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microwatt/sim_bram.vhdl

68 lines
2.2 KiB
VHDL

-- Single port Block RAM with one cycle output buffer
--
-- Simulated via C helpers
library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;
use std.textio.all;
library work;
use work.utils.all;
use work.sim_bram_helpers.all;
entity main_bram is
generic(
WIDTH : natural := 64;
HEIGHT_BITS : natural := 1024;
MEMORY_SIZE : natural := 65536;
RAM_INIT_FILE : string
);
port(
clk : in std_logic;
addr : in std_logic_vector(HEIGHT_BITS - 1 downto 0) ;
di : in std_logic_vector(WIDTH-1 downto 0);
do : out std_logic_vector(WIDTH-1 downto 0);
sel : in std_logic_vector((WIDTH/8)-1 downto 0);
re : in std_ulogic;
we : in std_ulogic
);
end entity main_bram;
architecture sim of main_bram is
constant WIDTH_BYTES : natural := WIDTH / 8;
constant pad_zeros : std_ulogic_vector(log2(WIDTH_BYTES)-1 downto 0)
:= (others => '0');
signal identifier : integer := behavioural_initialize(filename => RAM_INIT_FILE,
size => MEMORY_SIZE);
-- Others
signal obuf : std_logic_vector(WIDTH-1 downto 0);
begin
-- Actual RAM template
memory_0: process(clk)
variable ret_dat_v : std_ulogic_vector(63 downto 0);
variable addr64 : std_ulogic_vector(63 downto 0);
begin
if rising_edge(clk) then
addr64 := (others => '0');
addr64(HEIGHT_BITS + 2 downto 3) := addr;
if we = '1' then
report "RAM writing " & to_hstring(di) & " to " &
to_hstring(addr & pad_zeros) & " sel:" & to_hstring(sel);
behavioural_write(di, addr64, to_integer(unsigned(sel)), identifier);
end if;
if re = '1' then
behavioural_read(ret_dat_v, addr64, to_integer(unsigned(sel)), identifier);
report "RAM reading from " & to_hstring(addr & pad_zeros) &
" returns " & to_hstring(ret_dat_v);
obuf <= ret_dat_v(obuf'left downto 0);
end if;
do <= obuf;
end if;
end process;
end architecture sim;