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# Copyright(c) 1986 Association of Universities for Research in Astronomy Inc.
include <config.h>
include "ki.h"
# KB_ZAWT -- Wait for i/o to a binary file. Called after an asynchronous read
# or write has been issued on a channel. We are not called unless the device
# does not reside on the local node. If the last i/o transfer was a read then
# the ZAWT packet will be followed by the data which we must copy into the
# callers buffer, using the pointer saved when the read was posted. If the
# last i/o operation was a write then we assume that the write was successful
# and merely return the number of bytes written (error checking occurs
# elsewhere).
#
# read: sendpkt, rcvpkt, readdata
# write: sendpkt, senddata [nothing]
#
# (zard|zawr) (zawt)
#
# Note that the ZAWT function is processed locally in the case of a write,
# rather than being passed to the kernel server. This makes file write
# operations a pipelined operation, significantly increasing the opportunity
# for overlapped execution and increasing the data bandwidth. If the number
# of bytes transferred to the remote device is not what is requested then the
# remote kernel server will close the entire channel down (not just the
# multiplexed channel for the device), causing a ZAWRKS error in the local
# process.
#
# NOTE -- disregard the above regarding asynchronous reads. ZARD is currently
# implemented as a synchronous read. The comments are retained here to show
# how to speed up reads when the i/o system is made fully asynchronous.
procedure kb_zawt (device, chan, status)
int device # device driver code
int chan # channel assigned device
int status # receives nbytes transferred or ERR
include "kichan.com"
begin
status = k_status[chan]
end
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