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microwatt/fetch1.vhdl

74 lines
1.5 KiB
VHDL

library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;
library work;
use work.common.all;
entity fetch1 is
generic(
RESET_ADDRESS : std_logic_vector(63 downto 0)
);
port(
clk : in std_ulogic;
rst : in std_ulogic;
-- Control inputs:
stall_in : in std_ulogic;
flush_in : in std_ulogic;
-- redirect from execution unit
e_in : in Execute1ToFetch1Type;
-- fetch data out
f_out : out Fetch1ToFetch2Type
);
end entity fetch1;
architecture behaviour of fetch1 is
type reg_internal_type is record
nia_next : std_ulogic_vector(63 downto 0);
end record;
signal r_int, rin_int : reg_internal_type;
signal r, rin : Fetch1ToFetch2Type;
begin
regs : process(clk)
begin
if rising_edge(clk) then
r <= rin;
r_int <= rin_int;
end if;
end process;
comb : process(all)
variable v : Fetch1ToFetch2Type;
variable v_int : reg_internal_type;
begin
v := r;
v_int := r_int;
if stall_in = '0' then
v.nia := r_int.nia_next;
v_int.nia_next := std_logic_vector(unsigned(r_int.nia_next) + 4);
end if;
if e_in.redirect = '1' then
v.nia := e_in.redirect_nia;
v_int.nia_next := std_logic_vector(unsigned(e_in.redirect_nia) + 4);
end if;
if rst = '1' then
v.nia := RESET_ADDRESS;
v_int.nia_next := std_logic_vector(unsigned(RESET_ADDRESS) + 4);
end if;
-- Update registers
rin <= v;
rin_int <= v_int;
-- Update outputs
f_out <= r;
end process;
end architecture behaviour;