rom/exec/superstate.c

   1 /*
   2     Copyright © 1995-2017, 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
  12 #include "exec_intern.h"
  13
  14 /*****************************************************************************
  15
  16     NAME */
  17 #include <proto/exec.h>
  18
  19         AROS_LH0(APTR, SuperState,
  20
  21 /*  LOCATION */
  22         struct ExecBase *, SysBase, 25, Exec)
  23
  24 /*  FUNCTION
  25         Enter supervisor mode (like Supervisor()), but return on the user
  26         stack. This will mean that the user stack variables are still there.
  27         A call to UserState() will end this mode.
  28
  29     INPUTS
  30         None.
  31
  32     RESULT
  33         The old supervisor stack. This must be passed to UserState(). If the
  34         processor was already in supervisor mode, then this function will
  35         return NULL. In that case do NOT call UserState().
  36
  37     NOTES
  38         This is not a good function to use, it has limited scope, and will
  39         probably be even less useful in the future.
  40
  41     EXAMPLE
  42
  43     BUGS
  44         You can easily cause your system to cease operating normally.
  45
  46     SEE ALSO
  47         Supervisor(), UserState()
  48
  49     INTERNALS
  50         For extra details see Supervisor().
  51
  52 ******************************************************************************/
  53 {
  54     AROS_LIBFUNC_INIT
  55
  56 #if (AROS_FLAVOUR & AROS_FLAVOUR_STANDALONE)
  57     /*
  58      * This part works only on native AROS.
  59      * Hosted ports are running in a virtual machine with only single privilege
  60      * level available, so this function will simply return NULL.
  61      * cpu_SuperState() is an architecture-specific helper code written in asm.
  62      */
  63
  64     int super = KrnIsSuper();
  65
  66     D(bug("[SuperState] Current supervisor mode: %d\n", super));
  67
  68     if (!super)
  69     {
  70         APTR ssp = (APTR)Supervisor(cpu_SuperState);
  71
  72         D(bug("[SuperState] Saved SP 0x%p\n", ssp));
  73         return ssp;
  74     }
  75 #endif
  76
  77     return NULL;
  78
  79     AROS_LIBFUNC_EXIT
  80 } /* SuperState() */