datakit(3) [plan9 man page]

DATAKIT(3)						     Library Functions Manual							DATAKIT(3)

NAME

       incon, hsvme, hs386 - Datakit interface

SYNOPSIS

       bind -a #i /dev
       bind -a #h /dev

       #i/data
       #i/ctl
       #h/data
       #h/ctl

DESCRIPTION

       The  Datakit  interface	is  a stream directory containing a data and a control file.  Each write to the data file is a structured message.
       The first two bytes of the message are a 9-bit virtual circuit number, low order byte first.  The third byte is a control byte.	 The  rest
       are data bytes.	The data bytes are sent onto the Datakit virtual circuit, tagged as data, followed by the control byte, tagged as control.

       Messages  coming from Datakit are read from the data file in the same format.  A read terminates at the end of a message.  The largest pos-
       sible received message is 1024 + 3 bytes.

SEE ALSO

       dk(3)

SOURCE

       /sys/src/9/*/devhs.c
       /sys/src/9/*/devincon.c

																	DATAKIT(3)

ASYNC(3)						     Library Functions Manual							  ASYNC(3)

NAME

       async - framing for a serial line to Datakit

SYNOPSIS

       ctlfd = open(".../ctl", ORDWR);
       write(ctlfd, "push async", 10);

DESCRIPTION

       This is not a device, but rather a stream module (see stream(3)) that can be pushed onto a stream.  This module provides the framing neces-
       sary to treat a serial line as a Datakit trunk.	It is usually pushed onto a stream before the dkmux module.  The  frame  includes  a  CRC.
       Any received frames with an incorrect CRC are discarded.

       The format of a message upstream of the module is:

	      channel # low byte
	      channel # high byte
	      control byte (0 means none)
	      data bytes

       The format of a frame is:

	      0x7d
	      0x7d
	      channel # low byte
	      channel # high byte
	      crc low byte
	      crc high byte
	      0x7d
	      0x7d

       All control bytes in the frame are preceded by a 0x9d byte.  All 0x9d and 0x7d bytes in the data are followed by a 0x00 byte to distinguish
       them from framing or control specifiers.

SEE ALSO

       stream(3), cons(3), dk(3)

SOURCE

       /sys/src/9/port/stasync.c

																	  ASYNC(3)