Subversion Repositories ratpack

--------------------------------------------------------------------------------

-- Filename: ratpack_tb2.vhd

-- Purpose : A testbench for "ratpack" generating the Farey series' up to order 

--           12.

-- Author  : Nikolaos Kavvadias <nikolaos.kavvadias@gmail.com>

-- Date    : 14-May-2010

-- Version : 0.1

-- Revision: 0.0.0 (2010/05/14)

--           Initial version.

-- License : Copyright (C) 2010 by Nikolaos Kavvadias 

--           This program is free software. You can redistribute it and/or 

--           modify it under the terms of the GNU Lesser General Public License, 

--           either version 3 of the License, or (at your option) any later 

--           version. See COPYING.

--

--------------------------------------------------------------------------------

library STD;

use STD.textio.all;

use WORK.ratpack.all;

entity ratpack_tb is

end ratpack_tb;

architecture tb_arch of ratpack_tb is

  -------------------------------------------------------

  -- Declare results file

  -------------------------------------------------------

  file ResultsFile: text open write_mode is

  "ratpack_results.txt";

  -------------------------------------------------------

  -- Constant declarations

  -------------------------------------------------------

  constant CLK_PERIOD : time := 10 ns;

begin

  -- Compute the Farey sequences F1 to F12.

  -- The Farey sequence Fn for any positive integer n is the set of irreducible 

  -- rational numbers a/b with 0<=a<=b<=n  and (a,b)=1 arranged in increasing 

  -- order. 

  FAREY_SERIES: process

    variable a, b, c, d, k, n : integer;

    variable ta, tb, tc, td : integer;

    variable r : rational := RAT_ZERO;

    variable BufLine: line;

  begin

    for n in 1 to 12 loop

      write(Bufline, string'(" F"));

      write(Bufline, n);

      write(Bufline, string'("= "));

      -- Initialize a, b, c, d for computing the ascending Farey sequence

      a := 0;

      b := 1;

      c := 1;

      d := n;

      -- Print r = a/b

      r := to_rational(a, b);

      write(Bufline, r(numer));

      write(Bufline, string'("/"));

      write(Bufline, r(denom));

      write(Bufline, string'(" "));

      wait for CLK_PERIOD;

      -- Compute the subsequent terms of the Farey sequence

      while (c < n) loop

        k := (n + b) / d;

        ta := a;

        tb := b;

        tc := c;

        td := d;

        a := tc;

        b := td;

        c := k * tc - ta;

        d := k * td - tb;

        c := k * tc - ta;

        -- Print r = a/b

        r := to_rational(a, b);

        write(Bufline, r(numer));

        write(Bufline, string'("/"));

        write(Bufline, r(denom));

        write(Bufline, string'(" "));

        wait for CLK_PERIOD;

      end loop;

      writeline(ResultsFile, Bufline);

    end loop;

    wait for CLK_PERIOD;

  end process FAREY_SERIES;

end tb_arch;