1 // Copyright 2018 The gVisor Authors.
2 //
3 // Licensed under the Apache License, Version 2.0 (the "License");
4 // you may not use this file except in compliance with the License.
5 // You may obtain a copy of the License at
6 //
7 // http://www.apache.org/licenses/LICENSE-2.0
8 //
9 // Unless required by applicable law or agreed to in writing, software
10 // distributed under the License is distributed on an "AS IS" BASIS,
11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 // See the License for the specific language governing permissions and
13 // limitations under the License.
14 15 //go:build amd64 || arm64
16 // +build amd64 arm64
17 18 package bits
19 20 // TrailingZeros64 returns the number of bits before the least significant 1
21 // bit in x; in other words, it returns the index of the least significant 1
22 // bit in x. If x is 0, TrailingZeros64 returns 64.
23 func TrailingZeros64(x uint64) int
24 25 // MostSignificantOne64 returns the index of the most significant 1 bit in
26 // x. If x is 0, MostSignificantOne64 returns 64.
27 func MostSignificantOne64(x uint64) int
28 29 // ForEachSetBit64 calls f once for each set bit in x, with argument i equal to
30 // the set bit's index.
31 func ForEachSetBit64(x uint64, f func(i int)) {
32 for x != 0 {
33 i := TrailingZeros64(x)
34 f(i)
35 x &^= MaskOf64(i)
36 }
37 }
38