arch/all-mingw32/exec/permit.c

   1 /*
   2     Copyright © 1995-2001, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     Desc: Permit() - Allow tasks switches to occur.
   6     Lang: english
   7 */
   8
   9 #include <exec/types.h>
  10 #include <exec/execbase.h>
  11 #include <aros/libcall.h>
  12 #include <aros/atomic.h>
  13 #include <aros/debug.h>
  14 #include <proto/exec.h>
  15 #include <proto/kernel.h>
  16
  17 #undef Exec
  18 #ifdef UseExecstubs
  19 #    define Exec _Exec
  20 #endif
  21
  22 /*  NAME */
  23
  24         AROS_LH0(void, Permit,
  25
  26 /*  LOCATION */
  27         struct ExecBase *, SysBase, 23, Exec)
  28
  29 /*  FUNCTION
  30         This function will reactivate the task dispatcher after a call
  31         to Forbid(). Note that calls to Forbid() nest, and for every
  32         call to Forbid() you need a matching call to Permit().
  33
  34     INPUTS
  35         None.
  36
  37     RESULT
  38         Multitasking will be re-enabled.
  39
  40     NOTES
  41         This function preserves all registers.
  42
  43         To prevent deadlocks calling Wait() in forbidden state breaks
  44         the forbid - thus taskswitches may happen again.
  45
  46     EXAMPLE
  47         No you really don't want to use this function.
  48
  49 BUGS
  50     The only architecture that you can rely on the registers being
  51     saved is on the Motorola mc68000 family.
  52
  53 SEE ALSO
  54     Forbid(), Disable(), Enable(), Wait()
  55
  56 INTERNALS
  57     If you want to preserve all the registers, replace this function
  58     in your $(KERNEL) directory. Otherwise this function is
  59     satisfactory.
  60
  61 HISTORY
  62
  63 ******************************************************************************/
  64 #undef Exec
  65 {
  66     AROS_LIBFUNC_INIT
  67
  68     /*
  69         Task switches are allowed again, if a switch is pending, we
  70         should allow it.
  71      */
  72
  73     AROS_ATOMIC_DEC(SysBase->TDNestCnt);
  74
  75     if(    ( SysBase->TDNestCnt < 0 )
  76         && ( SysBase->IDNestCnt < 0 )
  77         && ( SysBase->AttnResched & 0x80 ) )
  78     {
  79         /* Haha, you re-enabled multitasking, only to have the rug
  80            pulled out from under you feet :)
  81
  82            Clear the Switch() pending flag.
  83          */
  84
  85         if (KernelBase && !KrnIsSuper()) KrnSchedule();
  86     }
  87
  88     AROS_LIBFUNC_EXIT
  89 } /* Permit() */