PreserveRegister MACRO
  MOVE.W \1R,D0
  OR.W #$8000,D0
  MOVE.W D0,Old\1
  ENDM

RestoreRegister MACRO
  MOVE.W #$7FFF,\1
  MOVE.W Old\1,\1
  ENDM
  
PreserveRegisters:
  PreserveRegister DMACON
  PreserveRegister INTENA
  PreserveRegister INTREQ
  PreserveRegister ADKCON
  
ReturnOwnership:
  RestoreRegister DMACON
  RestoreRegister INTENA
  RestoreRegister INTREQ
  RestoreRegister ADKCON
  
  CNOP 0,4
OldDMACON dc.w 0
OldINTENA dc.w 0
OldINTREQ dc.w 0
OldADKCON dc.w 0