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//
// Copyright 2020-2022 Sean C Foley
//
// 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 ipaddr
import "math/bits"
func getCoveringPrefixBlock(
first,
other ExtendedIPSegmentSeries) ExtendedIPSegmentSeries {
result := checkPrefixBlockContainment(first, other)
if result != nil {
return result
}
return applyOperatorToLowerUpper(first, other, false, coverWithPrefixBlockWrapped)[0]
}
func coverWithPrefixBlockWrapped(
lower,
upper ExtendedIPSegmentSeries) []ExtendedIPSegmentSeries {
return []ExtendedIPSegmentSeries{coverWithPrefixBlock(lower, upper)}
}
func coverWithPrefixBlock(
lower,
upper ExtendedIPSegmentSeries) ExtendedIPSegmentSeries {
segCount := lower.GetSegmentCount()
bitsPerSegment := lower.GetBitsPerSegment()
var currentSegment int
var previousSegmentBits BitCount
for ; currentSegment < segCount; currentSegment++ {
lowerSeg := lower.GetGenericSegment(currentSegment)
upperSeg := upper.GetGenericSegment(currentSegment)
var lowerValue, upperValue SegInt
lowerValue = lowerSeg.GetSegmentValue() //these are single addresses, so lower or upper value no different here
upperValue = upperSeg.GetSegmentValue()
differing := lowerValue ^ upperValue
if differing != 0 {
highestDifferingBitInRange := BitCount(bits.LeadingZeros32(differing)) - (SegIntSize - bitsPerSegment)
differingBitPrefixLen := highestDifferingBitInRange + previousSegmentBits
return lower.ToPrefixBlockLen(differingBitPrefixLen)
}
previousSegmentBits += bitsPerSegment
}
//all bits match, it's just a single address
return lower.ToPrefixBlockLen(lower.GetBitCount())
}
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