rom/exec/disable.c

   1 /*
   2     Copyright © 1995-2017, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     Desc: Disable() - Stop interrupts from occurring.
   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
  14 #include "exec_intern.h"
  15
  16 /*****************************************************************************/
  17 #undef  Exec
  18 #ifdef UseExecstubs
  19 #    define Exec _Exec
  20 #endif
  21
  22 /*  NAME */
  23 #include <proto/exec.h>
  24
  25         AROS_LH0(void, Disable,
  26
  27 /*  LOCATION */
  28         struct ExecBase *, SysBase, 20, Exec)
  29
  30 /*  FUNCTION
  31         This function will prevent interrupts from occuring (*). You can
  32         start the interrupts again with a call to Enable().
  33
  34         Note that calls to Disable() nest, and for every call to
  35         Disable() you need a matching call to Enable().
  36
  37         ***** WARNING *****
  38
  39         Using this function is considered very harmful, and it should only
  40         ever be used to protect data that could also be accessed in interrupts.
  41
  42         It is quite possible to either crash the system, or to prevent
  43         normal activities (disk/port i/o) from occuring.
  44
  45     INPUTS
  46
  47     RESULT
  48         Interrupts will be disabled AFTER this call returns.
  49
  50     NOTES
  51         This function preserves all registers.
  52
  53         To prevent deadlocks calling Wait() in disabled state breaks
  54         the disable - thus interrupts may happen again.
  55
  56         As the schedulers pre-emption is interrupt driven,
  57         this function has the side effect of disabling
  58         multitasking.
  59
  60         (*) On EXECSMP builds, Disable() only aplies to the processor
  61             it is called from (and needs to be re-enabled there also)
  62             Data which needs to be protected from parallel access will
  63             also require a spinlock.
  64
  65     EXAMPLE
  66         In most userspace code, you will not want to use this function.
  67
  68     BUGS
  69         The only architecture that you can rely on the registers being
  70         saved is on the Motorola mc68000 family.
  71
  72     SEE ALSO
  73         Forbid(), Permit(), Enable(), Wait()
  74
  75     INTERNALS
  76         This function must be replaced in the $(KERNEL) or $(ARCH)
  77         directories in order to do some work.
  78
  79 ******************************************************************************/
  80 {
  81 #undef Exec
  82
  83     AROS_LIBFUNC_INIT
  84
  85     D(bug("[Exec] Disable()\n");)
  86
  87     if (KernelBase)
  88         KrnCli();
  89
  90     IDNESTCOUNT_INC;
  91
  92     D(bug("[Exec] Disable: IDNESTCOUNT = %d\n", IDNESTCOUNT_GET);)
  93
  94     AROS_LIBFUNC_EXIT
  95 } /* Disable() */