Voice Software Reference: Programmer's Guide: dx

dx_setchxfercnt( )

Description | Cautions | Example | Errors | See Also

Name:

int dx_setchxfercnt(chdev, bufnum, bufsize_identifier)

Inputs:

int chdev

int bufnum
int bufsize_identifier

valid Dialogic channel device handle
allows for smaller driver data transfer buffer size
equate for a buffer size

Returns:

0 to indicate successful completion

-1 if failure

Includes:

srllib.h

dxxxlib.h

Mode:

Synchronous

Description

The dx_setchxfercnt( ) function sets the bulk queue buffer size for the channel. This function can change the size of the buffer used to transfer voice data between a user application and the Dialogic hardware. The dx_setchxfercnt(int chDev, int bufnum) allows a smaller driver data transfer buffer size. The minimum buffer size is now 1.5KB.

The largest available buffer size is 8K, which is the default. In general, this function is used in conjunction with the User I/O feature; for more information, see the dx_setuio function. This function sets up the frequency with which the application-registered read or write functions are called by the voice dll. For applications requiring more frequent access to voice data in smaller chunks, you can use this function on a per channel basis to lower the buffer size.

Parameter

Description

chdev

Specifies the valid device handle obtained when the device was opened using xx_open( ), where "xx" is the prefix identifying the device to be opened.

bufsize_identifier

Specifies the bulk queue buffer size for the channel. Use one of the following values:

1

Sets the buffer size to 8K (default).

0

Sets the buffer size to 4K.

4

Sets the buffer size to 2K.

6

Sets the buffer size to 1.5K.

Equates for these values are not available as #define in any header file.

Cautions

This function fails if an invalid device handle is specified.
Do not use this function unless it is absolutely necessary to change the data transfer size between a user application and Dialogic hardware. Setting the buffer size to a smaller value can degrade system performance because data is transferred in smaller chunks.
A wrong buffer size can result in loss of data.

Example

#include <windows.h>  
   #include "srllib.h"  
   #include "dxxxlib.h"  
   int dev;   /* Dialogic device handle */  
   /* Open board 1 channel 1 device */  
   if ((dev = dx_open("dxxxB1C1", 0)) == -1) {  
    /* Perform system error processing */  
   exit(1);  
   }  
   /* Set the bulk data transfer buffer size to 1.5 kilobytes  
   */  
   if (dx_setchxfercnt(dev, 6) == -1) {  
    printf("Error message = %s", ATDV_ERRMSGP(dev));  
   exit(1);  
   }

Errors

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

EDX_ BADPARM

Invalid parameter

EDX_SYSTEM

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

Name:	int dx_setchxfercnt(chdev, bufnum, bufsize_identifier)
Inputs:	int chdev int bufnum int bufsize_identifier	valid Dialogic channel device handle allows for smaller driver data transfer buffer size equate for a buffer size
Returns:	0 to indicate successful completion
	-1 if failure
Includes:	srllib.h
	dxxxlib.h
Mode:	Synchronous

Parameter	Description
chdev	Specifies the valid device handle obtained when the device was opened using xx_open( ), where "xx" is the prefix identifying the device to be opened.
bufsize_identifier	Specifies the bulk queue buffer size for the channel. Use one of the following values:
	1	Sets the buffer size to 8K (default).
	0	Sets the buffer size to 4K.
	4	Sets the buffer size to 2K.
	6	Sets the buffer size to 1.5K.

EDX_ BADPARM	Invalid parameter
EDX_SYSTEM	Error from operating system; use dx_fileerrno( ) to obtain error value