;//  TSR_2F.ASM
;//
;//  1. Check of program is already in memory    ( Fn 0 )
;//  2. Unload the program from memory           ( Fn 1 )
;//  3. Sleep the program in memory              ( Fn 2 )
;//  4. Awake the program in memory              ( Fn 3 )
;//
;//  (c) Victor A.Voilevitch, 1994-1996.

EXTRN _PROGRAM_ID     : BYTE

_TEXT SEGMENT BYTE PUBLIC 'CODE'
DGROUP GROUP _DATA
_TEXT ENDS
PUBLIC _NEW_2F
.MODEL SMALL

.CODE
_NEW_2F       PROC FAR

              cmp ah, _PROGRAM_ID
              jne chain_2F

              cmp al, 0
              jne next_01
              xor al,0FFh
              iret

next_01:      cmp al, 1
              jne next_02
              push bx
              db 0BBh
              dw ?
              push ds
              mov ds,bx
              db 0A3h
              dw ?
              pop ds
              pop bx
              iret

next_02:      cmp al, 2
              jne next_03
              push bx
              db 0BBh
              dw ?
              push ds
              mov ds,bx
              db 0A3h
              dw ?
              pop ds
              pop bx
              iret

next_03:      cmp al, 3
              jne chain_2F
              push bx
              db 0BBh
              dw ?
              push ds
              mov ds,bx
              mov ax, 0
              db 0A3h
              dw ?
              pop ds
              pop bx
              iret


chain_2F:     db 0EAh
_old_2F       dd ?

_NEW_2F       ENDP
              END