Implement an assembly code that counts the number of vowels in a given string?

Answer 1

.MODEL SMALL

.STACK 100H

.DATA

PROMPT_1 DB 'Enter a string : $'

PROMPT_2 DB 0DH,0AH,'No. of Vowels = $'

PROMPT_3 DB 0DH,0AH,'No. of Consonants = $'

STRING DB 50 DUP (?)

C_VOWELS DB 'AEIOU'

S_VOWELS DB 'aeiou'

C_CONSONANTS DB 'BCDFGHJKLMNPQRSTVWXYZ'

S_CONSONANTS DB 'bcdfghjklmnpqrstvwxyz'

.CODE

MAIN PROC

MOV AX, @DATA ; initialize DS and ES

MOV DS, AX

MOV ES, AX

LEA DX, PROMPT_1 ; load and display the string PROMPT_1

MOV AH, 9

INT 21H

LEA DI, STRING ; set DI=offset address of variable STRING

CALL READ_STR ; call the procedure READ_STR

XOR DX, DX ; clear DX

LEA SI, STRING ; set SI=offset address of variable STRING

OR BX, BX ; check BX for 0

JE @EXIT ; jump to label @EXIT if BX=0

@COUNT: ; jump label

LODSB ; set AL=DS:SI

LEA DI, C_VOWELS ; set DI=offset address of variable C_VOWELS

MOV CX, 5 ; set CX=5

REPNE SCASB ; check AL is capital vowel or not

JE @INCREMENT_VOWELS ; jump to label @INCREMENT_VOWELS if AL is

; capital vowel

LEA DI, S_VOWELS ; set DI=offset address of variable S_VOWELS

MOV CX, 5 ; set CX=5

REPNE SCASB ; check AL is small vowel or not

JE @INCREMENT_VOWELS ; jump to label @INCREMENT_VOWELS if AL is

; small vowel

LEA DI, C_CONSONANTS ; set DI=offset address of variable

; C_CONSONANTS

MOV CX, 21 ; set CX=21

REPNE SCASB ; check AL is capital consonant or not

JE @INCREMENT_CONSONANTS ; jump to label @INCREMENT_CONSONANTS if AL

; is capital consonant

LEA DI, S_CONSONANTS ; set DI=offset address of variable

; S_CONSONANTS

MOV CX, 21 ; set CX=21

REPNE SCASB ; check AL is small consonant or not

JE @INCREMENT_CONSONANTS ; jump to label @INCREMENT_CONSONANTS if AL

; is small consonants

JMP @NEXT ; otherwise, jump to label @NEXT

@INCREMENT_VOWELS: ; jump label

INC DL ; increment DL

JMP @NEXT ; jump to label @NEXT

@INCREMENT_CONSONANTS: ; jump label

INC DH ; increment DH

@NEXT: ; jump label

DEC BX ; decrement BX

JNE @COUNT ; jump to label @COUNT while BX!=0

@EXIT: ; jump label

MOV CX, DX ; set CX=DX

LEA DX, PROMPT_2 ; load and display the string PROMPT_2

MOV AH, 9

INT 21H

XOR AX, AX ; clear AX

MOV AL, CL ; set AL=CL

CALL OUTDEC ; call the procedure OUTDEC

LEA DX, PROMPT_3 ; load and display the string PROMPT_3

MOV AH, 9

INT 21H

XOR AX, AX ; clear AX

MOV AL, CH ; set AL=CH

CALL OUTDEC ; call the procedure OUTDEC

MOV AH, 4CH ; return control to DOS

INT 21H

MAIN ENDP

READ_STR PROC

; this procedure will read a string from user and store it

; input : DI=offset address of the string variabel

; output : BX=number of characters read

; : DI=offset address of the string variabel

PUSH AX ; push AX onto the STACK

PUSH DI ; push DI onto the STACK

CLD ; clear direction flag

XOR BX, BX ; clear BX

@INPUT_LOOP: ; loop label

MOV AH, 1 ; set input function

INT 21H ; read a character

CMP AL, 0DH ; compare AL with CR

JE @END_INPUT ; jump to label @END_INPUT if AL=CR

CMP AL, 08H ; compare AL with 08H

JNE @NOT_BACKSPACE ; jump to label @NOT_BACKSPACE if AL!=08H

CMP BX, 0 ; compare BX with 0

JE @INPUT_ERROR ; jump to label @INPUT_ERROR if BX=0

MOV AH, 2 ; set output function

MOV DL, 20H ; set DL=20H

INT 21H ; print a character

MOV DL, 08H ; set DL=08H

INT 21H ; print a character

DEC BX ; set BX=BX-1

DEC DI ; set DI=DI-1

JMP @INPUT_LOOP ; jump to label @INPUT_LOOP

@INPUT_ERROR: ; jump label

MOV AH, 2 ; set output function

MOV DL, 07H ; set DL=07H

INT 21H ; print a character

MOV DL, 20H ; set DL=20H

INT 21H ; print a character

JMP @INPUT_LOOP ; jump to label @INPUT_LOOP

@NOT_BACKSPACE: ; jump label

STOSB ; set ES:[DI]=AL

INC BX ; set BX=BX+1

JMP @INPUT_LOOP ; jump to label @INPUT_LOOP

@END_INPUT: ; jump label

POP DI ; pop a value from STACK into DI

POP AX ; pop a value from STACK into AX

RET

READ_STR ENDP

OUTDEC PROC

; this procedure will display a decimal number

; input : AX

; output : none

PUSH BX ; push BX onto the STACK

PUSH CX ; push CX onto the STACK

PUSH DX ; push DX onto the STACK

CMP AX, 0 ; compare AX with 0

JGE @START ; jump to label @START if AX>=0

PUSH AX ; push AX onto the STACK

MOV AH, 2 ; set output function

MOV DL, "-" ; set DL='-'

INT 21H ; print the character

POP AX ; pop a value from STACK into AX

NEG AX ; take 2's complement of AX

@START: ; jump label

XOR CX, CX ; clear CX

MOV BX, 10 ; set BX=10

@OUTPUT: ; loop label

XOR DX, DX ; clear DX

DIV BX ; divide AX by BX

PUSH DX ; push DX onto the STACK

INC CX ; increment CX

OR AX, AX ; take OR of Ax with AX

JNE @OUTPUT ; jump to label @OUTPUT if ZF=0

MOV AH, 2 ; set output function

@DISPLAY: ; loop label

POP DX ; pop a value from STACK to DX

OR DL, 30H ; convert decimal to ascii code

INT 21H ; print a character

LOOP @DISPLAY ; jump to label @DISPLAY if CX!=0

POP DX ; pop a value from STACK into DX

POP CX ; pop a value from STACK into CX

POP BX ; pop a value from STACK into BX

RET ; return control to the calling procedure

OUTDEC ENDP

END MAIN