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       comedi_mark_buffer_written - streaming buffer control


       #include <comedilib.h>

       int   comedi_mark_buffer_written   (comedi_t  *  device,  unsigned  int
       subdevice, unsigned int num_bytes);


       The function comedi_mark_buffer_written() is used on a  subdevice  that
       has a Comedi output command in progress.  It should only be used if you
       are using a mmap() (as opposed to calling write() on the  device  file)
       to  write data to Comedi’s buffer, since Comedi will automatically keep
       track of how many bytes have been transferred via write() calls.   This
       function  is  used  to  indicate  that  the next num_bytes bytes in the
       buffer are valid and may be sent to the device.  If there is an  error,
       -1 is returned.

                                28 October 2007