Subversion Repositories spi_boot

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--

-- SD/MMC Bootloader

-- Generic counter module

--

-- $Id: spi_counter.vhd,v 1.1 2005-02-08 20:41:33 arniml Exp $

--

-- Copyright (c) 2005, Arnim Laeuger (arniml@opencores.org)

--

-- All rights reserved, see COPYING.

--

-- Redistribution and use in source and synthezised forms, with or without

-- modification, are permitted provided that the following conditions are met:

--

-- Redistributions of source code must retain the above copyright notice,

-- this list of conditions and the following disclaimer.

--

-- Redistributions in synthesized form must reproduce the above copyright

-- notice, this list of conditions and the following disclaimer in the

-- documentation and/or other materials provided with the distribution.

--

-- Neither the name of the author nor the names of other contributors may

-- be used to endorse or promote products derived from this software without

-- specific prior written permission.

--

-- THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"

-- AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,

-- THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR

-- PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE

-- LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR

-- CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF

-- SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS

-- INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN

-- CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)

-- ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE

-- POSSIBILITY OF SUCH DAMAGE.

--

-- Please report bugs to the author, but before you do so, please

-- make sure that this is not a derivative work and that

-- you have the latest version of this file.

--

-- The latest version of this file can be found at:

--      http://www.opencores.org/projects.cgi/web/spi_boot/overview

--

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library ieee;

use ieee.std_logic_1164.all;

entity spi_counter is

  generic (

    cnt_width_g   : integer := 4;

    cnt_max_g     : integer := 15;

    reset_level_g : integer := 0

  );

  port (

    clk_i      : in  std_logic;

    reset_i    : in  std_logic;

    cnt_en_i   : in  boolean;

    cnt_o      : out std_logic_vector(cnt_width_g-1 downto 0);

    cnt_ovfl_o : out boolean

  );

end spi_counter;

library ieee;

use ieee.numeric_std.all;

use work.spi_boot_pack.all;

architecture rtl of spi_counter is

  signal cnt_q      : unsigned(cnt_width_g-1 downto 0);

  signal cnt_ovfl_s : boolean;

begin

  cnt: process (clk_i, reset_i)

  begin

    if reset_i = reset_level_g then

      cnt_q <= (others => '0');

    elsif clk_i'event and clk_i = '1' then

      if cnt_en_i then

        if not cnt_ovfl_s then

          cnt_q <= cnt_q + 1;

        else

          cnt_q <= (others => '0');

        end if;

      end if;

    end if;

  end process cnt;

  cnt_ovfl_s <= cnt_q = cnt_max_g;

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

  -- Output Mapping

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

  cnt_ovfl_o <= cnt_ovfl_s;

  cnt_o      <= std_logic_vector(cnt_q);

end rtl;

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