updated FIR and IIR filter doc

Signed-off-by: Ralph J. Steinhagen <[email protected]>

test/blocklib/core/filter/time_domain_filter.hpp

@@ -9,16 +9,14 @@ namespace gr::blocks::filter {
 
 using namespace fair::graph;
 
-/**
- * @brief Finite Impulse Response (FIR) filter class
- *
- * The transfer function of an FIR filter is given by:
- * H(z) = b[0] + b[1]*z^-1 + b[2]*z^-2 + ... + b[N]*z^-N
- *
- */
 template<typename T>
     requires std::floating_point<T>
-struct fir_filter : node<fir_filter<T>> {
+struct fir_filter : node<fir_filter<T>, Doc<R""(
+@brief Finite Impulse Response (FIR) filter class
+
+The transfer function of an FIR filter is given by:
+H(z) = b[0] + b[1]*z^-1 + b[2]*z^-2 + ... + b[N]*z^-N
+)"">> {
     IN<T>             in;
     OUT<T>            out;
     std::vector<T>    b{}; // feedforward coefficients
@@ -45,19 +43,17 @@ enum class IIRForm {
     DF_II_TRANSPOSED
 };
 
-/**
- * @brief Infinite Impulse Response (IIR) filter class
- *
- * b are the feed-forward coefficients (N.B. b[0] denoting the newest and n[-1] the previous sample)
- * a are the feedback coefficients
- *
- */
 template<typename T, IIRForm form = std::is_floating_point_v<T> ? IIRForm::DF_II : IIRForm::DF_I>
     requires std::floating_point<T>
-struct iir_filter : node<iir_filter<T, form>> {
+struct iir_filter : node<iir_filter<T, form>, Doc<R""(
+@brief Infinite Impulse Response (IIR) filter class
+
+b are the feed-forward coefficients (N.B. b[0] denoting the newest and n[-1] the previous sample)
+a are the feedback coefficients
+)"">> {
     IN<T>             in;
     OUT<T>            out;
-    std::vector<T>    b{ 1 }; // feedforward coefficients
+    std::vector<T>    b{ 1 }; // feed-forward coefficients
     std::vector<T>    a{ 1 }; // feedback coefficients
     history_buffer<T> inputHistory{ 32 };
     history_buffer<T> outputHistory{ 32 };