rom/exec/disable.c

   1 /*
   2     Copyright © 1995-2010, 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 #include <proto/kernel.h>
  14
  15 #include "exec_intern.h"
  16
  17 /*****************************************************************************/
  18 #undef  Exec
  19 #ifdef UseExecstubs
  20 #    define Exec _Exec
  21 #endif
  22
  23 /*  NAME */
  24 #include <proto/exec.h>
  25
  26         AROS_LH0(void, Disable,
  27
  28 /*  LOCATION */
  29         struct ExecBase *, SysBase, 20, Exec)
  30
  31 /*  FUNCTION
  32         This function will prevent interrupts from occuring. You can
  33         start the interrupts again with a call to Enable().
  34
  35         Note that calls to Disable() nest, and for every call to
  36         Disable() you need a matching call to Enable().
  37
  38         ***** WARNING *****
  39
  40         Using this function is considered very harmful, and it is
  41         not recommended to use this function for ** ANY ** reason.
  42
  43         It is quite possible to either crash the system, or to prevent
  44         normal activities (disk/port i/o) from occuring.
  45
  46         Note: As taskswitching is driven by the interrupts subsystem,
  47               this function has the side effect of disabling
  48               multitasking.
  49
  50     INPUTS
  51
  52     RESULT
  53         Interrupts will be disabled AFTER this call returns.
  54
  55     NOTES
  56         This function preserves all registers.
  57
  58         To prevent deadlocks calling Wait() in disabled state breaks
  59         the disable - thus interrupts may happen again.
  60
  61     EXAMPLE
  62         No you DEFINITELY don't want to use this function.
  63
  64     BUGS
  65         The only architecture that you can rely on the registers being
  66         saved is on the Motorola mc68000 family.
  67
  68     SEE ALSO
  69         Forbid(), Permit(), Enable(), Wait()
  70
  71     INTERNALS
  72         This function must be replaced in the $(KERNEL) or $(ARCH)
  73         directories in order to do some work.
  74
  75 ******************************************************************************/
  76 {
  77 #undef Exec
  78
  79     AROS_LIBFUNC_INIT
  80
  81     if (KernelBase)
  82         KrnCli();
  83
  84 #ifdef AROS_NO_ATOMIC_OPERATIONS
  85     /* Generic atomic operations in aros/atomic.h rely on Disable()/Enable() themselves,
  86        so we have to take care about it here. Otherwise we fall into endless loop.
  87        It is strongly recommended to implement real atomic operations in assembler.
  88        The same is done in Enable() */
  89     SysBase->IDNestCnt++;
  90 #else
  91     AROS_ATOMIC_INC(SysBase->IDNestCnt);
  92 #endif
  93
  94     AROS_LIBFUNC_EXIT
  95 } /* Disable() */