lkml.org 
[lkml]   [2005]   [Jun]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: .../asm-i386/bitops.h performance improvements
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.
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-06-15 18:12    [W:0.199 / U:0.484 seconds]
©2003-2014 Jasper Spaans. hosted at Digital Ocean