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Re: bitwise operations on registers
- From: Andrew Cagney <ac131313 at cygnus dot com>
- To: Eli Zaretskii <eliz at is dot elta dot co dot il>
- Cc: Andrew Morton <akpm at zip dot com dot au>, gdb at sources dot redhat dot com
- Date: Mon, 11 Mar 2002 10:35:11 -0500
- Subject: Re: bitwise operations on registers
- References: <Pine.SUN.3.91.1020311130105.17471A-100000@is>
> On Sun, 10 Mar 2002, Andrew Morton wrote:
>
>
>> (gdb) p $esp & 4
>> Argument to arithmetic operation not a number or boolean.
>> (gdb)
>>
>> I don't seem to be able to perform the `&' and `|' arithmetic
>> operators against machine registers.
>
>
> "p $eax & 4" works for me. Doesn't it work for you?
>
> As for $esp, I think GDB knows that it's not a number, so try
>
> (gdb) p (int)$esp & 4
>
> (I don't know whether the built-in knowledge GDB has about $esp should
> prevent it from working without the cast, though.)
Yes, try:
(gdb) p (void*)0 & 4
So, this a bug?
Andrew