Kirk Marat writes:
> A problem arises when transfering data from a word addressed
> computer like the A3000 to a byte addressed computer (eg a
> UNIX box). That is, when the 24 bit word is split into bytes,
> which byte is sent first?
This depends on the software on the Aspect 3000. Bytes of a 24
bit word on the Aspect are seperated out via rotation and masking.
There are two ways to rotate, and this results in two different
possible byte orderings.
> Does anyone out there know if there are byte order differences
> in the resulting UNIX file when an A3000 file is transfered to
> a UNIX computer by different methods?
Yes this is possible and depends on the software used.
> ie. Does a Bruknet transfer produce a different byte order
> than, say, a Kermit transfer? Do versions of bruknet
> running on big endian machines like a Sun or SGI result in
> the same byte order as bruknet on the little endian X32?
The Kermit protocol specifies the byte order of BINARY transfers.
The Kermit and NMR-Link software for the Aspect 2000/3000 use the
same format. Bruknet sends the data in other byte order, making it
different than the Kermit and NMR-link byte order. The byte
ordering is really specified by the Aspect software and just gets
written as a stream of bytes on the other machine.
If data is transferred to a little-endian machine and then sent to
a big-endian machine or vice versa, if transferred as a BINARY file
it will just be transferred as a stream of bytes. No changing of
the byte order will occur unless the transfer package intentionally
changes the byte ordering. As far as I know TCP/IP BINARY
transfers make no changes in byte ordering.
Therefore you need to know if the data was transferred via Kermit,
NMR-Link or UNIX Bruknet and the byte order of your machine to know
if a byte swap is necessary to convert the data.
protocol big-endian little-endian
--------------------------------------------------------------------
Kermit SWAP & EXT EXT
NMR-Link SWAP & EXT EXT
Bruknet EXT SWAP & EXT
Bruknet Binary NONE SWAP
SWAP = swap bytes, EXT = sign extend to 32 bits/word
Vax VMS Bruknet is a completely different story. If you need
information on this format I can fax you the necessary info.
Lightnet to the X-32 is also somewhat different.
I have to go now because I have a byte swap induced headache ;-}.
==================================================================
Joe Laughlin human: (508) 667-9580
Assistant Manager, machine: jsl@bii.bruker.com
Software Development
Bruker Instruments, Inc.
==================================================================
--================================================================== Joe Laughlin human: (508) 667-9580 Assistant Manager, machine: jsl@bii.bruker.com Software Development Bruker Instruments, Inc. ==================================================================