CristalCaveGem » LustreC » Lustrec-Tests

-- Copyright (C) 1996 Morgan Kaufmann Publishers, Inc

-- This file is part of VESTs (Vhdl tESTs).

-- VESTs is free software; you can redistribute it and/or modify it

-- under the terms of the GNU General Public License as published by the

-- Free Software Foundation; either version 2 of the License, or (at

-- your option) any later version. 

-- VESTs is distributed in the hope that it will be useful, but WITHOUT

-- ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

-- FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

-- for more details. 

-- You should have received a copy of the GNU General Public License

-- along with VESTs; if not, write to the Free Software Foundation,

-- Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA 

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

--

-- $Id: bv_images_body.vhd,v 1.3 2001-10-26 16:29:33 paw Exp $

-- $Revision: 1.3 $

--

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

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

--

--  bv_images package body.

--

--  Functions that return the string image of values.

--  Each image is a correctly formed literal according to the

--  rules of VHDL-93.

--

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

package body bv_images is

  -- Image of bit vector as binary bit string literal

  -- (in the format B"...")

  -- Length of result is bv'length + 3

  function image (bv : in bit_vector) return string is

    alias bv_norm : bit_vector(1 to bv'length) is bv;

    variable result : string(1 to bv'length + 3);

  begin

    result(1) := 'B';

    result(2) := '"';

    for index in bv_norm'range loop

      if bv_norm(index) = '0' then

        result(index + 2) := '0';

      else

        result(index + 2) := '1';

      end if;

    end loop;

    result(bv'length + 3) := '"';

    return result;

  end image;

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

  -- Image of bit vector as octal bit string literal

  -- (in the format O"...")

  -- Length of result is (bv'length+2)/3 + 3

  function image_octal (bv : in bit_vector) return string is

    constant nr_digits : natural := (bv'length + 2) / 3;

    variable result : string(1 to nr_digits + 3);

    variable bits : bit_vector(0 to 3*nr_digits - 1) := (others => '0');

    variable three_bits : bit_vector(0 to 2);

    variable digit : character;

  begin

    result(1) := 'O';

    result(2) := '"';

    bits(bits'right - bv'length + 1 to bits'right) := bv;

    for index in 0 to nr_digits - 1 loop

      three_bits := bits(3*index to 3*index + 2);

      case three_bits is

	when b"000" =>

	  digit := '0';

	when b"001" =>

	  digit := '1';

	when b"010" =>

	  digit := '2';

	when b"011" =>

	  digit := '3';

	when b"100" =>

	  digit := '4';

	when b"101" =>

	  digit := '5';

	when b"110" =>

	  digit := '6';

	when b"111" =>

	  digit := '7';

      end case;

      result(index + 3) := digit;

    end loop;

    result(nr_digits + 3) := '"';

    return result;

  end image_octal;

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

  -- Image of bit vector as hex bit string literal

  -- (in the format X"...")

  -- Length of result is (bv'length+3)/4 + 3

  function image_hex (bv : in bit_vector) return string is

    constant nr_digits : natural := (bv'length + 3) / 4;

    variable result : string(1 to nr_digits + 3);

    variable bits : bit_vector(0 to 4*nr_digits - 1) := (others => '0');

    variable four_bits : bit_vector(0 to 3);

    variable digit : character;

  begin

    result(1) := 'X';

    result(2) := '"';

    bits(bits'right - bv'length + 1 to bits'right) := bv;

    for index in 0 to nr_digits - 1 loop

      four_bits := bits(4*index to 4*index + 3);

      case four_bits is

	when b"0000" =>

	  digit := '0';

	when b"0001" =>

	  digit := '1';

	when b"0010" =>

	  digit := '2';

	when b"0011" =>

	  digit := '3';

	when b"0100" =>

	  digit := '4';

	when b"0101" =>

	  digit := '5';

	when b"0110" =>

	  digit := '6';

	when b"0111" =>

	  digit := '7';

	when b"1000" =>

	  digit := '8';

	when b"1001" =>

	  digit := '9';

	when b"1010" =>

	  digit := 'A';

	when b"1011" =>

	  digit := 'B';

	when b"1100" =>

	  digit := 'C';

	when b"1101" =>

	  digit := 'D';

	when b"1110" =>

	  digit := 'E';

	when b"1111" =>

	  digit := 'F';

      end case;

      result(index + 3) := digit;

    end loop;

    result(nr_digits + 3) := '"';

    return result;

  end image_hex;

end bv_images;