How to access high 16 bit of EAX?

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4 total messages Started by Diviner Chan Wed, 11 Sep 2002 20:01

#243

Author: Diviner Chan
Date: Wed, 11 Sep 2002 20:01

10 lines
1132 bytes

Hi all,

I want to access high 16 bits of EAX. But I can't find EAH in
Delphi. How to do that?

Thank you very much.

--
Best regards,
Diviner.

Re: How to access high 16 bit of EAX?

#144

Author: Christen Fihl
Date: Wed, 11 Sep 2002 20:20

11 lines
1335 bytes

You can use AL,AH,AX,EAX, but not EAH :(

You have to shift the bits down into one of those registers first.

  shr eax,16

Now AX is the high part of EAX and this was the high 16 bit of EAX

--
Christen Fihl
http://HSPascal.Fihl.net/

Re: How to access high 16 bit of EAX?

#147

Author: Pierre Maurette
Date: Thu, 12 Sep 2002 12:01

16 lines
1327 bytes

yes for
  shr eax, 16.

but also:
  bswap eax
  mov word ptr [blabla], ax
  bswap eax

  (eax is not changed)

You can try (why not ?):
mov dword ptr [blabla - 2], eax
(word ptr blabla is now *eah")
(if you can write dummy data at blabla - 2)

Pierre

Re: How to access high 16 bit of EAX?

#150

Author: Frederico Pissarra
Date: Thu, 12 Sep 2002 13:25

15 lines
1363 bytes

"Diviner Chan" <diviner@i-cable.com> wrote in message
news:3D7FA132.E6934D1@i-cable.com...
> Hi all,
>
> I want to access high 16 bits of EAX. But I can't find EAH in
> Delphi. How to do that?
>
> Thank you very much.
>

This is because there is no EAH alias register... (as AH or AL for AX)...
You have to shift EAX 16 bits right to get access to upper 16 bits! :)

Best Regards,
Fred

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