PowerOf2.cs

/* Copyright 2010-present MongoDB Inc.
*
* 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.
*/

usingSystem;

namespaceMongoDB.Bson
{
internalstaticclassPowerOf2
{
publicstaticboolIsPowerOf2(intn)
{
if(n<0||n>0x40000000)
{
thrownewArgumentOutOfRangeException(nameof(n));
}

varresult=(n&(n-1))==0;
returnresult;
}

publicstaticintRoundUpToPowerOf2(intn)
{
if(IsPowerOf2(n))
{
returnn;
}

// see: Hacker's Delight, by Henry S. Warren
n=n-1;
n=n|(n>>1);
n=n|(n>>2);
n=n|(n>>4);
n=n|(n>>8);
n=n|(n>>16);
returnn+1;
}
}
}