mirror of
https://github.com/superseriousbusiness/gotosocial.git
synced 2024-11-02 07:20:00 +00:00
33 lines
687 B
Go
33 lines
687 B
Go
|
package puddle
|
||
|
|
|
||
|
|
import "unsafe"
|
||
|
|
|
||
|
|
type ints interface {
|
||
|
|
int | int8 | int16 | int32 | int64 | uint | uint8 | uint16 | uint32 | uint64
|
||
|
|
}
|
||
|
|
|
||
|
|
// log2Int returns log2 of an integer. This function panics if val < 0. For val
|
||
|
|
// == 0, returns 0.
|
||
|
|
func log2Int[T ints](val T) uint8 {
|
||
|
|
if val <= 0 {
|
||
|
|
panic("log2 of non-positive number does not exist")
|
||
|
|
}
|
||
|
|
|
||
|
|
return log2IntRange(val, 0, uint8(8*unsafe.Sizeof(val)))
|
||
|
|
}
|
||
|
|
|
||
|
|
func log2IntRange[T ints](val T, begin, end uint8) uint8 {
|
||
|
|
length := end - begin
|
||
|
|
if length == 1 {
|
||
|
|
return begin
|
||
|
|
}
|
||
|
|
|
||
|
|
delim := begin + length/2
|
||
|
|
mask := T(1) << delim
|
||
|
|
if mask > val {
|
||
|
|
return log2IntRange(val, begin, delim)
|
||
|
|
} else {
|
||
|
|
return log2IntRange(val, delim, end)
|
||
|
|
}
|
||
|
|
}
|