Write an MASM program that will count the total number of characters, the number

Question

Write an MASM program that will count the total number of characters, the number of lowercase characters, the numbers of decimal digits, and the number of blank characters contained in a text.

Explanation / Answer

.stack 100h .data msj1 db 'Enter a line of text (132 max) : $' text db 133 ;MAX LENGTH 132, PLUS 1 FOR ENDING CHR(13). db ? ;LENGTH ENTERED BY USER. db 133 dup(?) ;THE STRING. digits dw 10 dup(0) ;ARRAY OF 10 COUNTERS FOR DIGITS. uppercase dw 26 dup(0) ;ARRAY OF 26 COUNTERS FOR UPPERCASE LETTERS. lowercase dw 26 dup(0) ;ARRAY OF 26 COUNTERS FOR LOWERCASE LETTERS. str db 6 dup('$') ;TO STORE NUMBER CONVERTED TO STRING. char db ' =$' space db ' $' .code ;INITIALIZE DATA SEGMENT. mov ax,@data mov ds,ax ;DISPLAY MESSAGE TO CAPTURE LINE OF TEXT. mov ah, 9 mov dx, offset msj1 int 21h ;CAPTURE LINE OF TEXT. mov ah, 0AH mov dx, offset text int 21h ;COUNT CHARACTERS OF THE LINE OF TEXT. mov si, offset text + 2 ;SI POINTS TO BEGINNING OF STRING. THE FIRST ;2 BYTES ARE FOR CONTROL (MAX LENGTH, LENGTH). repeat: ;CHECK IF CURRENT CHARACTER IS DIGIT, UPPERCASE OR LOWERCASE. mov bl, [ si ] ;GET CURRENT CHARACTER. call check_digit call check_lowercase ;NEXT CHARACTER. inc si mov bl, [ si ] cmp bl, 13 jne repeat ;IF NEXT CHARACTER IS NOT 13, REPEAT. ;DISPLAY COUNTERS. call clear_screen call display_digit_counters call display_lowercase_counters ;WAIT FOR A KEY. mov ah,7 int 21h ;FINISH PROGRAM. mov ax,4c00h int 21h ;------------------------------------------ ;THIS PROCEDURE DISPLAYS THE 10 COUNTERS OF THE ;ARRAY OF COUNTERS FOR DIGITS. proc display_digit_counters mov di, offset digits ;DI POINTS TO ARRAY. mov bp, 10 ;ARRAY LENGTH. display_digits: ;DISPLAY SPACE. mov ah, 9 mov dx, offset space int 21h ;CONVERT CURRENT COUNTER IN STRING. call dollars mov ax, [ di ] call number2string ;STRING RETURNS IN VARIABLE "STR". ;CONVERT CURRENT COUNTER IN CORRESPONDING DIGIT. FOR ;EXAMPLE, IF CURRENT COUNTER IS 3, CONVERT 3 IN '3'. mov ax, di ;GET CURRENT COUNTER OFFSET. sub ax, offset digits ;CONVERT TO 0..9. shr ax, 1 ;DIVIDE OFFSET BECAUSE COUNTERS ARE DW. add al, 48 ;CONVERT TO '0'..'9'. mov char, al ;STORE DIGIT IN STRING TO DISPLAY. ;DISPLAY DIGIT FOR CURRENT COUNTER BELONGS TO. mov ah, 9 mov dx, offset char int 21h ;DISPLAY CURRENT COUNTER. mov ah, 9 mov dx, offset str int 21h ;NEXT COUNTER TO DISPLAY. add di, 2 ;EVERY COUNTER IS DW (TWO BYTES). dec bp jnz display_digits ;IF ( BP > 0 ) JUMP. ret endp ;------------------------------------------ ;THIS PROCEDURE DISPLAYS THE 26 COUNTERS OF THE ;ARRAY OF COUNTERS FOR LOWERCASE LETTERS. proc display_lowercase_counters mov di, offset lowercase ;DI POINTS TO ARRAY. mov bp, 26 ;ARRAY LENGTH. display_lowercase: ;DISPLAY SPACE. mov ah, 9 mov dx, offset space int 21h ;CONVERT CURRENT COUNTER IN STRING. call dollars mov ax, [ di ] call number2string ;STRING RETURNS IN VARIABLE "STR". ;CONVERT CURRENT COUNTER IN CORRESPONDING LETTER. FOR ;EXAMPLE, IF CURRENT COUNTER IS 3, CONVERT 3 IN 'd'. mov ax, di ;GET CURRENT COUNTER OFFSET. sub ax, offset lowercase ;CONVERT TO 0..25. shr ax, 1 ;DIVIDE OFFSET BECAUSE COUNTERS ARE DW. add al, 97 ;CONVERT TO 'a'..'z'. mov char, al ;STORE LETTER IN STRING TO DISPLAY. ;DISPLAY LETTER FOR CURRENT COUNTER BELONGS TO. mov ah, 9 mov dx, offset char int 21h ;DISPLAY CURRENT COUNTER. mov ah, 9 mov dx, offset str int 21h ;NEXT COUNTER TO DISPLAY. add di, 2 ;EVERY COUNTER IS DW (TWO BYTES). dec bp jnz display_lowercase ;IF ( BP > 0 ) JUMP. ret endp ;------------------------------------------ ;THIS PROCEDURE CHECK IF THE CHARACTER IN BL ;IS A DIGIT ('0'..'9'). IF IT IS, INCREASES ;THE APPROPIATE COUNTER IN ARRAY "DIGITS". proc check_digit cmp bl, '0' jb not_a_digit ;IF AL < '0' FINISH. cmp bl, '9' ja not_a_digit ;IF AL > '9' FINISH. ;IF NO JUMP, AL IS A DIGIT. INCREASE COUNTER USING ;THE DIGIT AS OFFSET INSIDE THE ARRAY OF COUNTERS, ;FOR EXAMPLE, THE COUNTER FOR DIGIT '3' IS THE THIRD ;POSITION IN THE ARRAY. sub bl, 48 ;CONVERT DIGIT IN NUMBER ('0'..'9'->0..9). mov bh, 0 ;CLEAR BH TO USE BX. shl bx, 1 ;MULTIPLY BY 2 BECASE EVERY COUNTER IS DW (2 BYTES). add bx, offset digits ;BX POINTS TO THE APPROPIATE COUNTER. inc [ bx ] ;INCREASE COUNTER OF DIGIT. not_a_digit: ret endp ;------------------------------------------ ;THIS PROCEDURE CHECK IF THE CHARACTER IN BL IS ;A LOWERCASE LETTER ('a'..'z'). IF IT IS, INCREASE ;THE APPROPIATE COUNTER IN ARRAY "LOWERCASE". proc check_lowercase cmp bl, 'a' jb not_lowercase ;IF AL < 'a' FINISH. cmp bl, 'z' ja not_lowercase ;IF AL > 'z' FINISH. ;IF NO JUMP, AL IS A LOWERCASE LETTER. INCREASE COUNTER ;USING THE LETTER AS OFFSET INSIDE THE ARRAY OF COUNTERS, ;FOR EXAMPLE, THE COUNTER FOR LETTER 'c' IS THE THIRD ;POSITION IN THE ARRAY. sub bl, 97 ;CONVERT LETTER IN NUMBER ('a'..'z'->0..25). mov bh, 0 ;CLEAR BH TO USE BX. shl bx, 1 ;MULTIPLY BY 2 BECASE EVERY COUNTER IS DW (2 BYTES). add bx, offset lowercase ;BX POINTS TO THE APPROPIATE COUNTER. inc [ bx ] ;INCREASE COUNTER OF LOWERCASE LETTER. not_lowercase: ret endp ;------------------------------------------ ;NUMBER TO CONVERT MUST ENTER IN AX. ;ALGORITHM : EXTRACT DIGITS ONE BY ONE, STORE ;THEM IN STACK, THEN EXTRACT THEM IN REVERSE ;ORDER TO CONSTRUCT STRING. proc number2string mov bx, 10 ;DIGITS ARE EXTRACTED DIVIDING BY 10. mov cx, 0 ;COUNTER FOR EXTRACTED DIGITS. cycle1: mov dx, 0 ;NECESSARY TO DIVIDE BY BX. div bx ;DX:AX / 10 = AX:QUOTIENT DX:REMAINDER. push dx ;PRESERVE DIGIT EXTRACTED FOR LATER. inc cx ;INCREASE COUNTER FOR EVERY DIGIT EXTRACTED. cmp ax, 0 ;IF NUMBER IS jne cycle1 ;NOT ZERO, LOOP. ;NOW RETRIEVE PUSHED DIGITS. mov si, offset str cycle2: pop dx add dl, 48 ;CONVERT DIGIT TO CHARACTER. mov [ si ], dl inc si loop cycle2 ret endp ;------------------------------------------ ;FILLS VARIABLE STR WITH '$'. ;USED BEFORE CONVERT NUMBERS TO STRING, BECAUSE ;THESE STRINGS WILL BE DISPLAYED. proc dollars mov si, offset str mov cx, 6 six_dollars: mov al, '$' mov [ si ], al inc si loop six_dollars ret endp ;------------------------------------------ proc clear_screen mov ah,0 mov al,3 int 10H ret endp

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