Notes

Write an ALP to transfer a string from one location to another.
; STRING TRANSFER
DATA SEGMENT
STR1 DB ‘HOW ARE YOU’
STR2 DB 20 DUP(0)
COUNT DW 11
DATA ENDS
CODE SEGMENT
ASSUME CS:CODE,DS:DATA,ES:DATA
START: MOV AX,DATA
MOV DS,AX
MOV ES,AX
LEA SI,STR1
LEA DI,STR2
MOV CX,COUNT
CLD
REP MOVSB
MOV AH,4CH
INT 21H
CODE ENDS
END START
7.2 Write an ALP to reverse the string.
; REVERSE A STRING
DATA SEGMENT
STR1 DB "hello"
STR2 DB 5 DUP(?)
COUNT DW 13
DATA ENDS

CODE SEGMENT
ASSUME CS:CODE,DS:DATA,ES:DATA
START:MOV AX,DATA
MOV DS,AX
MOV ES,AX
MOV CX,COUNT
MOV SI,0
MOV DI,0
ADD DI,COUNT
DEC DI

AGAIN: MOV AL,STR1[SI]
MOV STR2[DI],AL
INC SI
DEC DI
LOOP AGAIN
MOV AH,4CH
INT 21H
CODE ENDS
END START

7.3 Write an ALP to find the Character in a string.
DATA SEGMENT
STR1 DB ‘INDUS UNIVERSITY’
LEN EQU $-STR1
FIND EQU ’Z’
MSG1 DB ‘CHARACTER FOUND$’
MSG2 DB ’CHARACTER NOT FOUND$’
DATA ENDS
CODE SEGMENT
ASSUME CS:CODE,DS:DATA
START: MOV AX,DATA
MOV DS,AX
MOV ES,AX
MOV AL,FIND
MOV CL,LEN
LEA SI,STR1
CLD
UP: SCASB
JZ DOWN
LOOP UP
LEA DX,MSG2
MOV AH,09H
INT 21H
JMP EXIT

DOWN: LEA DX,MSG1
MOV AH,09H
INT 21H
EXIT: MOV AH,4CH
INT 21H
CODE ENDS
END START

7.4 Write an ALP to check if the string is palindrome or not.
DATA SEGMENT
STR1 DB ‘REFER’
LEN EQU $-STR1
STR2 DB 20 DUP(0)
MSG1 DB “STRING IS PALINDROME”,”$”
MSG2 DxB “STRING IS NOT PALINDROME”,”$”
DATA ENDS
CODE SEGMENT
ASSUME CS:CODE,DS:DATA,ES:DATA
START: MOV AX,DATA
MOV DS,AX
MOV ES,AX
LEA SI,STR1
LEA DI,STR2+LEN-1
MOV CX,LEN
UP: CLD
LODSB
STD
STOSB
LOOP UP
LEA SI,STR1
LEA DI,STR2
MOV CL,LEN
BACK: MOV AL,[SI]
CMP AL,[DI]
JNZ NOT_PAL
INC SI
INC DI
DEC CL
JNZ BACK
PAL: LEA DX, MSG1 ; DISPLAY PALINDROME
MOV AH, 09H
INT 21H
JMP EXIT
NOT_PAL :LEA DX, MSG2 ; DISPLAY NOT PALINDROME
MOV AH, 09H
INT 21H
EXIT: MOV AH,4CH
INT 21H
CODE ENDS
END START

8 An ALP for 32 bit Addition and Subtraction
ADDITION:
DATA SEGMENT
ABC DD 12345678H
DEF DD 9ABCDEF0H
GHI DW ?
DATA ENDS
CODE SEGMENT
ASSUME CS:CODE, DS:DATA
START:
MOV AX,DATA
MOV DS,AX
MOV DL,00H
MOV AX, WORD PTR ABC
MOV BX, WORD PTR DEF
ADD AX,BX
MOV WORD PTR GHI,AX
MOV AX, WORD PTR ABC+2
MOV BX, WORD PTR DEF+2
ADC AX,BX
MOV WORD PTR GHI+2,AX
JNC MOVE
INC DL
MOVE: MOV BYTE PTR GHI+4,DL
INT 3
CODE ENDS
END START

SUBTRACTION:
DATA SEGMENT
ABC DD 9ABCDEF0H
DEF DD 12345678H
GHI DW ?
DATA ENDS
CODE SEGMENT
ASSUME CS:CODE, DS:DATA
START:
MOV AX,DATA
MOV DS,AX
MOV DL,00H
MOV AX, WORD PTR ABC
MOV BX, WORD PTR DEF
SUB AX,BX
MOV WORD PTR GHI,AX
MOV AX, WORD PTR ABC+2
MOV BX, WORD PTR DEF+2
SBB AX,BX
MOV WORD PTR GHI+2,AX
JNC MOVE
INC DL
MOVE: MOV BYTE PTR GHI+4,DL
INT 3
CODE ENDS
END START

8.2 An ALP for ASCII Adjust after Addition/Subtraction.
CODE SEGMENT
ASSUME CS:CODE
START: MOV AX,0901H
SUB AL,09H
AAS ; GIVE AX = 0802H
MOV AH,0
MOV AL,6
ADD AL,5
AAA; AH = 1 and AL = 1 ; represents BCD 11
MOV AH,4CH
INT 21H
CODE ENDS
END START
8.3 An ALP for ASCII Adjust after Multiplication.
CODE SEGMENT
ASSUME CS:CODE
START: MOV AL,5
MOV BL,7
MUL BL
AAM
MOV AH,4CH
INT 21H
CODE ENDS
END START