[FFmpeg-devel] av_ctz optimization

Ganesh Ajjanagadde gajjanag at mit.edu
Sun Oct 11 18:10:27 CEST 2015


On Sun, Oct 11, 2015 at 12:06 PM, James Almer <jamrial at gmail.com> wrote:
> On 10/11/2015 8:01 AM, Ronald S. Bultje wrote:
>> Hi,
>>
>> On Sat, Oct 10, 2015 at 10:50 PM, James Almer <jamrial at gmail.com> wrote:
>>
>>> On 10/10/2015 11:44 PM, Ganesh Ajjanagadde wrote:
>>>> Hi all,
>>>>
>>>> Turns out that the De-Bruijn method can be used to speed up av_ctz as
>>>> well. But before going about it, I was curious as to why such an
>>>> interface is actually public. It makes absolutely zero sense to me:
>>>> usage is limited exactly to one location, namely libavcodec/flacenc.c.
>>>> Was this an accident?
>>>>
>>>> Regards,
>>>> Ganesh
>>>
>>> It's not really public since intmath.h is not an installed header.
>>> Why it exists and is used instead of ff_ctz, i don't know.
>>
>>
>> Looks like it was added for use in flacenc, and we typically don't share
>> ff_ symbols between libraries. However, since it's inlined anyway, I'm not
>> sure anyone cares. Maybe time to remove it?
>>
>> Ronald
>
> We're still in ABI breaking season so it's fine if we do it asap.
> flacenc can use ff_ctz just fine.

Isn't that an API change and not an ABI change (it was in doc/APIchanges)?
Per the development rules, I think the most ideal name is avpriv_ctz.
However, I am fine with ff_ as well.

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