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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)
}
}
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