[alsa-devel] ALSA always writes _whole_ periods, right?

Hi ALSA devs,

I have a quick question regarding the filling of the usual ring buffer in RAM (used by sound controllers via DMA), just to be really sure:

Is it true, that ALSA always writes (via mmap'ing) _whole_ periods?

I took snd-dummy and modified it to use "ack()" method and tried to confirm, if the above is true _without_ memory mapping (classical read/write). It seem's to be true, ALSA is "filling up" the last (not always complete) period - e.g. if the played wav file is not a multiple of periodsize in length. But well, with mmap, I cannot see the copying action (done by ALSA library, right?) ... so, thus my question ;-) .

Thanks, Joachim