close all;
clear all;

% file: com8001r2.M
% modified: 8-29-02
% Author: MSS/Alain Zarembowitch
% 
%--------------------
% Generates baseband signal for the COM-8001 pattern generator
% Format is 2 (complex) * 10-bit (unsigned).
% Generate two sinewaves, at frequency fc1 and fc2.
%--------------------
fs = 200000;			% sampling rate 200 KHz typ.
nsamples = 200;	% simulation duration, expressed as number of complex samples
fc1 = 1000;				% sinewave1 in Hz
fc2 = -2000;			% sinewave2 in Hz
gain1 = 0.7				% amplitude scaling factor 
gain2 = 0.7				% amplitude scaling factor 


% for long simulations, store results in output file
[fid_o1,message]  = fopen('com8001r2.bin','w');
if(fid_o1 == -1)
   message
end


% initialization
last_i = 0;
last_q = 0;
current_i = 0;
current_q = 0;
b = dec2bin(0,10);

%------------------------------------------------------
% MAIN LOOP
%------------------------------------------------------

% loop signal processing (cannot use vectors)
for j = 1:nsamples
	i = j   
   
   % simulate the first sinewave
   phase1 = 2.*pi*fc1*(i-1)/fs;	% carrier phase
   carrier1_cos = cos(phase1);	
   carrier1_sin = sin(phase1);
   
   sigt1i = carrier1_cos*gain1;
   sigt1q = carrier1_sin*gain1;
   
   test1(i) = sigt1i;
   test2(i) = sigt1q;
   
   % simulate the second sinewave
   phase2 = 2.*pi*fc2*(i-1)/fs;	% carrier phase
   carrier2_cos = cos(phase2);	
   carrier2_sin = sin(phase2);
   
   sigt2i = carrier2_cos*gain2;
   sigt2q = carrier2_sin*gain2;
   
   test3(i) = sigt2i;
   test4(i) = sigt2q;
   
   % sum both signals. Scale to prevent overflow
   sigt3i = (sigt1i + sigt2i)/2.;
   sigt3q = (sigt1q + sigt2q)/2.;
   
   test5(i) = sigt3i;
   test6(i) = sigt3q;
     
   % convert samples to 10-bit unsigned format
   sigt3i = min(max((floor((sigt3i+1.)*511.5)),0.),1023);
   sigt3q = min(max((floor((sigt3q+1.)*511.5)),0.),1023);
   
   %invert bit order because of pinout
   a = dec2bin(sigt3i, 10);
   b(1) = a(10);
   b(2) = a(9);
   b(3) = a(8);
   b(4) = a(7);
   b(5) = a(6);
   b(6) = a(5);
   b(7) = a(4);
   b(8) = a(3);
   b(9) = a(2);
   b(10) = a(1);
   outputi = bin2dec(b);
   
   a = dec2bin(sigt3q, 10);
   b(1) = a(10);
   b(2) = a(9);
   b(3) = a(8);
   b(4) = a(7);
   b(5) = a(6);
   b(6) = a(5);
   b(7) = a(4);
   b(8) = a(3);
   b(9) = a(2);
   b(10) = a(1);
   outputq = bin2dec(b);
   
   
   % pack samples into byte-size format
   % wait until two complex samples are collected before writing into file (makes it easier to 
   % manage the byte alignments): 4 * 10-bits is a multiple of 8.
   if(mod(j,2) == 0)
      % even sample
      current_i = outputi;
      current_q = outputq;
      
      a = bitand(bitshift(last_q,-2), 255);
	   fprintf(fid_o1,'%c',a);
      a = bitand(bitor(bitshift(last_q,6),bitshift(last_i,-4)),255);
      fprintf(fid_o1,'%c',a);
      a = bitand(bitor(bitshift(last_i,4),bitshift(current_q,-6)),255);
      fprintf(fid_o1,'%c',a);
      a = bitand(bitor(bitshift(current_q,2),bitshift(current_i,-8)),255);
      fprintf(fid_o1,'%c',a);
      a = bitand(current_i,255);
      fprintf(fid_o1,'%c',a);
      
      % keep track of simulation progress
      if(mod(j,10000) == 0)
         j/10000
     	end;
      
   else
      % odd sample
	   % remember last sample
      last_i = outputi;
      last_q = outputq;
   end;
   
  subplot(3,1,1);
  title('First Sinewave');
  plot(test1);
  hold on;
  plot(test2,'r');
  ylabel('amplitude')
  
  subplot(3,1,2);
  title('Second Sinewave');
  plot(test3);
  hold on;
  plot(test4,'r');
  ylabel('amplitude')
  
  subplot(3,1,3);
  title('Scaled Sum of Both Sinewaves');
  plot(test5);
  hold on;
  plot(test6,'r');
  xlabel('samples');
  ylabel('amplitude')

  
 end   

% close opened files
fclose(fid_o1);