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%Header file generation for Wishbone compliant IIR core test

%Cleans workspace

clc;

clear all;

close all;

%Low-pass filter

%Cut-off frequencies

fs=8000;

fp1=425;

fp2=475;

fs1=410;

fs2=490;

%Ripples

Rp=3;

Rs=20;

%Normalized cut-off frequencies

Omp1=2*fp1/fs;

Omp2=2*fp2/fs;

Oms1=2*fs1/fs;

Oms2=2*fs2/fs;

%Filter order estimation

[N Omc]=buttord([Omp1 Omp2],[Oms1 Oms2],Rp,Rs);

%Filter design

[b_d a_d]=butter(N,Omc);

%Bits to use for each coefficient

Nbits=16;

%SOS structure

[SOS g] = tf2sos(b_d,a_d);

%Number of sections

Nsect=size(SOS,1);

%Gain for each section

gk=g^(1/Nsect);

%Fractional part

Q=floor(Nbits-1-log2(max([gk max(abs(SOS))])));

%Quantized coefficients

SOS_Q=round(SOS*2^Q);

%Quantized gain

gk_Q=round(gk*2^Q);

%Auxiliary variable

SOS_orig=SOS_Q;

%Header file generation

SOS=reshape(fliplr(SOS)',Nsect*3*2,1);

SOS_Q=reshape(fliplr(SOS_Q)',Nsect*3*2,1);

SOS_fprintf=[SOS_Q'; SOS'];

handle = fopen('../../IIR6/coefs_sos.h', 'wt');

fprintf(handle, '/*Second Order Sections (SOS) automatically generated header file*/\n');

fprintf(handle, '/*M.Eng. Alexander López Parrado*/\n\n');

fprintf(handle, '#include <stdint.h>\n');

fprintf(handle, '/*The number of sections*/\n');

fprintf(handle, '#define NSECT %d\n\n',Nsect);

fprintf(handle, '/*Number of bits in fractional part of coeffcients*/\n');

fprintf(handle, '/*Fixed point format with %d bits ([%d].[%d])*/\n',Nbits,Nbits-Q,Q);

fprintf(handle, '#define Q %d\n\n',Q);

fprintf(handle, '/*Gain on each stage*/');

fprintf(handle, '\nconst int16_t gk = %d;\n\n',gk_Q);

fprintf(handle, '/*Filter Coefficients ,b10,b11,b12,a10,a11,a12,b00,b01,b02,a00,a01,a02*/');

fprintf(handle, '\nconst int16_t SOS[NSECT*3*2] = {\n');

fprintf(handle, '%d, //%f\n', SOS_fprintf);

fprintf(handle, '};\n');

fclose(handle);