rom/exec/superstate.c

   1 /*
   2     Copyright © 1995-2011, 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 #include <aros/config.h>
  10 #include <aros/debug.h>
  11 #include <proto/kernel.h>
  12
  13 #include "exec_intern.h"
  14
  15 /*****************************************************************************
  16
  17     NAME */
  18 #include <proto/exec.h>
  19
  20         AROS_LH0(APTR, SuperState,
  21
  22 /*  LOCATION */
  23         struct ExecBase *, SysBase, 25, Exec)
  24
  25 /*  FUNCTION
  26         Enter supervisor mode (like Supervisor()), but return on the user
  27         stack. This will mean that the user stack variables are still there.
  28         A call to UserState() will end this mode.
  29
  30     INPUTS
  31         None.
  32
  33     RESULT
  34         The old supervisor stack. This must be passed to UserState(). If the
  35         processor was already in supervisor mode, then this function will
  36         return NULL. In that case do NOT call UserState().
  37
  38     NOTES
  39         This is not a good function to use, it has limited scope, and will
  40         probably be even less useful in the future.
  41
  42     EXAMPLE
  43
  44     BUGS
  45         You can easily cause your system to cease operating normally.
  46
  47     SEE ALSO
  48         Supervisor(), UserState()
  49
  50     INTERNALS
  51         For extra details see Supervisor().
  52
  53 ******************************************************************************/
  54 {
  55     AROS_LIBFUNC_INIT
  56
  57 #if (AROS_FLAVOUR & AROS_FLAVOUR_STANDALONE)
  58     /*
  59      * This part works only on native AROS.
  60      * Hosted ports are running in a virtual machine with only single privilege
  61      * level available, so this function will simply return NULL.
  62      * cpu_SuperState() is an architecture-specific helper code written in asm.
  63      */
  64
  65     int super = KrnIsSuper();
  66
  67     D(bug("[SuperState] Current supervisor mode: %d\n", super));
  68
  69     if (!super)
  70     {
  71         APTR ssp = (APTR)Supervisor(cpu_SuperState);
  72
  73         D(bug("[SuperState] Saved SP 0x%p\n", ssp));
  74         return ssp;
  75     }
  76 #endif
  77
  78     return NULL;
  79
  80     AROS_LIBFUNC_EXIT
  81 } /* SuperState() */