8085 program for Binary search

MicroprocessorMicrocontroller8085

Here we will see how to perform binary search in 8085.

Problem Statement:

Write 8085 Assembly language program to perform binary search on a set of data stored at location F110 to F119. The key is located at F100.

Discussion

To perform binary search, the array must be sorted. We are taking the lower limit into L and upper limit into H. The array location is stored at DE register pair. The mid is calculated using (H + L)/2. To perform this division, we are just shifting it to the right one time. Then put the mid value into D and check the item located using DE. if the number is same, then jump to end and store 1 at F101. This indicates that item is found, and also store the mid value as index. If the mid is not matched, then there are two case, if the number is smaller than the mid element, then it is in the lower half, so the upper limit will be mid – 1, in another case it will be in the other side, so the lower limit will be mid + 1. If the item is not found it will store 02 at location F101.

Input

Address
Data
F100
48


F110
04
F111
08
F112
22
F113
2B
F114
31
F115
38
F116
48
F117
51
F118
54
F119
62


 

Address
Data
F100
9D


F110
04
F111
08
F112
22
F113
2B
F114
31
F115
38
F116
48
F117
51
F118
54
F119
62


 

Flow Diagram

 

Program

Address
HEX Codes
Labels
Mnemonics
Comments
F000
3A, 00, F1
 
LDA F100
Load the key into A
F003
47

 
MOV B,A

Store key into B
F004
AF
 
XRA A
Clear Acc
F005
32, 03, F1

 
STA F103

Store number of iterations into F103H
F008
6F
 
MOV L,A
Store A into L also
F009
26, 09

 
MVI H,09

Load 9 into H
F00B
3A, 03, F1
START
LDA F103
load number of iterations into A
F00E
3C

 
INR A

Increase A
F00F
32, 03, F1
 
STA F103
Restore number of iterations
F012
7C

 
MOV A,H

Take the upper limit from H to A
F013
BD
 
CMP L
Compare A and L
F014
DA, 46, F0

 
JC L2

If CY = 1, jump to L2
F017
85
 
ADD L
Otherwise add L with A
F018
1F

 
RAR

Right rotate to get half of it
F019
4F
 
MOV C,A
Store mid value into C
F01A
D2, 1E, F0

 
JNC RESET

If CY = 0, jump to Reset
F01D
3F
 
CMC
Complement the carry
F01E
11, 10, F1

RESET
LXI D,F110

Load the initial address of array into DE
F021
83
 
ADD E
Add E and Mid
F022
5F

 
MOV E,A

Store index into E
F023
AF
 
XRA A
Clear A
F024
8A

 
ADC D

Add D with A with the carry
F025
57
 
MOV D,A
Restore A into D
F026
1A

 
LDAX D

Load A with the value of mid position
F027
B8
 
CMP B
compare it with Key
F028
DA, 34, F0

 
JC ELSE

If CY = 1, jump to ELSE
F02B
CA, 3A, F0
 
JZ PRINT
If they are same, jump to PRINT
F02E
79

 
MOV A,C

Take the mid from C to A
F02F
3D
 
DCR A
Decrease A to get mid – 1
F030
67

 
MOV H,A

Update the upper limit with mid – 1
F031
C3, 0B, F0
 
JMP START
Jump to START again
F034
79

ELSE
MOV A,C

Load the mid from C to A
F035
3C
 
INR A
increase A to get mid + 1
F036
7D

 
MOV A,L

update lower limit with mid + 1
F037
C3, 0B, F0
 
JMP START
Jump to START again
F03A
3E, 01

PRINT
MVI A,01

Load 1 as item is found
F03C
32, 01, F1
 
STA F101
Store result at F101
F03F
79

 
MOV A,C

Take the mid from C to A
F040
32, 02, F1
 
STA F102
Store index of the key into F102
F043
C3, 4B, F0

 
JMP END

End the task
F046
3E, 02
L2
MVI A,02
Load 2 into A that key not present
F048
32, 01, F1

 
STA F101

Store result at F102
F04B
76
END
HLT
Terminate the program

 

Output

Address
Data
F101
01
F102
06

 

Address
Data
F101
02
raja
Published on 17-Jun-2019 08:30:15
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