Subversion Repositories spi_boot

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

--

-- SD/MMC Bootloader

--

-- $Id: tb_pack-p.vhd 77 2009-04-01 19:53:14Z arniml $

--

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

library ieee;

use ieee.std_logic_1164.all;

use ieee.numeric_std.all;

package tb_pack is

  function calc_crc(payload : in std_logic_vector) return std_logic_vector;

  function calc_crc(payload : in unsigned) return unsigned;

  function to_string(value : in integer) return string;

end tb_pack;

package body tb_pack is

  function calc_crc(payload : in std_logic_vector) return std_logic_vector is

    variable crc_v  : std_logic_vector(6 downto 0);

    variable temp_v : std_logic;

  begin

    crc_v := (others => '0');

    for i in payload'high downto payload'low loop

      temp_v := payload(i) xor crc_v(6);

      crc_v(6 downto 4) := crc_v(5 downto 3);

      crc_v(3) := crc_v(2) xor temp_v;

      crc_v(2 downto 1) := crc_v(1 downto 0);

      crc_v(0) := temp_v;

    end loop;

    return crc_v;

  end calc_crc;

  function calc_crc(payload : in unsigned) return unsigned is

  begin

    return unsigned(calc_crc(std_logic_vector(payload)));

  end calc_crc;

  function to_string(value : in integer) return string is

    variable str: string (11 downto 1);

    variable val: integer := value;

    variable digit: natural;

    variable index: natural := 0;

  begin

    -- Taken from:

    --  textio package body.  This file is part of GHDL.

    --  Copyright (C) 2002 Tristan Gingold.

    --  Note: the absolute value of VAL cannot be directly taken, since

    --  it may be greather that the maximum value of an INTEGER.

    loop

      --  LRM93 7.2.6

      --  (A rem B) has the sign of A and an absolute value less then

      --   the absoulte value of B.

      digit := abs (val rem 10);

      val := val / 10;

      index := index + 1;

      str (index) := character'val(48 + digit);

      exit when val = 0;

    end loop;

    if value < 0 then

      index := index + 1;

      str(index) := '-';

    end if;

    return str;

  end to_string;

end tb_pack;