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Re: [Qemu-ppc] [PATCH v3 5/6] bitops: add BITNR macro
From: |
Alexey Kardashevskiy |
Subject: |
Re: [Qemu-ppc] [PATCH v3 5/6] bitops: add BITNR macro |
Date: |
Thu, 14 Nov 2013 16:51:55 +1100 |
User-agent: |
Mozilla/5.0 (X11; Linux i686 on x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.1.0 |
On 11/13/2013 11:04 PM, Paolo Bonzini wrote:
> Il 13/11/2013 03:40, Alexey Kardashevskiy ha scritto:
>> I looked further and did not find any use of ffs/clz so I wonder what did
>> you mean about bitops.h and what did I miss? I am confused.
>
> It's host-utils.h actually. The reason for the wrappers is twofold:
>
> (1) provide 32/64-bit functions instead of int/long/longlong;
>
> (2) support GCC <3.4.
>
> The wrappers are not usable where you have constant expressions as in
> your case. So your original patch is good IMO, except for the __ at the
> beginning of __BITNR.
There are 2 macros, one (BITNR) uses the other (__BITNR). What would the
good name be for BITNR then?
>
> Paolo
>
>> So I would suggest the following instead (if I really needed this BITNR but
>> I really do not :) )
>>
>> ===
>> bitops: add BITNR macro
>>
>> This adds a macro to calculate the highest single bit set. If more than
>> one bit is set, returns -1.
>
--
Alexey
[Qemu-ppc] [PATCH v3 3/6] target-ppc: add "compat" CPU option, Alexey Kardashevskiy, 2013/11/11
[Qemu-ppc] [PATCH v3 5/6] bitops: add BITNR macro, Alexey Kardashevskiy, 2013/11/11
[Qemu-ppc] [PATCH v3 2/6] target-ppc: make use of new -cpu suboptions handling, Alexey Kardashevskiy, 2013/11/11
[Qemu-ppc] [PATCH v3 6/6] target-ppc: demonstrate new "vsx" property, Alexey Kardashevskiy, 2013/11/11