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       comedi_mark_buffer_read - streaming buffer control


       #include <comedilib.h>

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


       The function comedi_mark_buffer_read() is used on a subdevice that  has
       a  Comedi input command in progress.  It should only be used if you are
       using a mmap() (as opposed to calling read() on  the  device  file)  to
       read  data  from  Comedi’s buffer, since Comedi will automatically keep
       track of how many bytes have been transferred via read()  calls.   This
       function  is  used  to  indicate  that  the next num_bytes bytes in the
       buffer are no longer needed and may  be  discarded.   If  there  is  an
       error, -1 is returned.

                                28 October 2007