rom/exec/wait.c

   1 /*
   2     Copyright © 1995-2015, 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 #include <proto/kernel.h>
  15
  16 #include "exec_intern.h"
  17
  18 /*****************************************************************************
  19
  20     NAME */
  21
  22         AROS_LH1(ULONG, Wait,
  23
  24 /*  SYNOPSIS */
  25         AROS_LHA(ULONG, signalSet, D0),
  26
  27 /*  LOCATION */
  28         struct ExecBase *, SysBase, 53, Exec)
  29
  30 /*  FUNCTION
  31         Wait until some signals are sent to the current task. If any signal
  32         of the specified set is already set when entering this function it
  33         returns immediately. Since almost any event in the OS can send a
  34         signal to your task if you specify it to do so signals are a very
  35         powerful mechanism.
  36
  37     INPUTS
  38         signalSet - The set of signals to wait for.
  39
  40     RESULT
  41         The set of active signals.
  42
  43     NOTES
  44         Naturally it's not allowed to wait in supervisor mode.
  45
  46         Calling Wait() breaks an active Disable() or Forbid().
  47
  48     EXAMPLE
  49
  50     BUGS
  51
  52     SEE ALSO
  53         Signal(), SetSignal(), AllocSignal(), FreeSignal()
  54
  55     INTERNALS
  56
  57     HISTORY
  58
  59 ******************************************************************************/
  60 {
  61     AROS_LIBFUNC_INIT
  62
  63     ULONG rcvd;
  64     struct Task *me;
  65
  66     /* Get pointer to current task - I'll need it very often */
  67     me = FindTask(NULL);
  68
  69     D(bug("[Exec] Wait(0x%08lX)\n", signalSet));
  70
  71     /* If at least one of the signals is already set do not wait. */
  72     while (!(me->tc_SigRecvd & signalSet))
  73     {
  74 #if defined(__AROSEXEC_SMP__)
  75         if (me->tc_State != TS_WAIT)
  76         {
  77 #endif
  78         D(bug("[Exec] Moving '%s' @ 0x%p to Task Wait queue\n", me->tc_Node.ln_Name, me));
  79         D(bug("[Exec] Task state = %08x\n", me->tc_State));
  80         /* Set the wait signal mask */
  81         me->tc_SigWait = signalSet;
  82
  83         /*
  84             Clear TDNestCnt (because Switch() will not care about it),
  85             but memorize it first. IDNestCnt is handled by Switch().
  86         */
  87         me->tc_TDNestCnt = TDNESTCOUNT_GET;
  88         TDNESTCOUNT_SET(-1);
  89
  90         /* Protect the task lists against access by other tasks. */
  91 #if defined(__AROSEXEC_SMP__)
  92             EXEC_SPINLOCK_LOCK(&PrivExecBase(SysBase)->TaskRunningSpinLock, SPINLOCK_MODE_WRITE);
  93 #endif
  94         Disable();
  95
  96 #if defined(__AROSEXEC_SMP__)
  97             Remove(&me->tc_Node);
  98             EXEC_SPINLOCK_UNLOCK(&PrivExecBase(SysBase)->TaskRunningSpinLock);
  99             Enable();
 100             EXEC_SPINLOCK_LOCK(&PrivExecBase(SysBase)->TaskWaitSpinLock, SPINLOCK_MODE_WRITE);
 101             Disable();
 102 #endif
 103         /* Move current task to the waiting list. */
 104         me->tc_State = TS_WAIT;
 105         Enqueue(&SysBase->TaskWait, &me->tc_Node);
 106 #if defined(__AROSEXEC_SMP__)
 107             EXEC_SPINLOCK_UNLOCK(&PrivExecBase(SysBase)->TaskWaitSpinLock);
 108 #endif
 109         /* And switch to the next ready task. */
 110         KrnSwitch();
 111
 112         /*
 113             OK. Somebody awakened me. This means that either the
 114             signals are there or it's just a finished task exception.
 115             Test again to be sure (see above).
 116         */
 117
 118         /* Restore TDNestCnt. */
 119         TDNESTCOUNT_SET(me->tc_TDNestCnt);
 120
 121         Enable();
 122 #if defined(__AROSEXEC_SMP__)
 123         }
 124  #endif
 125     }
 126     /* Get active signals. */
 127     rcvd = (me->tc_SigRecvd & signalSet);
 128
 129     /* And clear them. */
 130     me->tc_SigRecvd &= ~signalSet;
 131
 132     /* All done. */
 133     return rcvd;
 134
 135     AROS_LIBFUNC_EXIT
 136 }
 137