Xref: utzoo comp.arch:8015 comp.misc:4807 comp.lang.misc:2613 comp.protocols.misc:470
Path: utzoo!attcan!uunet!pdn!alan
From: alan@pdn.nm.paradyne.com (Alan Lovejoy)
Newsgroups: comp.arch,comp.misc,comp.lang.misc,comp.protocols.misc
Subject: Unification of big and little endian architectures.
Keywords: dump little-endian strings
Message-ID: <5462@pdn.nm.paradyne.com>
Date: 25 Jan 89 16:49:16 GMT
References: <170@microsoft.UUCP> <4008@hubcap.UUCP> <482@babbage.acc.virginia.edu> <7193@csli.STANFORD.EDU> <1371@X.UUCP>
Reply-To: alan@pdn.nm.paradyne.com (0000-Alan Lovejoy)
Organization: Paradyne Corporation, Largo, Florida
Lines: 43

In article <1371@X.UUCP> john@frog.UUCP (John Woods) writes:
>Ah, but consider the German for 1988: neunzehn hundert acht und achtzig
>(nine-and-ten hundred eight and eighty).  Middle-endian.  AHA!  Germans
>are PDP-11s!

Nein! Die PDP-11en sind Deutchen!   
(No! PDP-11s are German!)

It seems that several of the ccurrent RISC architectures provide for 
either big or little endian operation (Rx000, 88k, 29k, ?).  They do
this buy providing a global operating status that can be set by the
user to either big or little endian.

It would be better to provide load and store operations that are
specifically big or little endian:

LLE.W -- load little endian word
SLE.W -- store little endian word
LLE.L -- load little endian long
SLE.L -- store little endian long
LBE.W -- load big endian word
SBE.W -- store big endian word
LBE.L -- load big endian long
SBE.L -- store big endian long

In this scheme, applications would be responsible for keeping themselves
in sync with the endianness of their data, just as they already must
keep themselves in sync with the byte-length of their data.  Programmers
could choose the endianness of data as they saw fit--based either on
convenience or performance considerations.  Even if LBE.L takes more cycles
than LLE.L, it might still be used advantageously in a string comparison 
algorithm--or a 68k emulator.

If the Rx000 used this approach, then DEC would still have been free 
to write little-endian code (and code generators), but other peoples'
big-endian code would still run on DEC machines--as long as such code
brings its big-endian data sets along with it.

-- 
Alan Lovejoy; alan@pdn; 813-530-2211; ATT-Paradyne: 8550 Ulmerton, Largo, FL.
Disclaimer: I do not speak for ATT-Paradyne.  They do not speak for me. 
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