Subversion Repositories pcie_mini

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

-- Project    : Spartan-6 Integrated Block for PCI Express

-- File       : pcie_bram_s6.vhd

-- Description: BlockRAM module for Spartan-6 PCIe Block

--              The BRAM A port is the write port.

--              The BRAM B port is the read port.

--

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

library ieee;

use ieee.std_logic_1164.all;

use ieee.std_logic_unsigned.all;

library unisim;

use unisim.vcomponents.all;

entity pcie_bram_s6 is

  generic (

    DOB_REG   : integer := 0; --  1 use output register, 0 don't use output register

    WIDTH     : integer := 0  --  supported WIDTH values are: 4, 9, 18, 36

  );

  port (

    user_clk_i   : in  std_logic; --  user clock

    reset_i      : in  std_logic; --  bram reset

    wen_i        : in  std_logic; --  write enable

    waddr_i      : in  std_logic_vector(11 downto 0); --  write address

    wdata_i      : in  std_logic_vector(WIDTH-1 downto 0); --  write data

    ren_i        : in  std_logic; --  read enable

    rce_i        : in  std_logic; --  output register clock enable

    raddr_i      : in  std_logic_vector(11 downto 0); --  read address

    rdata_o      : out std_logic_vector(WIDTH-1 downto 0) --  read data

  );

end pcie_bram_s6;

architecture rtl of pcie_bram_s6 is

  function CALC_ADDR(constant WIDTH : in integer;

                     constant addr_in : in std_logic_vector(11 downto 0)

                    ) return std_logic_vector is

    variable ADDR : std_logic_vector(13 downto 0);

  begin

    if    WIDTH = 4 then  ADDR := addr_in(11 downto 0) & "00";

    elsif WIDTH = 9 then  ADDR := addr_in(10 downto 0) & "000";

    elsif WIDTH = 18 then ADDR := addr_in(9  downto 0) & "0000";

    else                  ADDR := addr_in(8  downto 0) & "00000"; -- WIDTH=36

    end if;

    return ADDR;

  end function CALC_ADDR;

  signal di_int     : std_logic_vector(31 downto 0);

  signal dip_int    : std_logic_vector(3 downto 0);

  signal do_int     : std_logic_vector(31 downto 0);

  signal dop_int    : std_logic_vector(3 downto 0);

  signal waddr_int  : std_logic_vector(13 downto 0);

  signal raddr_int  : std_logic_vector(13 downto 0);

  signal wen_int    : std_logic_vector(3 downto 0);

begin

  --synthesis translate_off

  process

  begin

    case WIDTH is

      when 4 | 9 | 18 | 36 =>

        null;

      when others =>

        report "ERROR: WIDTH size " & integer'image(WIDTH) & " is not supported."

          severity failure;

    end case;

    wait;

  end process;

  --synthesis translate_on

  -- Wire up BRAM I/Os to module I/Os - map data & parity bits appropriately

  width_36 : if (WIDTH = 36) generate

    di_int                <= wdata_i(31 downto 0);

    dip_int               <= wdata_i(35 downto 32);

    rdata_o(35 downto 32) <= dop_int;

    rdata_o(31 downto 0)  <= do_int;

  end generate width_36;

  width_18 : if (WIDTH = 18) generate

    di_int(31 downto 16)  <= (OTHERS => '0');

    di_int(15 downto 0)   <= wdata_i(15 downto 0);

    dip_int(3 downto 2)   <= (OTHERS => '0');

    dip_int(1 downto 0)   <= wdata_i(17 downto 16);

    rdata_o(17 downto 16) <= dop_int(1 downto 0);

    rdata_o(15 downto 0)  <= do_int(15 downto 0);

  end generate width_18;

  width_9 : if (WIDTH = 9) generate

    di_int(31 downto 8)   <= (OTHERS => '0');

    di_int(7 downto 0)    <= wdata_i(7 downto 0);

    dip_int(3 downto 1)   <= (OTHERS => '0');

    dip_int(0)            <= wdata_i(8);

    rdata_o(8)            <= dop_int(0);

    rdata_o(7 downto 0)   <= do_int(7 downto 0);

  end generate width_9;

  width_4 : if (WIDTH = 4) generate

    di_int(31 downto 4)   <= (OTHERS => '0');

    di_int(3 downto 0)    <= wdata_i(3 downto 0);

    dip_int               <= (OTHERS => '0');

    rdata_o               <= do_int(3 downto 0);

  end generate width_4;

  waddr_int <= CALC_ADDR(WIDTH, waddr_i);

  raddr_int <= CALC_ADDR(WIDTH, raddr_i);

  wen_int   <= wen_i & wen_i & wen_i & wen_i;

  ramb16 : RAMB16BWER

  generic map (

    DATA_WIDTH_A  => WIDTH,

    DATA_WIDTH_B  => WIDTH,

    DOA_REG       => 0,

    DOB_REG       => DOB_REG,

    WRITE_MODE_A  => "NO_CHANGE",

    WRITE_MODE_B  => "NO_CHANGE"

  )

  port map (

    CLKA           => user_clk_i,

    RSTA           => reset_i,

    DOA            => open,

    DOPA           => open,

    ADDRA          => waddr_int,

    DIA            => di_int,

    DIPA           => dip_int,

    ENA            => wen_i,

    WEA            => wen_int,

    REGCEA         => '0',

    CLKB           => user_clk_i,

    RSTB           => reset_i,

    WEB            => "0000",

    DIB            => x"00000000",

    DIPB           => "0000",

    ADDRB          => raddr_int,

    DOB            => do_int,

    DOPB           => dop_int,

    ENB            => ren_i,

    REGCEB         => rce_i

  );

end rtl;