FIR Static Parameters - 2021.2 English

Vitis High-Level Synthesis User Guide (UG1399)

Document ID
UG1399
ft:locale
English (United States)
Release Date
2021-12-15
Version
2021.2 English

The static parameters of the FIR define how the FIR IP is parameterized and specifies non-dynamic items such as the input and output widths, the number of fractional bits, the coefficient values, the interpolation and decimation rates. Most of these configurations have default values: there are no default values for the coefficients.

The hls_fir.h header file defines a struct hls::ip_fir::params_t that can be used to set the default values for most of the static parameters.

Important: There are no defaults defined for the coefficients. Therefore, Xilinx does not recommend using the pre-defined struct to directly initialize the FIR. A new user defined struct which specifies the coefficients should always be used to perform the static parameterization.

In this example, a new user struct my_config is defined and with a new value for the coefficients. The coefficients are specified as residing in array coeff_vec. All other parameters to the FIR use the default values.

struct myconfig : hls::ip_fir::params_t {
    static const double coeff_vec[sg_fir_srrc_coeffs_len];
};
static hls::FIR<myconfig> fir1;
fir1.run(fir_in, fir_out);

FIR Static Parameters describes the parameters used for the parametrization struct hls::ip_fir::params_t. FIR Struct Parameter Values provides the default values for the parameters and a list of possible values.