1. Lecture 5 Presented By Dr. Shazzad Hosain Asst. Prof. EECS, NSU

2. Agenda Logic Instructions – AND, OR, XOR and NOT TEST Instruction Shift and Rotate Instructions Stack Operations Introduction to Procedures

3. AND, OR and XOR Instructions AND destination, source OR destination, source XOR destination, source Memory-to-memory operations are not allowed Effect on flags – SF, ZF, PF reflect the result – AF is undefined – CF, OF = 0

4. Use of Logic Instructions Selectively modify the bits of destination – b AND 1 = b(b represents a bit, 0/1) – b AND 0 = 0 – b OR 0 = b – b OR 1 = 1 – b XOR 0 = b – b XOR 1 = ~b (complement of b) So, AND cab be used to clear specific destination bit OR can be used to set specific destination bit XOR can be used to complement specific destination bit

5. Examples Example 7.2: Clear the sign bit of AL while leaving the other bits unchanged. AND AL, 7Fh Example 7.3: Set the msb and lsb of AL while preserving the other bits. ORAL, 81h Example 7.4: Change the sign bit of DX XOR DX, 8000h 0111 1111 = 7Fh 1000 0001 = 81h

6. NOT Instruction Complement operation NOT destination Example 7.5: Complement the bits in AX NOTAX

7. Agenda Logic Instructions – AND, OR, XOR and NOT TEST Instruction Shift and Rotate Instructions Stack Operations Introduction to Procedures

8. TEST Instruction TEST performs AND on the destination TEST destination, source Effects on flags – SF, ZF, PF reflect the result – AF is undefined – CF, OF = 0 TEST vs. CMP – CMP is subtraction operation

9. TEST Example Jump to label BELOW if AL contains an even number TESET AL, 1; is AL even? JZBELOW; yes, go to BELOW

10. Agenda Logic Instructions – AND, OR, XOR and NOT TEST Instruction Shift and Rotate Instructions Stack Operations Introduction to Procedures

11. Shift and Rotate Instructions Two types of shift and rotate instructions – Logical Shift / Rotate – Arithmetic Shift/Rotate Both logical and arithmetic left shift are identical But right shifts are different

12. Shift and Rotate Instructions SHL DH, 3; DH = 1110 1111 DH = 0111 1000C = 1 SAL DH, 2; DH = 1110 1111 DH = 1011 1100C = 1 SHR DH, 3; DH = 1110 1111 DH = 0001 1101C = 1 SAR DH, 2; DH = 1110 1111 DH = 1111 1011C = 1

13. Rotate Instructions Let DH = 8Ah = 1000 1010 CF = 1 After first RCR DH = 1100 0101 CF = 0 After second RCR DH = 0110 0010 CF = 1

14. Agenda Logic Instructions – AND, OR, XOR and NOT TEST Instruction Shift and Rotate Instructions Stack Operations Introduction to Procedures

15. Stack vs. Queue Stack – LIFO : Last In First Out Queue – FIFO : First In First Out Stack Queue

16. PUSH vs. POP in Stack

17. Stack Operations

18. PUSH Instructions

19. POP Instructions

20. Stack example

21. Agenda Logic Instructions – AND, OR, XOR and NOT TEST Instruction Shift and Rotate Instructions Stack Operations Introduction to Procedures

22. Procedure Example Product = 0 REPEAT IF lsb of B is 1 THEN product = product + A END_IF Shift left A Shift right B UNTIL B = 0

23. References Ch 7, Assembly Language Programming – by Charls Marut Ch 4, Intel Microprocessors – by Brey