time-to-botec

Benchmark sampling in different programming languages
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main.js (2522B)

      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 HIGH = require( './high.js' );
     26 
     27 
     28 // VARIABLES //
     29 
     30 var FLOAT64_VIEW = new Float64Array( 1 );
     31 var UINT32_VIEW = new Uint32Array( FLOAT64_VIEW.buffer );
     32 
     33 
     34 // MAIN //
     35 
     36 /**
     37 * Returns an unsigned 32-bit integer corresponding to the more significant 32 bits of a double-precision floating-point number.
     38 *
     39 * ## Notes
     40 *
     41 * ```text
     42 * float64 (64 bits)
     43 * f := fraction (significand/mantissa) (52 bits)
     44 * e := exponent (11 bits)
     45 * s := sign bit (1 bit)
     46 *
     47 * |-------- -------- -------- -------- -------- -------- -------- --------|
     48 * |                                Float64                                |
     49 * |-------- -------- -------- -------- -------- -------- -------- --------|
     50 * |              Uint32               |               Uint32              |
     51 * |-------- -------- -------- -------- -------- -------- -------- --------|
     52 * ```
     53 *
     54 * If little endian (more significant bits last):
     55 *
     56 * ```text
     57 *                         <-- lower      higher -->
     58 * |   f7       f6       f5       f4       f3       f2    e2 | f1 |s|  e1  |
     59 * ```
     60 *
     61 * If big endian (more significant bits first):
     62 *
     63 * ```text
     64 *                         <-- higher      lower -->
     65 * |s| e1    e2 | f1     f2       f3       f4       f5        f6      f7   |
     66 * ```
     67 *
     68 * In which Uint32 can we find the higher order bits? If little endian, the second; if big endian, the first.
     69 *
     70 *
     71 * ## References
     72 *
     73 * -   [Open Group][1]
     74 *
     75 * [1]: http://pubs.opengroup.org/onlinepubs/9629399/chap14.htm
     76 *
     77 * @param {number} x - input value
     78 * @returns {uinteger32} higher order word
     79 *
     80 * @example
     81 * var w = getHighWord( 3.14e201 ); // => 01101001110001001000001011000011
     82 * // returns 1774486211
     83 */
     84 function getHighWord( x ) {
     85 	FLOAT64_VIEW[ 0 ] = x;
     86 	return UINT32_VIEW[ HIGH ];
     87 }
     88 
     89 
     90 // EXPORTS //
     91 
     92 module.exports = getHighWord;