Struct swar::Bits8

pub struct Bits8<N>(pub N);

This is used when every 8 bits is a number stored in parallel.

Methods

impl Bits8<u128>

pub fn from_element(e: u128) -> Self

Spread a single value out to each element. Must be able to fit.

use swar::*;

assert_eq!(Bits8::from_element(0xFE), Bits8(0xFEFE_FEFE_FEFE_FEFE_FEFE_FEFE_FEFE_FEFE));

pub fn union(left: Bits16<u128>, right: Bits16<u128>) -> Self

Takes two inputs that have half-sized elements and compresses them into half the space and puts them in the left and right sides of this.

use swar::*;

let input = Bits8(0xFEED_FACE_CAFE_BEEF_FEED_FACE_CAFE_BEEF);
let (left, right) = input.halve();
let output = Bits8::union(left, right);
assert_eq!(input, output);

pub fn sum_weight(self) -> u128

pub fn sum_weight2(self) -> Bits16<u128>

pub fn hwd(self, other: Self) -> Self

This computes the hamming weight distance from hamming weights.

use swar::*;

let bits = 8;
for a in 0u128..=bits as u128 {
    for b in 0u128..=bits as u128 {
        let aa = Bits8(a | a << bits);
        let bb = Bits8(b | b << bits);
        let out = aa.hwd(bb);
        let diff = (a as i128 - b as i128).abs() as u128;
        let expected = Bits8(diff | diff << bits);
        assert_eq!(out, expected, "got hamming distances {:016b} expected {:016b} ({:08b}, {:08b})", out.0, expected.0, a, b);
    }
}

pub fn split(self) -> (Bits16<u128>, Bits16<u128>)

pub fn halve(self) -> (Bits16<u128>, Bits16<u128>)

Takes the left and right sides and spreads them out so that the bits in each element are spread out into twice the amount of space.

use swar::*;

let input = Bits8(0xABCD << 64 | 0xDEAD);
let (left, right) = input.halve();
assert_eq!(left, Bits16(0x00AB_00CD));
assert_eq!(right, Bits16(0x00DE_00AD));

Trait Implementations

impl<N: Copy> Copy for Bits8<N>

impl<N: Debug> Debug for Bits8<N>

fn fmt(&self, f: &mut Formatter) -> Result

Formats the value using the given formatter.

impl<N: PartialEq> PartialEq<Bits8<N>> for Bits8<N>

fn eq(&self, other: &Bits8<N>) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Bits8<N>) -> bool

This method tests for !=.

impl<N: Eq> Eq for Bits8<N>

impl Add<Bits8<u128>> for Bits8<u128>

Note that you are responsible for dealing with overflow. Try to avoid overflow or use the split() method to add in two halves. You can use split() on the result to get the carry bits.

type Output = Self

The resulting type after applying the + operator.

fn add(self, rhs: Self) -> Self

Performs the + operation.

impl BitAnd<u128> for Bits8<u128>

type Output = Self

The resulting type after applying the & operator.

fn bitand(self, rhs: u128) -> Self

Performs the & operation.

impl Shr<u32> for Bits8<u128>

type Output = Self

The resulting type after applying the >> operator.

fn shr(self, rhs: u32) -> Self

Performs the >> operation.

impl<N: Clone> Clone for Bits8<N>

fn clone(&self) -> Bits8<N>

Returns a copy of the value.

default fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.