Introduction to DSP - Programming DSPs: index

The simple FIR filter equation:

can be implemented quite directly in C language:

y[n] = 0.0;
for (k = 0; k < N; k++)
y[n] = y[n] + c[k] * x[n-k];

But this naive code is inefficient:

The code is inefficient because:

• it uses array indices [i] rather than pointers *ptr
• it needs a lot of address arithmetic
• it repeatedly accesses the output array