memory_rnd.vhd

--**************************************
--
-- Block timer and wc load random
--
--  Dominique Gigi  March 2012
--
-- To be used with Sergio vi 
-- 16 lower bit is word count in bytes
-- 16 higher bit are time before next event
--
--**************************************

LIBRARY ieee;
--LIBRARY altera_mf;
--LIBRARY altera;


USE ieee.std_logic_1164.all;
use ieee.numeric_std.all;
use ieee.std_logic_unsigned.all;
--LIBRARY lpm;
--USE lpm.lpm_components.all; 
--USE altera_mf.altera_mf_components.all;
--USE altera.altera_primitives_components.all;

entity memory_rnd is

port (
    RST_lowClk  : IN std_logic;
    low_clk     : IN Std_logic;
    RST_PCIClk  : IN Std_logic;
    PCIe_clk        : IN std_logic;
    
    PCIe_dt     : IN std_logic_vector(31 downto 0);
    PCIe_func   : IN std_logic_vector(15 downto 0);
    PCIe_cs     : IN std_logic;
    PCIe_wen        : IN std_logic;
    
    start           : IN std_logic;
    
    wc              : OUT std_logic_vector(15 downto 0);
    RST_EvtClk  : IN std_logic;
    evt_clk     : IN std_logic;
    trigger     : OUT std_logic;
    end_evt     : IN std_logic
    );
end memory_rnd;

architecture behavioral of memory_rnd is


--component LPM_FIFO        !!!!!!!!!!!! ALTERA VERSION !!!!!!!!!!
--generic (
--      LPM_WIDTH           : natural;    -- MUST be greater than 0
--      LPM_WIDTHU          : natural := 1;    -- MUST be greater than 0
--      LPM_NUMWORDS        : natural;    -- MUST be greater than 0
--      LPM_SHOWAHEAD       : string := "ON";
--      LPM_TYPE            : string := L_FIFO;
--      LPM_HINT            : string := "UNUSED");
--  port (
--      DATA                    : in std_logic_vector(LPM_WIDTH-1 downto 0);
--      CLOCK               : in std_logic;
--      WRREQ               : in std_logic;
--      RDREQ               : in std_logic;
--      ACLR                    : in std_logic := '0';
--      SCLR                    : in std_logic := '0';
--      Q                       : out std_logic_vector(LPM_WIDTH-1 downto 0);
--      USEDW               : out std_logic_vector(LPM_WIDTHU-1 downto 0);
--      FULL                    : out std_logic;
--      EMPTY               : out std_logic);
--end component;

COMPONENT lpm_fifo
  PORT (
    clk : IN STD_LOGIC;
    rst : IN STD_LOGIC;
    din : IN STD_LOGIC_VECTOR(31 DOWNTO 0);
    wr_en : IN STD_LOGIC;
    rd_en : IN STD_LOGIC;
    dout : OUT STD_LOGIC_VECTOR(31 DOWNTO 0);
    full : OUT STD_LOGIC;
    empty : OUT STD_LOGIC
  );
END COMPONENT;
    
component resync  
port (
    reset                       : in std_logic;
    Free_clki               : in std_logic;
    clocki                  : in std_logic;
    clocko                  : in std_logic;
    input                       : in std_logic;
    output                  : out std_logic
    );
end component;

signal data_mux         : std_logic_vector(31 downto 0);
signal wen_mux              : std_logic;
-- signal pcie_dt_ltch  : std_logic_vector(31 downto 0);
signal low_wen_sync     : std_logic;
signal end_evt_sync     : std_logic;
signal fifo_dto             : std_logic_vector(31 downto 0);
signal timer                : std_logic_vector(15 downto 0);
signal timer_cnt            : std_logic;
signal trig                 : std_logic;
signal soft_reset           : std_logic;
 
--******************************************************************************
--************************<<  BEGIN    >>***************************************
--******************************************************************************
begin 

wen_resync:resync  
port map(
    reset                => RST_LowClk,
    Free_clki        => '1',
    clocki           => low_clk,
    input                => trig,
            
    clocko           => PCIe_clk,
    output           => low_wen_sync
    );

process(RST_PCIClk,PCIe_clk)
begin
    if RST_PCIClk = '0' then
        wen_mux <= '0';
        soft_reset <= '0';
    elsif rising_edge(PCIe_clk) then
        wen_mux <= '0';
        if low_wen_sync = '1' or (PCIe_wen = '1' and PCIe_func(5) = '1' and PCIe_cs = '1') then 
            wen_mux <= '1';
        end if;
        
        soft_reset <= '0';
        if (PCIe_wen = '1' and PCIe_func(0) = '1' and PCIe_cs = '1' and PCIe_dt(5) = '1' ) then
            soft_reset <= '1';
        end if;
        
        if (PCIe_wen = '1' and PCIe_func(5) = '1' and PCIe_cs = '1') then  
            data_mux <= PCIe_dt;
        else
            data_mux <= fifo_dto;
        end if;
    end if;
end process;



--fifo_rnd:LPM_FIFO     !!!!!!!!!!!!!!!!!!!!!ALTERA VERSION !!!!!!!!!!!!!!!!!!!!!!!!!
--generic map(
--  LPM_WIDTH       => 32,
--  LPM_WIDTHU      => 10,
--  LPM_NUMWORDS    => 1024)
--port map (
--  DATA                => data_mux,
--  CLOCK           => PCIe_clk,
--  WRREQ           => wen_mux,
--  RDREQ           => low_wen_sync,
--  ACLR                => soft_reset,
--  Q                   => fifo_dto
--  );  

fifo_rnd : lpm_fifo     --!!!!!!!!!!!!!!!!!!!! XILINX VERSION !!!!!!!!!!!!!!!!!
  PORT MAP (
    clk  => PCIe_clk,
    rst  => soft_reset,
    din  => data_mux,
    wr_en  => wen_mux,
    rd_en  => low_wen_sync,
    dout  => fifo_dto
--    full => full,
--    empty => empty
  );
    
End_evt_resync:resync  
port map(
    reset                => RST_EvtClk,
    Free_clki        => '1',        
    clocki           => evt_clk,
    input                => end_evt,
            
    clocko           => low_clk,
    output           => end_evt_sync
    );

process(RST_LowClk,low_clk)
begin
    if RST_LowClk = '0' then
        timer           <= (others => '0'); 
        timer_cnt       <= '0';
    elsif rising_edge(low_clk) then
        trig <= '0';
        if timer_cnt = '1' and timer(15 downto 1) = "000000000000000" then -- we don't chekc the lower bit in case of the delay is set to 0
            trig            <= '1';
        end if;
        
        if timer_cnt = '1' and timer(15 downto 1) = "000000000000000" then
            timer_cnt   <= '0';
        elsif end_evt_sync = '1' then
            timer_cnt   <= '1';
        end if;
            
        if  timer_cnt = '1' then
            timer       <= timer - "1";
        elsif end_evt_sync = '1' then
            timer       <= fifo_dto(31 downto 16);
        end if;
    end if;
end process;

trigger     <= low_wen_sync;    
wc          <= fifo_dto(15 downto 0);

end behavioral;