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roundup2.go
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roundup2.go
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// Copyright 2016 The Cockroach 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.
package util
// RoundUpPowerOfTwo returns the first power of 2 greater or equal to the number.
// Source: http://graphics.stanford.edu/%7Eseander/bithacks.html#RoundUpPowerOf2
func RoundUpPowerOfTwo(x int64) int64 {
x--
x |= x >> 1
x |= x >> 2
x |= x >> 4
x |= x >> 8
x |= x >> 16
x |= x >> 32
return x + 1
}