fn coef()

in src/dp.rs [39:79]

• 41 lines of code
• 1 McCabe index (conditional complexity)

fn coef(msg: &[u8], index: usize, bitlength: usize) -> u8 {
    match bitlength {
        8 => msg[index],
        4 => {
            let ix = index / 2;
            let byte = msg[ix];
            match index % 2 {
                0 => byte >> 4,
                1 => byte & 0xf,
                _ => unreachable!(),
            }
        }
        2 => {
            let ix = index / 4;
            let byte = msg[ix];
            match index % 4 {
                0 => byte >> 6,
                1 => (byte >> 4) & 0x3,
                2 => (byte >> 2) & 0x3,
                3 => byte & 0x3,
                _ => unreachable!(),
            }
        }
        1 => {
            let ix = index / 8;
            let byte = msg[ix];
            match index % 8 {
                0 => byte >> 7,
                1 => (byte >> 6) & 0x1,
                2 => (byte >> 5) & 0x1,
                3 => (byte >> 4) & 0x1,
                4 => (byte >> 3) & 0x1,
                5 => (byte >> 2) & 0x1,
                6 => (byte >> 1) & 0x1,
                7 => byte & 0x1,
                _ => unreachable!(),
            }
        }
        _ => unimplemented!(),
    }
}