rom/exec/switch.c

   1 /*
   2     Copyright © 1995-2001, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     Desc: Switch() - Switch to the next available task.
   6     Lang: english
   7 */
   8
   9 #include <exec/execbase.h>
  10
  11 /*****************************************************************************
  12
  13     NAME */
  14 #include <proto/exec.h>
  15
  16         AROS_LH0(void, Switch,
  17
  18 /*  LOCATION */
  19         struct ExecBase *, SysBase, 9, Exec)
  20
  21 /*  FUNCTION
  22         Switch to the next task which wishes to be run. This function has
  23         a similar effect to calling Dispatch(), however it may be called
  24         at any time, and will not lose the current task if it is of type
  25         TS_RUN.
  26
  27     INPUTS
  28
  29     RESULT
  30
  31     NOTES
  32         This function will preserve all its registers.
  33
  34     EXAMPLE
  35
  36     BUGS
  37
  38     SEE ALSO
  39         Dispatch(), Reschedule()
  40
  41     INTERNALS
  42         If you want to have this function save all its registers, you
  43         should replace this function in $(KERNEL) or $(ARCH).
  44
  45 ******************************************************************************/
  46 {
  47     AROS_LIBFUNC_INIT
  48
  49     struct Task *this = SysBase->ThisTask;
  50
  51     /*
  52         If the state is not TS_RUN then the task is already in a list
  53     */
  54
  55     /*
  56        This task (= the task that's running in the moment) is
  57        moved to the task ready list with Reschedule(), if necessary.
  58        After that a new task is taken from the task-ready list
  59        and is launched by doing the context switch. This happens
  60        in Dispatch().
  61     */
  62 return;
  63
  64     if( (this->tc_State == TS_RUN)
  65         && !(this->tc_Flags & TF_EXCEPT) )
  66     {
  67         this->tc_State = TS_READY;
  68
  69         /* Use Reschedule() to put the task in the correct list. */
  70         Reschedule(this);
  71     }
  72
  73     /* Call the dispatcher proper. */
  74     Dispatch();
  75
  76     AROS_LIBFUNC_EXIT
  77 } /* Switch() */