ram.vhd

source code of counter,ram,lfsr etc

library IEEE;
use IEEE.STD_LOGIC_1164.all;
use IEEE.Numeric_Std.all;

entity sync_ram1 is
  port (
    clock   : in  std_logic;
    we,rd   : in  std_logic;
    address : in  std_logic_vector(0 to 9);
    datain  : in  std_logic_vector(0 to 9);
    dataout : out std_logic_vector(0 to 9)
  );
end sync_ram1;

architecture RTL of sync_ram1 is

   type ram_type is array(0 to (2** address'length) -1) of std_logic_vector(datain'range);
   signal ram : ram_type;
   signal read_address : std_logic_vector(address'range);

begin
  RamProc: process(clock) is
  begin
    if rising_edge(clock) then
      if we = '1' then
        ram(to_integer(unsigned(address))) <= datain;
      end if;
      read_address <= address;
    end if; 
    if rd= '1' then
  dataout <= ram(to_integer(unsigned(read_address)));
  elsif rd='0' then
       dataout <="UUUUUUUUUU";
  end if;
  end process RamProc;
end architecture RTL;