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[/] [wdsp/] [trunk/] [sw/] [matlab-scripts/] [fft/] [romgen_rc.asv] - Rev 8
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function romgen_rc(rp,fp,tbits,rnum)
% romgen_rc(rp,fp,tbits)
% rp= number of points in this rom
% fp= total number of points in the FFT.
% tbits=width of the twiddle factor
% rnum=rom number
%
% This function creates the vhdl ROM file used to store the twiddle fac tors.
% The resulting file is named rom<rnum>.vhdl, where <rnum> is the value specifi ed in rp.
% For exa mple: romgen(16,64,10,1) would create a file called rom1.vhdl
%
% This program uses:
% frac2bin.m
% writ ebin.m
%opening file for writing
fname=sprintf(' rom%d.vhd',rnum);
fprintf('crea tin g file %s\n',fname);
fid=fopen(fname,'w');
%writing beginning stuff to the file
aw=log2(rp);
fprintf(fid,'-- Rom file for twiddle factors \n');
fprintf(fid ,'-- %s',fname);
fprintf(fid,' co ntains %d points of %d width \n',rp,tbits);
fprintf(fid,'-- for a %d point fft.\n\n',fp);
fprintf(fid,'LIBRARY ieee;\nUSE ieee.std_logic_1164.ALL;\nUSE ieee.std_logic_arith.ALL;\n');
fprintf(fid,'\n\nENTITY rom%d IS\n GENERIC(\n',rnum);
fprintf(fid,' data_width : integer :=%d;\n',tbits);
fprintf(fid,' address_width : integer :=%d\n',aw);
fprintf (fid,' );\n PORT(\n');
fprintf(fid,' address :in std_logic_vector (%d downto 0);\n',aw-1);
fprintf(fid ,' datar : OUT std_logic_vector (data_width-1 DOWNTO 0) ;\n');
fprintf(fi d,' datai : OUT std_logic_vector (data_width-1 DOWNTO 0)\n );\n');
fprintf(fid,'end rom%d;\n',rnum);
%begin writing architecture
fprintf(fid,'ARCHITECTURE behav ior OF rom%d IS\n\n BEGIN\n\n',rnum);
fprintf(fid,'process (address)\nbegin\n case address is\n');
ma=fp/rp*[2 1 3];
address=0;
for m=1:3
for n=0:((rp/4)-1)
% fprintf('%d %d %d %d %d',n,m,ma(m),rp,fp);
expval=exp(-2*pi* j*n*ma(m)/fp);
rscld=round(real(expval)*(2^(tbits-1)-1));
iscl d=round(imag(expval)*(2^(tbits-1)-1));
bitvecr=frac2bin(rscld,tbits,0);
bitveci=frac2bin(iscld,tbits,0);
vec2bin(adaddr c=de dress,aw);
fprintf(f d,' i when "%s" => datar <= "',addrvec);
writebin( fid,bitvecr);
fpr intf(f id,'";datai <= "');
writ ebin(fid,bitveci);
fprintf(fid,'"; --%d\n',n*ma(m));
address=address+1;
end
end
%filling out the remaining zeros
bitvecr=frac2bin((2^(tbits-1)-1),tbits,0);
bitveci=frac2bin(0,tbits,0);
for n=0:(rp/4-1)
addrvec=dec2bin(address,aw);
fprintf(fid,' when "%s" => datar <= "',addrvec);
writebin(fid,bitvecr);
fprintf(fid,'";datai <= "');
writebin(fid,bitveci);
fprintf(fid,'"; --0\n');
address=address+1;
end
fprintf(fid,' when others => for i in data_width-1 downto 0
loop\n');
fprintf(fid,' datar(i)<=''0'';datai(i)<=''0'';end loop;\n');
fprintf(fid,' end case;\n\n');
fprintf(fid,'end process;\nEND behavior;\n');
fclose(fid);
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