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* @license Apache-2.0
*
* Copyright (c) 2018 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';
// MAIN //
/**
* Computes an absolute value of a signed 32-bit integer in two's complement format.
*
* ## Method
*
* - Assume two's complement format.
* - Create a mask by applying a sign propagating right-shift. For negative integers, this results in all `1`'s. For nonnegative integers, this results in all `0`'s.
* - XOR the mask with `x`. For negative integers, this is the equivalent of a NOT. For nonnegative integers, this is a no-op.
* - Subtract the mask to recover the absolute value. For negative integers, this adds `1`, which is `-x` when using two's complement. For nonnegative integers, this subtracts `0`.
*
* @param {integer32} x - integer
* @returns {integer32} absolute value
*
* @example
* var v = labs( -10|0 );
* // returns 10
*/
function labs( x ) {
var mask;
var y;
y = x|0; // asm type annotation
mask = ( y >> 31 )|0; // asm type annotation
return ((y ^ mask) - mask)|0; // asm type annotation
}
// EXPORTS //
module.exports = labs;
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