Re: help sought, possible asm/cpu/other problem???

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#243

From: Dennis Cote
Date: Thu, 17 Jul 2008 14:11

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Bob Gonder wrote:
> 
> That would be hard to do as AH only has 8 bits.
> AL is bits 0-7 of EAX.
> AH is bits 8-15 of EAX ( 0x0100 to 0x8000 )

You are correct. My memory must have failed me. I assumed that LAHF 
loaded the entire flags register, but it only loads the low byte of the 
flags register.

> 
> The original code is correct for zf.
> Though with all the assembly, it would
> be clearer to continue with ASM.
> 
>          mov   edi, pAddr
>          repe  scasb
>          je return0

That is true as well.

The only other thing I can think of is that the ES register (used 
implicitly by the SCAS instructions) may have a different value than the 
DS register for some reason, thus EDI (i.e. pAddr) is not pointing at 
the expected memory when the SCAS is executed.

Dennis Cote

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Date: Thu, 17 Jul 2008 08:11:39 -0600
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