time-to-botec

Benchmark sampling in different programming languages
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modf.js (3932B)

      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( './../../../../base/assert/is-nan' );
     24 var toWords = require( '@stdlib/number/float64/base/to-words' );
     25 var fromWords = require( '@stdlib/number/float64/base/from-words' );
     26 var PINF = require( '@stdlib/constants/float64/pinf' );
     27 var FLOAT64_EXPONENT_BIAS = require( '@stdlib/constants/float64/exponent-bias' );
     28 var FLOAT64_HIGH_WORD_EXPONENT_MASK = require( '@stdlib/constants/float64/high-word-exponent-mask' ); // eslint-disable-line id-length
     29 var FLOAT64_HIGH_WORD_SIGNIFICAND_MASK = require( '@stdlib/constants/float64/high-word-significand-mask' ); // eslint-disable-line id-length
     30 
     31 
     32 // VARIABLES //
     33 
     34 // 4294967295 => 0xffffffff => 11111111111111111111111111111111
     35 var ALL_ONES = 4294967295>>>0; // asm type annotation
     36 
     37 // High/low words workspace:
     38 var WORDS = [ 0|0, 0|0 ]; // WARNING: not thread safe
     39 
     40 
     41 // MAIN //
     42 
     43 /**
     44 * Decomposes a double-precision floating-point number into integral and fractional parts, each having the same type and sign as the input value.
     45 *
     46 * @private
     47 * @param {(Array|TypedArray|Object)} out - output array
     48 * @param {number} x - input value
     49 * @returns {(Array|TypedArray|Object)} output array
     50 *
     51 * @example
     52 * var parts = modf( [ 0.0, 0.0 ], 3.14 );
     53 * // returns [ 3.0, 0.14000000000000012 ]
     54 */
     55 function modf( out, x ) {
     56 	var high;
     57 	var low;
     58 	var exp;
     59 	var i;
     60 
     61 	// Special cases...
     62 	if ( x < 1.0 ) {
     63 		if ( x < 0.0 ) {
     64 			modf( out, -x );
     65 			out[ 0 ] *= -1.0;
     66 			out[ 1 ] *= -1.0;
     67 			return out;
     68 		}
     69 		if ( x === 0.0 ) { // [ +-0, +-0 ]
     70 			out[ 0 ] = x;
     71 			out[ 1 ] = x;
     72 			return out;
     73 		}
     74 		out[ 0 ] = 0.0;
     75 		out[ 1 ] = x;
     76 		return out;
     77 	}
     78 	if ( isnan( x ) ) {
     79 		out[ 0 ] = NaN;
     80 		out[ 1 ] = NaN;
     81 		return out;
     82 	}
     83 	if ( x === PINF ) {
     84 		out[ 0 ] = PINF;
     85 		out[ 1 ] = 0.0;
     86 		return out;
     87 	}
     88 	// Decompose |x|...
     89 
     90 	// Extract the high and low words:
     91 	toWords( WORDS, x );
     92 	high = WORDS[ 0 ];
     93 	low = WORDS[ 1 ];
     94 
     95 	// Extract the unbiased exponent from the high word:
     96 	exp = ((high & FLOAT64_HIGH_WORD_EXPONENT_MASK) >> 20)|0; // asm type annotation
     97 	exp -= FLOAT64_EXPONENT_BIAS|0; // asm type annotation
     98 
     99 	// Handle smaller values (x < 2**20 = 1048576)...
    100 	if ( exp < 20 ) {
    101 		i = (FLOAT64_HIGH_WORD_SIGNIFICAND_MASK >> exp)|0; // asm type annotation
    102 
    103 		// Determine if `x` is integral by checking for significand bits which cannot be exponentiated away...
    104 		if ( ((high&i)|low) === 0 ) {
    105 			out[ 0 ] = x;
    106 			out[ 1 ] = 0.0;
    107 			return out;
    108 		}
    109 		// Turn off all the bits which cannot be exponentiated away:
    110 		high &= (~i);
    111 
    112 		// Generate the integral part:
    113 		i = fromWords( high, 0 );
    114 
    115 		// The fractional part is whatever is leftover:
    116 		out[ 0 ] = i;
    117 		out[ 1 ] = x - i;
    118 		return out;
    119 	}
    120 	// Check if `x` can even have a fractional part...
    121 	if ( exp > 51 ) {
    122 		// `x` is integral:
    123 		out[ 0 ] = x;
    124 		out[ 1 ] = 0.0;
    125 		return out;
    126 	}
    127 	i = ALL_ONES >>> (exp-20);
    128 
    129 	// Determine if `x` is integral by checking for less significant significand bits which cannot be exponentiated away...
    130 	if ( (low&i) === 0 ) {
    131 		out[ 0 ] = x;
    132 		out[ 1 ] = 0.0;
    133 		return out;
    134 	}
    135 	// Turn off all the bits which cannot be exponentiated away:
    136 	low &= (~i);
    137 
    138 	// Generate the integral part:
    139 	i = fromWords( high, low );
    140 
    141 	// The fractional part is whatever is leftover:
    142 	out[ 0 ] = i;
    143 	out[ 1 ] = x - i;
    144 	return out;
    145 }
    146 
    147 
    148 // EXPORTS //
    149 
    150 module.exports = modf;