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Diffstat (limited to 'unix/os/doc/zzwtmt.hlp')
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diff --git a/unix/os/doc/zzwtmt.hlp b/unix/os/doc/zzwtmt.hlp new file mode 100644 index 00000000..3a975055 --- /dev/null +++ b/unix/os/doc/zzwtmt.hlp @@ -0,0 +1,41 @@ +.help zzwtmt May84 "System Interface" +.ih +NAME +zzwtmt -- wait for i/o on a magtape file +.ih +SYNOPSIS +.nf +zzwtmt (chan, nrecords, nfiles, status) + +int chan # OS channel of magtape file +int nrecords # nrecords skipped +int nfiles # nfiles skipped +int status +.fi +.ih +DESCRIPTION +If a transfer is in progress on the channel \fIchan\fR process execution +is suspended until the transfer completes. +.ih +RETURN VALUE +ERR is returned in \fIstatus\fR if a read or write error occurred in the +last i/o transfer to the magtape device. +The number of tape records (blocks) and/or filemarks skipped in the last +read or write operation is returned in \fInrecords\fR and \fInfiles\fR. +The number of bytes read or written is returned in \fIstatus\fR. +In an ordinary read or write operation \fInrecords\fR will be positive one, +\fInfiles\fR will be zero, and \fIstatus\fR will be a positive number. +An attempt to read at EOF will result in a \fIstatus\fR of zero (zero bytes +were read). Repeated calls to \fBzzwtmt\fR will continue to return the +same values. +.ih +NOTES +The \fInfiles\fR parameter will not necessarily be set to 1 when a filemark +is read, hence it cannot be used to test for EOF. Some systems will leave +the tape positioned to just before a filemark when a filemark is encountered +in a read operation, while others will leave the tape positioned to just +after the filemark. +.ih +SEE ALSO +zzrdmt, zzwrmt, zfiomt +.endhelp |