wteam.vhd

简单的排队算法

----------------------------------------------------
-- Library
----------------------------------------------------
library IEEE;
use IEEE.std_logic_1164.all ;
use IEEE.std_logic_arith.all ;
use IEEE.std_logic_unsigned.all ;

----------------------------------------------------
-- entity
----------------------------------------------------
entity wteam is
  port (RST        : in    std_logic;
        CLK        : in    std_logic;                     
        A          : in    std_logic;                        
        B          : in    std_logic_vector (3 downto 0);    
        CH:out  std_logic_vector (3 downto 0);  
        CL:out  std_logic_vector (3 downto 0);  
        DH:out  std_logic_vector (3 downto 0);    
        DL:out  std_logic_vector (3 downto 0);   
        FH:out  std_logic_vector (3 downto 0);    
        FL:out  std_logic_vector (3 downto 0);   
        E: out  std_logic_vector (3 downto 0));
end wteam;

----------------------------------------------------
-- Architecture
----------------------------------------------------

architecture RTL of wteam is


   -- ** Internal signal declarations ** --
  signal s_guest_cnt_high       : std_logic_vector(3 downto 0);   
  signal s_guest_cnt_low        : std_logic_vector(3 downto 0);   
  signal s_sevice_cnt_high      : std_logic_vector(3 downto 0);   
  signal s_sevice_cnt_low       : std_logic_vector(3 downto 0);   
  signal n_wait_guest_high      : std_logic_vector(3 downto 0);          
  signal n_wait_guest_low       : std_logic_vector(3 downto 0);          


begin
p_function_cnt : process (RST, clk)
begin
  if (RST = '0') then
    s_guest_cnt_low  <= "0000";
    s_guest_cnt_high <= "0000";

  elsif (clk'event and clk = '1') then 
    if (A = '1') then
      if (s_guest_cnt_low = "1001") then                     
        s_guest_cnt_low <= "0000";
	if (s_guest_cnt_high < "1001") then
          s_guest_cnt_high <= s_guest_cnt_high + 1;
	else
          s_guest_cnt_high <= "0000";
        end if;
      elsif (s_guest_cnt_low < "1001") then
        s_guest_cnt_low <= s_guest_cnt_low + 1;
      elsif (s_guest_cnt_high > "1001") then        
        s_guest_cnt_high <= "0000";
      else
        s_guest_cnt_low <= "0000";
      end if;
    end if; 
  end if;
end process;

p_sevice_cnt : process (RST,
                        s_guest_cnt_low,
                        s_guest_cnt_high,
                        clk)
begin
  if ((RST = '0') or
      ((s_guest_cnt_low = "0000") and
       (s_guest_cnt_high = "0000")) or
      (s_guest_cnt_high < s_sevice_cnt_high)) then
    s_sevice_cnt_low <= "0000"; 
    s_sevice_cnt_high <= "0000";
   
  elsif (clk'event and clk = '1') then
    if (B > "0000") then
      if (s_sevice_cnt_low = "1001") then
        s_sevice_cnt_low <= "0000"; 
        if (s_sevice_cnt_high < "1001") then
          s_sevice_cnt_high <= s_sevice_cnt_high + 1;
        else
          s_sevice_cnt_high <= "0000";
	     end if;
      elsif (s_sevice_cnt_low < "1001") then
        s_sevice_cnt_low <= s_sevice_cnt_low + 1;
      elsif (s_sevice_cnt_high > "1001") then
        s_sevice_cnt_high <= "0000";
      end if;
    end if;
  end if;
end process;



p_wait_guest : process (s_guest_cnt_low,
                        s_guest_cnt_high,
            		s_sevice_cnt_low,
                        s_sevice_cnt_high)
begin
  if ((s_guest_cnt_low = "0000") and
      (s_guest_cnt_high = "0000")) then
    n_wait_guest_high <= "0000";
    n_wait_guest_low  <= "0000";

  elsif (s_guest_cnt_low > s_sevice_cnt_low) then
    n_wait_guest_high <= s_guest_cnt_high - s_sevice_cnt_high;
    n_wait_guest_low <= s_guest_cnt_low - s_sevice_cnt_low - 1;
  elsif ((n_wait_guest_high > 1) and 
         (s_guest_cnt_low < s_sevice_cnt_low)) then
    n_wait_guest_high <= s_guest_cnt_high - s_sevice_cnt_high - 1;
    n_wait_guest_low <= 10 - s_sevice_cnt_low - 1;
  else
    n_wait_guest_high <= "0000";
    n_wait_guest_low <= "0000";
  end if;
end process;


----------------------------------------------------
-- OUTPUT
----------------------------------------------------
  CH<= s_guest_cnt_high;
  CL<= s_guest_cnt_low;
  DH<= n_wait_guest_high;
  DL<= n_wait_guest_low;
  FH<= s_sevice_cnt_high;
  FL<= s_sevice_cnt_low;
  E <= not B;

end RTL;