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* @license Apache-2.0
*
* Copyright (c) 2025 The Stdlib Authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
'use strict';
// MODULES //
var isnanf = require( '@stdlib/math/base/assert/is-nanf' );
var isInfinitef = require( '@stdlib/math/base/assert/is-infinitef' );
var normalize = require( '@stdlib/number/float32/base/normalize' ).assign;
var floatExp = require( '@stdlib/number/float32/base/exponent' );
var toWordf = require( '@stdlib/number/float32/base/to-word' );
var fromWordf = require( '@stdlib/number/float32/base/from-word' );
var f32 = require( '@stdlib/number/float64/base/to-float32' );
// VARIABLES //
// Exponent all 0s: 1 00000000 11111111111111111111111 => 2155872255
var CLEAR_EXP_MASK = 0x807fffff>>>0; // asm type annotation
// Exponent equal to 126 (BIAS-1): 0 01111110 00000000000000000000000 => 1056964608
var SET_EXP_MASK = 0x3f000000|0; // asm type annotation
// Normalization workspace:
var X = [ 0.0, 0.0 ]; // WARNING: not thread safe
// MAIN //
/**
* Splits a single-precision floating-point number into a normalized fraction and an integer power of two and assigns results to a provided output array.
*
* @private
* @param {number} x - input value
* @param {Collection} out - output array
* @param {integer} stride - output array stride
* @param {NonNegativeInteger} offset - output array index offset
* @returns {Collection} output array
*
* @example
* var out = frexpf( 4.0, [ 0.0, 0 ], 1, 0 );
* // returns [ 0.5, 3 ]
*
* @example
* var out = frexpf( 0.0, [ 0.0, 0 ], 1, 0 );
* // returns [ 0.0, 0 ]
*
* @example
* var out = frexpf( -0.0, [ 0.0, 0 ], 1, 0 );
* // returns [ -0.0, 0 ]
*
* @example
* var out = frexpf( NaN, [ 0.0, 0 ], 1, 0 );
* // returns [ NaN, 0 ]
*
* @example
* var out = frexpf( Infinity, [ 0.0, 0 ], 1, 0 );
* // returns [ Infinity , 0 ]
*
* @example
* var out = frexpf( -Infinity, [ 0.0, 0 ], 1, 0 );
* // returns [ -Infinity , 0 ]
*/
function frexpf( x, out, stride, offset ) {
var word;
var exp;
x = f32( x );
if (
x === 0.0 || // handles -0
isnanf( x ) ||
isInfinitef( x )
) {
out[ offset ] = x;
out[ offset + stride ] = 0;
return out;
}
// If `x` is subnormal, normalize it...
normalize( x, X, 1, 0 );
// Extract the exponent from `x` and add the normalization exponent:
exp = floatExp( X[0] ) + X[ 1 ] + 1;
// Convert the normalized floating-point number to an unsigned 32-bit integer:
word = toWordf( X[ 0 ] );
// Clear the exponent bits within the word:
word &= CLEAR_EXP_MASK;
// Set the exponent bits within the word to BIAS-1 (127-1=126):
word |= SET_EXP_MASK;
// Create a new floating-point number:
x = fromWordf( word );
out[ offset ] = x;
out[ offset + stride ] = exp;
return out;
}
// EXPORTS //
module.exports = frexpf;
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