FIFO用RAM怎么实现啊

wtuestc

RT

hahaear

控制好地址的产生即可

wtuestc

-- A First-in First-out Memory
-- a first-in first out memory, uses a synchronising clock
-- generics allow fifos of different sizes to be instantiated
-- download from: www.fpga.com.cn & www.pld.com.cn
library IEEE;
use IEEE.Std_logic_1164.all;
entity FIFOMXN is
   generic(m, n : Positive := 8); --m is fifo depth, n is fifo width
   port(RESET, WRREQ, RDREQ, CLOCK : in Std_logic;
         DATAIN : in Std_logic_vector((n-1) downto 0);
         DATAOUT : out Std_logic_vector((n-1) downto 0);
         FULL, EMPTY : inout Std_logic);
end FIFOMXN;
architecture V2 of FIFOMXN is
   type Fifo_array is array(0 to (m-1)) of Bit_vector((n-1) downto 0);
   signal Fifo_memory : Fifo_array;
   signal Wraddr, Rdaddr, Offset : Natural range 0 to (m-1);
   signal Rdpulse, Wrpulse, Q1, Q2, Q3, Q4 : Std_logic;
   signal Databuffer : Bit_vector((n-1) downto 0);
begin
--pulse synchronisers for WRREQ and RDREQ
--modified for Synplify to a process
sync_ffs : process
        begin
                wait until rising_edge(CLOCK);
                Q1 <= WRREQ;
                Q2 <= Q1;
                Q3 <= RDREQ;
                Q4 <= Q3;
end process;
--concurrent logic to generate pulses
Wrpulse <= Q2 and not(Q1);
Rdpulse <= Q4 and not(Q3);   

Fifo_read : process
   begin
      wait until rising_edge(CLOCK);
      if RESET = '1' then
         Rdaddr <= 0;
         Databuffer <= (others => '0');
      elsif (Rdpulse = '1' and EMPTY = '0') then
         Databuffer <= Fifo_memory(Rdaddr);
         Rdaddr <= (Rdaddr + 1) mod m;
      end if;
   end process;

Fifo_write : process
   begin
      wait until rising_edge(CLOCK);
      if RESET = '1' then
         Wraddr <= 0;
      elsif (Wrpulse = '1' and FULL = '0') then
         Fifo_memory(Wraddr) <= To_Bitvector(DATAIN);
         Wraddr <= (Wraddr + 1) mod m;
      end if;
   end process;
Offset <= (Wraddr - Rdaddr) when (Wraddr > Rdaddr)
            else (m - (Rdaddr - Wraddr)) when (Rdaddr > Wraddr)
            else 0;
EMPTY <= '1' when (Offset = 0) else '0';
FULL <= '1' when (Offset = (m-1)) else '0';
DATAOUT <= To_Stdlogicvector(Databuffer) when RDREQ = '0'
            else (others => 'Z');
end V2;
那句Rdaddr <= (Rdaddr + 1) mod m;怎么理解

shadow

不难，说真得。我用SBSRAM实现过，细节考虑好就成了！

jingli888ca

建议看看SNUG论文，其中有很好的实现方法。

hattic

不错的东东

MOSFET

双端口RAM