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use ::{ U, S, L };
use ::rot_const::*;


pub fn norx(state: &mut [U; S]) {
    for _ in 0..L {
        f(state);
    }
}

/// The full round
pub fn f(state: &mut [U; S]) {
    macro_rules! G {
        ( $a:expr, $b:expr, $c:expr, $d:expr ) => {
            let (a, b, c, d) = g($a, $b, $c, $d);
            $a = a; $b = b; $c = c; $d = d;
        }
    }

    // Column step
    G!(state[ 0], state[ 4], state[ 8], state[12]);
    G!(state[ 1], state[ 5], state[ 9], state[13]);
    G!(state[ 2], state[ 6], state[10], state[14]);
    G!(state[ 3], state[ 7], state[11], state[15]);
    // Diagonal step
    G!(state[ 0], state[ 5], state[10], state[15]);
    G!(state[ 1], state[ 6], state[11], state[12]);
    G!(state[ 2], state[ 7], state[ 8], state[13]);
    G!(state[ 3], state[ 4], state[ 9], state[14]);
}

/// The nonlinear primitive
#[inline]
fn h(a: U, b: U) -> U {
    (a ^ b) ^ ((a & b) << 1)
}

/// The quarter-round
#[inline]
fn g(mut a: U, mut b: U, mut c: U, mut d: U) -> (U, U, U, U) {
    a = h(a, b); d ^= a; d = d.rotate_right(R0);
    c = h(c, d); b ^= c; b = b.rotate_right(R1);
    a = h(a, b); d ^= a; d = d.rotate_right(R2);
    c = h(c, d); b ^= c; b = b.rotate_right(R3);
    (a, b, c, d)
}