I have an audio in-out program in C for the ADSP-BF706 EZ-KIT mini, about 80 lines in length. It's simple and very easy to understand. It's also completely self-contained - it doesn't use any of the header files that the "TalkThrough_BF706Mini.c" program uses (supplied with the kit). It includes a basic TWI driver, SPORT0 set up and configuration routine for the on board codec (ADAU1761). With some simple modifications it can be used for filtering, both FIR and IIR. The file is attached. All welcome to use free.
It would be interesting to compare the efficiencies of block processing and sample-by-sample processing. In the example code I give, sample-by-sample allows up to 8000 32-bit FIR filter coefficients at a sample rate of 48 kHz. For 16-bit, it's about 13000. Anyone done any speed comparisons with block mode? I have not implemented block mode FIR yet - am I correct in assuming it would be better (time domain, not FFT based filtering)?