Rotate operand1 left. The number of rotates is set by operand2.
shift all bits left, the bit that goes off is set to
CF and the same bit is inserted to the right-most position.
MOV AL, 1Ch ; AL = 00011100b
ROL AL, 1 ; AL = 00111000b, CF=0.
OF=0 if first operand keeps original sign.