Problem 6 : Program Analysis

• Analyze the following program.

  ; ========= Data Section ========== MessageZero db 'Zero ','$' MessageOne db 'One ' ,'$' ; ========= Code Section ========== ... MOV CL, 0 MOV AL, 3 SLoop: MOV AH, 1 SHL AH, CL AND AH, AL JZ zip MOV DX, offset MessageOne JMP done zip: MOV DX, offset MessageZero JMP done done: CALL dspmsg INC CL CMP CL, 4 JB SLoop ...

• How many times is the procedure dspmsg called ?
  (i.e., how many times do we pass the SLoop: and Done: labels) (4 pts)

• What are the binary values of AH just after each SHL AH, CL command ? (4 pts)
• Show the output of the program.
  (i.e., what messages are displayed on the screen ?) (8 pts)

• Describe (in one or two sentances) what the program is doing. (4 pts)