.model small

.stack 100h

.data

msgIntro DB "4-a uzd: Programa pakeicia ivestos eilutes raidziu skyriu ir eilutes ilgi.$"
msgIvesk DB 0Dh, 0Ah, "Iveskite:$"
msgIsvesk DB 0Dh, 0Ah, "Pakeista eilute:$"
msgIlgis DB 0Dh, 0Ah, "Eilutes ilgis:$"
msgError DB 0Dh, 0Ah, "Klaida!$"

BUFMAX  DB 255
BUFSIZE DB 0
BUF     DB 255 DUP(?) 

.code
START:

mov ax, @data
mov ds, ax
mov es, ax

mov dx, offset msgIntro
call WRITE

mov dx, offset msgIvesk
call WRITE

mov dx, offset BUFMAX
mov ah, 0Ah
int 21h

mov dx, offset msgIsvesk
call WRITE

;nuskaitom eilutes ilgi
cld
mov si, offset BUFSIZE
lodsb
mov cl, al
xor ch, ch

;xz
mov di, si

;ciklas
CHECK:

lodsb

cmp al, 'A'
jb DoNothing
cmp al, 'Z'
jbe Keisk_i_Mazaja
cmp al, 'a'
jb DoNothing
cmp al, 'z'
jbe Keisk_i_Didziaja
cmp al, 'z'
ja DoNothing

Keisk_i_Didziaja:
sub al, 20h
jmp DoNothing

Keisk_i_Mazaja:
add al, 20h
jmp DoNothing

DoNothing:
stosb

loop CHECK

;

mov al, "$"
stosb
mov dx, offset BUF
mov ah, 9
int 21h

;xor al, al
;mov dx, offset BUFSIZE
;mov ah, 9
;int 21h
;mov dx, offset msgIlgis
;mov ah, 9
;int 21h

mov ax, 4C00h
int 21h

WRITE PROC

push ax
mov ah, 9h
int 21h
pop ax
ret
WRITE ENDP

END START