[FFmpeg-devel] [PATCH] dsputil: add bswap16_buf()

Måns Rullgård mans
Mon Jun 14 21:04:10 CEST 2010

Reimar D?ffinger <Reimar.Doeffinger at gmx.de> writes:

> On Mon, Jun 14, 2010 at 02:32:36PM +0200, Michael Niedermayer wrote:
>> On Mon, Jun 14, 2010 at 01:15:47PM +0100, M?ns Rullg?rd wrote:
>> > > how much alignment can we assume to have for dst/src? and len?
>> > 
>> > I don't know as I haven't located every place that could use this
>> > function.
>> the alignment requirements are prerequesit to writing optimized
>> implementations. And would be part of the API of bswap16_buf()
> Does it make enough of a speed difference that it is necessary
> to assume more than natural alignment?

I have no idea.

> Doing at most 7 iterations before and after in plain C might not
> have a relevant cost in most cases...

If source and dest are aligned differently it's not quite that simple.

M?ns Rullg?rd
mans at mansr.com

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