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Date: Wed, 15 Jun 2005 21:10:26 +0200 (CEST)
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
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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.
-- 
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