fn swap_e(cpu: &mut Cpu) {
        let e = cpu.e();

        let r = swap(cpu, e);

        cpu.set_e(r);
    }
/// Swap low and high nibbles of `E`
Swap low and high nibbles of `E`
Swap low and high nibbles of ` E `
fn swap_e(cpu: &mut Cpu) {
        let e = cpu.e();
        let r = swap(cpu, e);
        cpu.set_e(r);
    }
fn swap_e ( cpu : & mut Cpu ) { let e = cpu . e ( ) ; let r = swap ( cpu , e ) ; cpu . set_e ( r ) ; }
Swap low and high nibbles of `E`
Swap low and high nibbles of ` E `
cpu
&mut Cpu
cpu
&mut Cpu