Initial commit

1 files changed, 37 insertions, 0 deletions

diff --git a/sys/fio/fswapfd.x b/sys/fio/fswapfd.x
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--- /dev/null
+++ b/sys/fio/fswapfd.x
@@ -0,0 +1,37 @@
+# Copyright(c) 1986 Association of Universities for Research in Astronomy Inc.
+
+include	<config.h>
+include	<fio.h>
+
+define	SWAPI		{tempi=$1;$1=$2;$2=tempi}
+define	SWAPL		{templ=$1;$1=$2;$2=templ}
+define	SWAPP		{tempp=$1;$1=$2;$2=tempp}
+
+# FSWAPFD -- Swap the file descriptors of two open files.  All i/o to file
+# fd1 is redirected to fd2 and vice versa, until the swap is reversed.
+# We are used by FREDIR to temporarily redirect i/o (normally to one of the
+# standard streams) to a special file.  If CLOSE is called to close a
+# redirected file, we are called to unswap the two streams and then the
+# redirection file is closed.  All the i/o pointers, buffer pointers, and
+# so on of the original stream are restored to exactly the condition they
+# were in before (unless i/o has occurred on the other file during the
+# interim).
+
+procedure fswapfd (fd1, fd2)
+
+int	fd1, fd2		# file descriptors to be swapped.
+int	tempi
+long	templ
+pointer	tempp
+include	<fio.com>
+
+begin
+ 	SWAPL (boffset[fd1], boffset[fd2])
+ 	SWAPP (bufptr[fd1], bufptr[fd2])
+ 	SWAPP (buftop[fd1], buftop[fd2])
+ 	SWAPP (iop[fd1], iop[fd2])
+ 	SWAPP (itop[fd1], itop[fd2])
+ 	SWAPP (otop[fd1], otop[fd2])
+ 	SWAPP (fiodes[fd1], fiodes[fd2])
+ 	SWAPI (redir_fd[fd1], redir_fd[fd2])
+end