time-to-botec

Benchmark sampling in different programming languages
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main.js (3157B)

      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 Uint32Array = require( '@stdlib/array/uint32' );
     24 var Float64Array = require( '@stdlib/array/float64' );
     25 var indices = require( './indices.js' );
     26 
     27 
     28 // VARIABLES //
     29 
     30 var FLOAT64_VIEW = new Float64Array( 1 );
     31 var UINT32_VIEW = new Uint32Array( FLOAT64_VIEW.buffer );
     32 
     33 var HIGH = indices.HIGH;
     34 var LOW = indices.LOW;
     35 
     36 
     37 // MAIN //
     38 
     39 /**
     40 * Creates a double-precision floating-point number from a higher order word (unsigned 32-bit integer) and a lower order word (unsigned 32-bit integer).
     41 *
     42 * ## Notes
     43 *
     44 * ```text
     45 * float64 (64 bits)
     46 * f := fraction (significand/mantissa) (52 bits)
     47 * e := exponent (11 bits)
     48 * s := sign bit (1 bit)
     49 *
     50 * |-------- -------- -------- -------- -------- -------- -------- --------|
     51 * |                                Float64                                |
     52 * |-------- -------- -------- -------- -------- -------- -------- --------|
     53 * |              Uint32               |               Uint32              |
     54 * |-------- -------- -------- -------- -------- -------- -------- --------|
     55 * ```
     56 *
     57 * If little endian (more significant bits last):
     58 *
     59 * ```text
     60 *                         <-- lower      higher -->
     61 * |   f7       f6       f5       f4       f3       f2    e2 | f1 |s|  e1  |
     62 * ```
     63 *
     64 * If big endian (more significant bits first):
     65 *
     66 * ```text
     67 *                         <-- higher      lower -->
     68 * |s| e1    e2 | f1     f2       f3       f4       f5        f6      f7   |
     69 * ```
     70 *
     71 *
     72 * In which Uint32 should we place the higher order bits? If little endian, the second; if big endian, the first.
     73 *
     74 *
     75 * ## References
     76 *
     77 * -   [Open Group][1]
     78 *
     79 * [1]: http://pubs.opengroup.org/onlinepubs/9629399/chap14.htm
     80 *
     81 * @param {uinteger32} high - higher order word (unsigned 32-bit integer)
     82 * @param {uinteger32} low - lower order word (unsigned 32-bit integer)
     83 * @returns {number} floating-point number
     84 *
     85 * @example
     86 * var v = fromWords( 1774486211, 2479577218 );
     87 * // returns 3.14e201
     88 *
     89 * @example
     90 * var v = fromWords( 3221823995, 1413754136 );
     91 * // returns -3.141592653589793
     92 *
     93 * @example
     94 * var v = fromWords( 0, 0 );
     95 * // returns 0.0
     96 *
     97 * @example
     98 * var v = fromWords( 2147483648, 0 );
     99 * // returns -0.0
    100 *
    101 * @example
    102 * var v = fromWords( 2146959360, 0 );
    103 * // returns NaN
    104 *
    105 * @example
    106 * var v = fromWords( 2146435072, 0 );
    107 * // returns Infinity
    108 *
    109 * @example
    110 * var v = fromWords( 4293918720, 0 );
    111 * // returns -Infinity
    112 */
    113 function fromWords( high, low ) {
    114 	UINT32_VIEW[ HIGH ] = high;
    115 	UINT32_VIEW[ LOW ] = low;
    116 	return FLOAT64_VIEW[ 0 ];
    117 }
    118 
    119 
    120 // EXPORTS //
    121 
    122 module.exports = fromWords;