tb(4) [bsd man page]

TB(4)							     Kernel Interfaces Manual							     TB(4)

NAME

       tb - line discipline for digitizing devices

SYNOPSIS

       /sys/conf/SYSTEM:
	    NTB  1    # RS232 interface for Genisco/Hitachi tablets

DESCRIPTION

       This  line  discipline  provides  a polled interface to many common digitizing devices which are connected to a host through a serial line.
       When these devices stream data at high speed, the use of the line discipline is critical in minimizing the number  of  samples  that  would
       otherwise be lost due to buffer exhaustion in the tty(4) handler.

       The line discipline is enabled by a sequence:

	    #include <sys/tablet.h>
	    int ldisc = TBLDISC, fildes; ...
	    ioctl(fildes, TIOCSETD, &ldisc);

       A typical application program then polls the digitizing device by reading a binary data structure which contains: the current X and Y posi-
       tions (in the device coordinate space), up-down status of the buttons or pen stylus, proximity information (when available), and a count of
       the  number  of samples received from the input device since it was opened.  In addition, devices such as the GTCO append tilt and pressure
       information to the end of the aforementioned structure.	For the Polhemus 3-D digitizer the structure read is completely  different.  Refer
       to the include file for a complete description.

       While  in  tablet mode, normal teletype input and output functions take place.  Thus, if an 8 bit output data path is desired, it is neces-
       sary to prepare the output line by putting it into RAW mode using ioctl(2).  This must be done before changing the  discipline  with  TIOC-
       SETD, as most ioctl(2) calls are disabled while in tablet line-discipline mode.

       The  line  discipline supports ioctl(2) requests to get/set the operating mode, and to get/set the tablet type and operating mode by or-ing
       the two values together.

       The line discipline supports digitizing devices which are compatible with Hitachi, GTCO, or Polhemus protocol formats.  For  Hitachi  there
       are several formats with that used in the newer model HDG-1111B the most common.

SEE ALSO

       tty(4)

DIAGNOSTICS

       None.

3rd Berkeley Distribution					  August 1, 1987							     TB(4)

NG_H4(4)						   BSD Kernel Interfaces Manual 						  NG_H4(4)

NAME

     ng_h4 -- Netgraph node type that is also an H4 line discipline

SYNOPSIS

     #include <sys/types.h>
     #include <netgraph/bluetooth/include/ng_h4.h>

DESCRIPTION

     The h4 node type is both a persistent Netgraph node type and a H4 line discipline.  It implements a Bluetooth HCI UART transport layer as per
     chapter H4 of the Bluetooth Specification Book v1.1.  A new node is created when the corresponding line discipline, H4DISC, is registered on
     a tty device (see tty(4)).

     The node has a single hook called hook.  Incoming bytes received on the tty device are re-assembled into HCI frames (according to the
     length).  Full HCI frames are sent out on the hook.  HCI frames received on hook are transmitted out on the tty device.  No modification to
     the data is performed in either direction.  While the line discipline is installed on a tty, the normal read and write operations are
     unavailable, returning EIO.

     Information about the node is available via the netgraph ioctl(2) command NGIOCGINFO.  This command returns a struct nodeinfo similar to the
     NGM_NODEINFO netgraph(4) control message.

HOOKS

     This node type supports the following hooks:

     hook  single HCI frame contained in single mbuf structure.

CONTROL MESSAGES

     This node type supports the generic control messages, plus the following:

     NGM_H4_NODE_RESET
	  Reset the node.

     NGM_H4_NODE_GET_STATE
	  Returns current receiving state for the node.

     NGM_H4_NODE_GET_DEBUG
	  Returns an integer containing the current debug level for the node.

     NGM_H4_NODE_SET_DEBUG
	  This command takes an integer argument and sets current debug level for the node.

     NGM_H4_NODE_GET_QLEN
	  Returns current length of outgoing queue for the node.

     NGM_H4_NODE_SET_QLEN
	  This command takes an integer argument and sets maximum length of outgoing queue for the node.

     NGM_H4_NODE_GET_STAT
	  Returns various statistic information for the node, such as: number of bytes (frames) sent, number of bytes (frames) received and number
	  of input (output) errors.

     NGM_H4_NODE_RESET_STAT
	  Reset all statistic counters to zero.

SHUTDOWN

     This node shuts down when the corresponding device is closed (or the line discipline is uninstalled on the device).

SEE ALSO

     ioctl(2), netgraph(4), tty(4), ngctl(8)

HISTORY

     The h4 node type was implemented in FreeBSD 5.0.

AUTHORS

     Maksim Yevmenkin <m_evmenkin@yahoo.com>

BUGS

     This node still uses spltty(9) to lock tty layer.	This is wrong.

BSD
								   June 14, 2002							       BSD