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pub trait BitLength {
type Output;
/// Returns bit length of a number.
///
/// ```
/// use traiter::numbers::BitLength;
/// // signed integers
/// assert_eq!(BitLength::bit_length(-1i8), 1usize);
/// assert_eq!(BitLength::bit_length(0i8), 0usize);
/// assert_eq!(BitLength::bit_length(1i8), 1usize);
/// // unsigned integers
/// assert_eq!(BitLength::bit_length(0u8), 0usize);
/// assert_eq!(BitLength::bit_length(1u8), 1usize);
/// assert_eq!(BitLength::bit_length(2u8), 2usize);
/// ```
fn bit_length(self) -> Self::Output;
}
macro_rules! signed_integer_bit_length_impl {
($($integer:ty)*) => ($(
impl BitLength for $integer {
type Output = usize;
#[inline(always)]
fn bit_length(self) -> Self::Output {
(<$integer>::BITS as usize)
- (self.abs().leading_zeros() as usize)
}
}
)*)
}
signed_integer_bit_length_impl!(i8 i16 i32 i64 i128 isize);
macro_rules! unsigned_integer_bit_length_impl {
($($integer:ty)*) => ($(
impl BitLength for $integer {
type Output = usize;
#[inline(always)]
fn bit_length(self) -> Self::Output {
(<$integer>::BITS as usize) - (self.leading_zeros() as usize)
}
}
)*)
}
unsigned_integer_bit_length_impl!(u8 u16 u32 u64 u128 usize);