%Daniel Linnen
%Project Program 5



%opening the file

f1=fopen('C:\ELE498D\xn.dat', 'r');

%initializing arrays
x=zeros(256,1);
h=zeros(256,1);
%declaration

k=0;
count=1;
m=0;
q0=0;
q1=0;
q2=0;
q3=0;
q4=0;

%start of program

while(count==1)
    
    %reading file
    
    [xn,count] = fread(f1, 1, 'short');
    if(count==0)
        break;
    end
    
    %converting from integers
    
    xn = xn/32768;
    
    %insertion of random noise
    
    xn = xn + 0.01*rand;
    
    %update the input buffer
    
    for i=256:-1:2
        x(i)=x(i-1);
    end
    x(1)=xn;
   
    
    %incrimenting counting variable
   k=k+1;
   
   %checking to see if %50 of the input is new
   
   if(k==128)
       
       %doing a 128 point DFT on the input
       
       q=fft(x,256);
       
       %checking for the maximums
       
       for i=1:128
           
           %initializing the flags
           %these flags tell the program if a magnitude is already a
           %maximum so it doesnt record a maximum multiple times
           
           flag0=1;
           flag1=1;
           flag2=1;
           flag3=1;
           
           %calculating the magnitude of the current input
           
           mag=abs(real(q(i)));
           
           %doing comparisons and checking of flags
           
               if(mag>q0)
                   flag0=0;
                   q0=mag;
                   qn0=i;
               end
               if(mag>q1 && flag0)
                   flag1=0;
                   q1=mag;
                   qn1=i;
               end
               if(mag>q2 && flag0 && flag1)
                   flag2=0;
                   q2=mag;
                   qn2=i;
               end
               if(mag>q3 && flag0 && flag1 && flag2)
                   flag3=0;
                   q3=mag;
                   qn3=i;
               end
               if(mag>q4 && flag0 && flag1 && flag2 && flag3)
                   q4=mag;
                   qn4=i;
               end
           end
           
           %setting values other than the top 5 frequency bins to zero
           h=zeros(256,1);
           
           for i=1:128
               if((i>=(qn0-2) && i<=(qn0+2)) || (i>=(qn1-2) && i<=(qn1+2)) || (i>=(qn2-2) && i<=(qn2+2)) || (i>=(qn3-2) && i<=(qn3+2)) || (i>=(qn4-2) && i<=(qn4+2)))
                   h(i)=1;
                   h(256-i)=1;
               else
                   h(i)=0.001;
                   h(256-i)=0.001;                   
               end
           end
           g=dot(q,h);
           
           
           %doing inverse of a 128 point DFT
           
           y1=ifft(g,256);
           
           %preparing output for plotting or listening
           
           for n=1:128
               y(m+n)=y1(n+128);
           end
           m=m+128;
           
           %reinitialization of k
           
           k=0;
   end
end