Analog Devices VISUALDSP++ 3.5 Manual page 459

#define cfir_init(state, coeffs, delay, ncoeffs)
(state).h = (coeffs);
(state).d = (delay);
(state).p = (delay);
(state).k = (ncoeffs)
The characteristics of the filter (passband, stopband, etc.) are dependent
upon the number of complex filter coefficients and their values. A pointer
to the coefficients should be stored in
number of coefficients.
Each filter should have its own delay line which is a vector of type
complex_fract16
The vector should be cleared to zero before calling the function for the
first time and should not otherwise be modified by the user program. The
structure member
function uses
s->p
Algorithm
−
p 1
∑
=
y k ( ) h i ( ) * (
=
i 0
Domain
-1.0 to +1.0
VisualDSP++ 3.5 C/C++ Compiler and Library Manual
for ADSP-219x DSPs
\
\
\
and whose length is equal to the number of coefficients.
should be set to the start of the delay line, and the
s->d
to keep track of its current position within the vector.
− =
x k i ) fo r k 0 1 , , . . .
DSP Run-Time Library
, and should be set to the
s->h s->k
n
\
4-43