CODE LSHIFT ( n u -- n )
    BC POP, ( u )
    HL POP, ( n )
    chkPS,
    B C LDrr,
    B INCr, B DECr, IFNZ,
        BEGIN,
            L SLA, H RL,
        DJNZ, AGAIN,
    THEN,
    HL PUSH,
;CODE