.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:$"
msgError DB 0Dh, 0Ah, "Klaida!$"

BUFMAX  DB 255
BUFSIZE DB ?
BUF     DB 120 DUP(?) 
;;BUFOUT    DB 120 DUP(?) 

.code
START:

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

mov dx, offset msgIntro
mov ah, 9
int 21h

mov dx, offset msgIvesk
mov ah, 9
int 21h

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
push si
pop di

;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_Mazaja:
sub al, 20h
jmp DoNothing

Keisk_i_Didziaja:
add al, 20h
jmp DoNothing

DoNothing:
stosb

Klaida:
xor ax, ax
dec ax

loop CHECK

;

mov al, '$'
stosb
mov dx, offset BUF

mov ax, 4C00h
int 21h

write PROC

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

END START