Task26.asm

Write a subroutine which copies contents of string1 into another string but without spaces and punctuation marks. For example, if it is provided the following string
String1 DB “Mr. Ali, Usman, & Anwar! Doing what???? want to travel????”, ‘0’
It should return
String2 DB “MrAliUsmanAnwarDoingwhatwanttotravel”, ‘0’

[org 0x0100]
jmp start 

clrscr: push es 
 push ax 
 push cx 
 push di 
 mov ax, 0xb800 
 mov es, ax ; point es to video base 
 xor di, di ; point di to top left column 
 mov ax, 0x0720 ; space char in normal attribute 
 mov cx, 2000 ; number of screen locations 
 cld ; auto increment mode 
 rep stosw ; clear the whole screen 
 pop di 
 pop cx 
 pop ax 
 pop es 
 ret


strlen: push bp 
 mov bp,sp 
 push es 
 push cx 
 push di 
 les di, [bp+4] ; point es:di to string 
 mov cx, 0xffff ; load maximum number in cx 
 xor al, al ; load a zero in al 
 repne scasb ; find zero in the string 
 mov ax, 0xffff ; load maximum number in ax 
 sub ax, cx ; find change in cx 
 dec ax ; exclude null from length 
 pop di 
 pop cx 
 pop es 
 pop bp 
 ret 4 
; subroutine to print a string 
; takes the x position, y position, attribute, and address of a null 
; terminated string as parameters 

printstr: 
 push bp 
 mov bp, sp 
 push es 
 push ax 
 push cx 
 push si 
 push di 
 push ds ; push segment of string 
 mov ax, [bp+4] 
 push ax ; push offset of string 
 call strlen 
 cmp ax, 0 ; is the string empty 
 jz exit ; no printing if string is empty
 mov cx, ax ; save length in cx 
 mov ax, 0xb800 
 mov es, ax ; point es to video base 
 mov al, 80 ; load al with columns per row 
 mul byte [bp+8] ; multiply with y position 
 add ax, [bp+10] ; add x position 
 shl ax, 1 ; turn into byte offset 
 mov di,ax ; point di to required location 
 mov si, [bp+4] ; point si to string 
 mov ah, [bp+6] ; load attribute in ah 
 cld ; auto increment mode 
nextchar: 
 lodsb ; load next char in al  
 cmp al,0x41
 jl here
 cmp al,0x7A
 jg here
 stosw ; print char/attribute pair
 here: 
 loop nextchar ; repeat for the whole string 
exit:
 pop di 
 pop si 
 pop cx 
 pop ax 
 pop es 
 pop bp 
 ret 8

 
start: 
 call clrscr ; call the clrscr subroutine 
 mov ax, 30 
 push ax ; push x position 
 mov ax, 20 
 push ax ; push y position 
 mov ax, 15 ; blue on black attribute 
 push ax ; push attribute 
 mov ax, message 
 push ax ; push address of message 
 call printstr ; call the printstr subroutine 
 mov ax, 0x4c00 ; terminate program 
 int 0x21 

message: db 'Mr. Ali, Usman, & Anwar! Doing what???? want to travel????', 0 ; null terminated string