LB_5

AStack  SEGMENT STACK
    DB 1024 DUP(?)
AStack  ENDS

DATA    SEGMENT
    KEEP_CS DW 0
    KEEP_IP DW 0
    MESSAGE DB 'Hello!', 0dh, 0ah, '$'
    END_MES DB 'end', 0dh, 0ah, '$'
    FLAG    DB 0
DATA    ENDS

CODE    SEGMENT
    ASSUME CS:CODE, DS:DATA, SS:AStack

WriteMsg  PROC  NEAR
          mov AH, 9
          int 21h
          ret
WriteMsg  ENDP

FUNC PROC FAR
        cmp  FLAG, 0
        jne  func_end
        mov  FLAG, 1

        push ax
        push bx
        push cx
        push dx
        push ds


        mov dx, OFFSET MESSAGE
        mov cx, 4
        lp:
            call WriteMsg
            loop lp

        xor  cx, cx
        mov  cx, 20
        update_dx:
        mov  dx, 0ffffh
        wait_loop:
        nop
        dec  dx
        cmp  dx, 0
        jne  wait_loop
        loop update_dx

        mov dx, OFFSET END_MES
        call WriteMsg

        pop ds
        pop dx
        pop cx
        pop bx
        pop ax
        func_end:
        mov al, 20h
        out 20h, al
        iret
FUNC ENDP

main proc far
    push ds
    xor  ax, ax
    push ax

    mov  ax, DATA
    mov  ds, ax

    mov  ah, 35h
    mov  al, 16h
    int  21h
    mov  KEEP_CS, es
    mov  KEEP_IP, bx


    push ds
    mov  dx, offset FUNC
    mov  ax, seg FUNC
    mov  ds, ax
    mov  ah, 25h
    mov  al, 16h
    int  21h
    pop  ds

    input_loop:
     in   al, 60h
     cmp  al, 30h
     jne  input_loop
     mov al, 100
     int  16h

    cli

    push ds
    mov  dx, KEEP_IP
    mov  ax, KEEP_CS
    mov  ds, ax
    mov  ah, 25h
    mov  al, 16h
    int  21h
    pop  ds

    sti

    ret

main endp

my_code ends
end main