mirror of
https://github.com/go-gitea/gitea
synced 2024-12-27 02:54:27 +00:00
37 lines
461 B
Go
37 lines
461 B
Go
|
// +build !go1.9
|
||
|
|
|
||
|
|
package roaring
|
||
|
|
|
||
|
|
// LeadingZeroBits returns the number of consecutive most significant zero
|
||
|
|
// bits of x.
|
||
|
|
func countLeadingZeros(i uint64) int {
|
||
|
|
if i == 0 {
|
||
|
|
return 64
|
||
|
|
}
|
||
|
|
n := 1
|
||
|
|
x := uint32(i >> 32)
|
||
|
|
if x == 0 {
|
||
|
|
n += 32
|
||
|
|
x = uint32(i)
|
||
|
|
}
|
||
|
|
if (x >> 16) == 0 {
|
||
|
|
n += 16
|
||
|
|
x <<= 16
|
||
|
|
}
|
||
|
|
if (x >> 24) == 0 {
|
||
|
|
n += 8
|
||
|
|
x <<= 8
|
||
|
|
}
|
||
|
|
if x>>28 == 0 {
|
||
|
|
n += 4
|
||
|
|
x <<= 4
|
||
|
|
}
|
||
|
|
if x>>30 == 0 {
|
||
|
|
n += 2
|
||
|
|
x <<= 2
|
||
|
|
|
||
|
|
}
|
||
|
|
n -= int(x >> 31)
|
||
|
|
return n
|
||
|
|
}
|