Trait constriction::BitArray[−][src]

pub unsafe trait BitArray: PrimInt + Unsigned + WrappingAdd + WrappingSub + LowerHex + UpperHex + Binary + Default + Copy + Display + Debug + Eq + Hash + 'static {
    type NonZero: NonZeroBitArray<Base = Self>;

    const BITS: usize;
    fn into_nonzero(self) -> Option<Self::NonZero> { ... }

    unsafe fn into_nonzero_unchecked(self) -> Self::NonZero { ... }
}
Expand description

A trait for bit strings of fixed (and usually small) length.

Short fixed-length bit strings are fundamental building blocks of efficient entropy coding algorithms. They are currently used for the following purposes:

  • to represent the smallest unit of compressed data (see [Code::Word]);
  • to represent probabilities in fixed point arithmetic (see [EntropyModel::Probability]); and
  • the internal state of entropy coders (see [Code::State]) is typically comprised of one or more BitArrays, although this is not a requirement.

This trait is implemented on all primitive unsigned integer types. It is not recommended to implement this trait for custom types since coders will assume, for performance considerations, that BitArrays can be represented and manipulated efficiently in hardware.

Safety

This trait is marked unsafe so that entropy coders may rely on the assumption that all BitArrays have precisely the same behavior as builtin unsigned integer types, and that BitArray::BITS has the correct value.

Associated Types

type NonZero: NonZeroBitArray<Base = Self>[src]

Associated Constants

const BITS: usize[src]

Expand description

The (fixed) length of the BitArray in bits.

Defaults to 8 * core::mem::size_of::<Self>(), which is suitable for all primitive unsigned integers.

This could arguably be called LEN instead, but that may be confusing since “lengths” are typically not measured in bits in the Rust ecosystem.

Provided methods

fn into_nonzero(self) -> Option<Self::NonZero>[src]

unsafe fn into_nonzero_unchecked(self) -> Self::NonZero[src]

Expand description

Safety

The provided value must be nonzero.

Implementations on Foreign Types

impl BitArray for u8[src]

type NonZero = NonZeroU8

impl BitArray for u16[src]

type NonZero = NonZeroU16

impl BitArray for u32[src]

type NonZero = NonZeroU32

impl BitArray for u64[src]

type NonZero = NonZeroU64

impl BitArray for u128[src]

type NonZero = NonZeroU128

impl BitArray for usize[src]

type NonZero = NonZeroUsize

Implementors