Hi guys

I am new in DSP programming, I do not understand update delay in the code below. It is in the FIR filter.


for (i = N-1; i > 0; i--)
d = d[i-1]; //update delays with data move


how the delay is implemented and what usage

 

This is implementing your delay line/buffer. Presumably you shift in new data first, then shift everything down, every sample. You'll then loop over the delay line with your coefficients for the MAC operations.

FYI, use a circular buffer with pointers instead. This implementation, while it will work for lower order filters, is very inefficient and wastes many clock cycles.