| Re: open,/record - classification [message #711] |
Wed, 25 November 1992 03:01  |
knipp
Messages: 68
Registered: January 1993
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Member |
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William Thompson (thompson@stars.gsfc.nasa.gov (William Thompson, code 682.1, x2040)
writes ...
> My experience is with IDL, not PV-WAVE, but this should still hold true. You
> can open a tape device in Unix and do I/O using READU and WRITEU. At least I
> was able to do this with an Exabyte tape drive on a Sun. You can also spawn
> out to the OS to send commands such as
>
> mt -f /dev/nrst1 fsf 1
>
> ...
>
> At one time I tried to write IDL procedures for Unix that imitated as closely
> as possible the VMS tape utilities: TAPRD, TAPWRT, etc. I stopped working on
> it, though, when I realized that there was no way to obtain the actual number
> of bytes read in, as one could with the VMS routines. One place that was
> crucial for us was in reading FITS tapes--we needed to be able to tell if the
> tape was written using 2880 byte or 28800 byte records.
>
> Bill Thompson
Dear Bill,
thank you for your answer.
I've tried OPENU together with READU/WRITEU. It worked perfectely well
for records up to ~ 1000 bytes long.
Unfortunately it did NOT with larger record-lengths (say 10000, 16000 or
even 19000 bytes long - which I have to deal with).
If anybody could help me to overcome this problem (without spawning
a command like 'dd' to the OS) I'll be very grateful.
Regarding your problem (2880 or 28800 byte records) :
Have you tried the UNIX-command 'tcopy' ?
K.Knipp
(Does nobody know something about classification in WAVE ?)
Karlheinz Knipp Tel. 0511 - 762 4922
Universitaet Hannover Fax. 0511 - 762 2483
Institut fuer Photogrammetrie Mail. knipp@ipi.uni-hannover.de
Nienburger Str.1
3000 Hannover 1
FRG
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