ms_listen( )

---

Cautions | Errors | Example | See Also

Name:	int ms_listen (devh, tsinfop)
Inputs:	int devh	MSI station device handle
	SC_TSINFO *tsinfop	pointer to TDM bus time slot information structure
Returns:	0 on success -1 on failure
Includes:	srllib.h dtilib.h msilib.h
Category:	TDM Bus Routing
Mode:	asynchronous
Platform:	DI, HDSI, Springware

Description

The ms_listen( ) function connects the receive channel of a station to a TDM bus time slot.

Parameter	Description
devh	the board device handle
tsinfop	pointer to the TDM bus time slot information structure, see SC_TSINFO for details.

Notes:

1. An MSI station device can listen to one and only one time slot at a time, however, multiple devices may listen to the same time slot at the same time.
2. We recommend that you issue a call to ms_unlisten( ) before invoking this function.

Cautions

• The ms_listen( ) function can take up to 30 msec to execute when running under the Linux® operating system. On the Windows® operating system, this function executes in approximately 1 msec.
• This function fails when:
  • An invalid station handle is specified
  • The TDM bus time slot number is invalid
• By default, MSI stations do not drive audio data onto their assigned TDM bus time slot. MSI stations only transmit audio data after receiving an ms_listen( ) command. An application requiring an MSI station to transmit audio data without listening to another device (as in half-duplex mode) can have the MSI station listen to its own TDM bus time slot. This is accomplished as shown in the code sample below:

#include <windows.h>      /* For Windows applications only */
#include "srllib.h"
#include "dtilib.h"
#include "msilib.h"
#include "errno.h"  
int  chdev1;              /* Channel dev descriptor */
int  tsdev1;              /* Time slot dev desc */
SC_TSINFO  tsinfo;        /* Time slot info     */
long scts;                /* SCbus time slot    */  
/* Open board 1, channel 1 device */
if ((chdev1 = ms_open("msiB1C1",0) == -1) {
    printf("Cannot open MSIB1C1. errno = %d", errno);
    exit(1);
}  
if ((tsdev1 = dt_open("dtiB1T1",0) == -1) {
    printf("Cannot open dtiB1T1. errno = %d", errno);
    exit(1);
}  
/* Setup SC_TSINFO structure  */  
tsinfo.sc_numts = 1;
tsinfo.sc_tsarray = &scts;  
/* Get transmit time slot of MSI/SC device chdev1*/
if (ms_getxmitslot(chdev1, &tsinfo) == -1){
    printf("Error Message = %s",ATDV_ERRMSGP(chdev1));
    exit(1);
}  
/* Make chdev1 listen to itself */
if (ms_listen(chdev1, &tsinfo) == -1){
    printf("Error Message = %s",ATDV_ERRMSGP(chdev1));
    exit(1);
}  
/* chdev1 is now transmitting on its SCbus time slot. Now, make tsdev1 listen to chdev1 */
if (dt_listen(tsdev1, &tsinfo) == -1){
    printf("Error Message = %s",ATDV_ERRMSGP(tsdev1));
    exit(1);
}  
/* Continue processing */
if (dt_close(tsdev1) == -1){
    printf("Could not Close msiB1C1. errno = %d", errno);
    exit(1);
}
if (ms_close(chdev1) == -1){
    printf("Could not Close msiB1C1. errno = %d", errno);
    exit(1);
} 
 

Errors

If this function returns -1 to indicate failure, obtain the reason for the error by calling the SRL standard attribute function ATDV_LASTERR( ) or ATDV_ERRMSGP( ) to retrieve either the error code or a pointer to the error description, respectively.

Refer to the error type tables found in Chapter 5, "Error Codes".

Example

#include <windows.h>           /* For Windows applications only */
#include "srllib.h"
#include "dtilib.h"
#include "msilib.h"
#include "errno.h" 
int       chdev1, tsdev4;      /* Chan dev descriptor variables */
SC_TSINFO tsinfo;              /* Time slot information structure */
long       scts;               /* SCbus time slot */  
/* Open board 1, channel 1 device */
if ((chdev1 = ms_open("msiB1C1",0)) == -1) {
    printf( "Cannot open MSI B1, C1: errno=%d", errno);
    exit(1);
}
/* Open board 1, time slot 4 device */
if ((tsdev1 = dt_open("dtiB1T4",0)) == -1) {
    printf( "Cannot open DTI B1, T4: errno=%d", errno);
    exit(1);
}
/* Set up SC_TSINFO structure */
tsinfo.sc_numts = 1;
tsinfo.sc_tsarray = &scts;  
/* Get time slot on which DTI board 1, time slot 4 is transmitting */
if (dt_getxmitslot(tsdev4,&tsinfo) == -1) {
    printf("Error message = %s", ATDV_ERRMSGP(chdev));
    exit(1);
}  
/* Make MSI board 1, station 1 listen to transmit time slot
     of DTI Board 1 time slot 4 on SCbus */
if (ms_listen(chdev1,&tsinfo) == -1) {
    printf("Error Message = %s",ATDV_ERRMSGP(tsdev4));
    exit(1);
}  

See Also

• ms_getxmitslot( )
• ms_unlisten( )

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