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1 files changed, 83 insertions, 0 deletions

diff --git a/sys/fio/areadb.x b/sys/fio/areadb.x
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+# Copyright(c) 1986 Association of Universities for Research in Astronomy Inc.
+
+include	<mach.h>
+include	<syserr.h>
+include	<config.h>
+include	<fio.h>
+
+# AREADB -- Asychronous byte-oriented block read from a binary file.  Reads
+# can only start at a character offset which is an integral multiple of the
+# file block size.
+
+procedure areadb (fd, buffer, maxbytes, byte_offset)
+
+int	fd			# FIO file descriptor
+int	maxbytes		# maximum number of machine bytes to read
+char	buffer[ARB]		# buffer into to which data is to be read
+long	byte_offset		# one-indexed byte offset in file
+
+long	file_offset
+int	junk, awaitb()
+errchk	filerr, syserr
+include	<fio.com>
+
+begin
+	fp = fiodes[fd]
+	if (fd <= 0 || fp == NULL)
+	    call syserr (SYS_FILENOTOPEN)
+
+	# If channel is active, wait for completion.  Do not abort if await is
+	# not called between i/o requests, since this is what happens when an
+	# error occurs, ant it would lead to a file error following error
+	# restart.
+
+	if (FCIOMODE(fp) != INACTIVE)
+	    junk = awaitb (FAFD(fp))
+
+	if (FBLKSIZE(fp) == 0)				# streaming device
+	    ;
+	else if (byte_offset < 1)
+	    call filerr (FNAME(fp), SYS_FARDOOB)
+	else if (FILSIZE(fp) >= 0 && byte_offset - (FILSIZE(fp)*SZB_CHAR) > 1) {
+	    FNBYTES(fp) = 0				# return EOF
+	    return
+	}
+
+	# If not a streaming device, check alignment of block.  If streaming
+	# device, file offset passed to z-routine must be zero.
+
+	file_offset = byte_offset
+	if (FBLKSIZE(fp) > 0) {
+	    if (mod (byte_offset-1, (FBLKSIZE(fp)*SZB_CHAR)) != 0)
+		call filerr (FNAME(fp), SYS_FARDALIGN)
+	} else
+	    file_offset = 0
+
+	call zlocva (buffer, FLOCBUF(fp))
+	FCIOMODE(fp) = READ_IN_PROGRESS
+	FFIOMODE(fp) = READ_IN_PROGRESS
+	FAFD(fp) = fd
+
+	# If the CLOSE flag is set for the channel, open and close the channel
+	# at the host level every time an i/o operation takes place.  (Used to
+	# save host channel descriptors).  The code is structured so that the
+	# FCLOSEFD flag may change state at any time, with the channel being
+	# left either closed or open the next time we are called.  Any open or
+	# read errors are reported as read errors when AWAITB is later called.
+
+	if (FCLOSEFD(fp) == NO && FCHAN(fp) != ERR)
+	    call zcall4 (ZARDBF(fp), FCHAN(fp), buffer, maxbytes, file_offset)
+	else {
+	    if (FCHAN(fp) == ERR)
+		call zcall3 (FDEVOPEN(fp), FPKOSFN(fp), FMODE(fp), FCHAN(fp))
+	    if (FCHAN(fp) != ERR) {
+		call zcall4 (ZARDBF(fp),
+		    FCHAN(fp), buffer, maxbytes, file_offset)
+		if (FCLOSEFD(fp) == YES) {
+		    junk = awaitb (FAFD(fp))
+		    call zcall2 (ZCLSBF(fp), FCHAN(fp), junk)
+		    FCHAN(fp) = ERR
+		}
+	    }
+	}
+end