Path: utzoo!attcan!uunet!lll-winken!ames!xanth!mcnc!rti!xyzzy!throopw
From: throopw@xyzzy.UUCP (Wayne A. Throop)
Newsgroups: comp.arch
Subject: Re: Endian wars
Message-ID: <3089@xyzzy.UUCP>
Date: 27 Jan 89 15:30:13 GMT
References: <6133@columbia.edu> <3505@tekcrl.CRL.TEK.COM>
Organization: Data General, RTP NC.
Lines: 31

> stevev@tekchips.CRL.TEK.COM (Steve Vegdahl)
>> eppstein@garfield (David Eppstein)
>> Big endian lets you use integer comparison instructions to do string
>> compares a word at a time.
> This depends on how strings are represented.  [...]
> consider a representation of strings where the characters are laid out
> "backwards" in memory; [...]
> Now, big endian and little endian find their roles reversed WRT the
> above optimization.

True, true... BUT this role reversal is by no means "free".  Now the
little-endian-but-backwards-strings machine cannot use the same routines
to allocate, read, write, and otherwise treat as an uninterpreted bucket
of bits strings and non-strings.  All manipulators of pointers will
have to "know" what they point at.  There will be much "duplicated" code
on this machine relative to a machine where all memory-chunks are
addressed by their "least" (or greatest) component-address.  And of course
all the attendant bugs that occur when a pointer of one kind is
fed to a routine expecting the other kind.

Not that these problems are insolvable.  It may (possibly) even be
worthwhile to do things this way.  But the big-endian way is still
superior in this respect, and making this change is only trading one
difficulty for another.  (Of course, the little-endian way is superior
in other respects.)

--
There are two ways to write error-free programs;
only the third one works.
                                        --- Alan J. Perlis
-- 
Wayne Throop      <the-known-world>!mcnc!rti!xyzzy!throopw