Article View: comp.arch
Article #12831Re: byte order: be reasonable - do it my way...
From: Wolfgang Rupprecht
Date: Wed, 14 Jan 1987 16:35
Date: Wed, 14 Jan 1987 16:35
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1565 bytes
In article <> mwm@cuuxb.UUCP (Marc W. Mengel) writes:
> The bit notation is strictly notational, and has no bearing on
> the operation of the cpu. One could go entirely through any
> MC68000 book and replace the bit-numbers appropriately throughout.
>
> Bit notation (what way you number which bits) has no relation
> to byte ordering. I could number my bits:
> 13579BDF2468ACE
> 000000000000001
> to represent the number 1 if I so chose. Saying that byte ordering
> that proceeds in the opposite direction to bit ordering is
> some how "inconsistent" is part of your argument, I would maintain
> that it is moot.
Unfortunately thats not the case. Look at the BSET, BCLR, BTST (bit
set, clear and test) instructions. If you do a:
BSET.L d0, somelocation
with #31 in d0, you have set the MSB (byte 0!) of the long-word. This
is *LOW* endian.
--
Wolfgang Rupprecht {harvard|decvax!cca|mit-eddie}!lmi-angel!wsr
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Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: arc1-ca.pugleaf.net!utzoo!mnetor!seismo!ut-sally!husc6!necntc!adelie!mirror!cca!lmi-angel!wsr From: wsr@lmi-angel.UUCP (Wolfgang Rupprecht) Newsgroups: comp.arch,comp.sys.intel,comp.sys.m68k Subject: Re: byte order: be reasonable - do it my way... Message-ID: <112@lmi-angel.UUCP> Date: Wed, 14-Jan-87 11:35:32 EST Article-I.D.: lmi-ange.112 Posted: Wed Jan 14 11:35:32 1987 Date-Received: Sat, 17-Jan-87 00:54:31 EST References: <760@orcisi.UUCP> Reply-To: wsr@lmi-angel.UUCP (Wolfgang Rupprecht) Organization: LISP Machine, Inc (Cambridge Engineering HQ) Lines: 23