arch/.unmaintained/arm-all/exec/enable.c

   1 /*
   2     Copyright © 1995-2001, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     Desc: Enable() - Allow interrupts to occur after Disable().
   6     Lang: english
   7 */
   8
   9 #include <exec/types.h>
  10 #include <exec/execbase.h>
  11 #include <aros/libcall.h>
  12 #include <asm/registers.h>
  13
  14 /*****************************************************************************/
  15 #undef Exec
  16 #ifdef UseExecstubs
  17 #    define Exec _Exec
  18 #endif
  19
  20 /*  NAME */
  21 #include <proto/exec.h>
  22
  23         AROS_LH0(void, Enable,
  24
  25 /*  LOCATION */
  26         struct ExecBase *, SysBase, 21, Exec)
  27
  28 /*  FUNCTION
  29         This function will allow interrupts to occur after they have
  30         been disabled by Disable().
  31
  32         Note that calls to Disable() nest, and for every call to
  33         Disable() you need a matching call to Enable().
  34
  35         ***** WARNING *****
  36
  37         Using this function is considered very harmful, and it is
  38         not recommended to use this function for ** ANY ** reason.
  39
  40         It is quite possible to either crash the system, or to prevent
  41         normal activities (disk/port i/o) from occuring.
  42
  43         Note: As taskswitching is driven by the interrupts subsystem,
  44               this function has the side effect of disabling
  45               multitasking.
  46
  47     INPUTS
  48         None.
  49
  50     RESULT
  51         Interrupts will be enabled again when this call returns.
  52
  53     NOTES
  54         This function preserves all registers.
  55
  56         To prevent deadlocks calling Wait() in disabled state breaks
  57         the disable - thus interrupts may happen again.
  58
  59     EXAMPLE
  60         No you DEFINITATELY don't want to use this function.
  61
  62     BUGS
  63         The only architecture that you can rely on the registers being
  64         saved is on the Motorola mc68000 family.
  65
  66     SEE ALSO
  67         Forbid(), Permit(), Disable(), Wait()
  68
  69     INTERNALS
  70         This function must be replaced in the $(KERNEL) or $(ARCH)
  71         directories in order to do some work.
  72
  73     HISTORY
  74
  75 ******************************************************************************/
  76 {
  77 #undef Exec
  78
  79         AROS_LIBFUNC_INIT
  80
  81         if( --SysBase->IDNestCnt < 0) {
  82                 SetSR(0x00000000, 0x00000080);
  83         }
  84
  85         AROS_LIBFUNC_EXIT
  86 } /* Enable() */