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NG_H4(4)	       FreeBSD 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 cre-
     ated 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: num-
	     ber 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.

FreeBSD	9.2			 June 14, 2002			   FreeBSD 9.2

NAME | SYNOPSIS | DESCRIPTION | HOOKS | CONTROL MESSAGES | SHUTDOWN | SEE ALSO | HISTORY | AUTHORS | BUGS

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