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From: Darryl Miles <darryl@netbauds.net>
To: hugang <linuxbest@sina.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: Abort x86 assemble code
Date: Thu, 04 Jan 2001 08:08:36 +0000	[thread overview]
Message-ID: <3A542F83.4BD3B30B@netbauds.net> (raw)


hugang <linuxbest@sina.com> wrote:
>	I have following code ,and I can not understand the mark line,who can tell me.thanks.
> 00000ec7 xorl   0x400dec(,%eax,4),%ecx		????<-----------------What it to do.

extern u_int32_t eax;
extern u_int32_t ecx;

{
	u_int32_t *ptr;

	ptr = (u_int32_t *)((eax * 4) + 0x400dec);

	ecx ^= *ptr;
}


Commonly used in the above form (with a fixed displacement) to access a
32bit value within an array of 32bit values.

The array start offset would be hardwired at 0x400dec, the zero based
index into the array is provided by eax.


-- 
Darryl Miles
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             reply	other threads:[~2001-01-04  8:09 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2001-01-04  8:08 Darryl Miles [this message]
  -- strict thread matches above, loose matches on Subject: below --
2001-01-04  6:02 Abort x86 assemble code hugang

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