arch/.unmaintained/m68k-emul/preparecontext.c

   1 /*
   2     Copyright © 1995-2001, The AROS Development Team. All rights reserved.
   3     $Id$
   4 */
   5
   6 #include <exec/types.h>
   7 #include <aros/libcall.h>
   8
   9 #error "PrepareContext() has been changed. Additional tagList param, etc."
  10 #error "This one here needs to be rewritten!"
  11
  12 /*****************************************************************************
  13
  14     NAME */
  15
  16         AROS_LH3I(APTR, PrepareContext,
  17
  18 /*  SYNOPSIS */
  19         AROS_LHA(APTR, stackPointer, A0),
  20         AROS_LHA(APTR, entryPoint,   A1),
  21         AROS_LHA(APTR, fallBack,     A2),
  22
  23 /*  LOCATION */
  24         struct ExecBase *, SysBase, 6, Exec)
  25
  26 /*  FUNCTION
  27         Allocates the space required to hold a new set of registers on the
  28         Stack given by stackPointer and clears the area except for pc which
  29         is set to the address given by entryPoint.
  30
  31     INPUTS
  32         stackPointer - Pointer to a scpecific stack
  33         entryPoint   - Address of the function to call when the new context
  34                        becomes active.
  35         fallBack     - Address to be called when the entryPoint function ended
  36                        with an rts.
  37
  38     RESULT
  39         The new Stackpointer with the underlying context.
  40
  41     NOTES
  42         This function is for internal use by exec only.
  43
  44         This function is processor dependant.
  45
  46     EXAMPLE
  47
  48     BUGS
  49
  50     SEE ALSO
  51         SwitchTasks()
  52
  53     INTERNALS
  54
  55     HISTORY
  56
  57 ******************************************************************************/
  58 {
  59     AROS_LIBFUNC_INIT
  60     UBYTE *sp=(UBYTE *)stackPointer;
  61     int i;
  62
  63     /*
  64         mc68000 version. As long as no FPU is in use this works for the
  65         other mc680xx brands as well.
  66     */
  67
  68     /* Push fallback address */
  69     sp-=sizeof(APTR);
  70     *(APTR *)sp=fallBack;
  71
  72     /* Now push the context. Prepare a rts first (pc). */
  73     sp-=sizeof(APTR);
  74     *(APTR *)sp=entryPoint;
  75
  76     /* Push 15 registers */
  77     for(i=0;i<15;i++)
  78     {
  79         sp-=sizeof(LONG);
  80         *(LONG *)sp=0;
  81     }
  82
  83     return sp;
  84     AROS_LIBFUNC_EXIT
  85 } /* PrepareContext */