// TSR_2 Example //Scout

equals  _KeyboardFlags  = 0417h

(expr	Terminate (?)
	ax=4C^1; 21h=.int
expr)

(expr	JumpFAR ?) -> bytes   =0EAh, ^1(4)

(expr	SetVector (?)
	di=OFFSET Old_Int_^1
	dx=OFFSET Int_^1
	al=^1
	call	Set_Vector
expr)

(expr	RestoreVector (?)
	si=OFFSET Old_Int_^1
	al=^1
	call	Restore_Vector
expr)

(expr	ChkVector (?, ?)
	dx=^2
	al=^1
	si=OFFSET Int_^1
	call	Chk_Vector
expr)

(expr	FreeEnvironment
	es=WORD PTR ds:[2Ch]
	ah=49h; 21h=.int
expr)

(expr	TSR (?)
	dx=OFFSET ^1; 27h=.int
expr)

(expr	ChkInstall (?)
	if ax=^1 then al=0FFh; cs=.push; es=.pop; .iret
	JumpFAR Old_Int_2Fh
expr)

(expr	FreeMemory
	ah=49h; 21h=.int
expr)

equals  HotKey          =       3920h,
        ShiftStatus     =       00000001b

equals  BufferSize      =       0

equals  Request         =       5678h,
	Reply		=	8765h,
        MaxAttempt      =       3

        MODEL   Tiny, Pascal
	.ORG	100h
        PROGRAM TSR_2
        .LOCALS _@

	goto	Initialize

bytes   Flags           =       00000000b,
        Attempts,
        SaveAH

ddata   In_DOS_Flag

(proc	FAR	Int_28h()[]
	.sti
        (if cs:Flags.test.00000001b<>
          cs:Flags=.or.00000010b; call Process(); cs:Flags=.and.11111101b
	if)
	.cli
	JumpFAR Old_Int_28h
proc)

(proc	FAR	Int_16h()[]
        (if cs:Flags.test.00000100b=
          (if ah.test.11101110b<>
	    if ax<>Request goto Pass_16h
	    ax=Reply; push cs; pop es; .iret
	  if)
          if cs:Flags.test.00000001b<> then call Process()
          (if ah.test.00000001b=
	    (while
	      cs:SaveAH=ah
	      .sti; .pushf; .cli; call DWORD PTR cs:Old_Int_16h()
              if ax<>HotKey then .iret
              call ChkShiftStatus()
              if <> then .iret
              call Process()
	      ah=cs:SaveAH
	    while)
	  if)
	  cs:SaveAH=ah; cs:SaveAH=-1
	  .sti; .pushf; .cli; call DWORD PTR cs:Old_Int_16h()
          (if <> and ax=HotKey
            call ChkShiftStatus()
            if <> then 2=.retf
	    ah=cs:SaveAH
	    .pushf; .cli; call DWORD PTR cs:Old_Int_16h()
            call Process()
	  if)
	  2=.retf
	if)
Pass_16h:
	JumpFAR Old_Int_16h
proc)

(proc   ChkShiftStatus()[ax,es]
        es=ax=0
        al=BYTE PTR es:[_KeyboardFlags]; al=.and.00001111b
        al=.cmp.ShiftStatus
        return
proc)

(proc   Process()[]
	.cli
        (if cs:Flags.test.00000100b=
          cs:Flags=.or.00000100b; call Main_Shell(); cs:Flags=.and.11111011b
	if)
	.sti
	return
proc)

(proc	Main_Shell()[]
        (if cs:Flags.test.00000010b=
	  (save bx,ds
	    bx=.lds.cs:In_DOS_Flag
	    BYTE PTR ds:[bx]=.cmp.00h
	  save)
	  if <> goto Skip_PopUp
	if)
        .sti; call Main(); .cli
	cs:Flags=.and.11111110b; return
Skip_PopUp:
        (if cs:Flags.test.00000001b<>
	  cs:Attempts=-1; if <> then return
          (save ax) ax=0E07h; 10h=.int
	  cs:Flags=.and.11111110b
	  return
	if)
	cs:Flags=.or.00000001b; cs:Attempts=MaxAttempt
	return
proc)

(proc   Main()[ax,cx]
//      [ Куча всего ]
//      Например:

        ax=0E07h; 10h=.int

	return
proc)

Initialize:
// Проверить наличие себя в памяти
	ax=Request; 16h=.int
	(if ax<>Reply
// Install
	  ah=34h; 21h=.int
	  WORD PTR In_DOS_Flag=bx; (WORD PTR In_DOS_Flag+2)=es
	  SetVector (16h)
	  SetVector (28h)
	  FreeEnvironment
          TSR (Initialize+BufferSize)
	if)
// UnInstall
	ChkVector (16h, es)
        if is carry goto Finish
	ChkVector (28h, )
        if is carry goto Finish
	RestoreVector (16h)
	RestoreVector (28h)
	FreeMemory
	goto	Finish
Finish:
	Terminate (00h)

(proc   Set_Vector()[]
	ah=35h; 21h=.int
	WORD PTR [di]=bx
	WORD PTR [di+2]=es
	ah=25h; 21h=.int
	return
proc)

(proc	Restore_Vector()[ds]
	dx=.lds.DWORD PTR es:[si]
	ah=25h; 21h=.int
	return
proc)

(proc	Chk_Vector()[]
	ah=35h; 21h=.int
	bx=-si
	ax=es-dx.or.bx
	.clc
	if <> then .stc
	return
proc)