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
   9 #define DEBUG 0
  10 #include <aros/debug.h>
  11
  12 #include <exec/execbase.h>
  13 #include <aros/libcall.h>
  14 #include <proto/exec.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     ULONG rcvd;
  68
  69     D(bug("[Exec] Wait(%08lX)\n", signalSet);)
  70     Disable();
  71
  72     /* If at least one of the signals is already set do not wait. */
  73     while (!(thisTask->tc_SigRecvd & signalSet))
  74     {
  75         /* Set the wait signal mask */
  76         thisTask->tc_SigWait = signalSet;
  77
  78         D(bug("[Exec] Wait: Moving '%s' @ 0x%p to Task Wait queue\n", thisTask->tc_Node.ln_Name, thisTask);)
  79         D(bug("[Exec] Wait: Task state = %08x\n", thisTask->tc_State);)
  80
  81         /*
  82             Clear TDNestCnt (because Switch() will not care about it),
  83             but memorize it first. IDNestCnt is handled by Switch().
  84             */
  85         thisTask->tc_TDNestCnt = TDNESTCOUNT_GET;
  86         D(bug("[Exec] Wait: Task TDNestCount = %d\n", thisTask->tc_TDNestCnt);)
  87         TDNESTCOUNT_SET(-1);
  88
  89         thisTask->tc_State = TS_WAIT;
  90         // nb: on smp builds switch will move us.
  91 #if !defined(__AROSEXEC_SMP__)
  92         /* Move current task to the waiting list. */
  93         Enqueue(&SysBase->TaskWait, &thisTask->tc_Node);
  94 #endif
  95
  96         /* And switch to the next ready task. */
  97         KrnSwitch();
  98
  99         /*
 100             OK. Somebody awakened us. This means that either the
 101             signals are there or it's just a finished task exception.
 102             Test again to be sure (see above).
 103         */
 104         D(bug("[Exec] Wait: Awoken...\n");)
 105
 106         /* Restore TDNestCnt. */
 107         TDNESTCOUNT_SET(thisTask->tc_TDNestCnt);
 108     }
 109     /* Get active signals. */
 110     rcvd = (thisTask->tc_SigRecvd & signalSet);
 111
 112     /* And clear them. */
 113 #if defined(__AROSEXEC_SMP__)
 114     __AROS_ATOMIC_AND_L(thisTask->tc_SigRecvd, ~signalSet);
 115 #else
 116     thisTask->tc_SigRecvd &= ~signalSet;
 117 #endif
 118     Enable();
 119
 120     /* All done. */
 121     return rcvd;
 122
 123     AROS_LIBFUNC_EXIT
 124 }
 125