外部データ ファイルからのブロック RAM 初期化のコード例 (VHDL) - 2023.2 日本語

ファイル名: rams_init_file.vhd

-- Initializing Block RAM from external data file
-- File: rams_init_file.vhd

library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;
use std.textio.all;

entity rams_init_file is
port(
clk : in std_logic;
we : in std_logic;
addr : in std_logic_vector(5 downto 0);
din : in std_logic_vector(31 downto 0);
dout : out std_logic_vector(31 downto 0)
);
end rams_init_file;

architecture syn of rams_init_file is
type RamType is array (0 to 63) of bit_vector(31 downto 0);

impure function InitRamFromFile(RamFileName : in string) return RamType is
FILE RamFile : text is in RamFileName;
variable RamFileLine : line;
variable RAM : RamType;
begin
for I in RamType'range loop
readline(RamFile, RamFileLine);
read(RamFileLine, RAM(I));
end loop;
return RAM;
end function;

signal RAM : RamType := InitRamFromFile("rams_init_file.data");
begin
process(clk)
begin
if clk'event and clk = '1' then
if we = '1' then
RAM(to_integer(unsigned(addr))) <= to_bitvector(din);
end if;
dout <= to_stdlogicvector(RAM(to_integer(unsigned(addr))));
end if;
end process;

end syn;