--include this library for file handling in VHDL.

library std;

use std.textio.all;  --include package textio.vhd

--entity declaration

entity filehandle is

end filehandle;

--architecture definition

architecture Behavioral of filehandle is

--period of clock,bit for indicating end of file.

signal clock,endoffile : bit := '0';

--data read from the file.

signal    dataread : real;

--data to be saved into the output file.

signal    datatosave : real;

--line number of the file read or written.

signal    linenumber : integer:=1; 

begin

clock <= not (clock) after 1 ns;    --clock with time period 2 ns

--read process

reading :

process

    file   infile    : text is in  "C:\Users\Deton@tor\Documents\02217 Design of Arithmetic Processors\aes\1.txt";   --declare input file

    variable  inline    : line; --line number declaration

    variable  dataread1    : real;

begin

wait until clock = '1' and clock'event;

if (not endfile(infile)) then   --checking the "END OF FILE" is not reached.

readline(infile, inline);       --reading a line from the file.

  --reading the data from the line and putting it in a real type variable.

read(inline, dataread1);

dataread <=dataread1;   --put the value available in variable in a signal.

else

endoffile <='1';         --set signal to tell end of file read file is reached.

end if;

end process reading;

--write process

writing :

process

    file      outfile  : text is out "C:\Users\Deton@tor\Documents\02217 Design of Arithmetic Processors\aes\2.txt";  --declare output file

    variable  outline  : line;   --line number declaration  

  begin

wait until clock = '0' and clock'event;

if(endoffile='0') then   --if the file end is not reached.

--write(linenumber,value(real type),justified(side),field(width),digits(natural));

write(outline, dataread, right, 16, 12);

-- write line to external file.

writeline(outfile, outline);

linenumber <= linenumber + 1;

else

null;

end if;

end process writing;

end Behavioral;