out; 58 var s; 59 var i; 60 61 out = []; 62 s = 1; 63 for ( i = 0; i < shape.length; i++ ) { 64 out.push( s ); 65 s *= shape[ i ]; 66 } 67 return out; 68 } 69 70 71 // MAIN // 72 73 /** 74 * Generates a stride array from an array shape. 75 * 76 * @param {NonNegativeIntegerArray} shape - array shape 77 * @param {string} order - specifies whether an array is row-major (C-style) or column-major (Fortran-style) 78 * @returns {Array} array strides 79 * 80 * @example 81 * var s = shape2strides( [ 3, 2 ], 'row-major' ); 82 * // returns [ 2, 1 ] 83 * 84 * s = shape2strides( [ 3, 2 ], 'column-major' ); 85 * // returns [ 1, 3 ] 86 */ 87 function shape2strides( shape, order ) { 88 if ( order === 'column-major' ) { 89 return columnmajor( shape ); 90 } 91 return rowmajor( shape ); 92 } 93 94 95 // EXPORTS // 96 97 module.exports = shape2strides;