Read in samples from channels in one go

[sflower]

I'm looking for some feedback on a modification I have had to make in order to integrate ADAT TX functionality into our products. I have just made the changes in the adat_transmit_port_until_ct_4x function as an example, but they would also be required for adat_transmit_port_until_ct_2x and adat_transmit_port_until_ct_1x.

Currently the non-ADAT_TX_USE_SHARED_BUFF implementation will take almost a whole sample period to consume 8 samples from the delivery thread, this is because it consumes and transmits two samples at a time.

These changes make it consume all 8 samples from the channel at the start of the loop, then transmit the 8 samples. This reduces the amount of time required to send all 8 samples from the delivery thread by an order of magnitude.

These changes would bring the performance much more inline with the ADAT_TX_USE_SHARED_BUFF implementation.

[sflower]

Thanks Henk - that all makes a lot of sense.

I've just done some further testing of the new implementation, and I'm not seeing any data corruption. I'm feeding the ADAT TX thread fixed values - 0xCCCCCC00, and then from another product that uses the ADAT RX module, reading in 1024 sample at a time. Once the ADAT RX thread has locked on, I have not seen one sample come in with an incorrect value at 44.1kHz or 48kHz.

I have also just recorded the ADAT data to an audio file, so I could check over a longer period of time. So far over a 2 minute period, I have not been able to find any errors.

For this testing and in the actual production firmware I've been using a 50MIPS thread, and the adat_transmit_port_until_ct_2x function.