sr_waitevtEx( )

Description | Cautions | Examples | Errors | See Also

Name:	long sr_waitevtEx(handlep, handlecnt, timeout, event_handlep)
Inputs:	long *handlep	pointer to array of handles to wait for event on
	int handlecnt	count of valid handles pointed to by handlep
	long timeout	timeout in milliseconds (msec)
	long *event_handlep	pointer where to return event handle
Returns:	0 if success
	-1 if timeout
Includes:	srllib.h
Type:	Event Control function

Description

The sr_waitevtEx( ) function waits for events on certain devices. This function is an extended version of the standard sr_waitevt( ) function. It is used to asynchronously wait for any event to occur on any of the handles passed to the functions. It detects events from devices opened through any of the device-specific xx_open( ) function calls for that device.

Parameter	Description
handlep	Points to an array of opened handles.
handlecnt	Indicates how many devices are contained in the array.
timeout	A timeout value of -1 instructs sr_waitevt( ) to wait indefinitely for the next event. Use timeout 0 when the SRL event must return imediately, regardlesss of whether or not an event is present in the SRL event queue.
event_handlep	When an event is reported, an event handle is passed backed to the application through the event_handlep argument. The value returned here should be passed to the sr_getevtdev( ) , sr_getevttype( ) , sr_getevtlen( ), and sr_getevtdatap( ) functions to retrieve the event information.

The sr_waitevtEx( ) function can be used in a single-threaded or multithreaded application. Furthermore, functions initiated asynchronously from one thread can be completed and have the event returned by sr_waitevtEx( ) running in another thread. An application might also have multiple threads blocked in sr_waitevtEx( ) waiting for events on the same device, however it is indeterminate which thread picks up the event, so each thread should be running the same state machine.

Cautions

The sr_waitevt( ) and sr_waitevtEx( ) functions should not be used in the same application.

The sr_waitevtEx( ) function can NOT be used in conjunction with handlers.

Example

#include <srllib.h>  
#include <windows.h>  
#include <dxxxlib.h>
  
long  chdev[MAXDEVS];  
unsigned long  evt_handle;
  
main( ... )  
{  
   char channel_name[12];  
   int ch;
  
   for (ch = 0; ch < MAXDEVS; ch++) {  
      /* Build the channel name for each channel */  
      if ( (chdev[ch] = dx_open(channel_name, 0) ) == -1 ) {  
            printf("dx_open failed\n");  
            exit(1);  
       }  
   }
  
   /*  
    * Now initialize each device setting up the event masks and then issue  
    * the command asynchronously to start off the state machine.  
    */  
   for (ch = 0; ch < MAXDEVS; ch++) {  
        /* Set up the event masks and other initialization */
  
        /* set the channel onhook asynchronously */  
        if (dx_sethook( chdev[ch]. DX_ONHOOK, EV_ASYNC) == -1) {  
            /* sethook failed, handle the error */  
        }  
   }
  
   /* This is the main loop to control the Voice hardware */  
   while (FOREVER) {
  
        /* wait for the event */  
        sr_waitevtEx( chdev, MAXDEVS, -1, &evt_handle);  
        process_event( evt_handle);
  
    }
  
    int process_event( ehandle)  
        unsigned long ehandle;  
    {  
          int  voxhandle = sr_getevtdev(ehandle);
  
          switch(sr_getevttype(ehandle)) {  
          case TDX_CST:  
                   .  
                  break;
  
          case TDX_PLAY:  
                    .  
                  break;
  
           }
  
    }

Errors

If this function returns -1 to indicate failure, obtain the reason for the error by calling the SRL standard attribute function ATDV_LASTERR(SRL_DEVICE) or ATDV_ERRMSGP(SRL_DEVICE) to retrieve either the error code or a pointer to the error description, respectively. One of the following errors may be returned:

ESR_SYS

Error from operating system; use dx_fileerrno( ) to obtain error value.

ESR_TMOUT

Timed out waiting for event

See Also

• sr_waitevt( )
• sr_getevtdev( )
• sr_getevttype( )
• sr_getevtlen( )
• sr_getevtdatap( )
• The appropriate technology-specific Programmer's Guide

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