From: Bodo Eggert <7eggert@gmx.de>
To: "Maciej W. Rozycki" <macro@linux-mips.org>
Cc: "Richard B. Johnson" <linux-os@analogic.com>,
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 21:10:26 +0200 (CEST) [thread overview]
Message-ID: <Pine.LNX.4.58.0506152053010.3184@be1.lrz> (raw)
In-Reply-To: <Pine.LNX.4.61L.0506151723460.13835@blysk.ds.pg.gda.pl>
On Wed, 15 Jun 2005, Maciej W. Rozycki wrote:
> On Wed, 15 Jun 2005, Richard B. Johnson wrote:
> > 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.
>
> And "m" is presumably described in details elsewhere as the semantics is
> common for all instructions involving address calculation.
My documentation says:
lea reg16, mem
Available on 8086, 80186, 80286, 80386, 80486
32-bit-extension available
Opcode: 8D mod reg r/m
reg will be the target register (AX .. DI), and mod and r/m will select
something like a direct address, a register or a combination like
BP+DI+ofs (I won't copy the table). A multiplier is not mentioned there.
--
Microwave: Signal from a friendly micro...
next prev parent reply other threads:[~2005-06-15 19:11 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 ` Bodo Eggert
2005-06-15 15:30 ` Maciej W. Rozycki
2005-06-15 16:06 ` Richard B. Johnson
2005-06-15 16:29 ` Maciej W. Rozycki
2005-06-15 19:10 ` Bodo Eggert [this message]
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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