Hi Jonathan, On 5/11/19 10:48 AM, Jonathan Cameron wrote: > On Thu, 9 May 2019 12:54:34 +0200 > Gaëtan Carlier <gcembed@xxxxxxxxx> wrote: > >> Dear, >> >> I have a question about the function iio_push_to_buffers_with_timestamp(). >> >> How kernel knows the size of the buffer ? Should the buffer always be 128 bits (with last 64 bits for timestamp) ? > Hi Gaëtan, > > All fields in IIO buffers are 'naturally' aligned and must be power of 2 size > (8, 16, 32, 64) > > This function is a bit 'odd' in that it needs a buffer that has space to insert > the 64 bit aligned, 64 bit timestamp. > > So if your devices other channels fit in 64 bits then your conclusion is > correct. If you have more channels then it may well be that the buffer > is already greater than 64 bits long before leaving space for the timestamp > and hence your buffer may need to be 192, 256 etc.. > Thank you for your reply. > Hope that answers your question, So, I still have a question. How IIO functions knows how many space is available because it handles "void *". Is the size of allocated buffer stored somewhere ? > > Jonathan > >> >> Best regards, >> Gaëtan. > Best regards, Gaëtan.
