dx_setdevuio( )

Description | Cautions | Errors | Example | See Also

Name:	int dx_setdevuio(chdev, setuiop, getuiopp)
Inputs:	int chdev	Valid Dialogic channel device handle
	DX_UIO *setuiop	Pointer to user I/O routines structure
	DX_UIO **getuiopp	Pointer to return pointer for user I/O routines structure
	short evtlen	Length of the data block in bytes
	unsigned short flags	SENDSELF/SENDOTHERS/SENDALL
Returns:	0 if successful
	-1 error return code
Includes:	dxxxlib.h
	srllib.h
Mode:	Synchronous

Description

The dx_setdevuio( ) function will enable the application to install and retrieve user-defined I/O functions on a per Dialogic channel device basis. The user I/O functions installed using this function will be used on all subsequent I/O operations performed on the channel even if the application installs global user I/O functions for all devices using the dx_setuio( ) function. The user I/O functions are installed by installing a pointer to a DX_UIO structure which contains addresses of the user-defined I/O functions.

The first argument to the function is chdev, the descriptor of a Dialogic channel device. This specifies the channel for which the user-defined I/O functions will be installed. The second argument, setuiop, is a pointer to an application-defined global DX_UIO structure which contains the addresses of the user-defined I/O functions. This pointer to the DX_UIO structure will be stored in the Dialogic Voice DLL for the specified chdev channel device. The application must not overwrite the DX_UIO structure until dx_setdevuio( ) has been called again for this device with the pointer to another DX_UIO structure. The third argument, getuiopp, is the address of a pointer to a DX_UIO structure. Any previously installed I/O functions for the chdev device are returned to the application as a pointer to DX_UIO structure in getuiopp. If this is the first time dx_setdevuio( ) is called for a device, then getuiopp will be filled with the pointer to the global DX_UIO structure which may contain addresses of the user-defined I/O function that apply to all devices.

Either of setuiop or getuiopp may be NULL, but not both at the same time. If getuiopp is NULL, the dx_setdevuio( ) function will only install the user I/O functions specified via the DX_UIO pointer in setuiop but will not return the address of the previously installed DX_UIO structure. If setuiop is NULL, then the previously installed DX_UIO structure pointer will be returned in getuiopp but no new functions will be installed.

Cautions

The DX_UIO structure pointed to by setuiop must not be altered until the next call to dx_setdevuio( ) with new values for user-defined I/O functions.

For proper operation, it is the application's responsibility to properly define the three DX_UIO user routines; u_read, u_write and u_seek. Refer to the DX_UIO structure in the chapter on Data Structures for more information.

Errors

If the function returns -1 to indicate an error, use the SRL Standard Attribute function ATDV_LASTERR( ) to obtain the error code or you can use ATDV_ERRMSGP( ) to obtain a descriptive error message. The error codes returned by ATDV_LASTERR( ) are:

Equate	Returned When
EDX_BADPARM	Invalid Parameter
EDX_BADDEV	Invalid Device Descriptor

Example

#include "windows.h"

#include "srllib.h"

#include "dxxxlib.h"



int chdev;                       /* channel descriptor */

DX_UIO devio;                    /* User defined I/O functions */

DX_UIO *getiop;                  /* Retrieve I/O functions */





int appread(fd, ptr, cnt)

     int            fd;

     char          *ptr;

     unsigned       cnt;

{

     printf("appread: Read request\n");

     return(read(fd, ptr, cnt));

}





int appwrite(fd, ptr, cnt)

     int               fd;

     char             *ptr;

     unsigned          cnt;

{

     printf("appwrite: Write request\n");

     return(write(fd, ptr, cnt));

}





int appseek(fd, offset, whence)

     int               fd;

     long              offset;

     int               whence;

{

     printf("appseek: Seek request\n");

     return(lseek(fd, offset, whence));

}

  
   
main(argc, argv)  
     int          argc;  
     char     *argv[];  
{
  
/* Open channel */  
if ((chdev = dx_open("dxxxB1C1",0)) == -1) {  
     printf("Cannot open channel\n");  
     /* Perform system error processing */  
     exit(1);  
}  
     .  
     .  /* Other initialization */  
     .  
/* Initialize the device specific UIO structure */  
devio.u_read  = appread;  
devio.u_write = appwrite;  
devio.u_seek  = appseek;
  
/* Install the applications I/O routines */  
if (dx_setdevuio(chdev, &devio, &getiop) == -1) {  
     printf("error registering the UIO routines = %d\n", ATDV_LASTERR(chdev) );  
   }}

See Also

dx_setuio( )

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