40 lines
1.2 KiB
Go
40 lines
1.2 KiB
Go
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// Copyright 2018 Google Inc. All rights reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// +build go1.9
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package s2
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// This file is for the bit manipulation code post-Go 1.9.
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import "math/bits"
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// findMSBSetNonZero64 returns the index (between 0 and 63) of the most
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// significant set bit. Passing zero to this function return zero.
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func findMSBSetNonZero64(x uint64) int {
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if x == 0 {
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return 0
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}
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return 63 - bits.LeadingZeros64(x)
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}
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// findLSBSetNonZero64 returns the index (between 0 and 63) of the least
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// significant set bit. Passing zero to this function return zero.
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func findLSBSetNonZero64(x uint64) int {
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if x == 0 {
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return 0
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}
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return bits.TrailingZeros64(x)
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}
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