arch/i386-pc/exec/superstate.c

   1 /*
   2     Copyright © 1995-2001, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     Desc: SuperState() - Switch the processor into a higher plane.
   6     Lang: english
   7 */
   8
   9 void exec_SuperState(); /* defined in corelow.S */
  10
  11 /*****************************************************************************
  12
  13     NAME */
  14 #include <proto/exec.h>
  15
  16         AROS_LH0(APTR, SuperState,
  17
  18 /*  LOCATION */
  19         struct ExecBase *, SysBase, 25, Exec)
  20
  21 /*  FUNCTION
  22         Enter supervisor mode (like Supervisor()), but return on the user
  23         stack. This will mean that the user stack variables are still there.
  24         A call to UserState() will end this mode.
  25
  26     INPUTS
  27         None.
  28
  29     RESULT
  30         The old supervisor stack. This must be passed to UserState(). If the
  31         processor was already in supervisor mode, then this function will
  32         return NULL. In that case do NOT call UserState().
  33
  34     NOTES
  35         This is not a good function to use, it has limited scope, and will
  36         probably be even less useful in the future.
  37
  38     EXAMPLE
  39
  40     BUGS
  41         You can easily cause your system to cease operating normally.
  42
  43     SEE ALSO
  44         Supervisor(), UserState()
  45
  46     INTERNALS
  47         For extra details see Supervisor().
  48
  49     HISTORY
  50
  51 ******************************************************************************/
  52 {
  53     AROS_LIBFUNC_INIT
  54     APTR retval;
  55     /*  Again see a real implementation for more information.
  56
  57         You will have to change into supervisor mode, and then change the
  58         stack to the original user stack before returning.
  59     */
  60
  61     /* We have to return something. NULL is an invalid address for a
  62        stack, so it could be used to say that this function does
  63        nothing.
  64     */
  65     return (APTR)Supervisor(exec_SuperState);
  66
  67     AROS_LIBFUNC_EXIT
  68 } /* SuperState() */