Subversion Repositories pcounter

--
-- * pipelined synchronous pulse counter *
--  pdchain -- multi-bit counter top-level entity
--
-- fast counter for slow-carry architectures
-- non-monotonic counting, value calculable by HDL/CPU
--
-- idea&code by Marek Peca <mp@duch.cz> 08/2012
-- Vyzkumny a zkusebni letecky ustav, a.s. http://vzlu.cz/
-- thanks to Michael Vacek <michael.vacek@vzlu.cz> for testing
--
 
library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;
 
entity pdchain is
  generic (
    n: natural := 32
  );
  port (
    clock: in std_logic;
    en: in std_logic;
    q: out std_logic_vector (n-1 downto 0)
  );
end pdchain;
 
architecture behavioral of pdchain is
  component pdivtwo
    port (
      clock: in std_logic;
      en: in std_logic;
      q, p: out std_logic
    );
  end component;
  --
  signal b: std_logic_vector (q'range);
begin
  q0: pdivtwo
    port map (
      clock => clock, en => en, p => b(0), q => q(0)
    );
  ch: for k in 1 to b'high generate
    qk: pdivtwo
      port map (
        clock => clock, en => b(k-1), p => b(k), q => q(k)
      );
  end generate;
end behavioral;