monix.execution.internal.math.scala Maven / Gradle / Ivy
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/*
* Copyright (c) 2014-2019 by The Monix Project Developers.
* See the project homepage at: https://monix.io
*
* 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.
*/
package monix.execution.internal
import scala.math.{ceil, round}
private[monix] object math {
/** Natural log of 2 */
val lnOf2 = scala.math.log(2)
/**
* Calculates the base 2 logarithm of the given argument.
*
* @return a number such that 2^nr^ is equal to our argument.
*/
def log2(x: Double): Double = {
scala.math.log(x) / lnOf2
}
/**
* Given a positive integer, rounds it to the nearest power of two.
* Note that the maximum that this function can
* return is 2^30^ (or 1,073,741,824).
*
* @return an integer that is a power of 2 and that is "closest"
* to the given argument.
*/
def roundToPowerOf2(nr: Int): Int = {
require(nr >= 0, "nr must be positive")
val bit = round(log2(nr))
1 << (if (bit > 30) 30 else bit.toInt)
}
/**
* Given a long, rounds it to the nearest power of two.
* Note that the maximum that this function can
* return is 2^62^ (or 4,611,686,018,427,387,904).
*
* @return a long that is a power of 2 and that is "closest"
* to the given argument.
*/
def roundToPowerOf2(nr: Long) = {
require(nr >= 0, "nr must be positive")
val bit = round(log2(nr))
1L << (if (bit > 62) 62 else bit.toInt)
}
/**
* Given a positive integer, returns the next power of 2 that is bigger
* than our argument, or the maximum that this function can
* return which is 2^30^ (or 1,073,741,824).
*
* @return an integer that is a power of 2, that is bigger or
* equal with our argument and that is "closest" to it.
*/
def nextPowerOf2(nr: Int): Int = {
require(nr >= 0, "nr must be positive")
val bit = ceil(log2(nr))
1 << (if (bit > 30) 30 else bit.toInt)
}
/**
* Given a positive long, returns the next power of 2 that is bigger
* than our argument, or the maximum that this function can
* return which is 2^62^ (or 4,611,686,018,427,387,904).
*
* @return a long that is a power of 2 and that is "closest"
* to the given argument.
*/
def nextPowerOf2(nr: Long) = {
require(nr >= 0, "nr must be positive")
val bit = ceil(log2(nr))
1L << (if (bit > 62) 62 else bit.toInt)
}
}