This document discusses jumps in assembly language, including unconditional jumps and conditional jumps. It defines an unconditional jump as a jump without a condition, using the JMP instruction. Conditional jumps use conditions and compare instructions like CMP. Conditional jump instructions include JE/JZ for equal, JNE/JNZ for not equal, JA/JNBE for above, JB/JNAE for below, and others. It also discusses comparing signed vs unsigned numbers and the flags tested for each conditional jump instruction.

1. ASSEMBLY LANGUAGE
COURCE CODE#CSC221
JUMPS
BY:
NADEEM AHMED

2. JUMP
 A jump is a instruction used to control the flow of
program.
Types of jumps:
1. Unconditional Jump
2. Conditional Jump

3. Unconditional Jump
 A jump without using any condition is known as
unconditional jump.
Or
Jump to label without any condition.
syntax:
JMP label_name
Example:
Label1:
mov dl,'a'
mov ah,02
int 21h
jmp Label1

4. Conditional Jump
 A jump with using condition is known as
conditional jump.
Or
Jump to label with condition.
syntax:
J<condition> label_name
(Let us discuss the CMP instruction before discussing the
conditional instructions.)

5. CMP Instruction
 Compares the destination operand to the source operand
Nondestructive subtraction of source from destination (destination
operand is not changed)
Syntax:
CMP destination, source
Note:
Cmp reg, reg Cmp dl,aI
Cmp reg, constant Cmp dl, 3
Cmp reg, [memory address] Cmp dl, [sI]
(1 of 3)

6. CMP Instruction
• Case 3: destination > source
mov al,6
mov bl,5
cmp al,bl
; ZF = 0, CF = 0
(2 of 3)
mov al,5
mov bl,5
cmp al,bl
; Zero flag set
Case 1: destination == source
mov al,4
mov bl,5
cmp al,bl
; Carry flag set
• Case 2: destination < source
The comparisons shown here are performed with “Unsigned"
integers.

7. CMP Instruction (3 of 3)
• Case 1: destination >source
mov al,5
Mov bl,-2
cmp al,bl
; Sign flag == Overflow flag
• Case 2 : destination < source
mov al,-1
Mov bl,5
cmp al,bl
; Sign flag != Overflow flag
The comparisons shown here are performed with "signed"
integers.

8. Conditional Jump For Unsigned Numbers
 Following are the conditional jump instructions used on
unsigned data used for logical operations −
Instruction Description Flags tested
JE/JZ Jump Equal or Jump Zero ZF
JNE/JNZ Jump not Equal or Jump Not Zero ZF
JA/JNBE Jump Above or Jump Not Below/Equal CF, ZF
JAE/JNB Jump Above/Equal or Jump Not Below CF
JB/JNAE Jump Below or Jump Not Above/Equal CF
JBE/JNA Jump Below/Equal or Jump Not Above AF, CF

9. Conditional Jump For Signed Numbers
 Following are the conditional jump instructions used on
unsigned data used for logical operations −
Instruction Description Flags tested
JE/JZ Jump Equal or Jump Zero ZF
JNE/JNZ Jump not Equal or Jump Not Zero ZF
JG/JNLE Jump Greater or Jump Not Less/Equal OF, SF, ZF
JGE/JNL Jump Greater/Equal or Jump Not Less OF, SF
JL/JNGE Jump Less or Jump Not Greater/Equal OF, SF
JLE/JNG Jump Less/Equal or Jump Not Greater OF, SF, ZF

10. Conditional Jump With Flags
 The following conditional jump instructions have special
uses and check the value of flags −
Instruction Description Flags tested
JC Jump If Carry CF
JNC Jump If No Carry CF
JO Jump If Overflow OF
JNO Jump If No Overflow OF
JP/JPE Jump Parity or Jump Parity Even PF
JNP/JPO Jump No Parity or Jump Parity Odd PF
JS Jump Sign (negative value) SF
JNS Jump No Sign (positive value) SF

11. Any Question?