Re: .../asm-i386/bitops.h performance improvements

[Stephen Rothwell]

On Wed, 15 Jun 2005 21:10:26 +0200 (CEST) Bodo Eggert <7eggert@xxxxxx> wrote:
>
> 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.

In 32 bit mode on the 386 and above, a two byte version of the "mod reg
r/m" is possible which contains the scaling field ...

On the 386, using a second register in the ea calculation costs another
cycle.

-- 
Cheers,
Stephen Rothwell                    sfr@xxxxxxxxxxxxxxxx
http://www.canb.auug.org.au/~sfr/

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