nshcat / bitmatch

A Rust crate that allows you to match, bind, and pack the individual bits of integers.

Bitmatch

The bitmatch crate provides tools for packing and unpacking integers as sequences of bits.

Examples

Using #[bitmatch] with a let unpacks the bits into separate single-character variables for each letter you use.

Using bitpack!() re-packs the bits from those single-character variables into a single integer.

use bitmatch::bitmatch;

#[bitmatch]
fn interleave(n: u8) -> u8 {
    #[bitmatch]
    let "xxxx_yyyy" = n;
    bitpack!("xyxy_xyxy")
}

fn main() {
    assert_eq!(interleave(0xF0), 0xAA);
}

You can use #[bitmatch] on a match as well, and it will ensure that the literal portions match, and bind the variable portions.

use bitmatch::bitmatch;
#[bitmatch]
fn decode(inst: u8) -> String {
    #[bitmatch]
    match inst {
        "00oo_aabb" => format!("Op {}, {}, {}", o, a, b),
        "0100_aaii" => format!("Val {}, {}", a, i),
        "01??_????" => format!("Invalid"),
        "10ii_aabb" => format!("Ld {}, {}, {}", a, b, i),
        "11ii_aabb" => format!("St {}, {}, {}", a, b, i),
    }
}