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From: "Richard B. Johnson" <linux-os@analogic.com>
To: "Maciej W. Rozycki" <macro@linux-mips.org>
Cc: 7eggert@gmx.de, Gene Heskett <gene.heskett@verizon.net>,
	cutaway@bellsouth.net, linux-kernel@vger.kernel.org
Subject: Re: .../asm-i386/bitops.h  performance improvements
Date: Wed, 15 Jun 2005 12:06:28 -0400 (EDT)	[thread overview]
Message-ID: <Pine.LNX.4.61.0506151200490.24211@chaos.analogic.com> (raw)
In-Reply-To: <Pine.LNX.4.61L.0506151629270.13835@blysk.ds.pg.gda.pl>

On Wed, 15 Jun 2005, Maciej W. Rozycki wrote:

> On Wed, 15 Jun 2005, Bodo Eggert wrote:
>
>> lea is an 8086 instruction. All clones have it in it's basic form. However,
>> the multiplicator is not documented for i486, therefore it will be a i586
>> extension.
>
> Huh?  The SIB byte has been added in the original i386 with 32-bit
> addressing.
>
>  Maciej

Well the __documented__ '486 LEA instruction doesn't
even allow the double-register indirect. It's just

 	LEA r16,m
 	LEA r32,m

... repeated twice

Page 26-190,  Intel486(tm) Microprocessor Programmer's Reference
Manual. ISBN 1-55512-195-4. The instruction may have been one
of those "immature features", read broken.

Cheers,
Dick Johnson
Penguin : Linux version 2.6.11.9 on an i686 machine (5537.79 BogoMips).
  Notice : All mail here is now cached for review by Dictator Bush.
                  98.36% of all statistics are fiction.

  reply	other threads:[~2005-06-15 16:07 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <4fB8l-73q-9@gated-at.bofh.it>
     [not found] ` <4fF2j-1Lo-19@gated-at.bofh.it>
2005-06-15 14:57   ` .../asm-i386/bitops.h performance improvements Bodo Eggert
2005-06-15 15:30     ` Maciej W. Rozycki
2005-06-15 16:06       ` Richard B. Johnson [this message]
2005-06-15 16:29         ` Maciej W. Rozycki
2005-06-15 19:10           ` Bodo Eggert
2005-06-16  3:26             ` Stephen Rothwell
2005-06-16  7:10             ` Mikael Pettersson
2005-06-15 23:53     ` cutaway
2005-06-15  8:53 cutaway
2005-06-15 12:18 ` Gene Heskett
2005-06-15 13:06   ` Richard B. Johnson
2005-06-15 19:18   ` cutaway
2005-06-15 15:34 ` Maciej W. Rozycki
2005-06-15 23:48   ` cutaway

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