fft_real.m

ADSP-TS101S and ADSP-TS201S Real and Complex radix-2 C-callable FFT

%_______________________________________________________________________
% FFT_REAL.M          Matlab script to plot ADSP-TS201 FFT results
%
%_______________________________________________________________________

clear all;
close all;

%please introduce here the number X from the assembly program. 
%Nothing else is to be done
N='1024';


input_file=['inputs/input',N,'.dat'];
output_file=['outputs/output_real_',N,'.dat'];
output_matlab_file=['outputs/output_real_',N,'_matlab.dat'];

%//load input file from generated random value.
        fid = fopen(input_file, 'r');
            [a, count] = fscanf (fid, '%f%c');
        fclose(fid);
        %I have to eliminate the comma that is wrtten after each input number

        for i=1:size(a)/2
            input(i,1)=a(2*i-1);
        end;


                    %//input is NOT complex, so the points of FFT must be halved.
N1=length(input);  %//get the length of input file and points for FFT.

infft=fft(input,N1);    %//FFT of input.

    fin = fopen(output_matlab_file, 'wt');
        for i=1:N1/2
          fprintf(fin, '%g\n%g\n', 2*real(infft(i,1)), 2*imag(infft(i,1)));
        end;
    fclose(fin);



inrealfft_in=infft(1:N1/2);  %need only half points because of TS input.

for i=1:N1/2
    inrealfft(1,i)=inrealfft_in(i,1); %//change the matrix format.
end


s=load (output_file);      %//load file output of optimized FFT for TigerSHARC TS-101.
output=s/2;         %//output of optimized FFT for TigerSHARC TS-101.




for k=1:N1/2
    outreal(k)=output(2*k-1);
    outimag(k)=output(2*k);
end

realoutput=complex(outreal, outimag);

x=0:1/N1:1-1/N1;
y=0:1/(N1/2):1-1/(N1/2);
mlb=20*log10(abs(inrealfft));
%chip=20*log10(sqrt((outreal.*outreal)+(outimag.*outimag)));
chip=20*log10(abs(realoutput));

figure
subplot(2,2,1);
plot(x,input)      %//plot input data.
grid
title([N,' Real Input data'])

subplot(2,2,2);
plot(y,mlb,'r',y,chip,'g')      %//plot Log Magnitude comparison TigerSHARC vs MATLAB.
grid
title('Log Magnitude Comparison, TS in green')

subplot(2,2,3);
plot(y,abs(inrealfft),'r',y,abs(realoutput),'g')  %//plot Magnitude comparison TigerSHARC vs MATLAB.
grid
title('Magnitude Comparison, TS in green')

subplot(2,2,4);
plot(y,abs(inrealfft)-abs(realoutput))    %//plot Error Magnitude TigerSHARC vs MATLAB.
grid
title('Error in Magnitude')


figure
subplot(2,2,1);
plot(y,real(inrealfft),'r',y,outreal,'g')
grid
title('Real Part Comparison, TS in green')
subplot(2,2,2);
plot(y,real(inrealfft)-outreal)
grid
title('Error in Real')
subplot(2,2,3);
plot(y,imag(inrealfft),'r',y,outimag,'g')
grid
title('Imaginary Part Comparison, TS in green')
subplot(2,2,4);
plot(y,imag(inrealfft)-outimag)
grid
title('Error in Imaginary')