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368 Voice API for Windows Operating Systems Library Reference — November 2003
dx_setchxfercnt( ) — set the bulk queue buffer size
!
!!
! Cautions
• This function fails if an invalid device handle is specified.
• Do not use this function unless it is absolutely necessary to change the bulk queue buffer size
between a user application and Intel® telecom 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.
• On DM3 boards, it is not recommended to set the bulk queue buffer size to less than 2 kbytes
as this can result in loss of data (underrun condition) under high density load. To monitor
underrun conditions, set DM_UNDERRUN in dx_setevtmsk( ).
!
!!
! Errors
If the function returns -1, use the Standard Runtime Library (SRL) Standard Attribute function
ATDV_LASTERR( ) to obtain the error code or use ATDV_ERRMSGP( ) to obtain a descriptive
error message. One of the following error codes may be returned:
EDX_ BADPARM
Invalid parameter
EDX_SYSTEM
Error from operating system; use dx_fileerrno( ) to obtain error value
!
!!
! Example
#include <windows.h>
#include "srllib.h"
#include "dxxxlib.h"
main()
{
int dev; /* 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);
}
}
!
!!
! See Also
• dx_setuio( )
• dx_playiottdata( )
• dx_reciottdata( )
• DXCH_XFERBUFSIZE in dx_setparm( )