create_table.js (1476B)
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 // MODULES // 22 23 var isnan = require( '@stdlib/math/base/assert/is-nan' ); 24 25 26 // VARIABLES // 27 28 var NUM_WARMUPS = 8; 29 30 31 // MAIN // 32 33 /** 34 * Initializes a shuffle table. 35 * 36 * @private 37 * @param {PRNG} rand - pseudorandom number generator 38 * @param {Int32Array} table - table 39 * @param {PositiveInteger} N - table size 40 * @throws {Error} PRNG returned `NaN` 41 * @returns {NumberArray} shuffle table 42 */ 43 function createTable( rand, table, N ) { 44 var v; 45 var i; 46 47 // "warm-up" the PRNG... 48 for ( i = 0; i < NUM_WARMUPS; i++ ) { 49 v = rand(); 50 51 // Prevent the above loop from being discarded by the compiler... 52 if ( isnan( v ) ) { 53 throw new Error( 'unexpected error. PRNG returned `NaN`.' ); 54 } 55 } 56 // Initialize the shuffle table... 57 for ( i = N-1; i >= 0; i-- ) { 58 table[ i ] = rand(); 59 } 60 return table; 61 } 62 63 64 // EXPORTS // 65 66 module.exports = createTable;