Trait constriction::BitArray

source ·

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

    const BITS: usize = _;

    // Provided methods
    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 stream::Code::Word);
to represent probabilities in fixed point arithmetic (see stream::model::EntropyModel::Probability); and
the internal state of entropy coders (see stream::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.