Re: Abort x86 assemble code

Darryl Miles (darryl@netbauds.net)
Thu, 04 Jan 2001 08:08:36 +0000

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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