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 #if defined(__AROSEXEC_SMP__)
  18 #include "etask.h"
  19 #endif
  20
  21 /*****************************************************************************
  22
  23     NAME */
  24
  25         AROS_LH1(ULONG, Wait,
  26
  27 /*  SYNOPSIS */
  28         AROS_LHA(ULONG, signalSet, D0),
  29
  30 /*  LOCATION */
  31         struct ExecBase *, SysBase, 53, Exec)
  32
  33 /*  FUNCTION
  34         Wait until some signals are sent to the current task. If any signal
  35         of the specified set is already set when entering this function it
  36         returns immediately. Since almost any event in the OS can send a
  37         signal to your task if you specify it to do so signals are a very
  38         powerful mechanism.
  39
  40     INPUTS
  41         signalSet - The set of signals to wait for.
  42
  43     RESULT
  44         The set of active signals.
  45
  46     NOTES
  47         Naturally it's not allowed to wait in supervisor mode.
  48
  49         Calling Wait() breaks an active Disable() or Forbid().
  50
  51     EXAMPLE
  52
  53     BUGS
  54
  55     SEE ALSO
  56         Signal(), SetSignal(), AllocSignal(), FreeSignal()
  57
  58     INTERNALS
  59
  60     HISTORY
  61
  62 ******************************************************************************/
  63 {
  64     AROS_LIBFUNC_INIT
  65
  66     struct Task *ThisTask = GET_THIS_TASK;
  67 #if defined(__AROSEXEC_SMP__)
  68     spinlock_t *task_listlock = NULL;
  69 #endif
  70     ULONG rcvd;
  71
  72     D(bug("[Exec] Wait(%08lX)\n", signalSet));
  73 #if !defined(__AROSEXEC_SMP__)
  74     Disable();
  75 #endif
  76
  77     /* If at least one of the signals is already set do not wait. */
  78     while (!(ThisTask->tc_SigRecvd & signalSet))
  79     {
  80         /* Set the wait signal mask */
  81         ThisTask->tc_SigWait = signalSet;
  82 #if defined(__AROSEXEC_SMP__)
  83         if (ThisTask->tc_State != TS_WAIT)
  84         {
  85 #endif
  86         D(bug("[Exec] Moving '%s' @ 0x%p to Task Wait queue\n", ThisTask->tc_Node.ln_Name, ThisTask));
  87         D(bug("[Exec] Task state = %08x\n", ThisTask->tc_State));
  88
  89         /* Protect the task lists against access by other tasks. */
  90 #if defined(__AROSEXEC_SMP__)
  91             switch (ThisTask->tc_State)
  92             {
  93                 case TS_RUN:
  94                     task_listlock = &PrivExecBase(SysBase)->TaskRunningSpinLock;
  95                     break;
  96                 default:
  97                     task_listlock = &PrivExecBase(SysBase)->TaskReadySpinLock;
  98                     break;
  99             }
 100             EXEC_SPINLOCK_LOCK(task_listlock, SPINLOCK_MODE_WRITE);
 101             Forbid();
 102             Remove(&ThisTask->tc_Node);
 103             EXEC_SPINLOCK_UNLOCK(task_listlock);
 104             Permit();
 105             EXEC_SPINLOCK_LOCK(&PrivExecBase(SysBase)->TaskWaitSpinLock, SPINLOCK_MODE_WRITE);
 106             Forbid();
 107 #endif
 108         /*
 109             Clear TDNestCnt (because Switch() will not care about it),
 110             but memorize it first. IDNestCnt is handled by Switch().
 111         */
 112         ThisTask->tc_TDNestCnt = TDNESTCOUNT_GET;
 113         TDNESTCOUNT_SET(-1);
 114
 115         /* Move current task to the waiting list. */
 116         ThisTask->tc_State = TS_WAIT;
 117         Enqueue(&SysBase->TaskWait, &ThisTask->tc_Node);
 118 #if defined(__AROSEXEC_SMP__)
 119             EXEC_SPINLOCK_UNLOCK(&PrivExecBase(SysBase)->TaskWaitSpinLock);
 120         }
 121         else
 122         {
 123             Forbid();
 124             ThisTask->tc_TDNestCnt = TDNESTCOUNT_GET;
 125             TDNESTCOUNT_SET(-1);
 126         }
 127 #endif
 128         /* And switch to the next ready task. */
 129         KrnSwitch();
 130
 131         /*
 132             OK. Somebody awakened us. This means that either the
 133             signals are there or it's just a finished task exception.
 134             Test again to be sure (see above).
 135         */
 136
 137         /* Restore TDNestCnt. */
 138         TDNESTCOUNT_SET(ThisTask->tc_TDNestCnt);
 139
 140 #if defined(__AROSEXEC_SMP__)
 141         Permit();
 142 #endif
 143     }
 144     /* Get active signals. */
 145     rcvd = (ThisTask->tc_SigRecvd & signalSet);
 146
 147     /* And clear them. */
 148 #if defined(__AROSEXEC_SMP__)
 149     EXEC_SPINLOCK_LOCK(&IntETask(ThisTask->tc_UnionETask.tc_ETask)->iet_TaskLock, SPINLOCK_MODE_WRITE);
 150     Disable();
 151 #endif
 152     ThisTask->tc_SigRecvd &= ~signalSet;
 153 #if defined(__AROSEXEC_SMP__)
 154     EXEC_SPINLOCK_UNLOCK(&IntETask(ThisTask->tc_UnionETask.tc_ETask)->iet_TaskLock);
 155 #endif
 156     Enable();
 157
 158     /* All done. */
 159     return rcvd;
 160
 161     AROS_LIBFUNC_EXIT
 162 }
 163