rom/exec/wait.c

   1 /*
   2     Copyright © 1995-2017, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     Desc: Wait for some signal.
   6     Lang: english
   7 */
   8 #define DEBUG 0
   9
  10 #include <aros/debug.h>
  11 #include <exec/execbase.h>
  12 #include <aros/libcall.h>
  13 #include <proto/exec.h>
  14
  15 #include "exec_intern.h"
  16 #if defined(__AROSEXEC_SMP__)
  17 #include "etask.h"
  18 #endif
  19
  20 /*****************************************************************************
  21
  22     NAME */
  23
  24         AROS_LH1(ULONG, Wait,
  25
  26 /*  SYNOPSIS */
  27         AROS_LHA(ULONG, signalSet, D0),
  28
  29 /*  LOCATION */
  30         struct ExecBase *, SysBase, 53, Exec)
  31
  32 /*  FUNCTION
  33         Wait until some signals are sent to the current task. If any signal
  34         of the specified set is already set when entering this function it
  35         returns immediately. Since almost any event in the OS can send a
  36         signal to your task if you specify it to do so signals are a very
  37         powerful mechanism.
  38
  39     INPUTS
  40         signalSet - The set of signals to wait for.
  41
  42     RESULT
  43         The set of active signals.
  44
  45     NOTES
  46         Naturally it's not allowed to wait in supervisor mode.
  47
  48         Calling Wait() breaks an active Disable() or Forbid().
  49
  50     EXAMPLE
  51
  52     BUGS
  53
  54     SEE ALSO
  55         Signal(), SetSignal(), AllocSignal(), FreeSignal()
  56
  57     INTERNALS
  58
  59     HISTORY
  60
  61 ******************************************************************************/
  62 {
  63     AROS_LIBFUNC_INIT
  64
  65     struct Task *thisTask = GET_THIS_TASK;
  66     ULONG rcvd;
  67
  68     D(bug("[Exec] Wait(%08lX)\n", signalSet);)
  69     Disable();
  70
  71     /* If at least one of the signals is already set do not wait. */
  72     while (!(thisTask->tc_SigRecvd & signalSet))
  73     {
  74         /* Set the wait signal mask */
  75         thisTask->tc_SigWait = signalSet;
  76
  77         D(bug("[Exec] Moving '%s' @ 0x%p to Task Wait queue\n", thisTask->tc_Node.ln_Name, thisTask);)
  78         D(bug("[Exec] Task state = %08x\n", thisTask->tc_State);)
  79
  80         /*
  81             Clear TDNestCnt (because Switch() will not care about it),
  82             but memorize it first. IDNestCnt is handled by Switch().
  83             */
  84         thisTask->tc_TDNestCnt = TDNESTCOUNT_GET;
  85         TDNESTCOUNT_SET(-1);
  86
  87         thisTask->tc_State = TS_WAIT;
  88         // nb: on smp builds switch will move us.
  89 #if !defined(__AROSEXEC_SMP__)
  90         /* Move current task to the waiting list. */
  91         Enqueue(&SysBase->TaskWait, &thisTask->tc_Node);
  92 #endif
  93
  94         /* And switch to the next ready task. */
  95         KrnSwitch();
  96
  97         /*
  98             OK. Somebody awakened us. This means that either the
  99             signals are there or it's just a finished task exception.
 100             Test again to be sure (see above).
 101         */
 102
 103         /* Restore TDNestCnt. */
 104         TDNESTCOUNT_SET(thisTask->tc_TDNestCnt);
 105     }
 106     /* Get active signals. */
 107     rcvd = (thisTask->tc_SigRecvd & signalSet);
 108
 109     /* And clear them. */
 110 #if defined(__AROSEXEC_SMP__)
 111     __AROS_ATOMIC_AND_L(thisTask->tc_SigRecvd, ~signalSet);
 112 #else
 113     thisTask->tc_SigRecvd &= ~signalSet;
 114 #endif
 115     Enable();
 116
 117     /* All done. */
 118     return rcvd;
 119
 120     AROS_LIBFUNC_EXIT
 121 }
 122