microrom.vhd

DLX CPU VHDL CODE UNIVERSITY

library IEEE;
use STD.textio.all;
use IEEE.std_logic_1164.all;
use work.dp32_types.all;




entity microrom is

  generic ( Tac_read : Time := 4 ns;
            load_file_name : string := "microcode.txt" );

  port ( a : in bus_bit_32 bus;
	 d : out bit_96
         );

end microrom;

architecture file_loaded of microrom is


begin

  mem_behavior : process 


   type memory_array is
	array (natural range 0 to 128198 ) of bit_96;

  variable mc : memory_array;

  procedure load is

     file binary_file : text is in load_file_name;
     variable L : line;
     variable ch : character;
     variable addr : bit_32;
     variable data : bit_96;

     procedure read_2 ( L : inout line; n1 : out bit_32; n2 : out bit_96 ) is

	variable t : natural :=0;
	variable ta : bit_vector (3 downto 0);
	variable tb : bit;
     begin
        for i in 1 to 8 loop
   --*********errors near here cause my bad format in microcode.txt
          ch:=L(i);
	  if '0' <= ch and ch <= '9' then
            t :=  character'pos(ch) - character'pos('0');
          elsif 'A' <= ch and ch <= 'F' then
            t :=  character'pos(ch) - character'pos('A') + 10;
          elsif 'a' <= ch and ch <= 'f' then
            t := character'pos(ch) - character'pos('a') + 10;
          end if;
	  natural_to_bits(t,ta);
	  n1 ( (-i+9)*4-1 downto (-i+8)*4 ) := ta;
        end loop;

	
	for i in 30 to 30+95 loop
          ch:=L(i);
          if '0' = ch then
		tb:='0';
	  else
		tb:='1';
	  end if;

          n2 (i-30 ) := tb;
        end loop;
    end read_2;


    begin
	
  while not endfile(binary_file) loop   
        readline(binary_file, L);
        if(L(1)='!') then
	else
	   read_2(L, addr,data);
--	assert false report vector_to_string(addr) severity warning;

 	   mc(bits_to_uint(addr)) := data;
	
   end if;


      end loop;

    end load;


    procedure do_read is
    begin
      --assert false report vector_to_string(a) severity warning;
      d <=  mc(bits_to_uint(a)) after Tac_read;
      --assert false report vector_to_string(mc(bits_to_uint(a))) severity warning;
    end do_read;


  variable bit_temp : bit;
  begin


    load;  -- read binary memory image into memory array

    loop

	wait for 1 ns;	

	do_read;
    end loop;
     
  end process mem_behavior;

end file_loaded;