{ interrup.inc by Kari Lammassaari }

Var OldInt :Array[0..2] Of Byte;
    DosInt :Array[0..2] Of Byte Absolute $0038;
    IntervalCounter :Integer;

Procedure Interrupt; {
                       This procedure is NEVER called by Pascal.
                       It's the code where the interrupt is redirected to.
                     }
  Begin
      Inline (
               $F3/
               $F5/$C5/$D5/$E5/$D9/$F5/$C5/$D5/$E5/$DD/$E5/$FD/$E5/
               $DD/$21/$00/$00/
               $DD/$7E/$0/$3C/$DD/$77/$0/$DD/$BE/$1/$20/$7/$AF/$DD/$77/$0/
               $CD/$00/$00/
               $FD/$E1/$DD/$E1/$E1/$D1/$C1/$F1/$D9/$E1/$D1/
               $C1/$F1/
               $00/
               $c3/0/0  {Here comes orig addr from ($0038) }
             );
  End;

Procedure RemoveInterrupt;

  Begin
     Inline($f3);
     Move(OldInt,DosInt,3);
     Inline($fb);
  End;

Procedure SetInterrupt(IntProcAddr:Integer;IntervalValue:Byte);

 Var IntAddr :Integer;
     i       :Byte;
 Begin

    ErrorPtr := Addr(RemoveInterrupt);

    IntervalCounter := IntervalValue*256;

    IntAddr := Addr(Interrupt);
    Move(DosInt,Oldint,3);          {Save Original Interrupt Addr};
    For i := 0 to 2 Do Mem[IntAddr+51+i] := Mem[$38+i];

    Mem[IntAddr+35] := Lo(IntProcAddr);
    Mem[IntAddr+36] := Hi(IntProcAddr);

    Mem[IntAddr + 16] := Lo(Addr(IntervalCounter));
    Mem[IntAddr + 17] := Hi(Addr(IntervalCounter));

    Inline($f3);
    Mem[$39] := Lo(IntAddr);
    Mem[$3a] := Hi(IntAddr);
    Inline($fb);

 End;