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authorJoseph Hunkeler <jhunkeler@gmail.com>2015-07-08 20:46:52 -0400
committerJoseph Hunkeler <jhunkeler@gmail.com>2015-07-08 20:46:52 -0400
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+.help zzwrmt May84 "System Interface"
+.ih
+NAME
+zzwrmt -- asynchronous write to a magtape file
+.ih
+SYNOPSIS
+.nf
+zzwrmt (chan, buf, nbytes)
+
+int chan # OS channel of magtape file
+char buf[nbytes] # buffer containing the data
+int nbytes # number of bytes to be written
+.fi
+.ih
+DESCRIPTION
+Initiate a write of exactly \fInbytes\fR bytes from the buffer \fIbuf\fR to
+the magtape channel \fIchan\fR. Each call to \fBzzwrmt\fR writes one tape
+block. Successive tape blocks may vary in size. A request to write zero
+bytes is ignored.
+.ih
+RETURN VALUE
+The wait primitive \fBzzwtmt\fR must be called after every asynchronous write
+to get the transfer status. ERR is returned if a write error occurs or if the
+channel number is illegal. If the write operation is successful the actual
+number of bytes written is returned.
+.ih
+NOTES
+The transfer is NOT guaranteed to be asynchronous and the calling program
+must not assume that \fBzzwrmt\fR will return immediately.
+The \fBzzwtmt\fR primitive must be called and the status checked before
+issuing another i/o request to the channel. Only a single request may be
+pending on a channel at a time.
+.ih
+SEE ALSO
+zzopmt, zzwtmt, zfiomt
+.endhelp