init

pub fn init(init_s: u64) Isaac64 {
    var isaac = Isaac64{
        .r = undefined,
        .m = undefined,
        .a = undefined,
        .b = undefined,
        .c = undefined,
        .i = undefined,
    };

    // seed == 0 => same result as the unseeded reference implementation
    isaac.seed(init_s, 1);
    return isaac;
}