fifo: Reformat

Signed-off-by: Anton Blanchard <anton@linux.ibm.com>
pull/93/head
Anton Blanchard 4 years ago committed by Anton Blanchard
parent ad6c6790f9
commit 7aaed5abd5

@ -7,85 +7,85 @@ use ieee.std_logic_1164.all;
--! @brief A generic FIFO module.
--! Adopted from the FIFO module in <https://github.com/skordal/smallthings>.
entity pp_fifo is
generic(
DEPTH : natural := 64;
WIDTH : natural := 32
);
port(
-- Control lines:
clk : in std_logic;
reset : in std_logic;
generic(
DEPTH : natural := 64;
WIDTH : natural := 32
);
port(
-- Control lines:
clk : in std_logic;
reset : in std_logic;

-- Status lines:
full : out std_logic;
empty : out std_logic;
-- Status lines:
full : out std_logic;
empty : out std_logic;

-- Data in:
data_in : in std_logic_vector(WIDTH - 1 downto 0);
data_out : out std_logic_vector(WIDTH - 1 downto 0);
push, pop : in std_logic
);
-- Data in:
data_in : in std_logic_vector(WIDTH - 1 downto 0);
data_out : out std_logic_vector(WIDTH - 1 downto 0);
push, pop : in std_logic
);
end entity pp_fifo;

architecture behaviour of pp_fifo is

type memory_array is array(0 to DEPTH - 1) of std_logic_vector(WIDTH - 1 downto 0);
signal memory : memory_array := (others => (others => '0'));
type memory_array is array(0 to DEPTH - 1) of std_logic_vector(WIDTH - 1 downto 0);
signal memory : memory_array := (others => (others => '0'));

subtype index_type is integer range 0 to DEPTH - 1;
signal top, bottom : index_type;
subtype index_type is integer range 0 to DEPTH - 1;
signal top, bottom : index_type;

type fifo_op is (FIFO_POP, FIFO_PUSH);
signal prev_op : fifo_op := FIFO_POP;
type fifo_op is (FIFO_POP, FIFO_PUSH);
signal prev_op : fifo_op := FIFO_POP;

begin

empty <= '1' when top = bottom and prev_op = FIFO_POP else '0';
full <= '1' when top = bottom and prev_op = FIFO_PUSH else '0';
empty <= '1' when top = bottom and prev_op = FIFO_POP else '0';
full <= '1' when top = bottom and prev_op = FIFO_PUSH else '0';

read: process(clk)
begin
if rising_edge(clk) then
if reset = '1' then
bottom <= 0;
else
if pop = '1' then
data_out <= memory(bottom);
bottom <= (bottom + 1) mod DEPTH;
end if;
end if;
end if;
end process read;
read: process(clk)
begin
if rising_edge(clk) then
if reset = '1' then
bottom <= 0;
else
if pop = '1' then
data_out <= memory(bottom);
bottom <= (bottom + 1) mod DEPTH;
end if;
end if;
end if;
end process read;

write: process(clk)
begin
if rising_edge(clk) then
if reset = '1' then
top <= 0;
else
if push = '1' then
memory(top) <= data_in;
top <= (top + 1) mod DEPTH;
end if;
end if;
end if;
end process write;
write: process(clk)
begin
if rising_edge(clk) then
if reset = '1' then
top <= 0;
else
if push = '1' then
memory(top) <= data_in;
top <= (top + 1) mod DEPTH;
end if;
end if;
end if;
end process write;

set_prev_op: process(clk)
begin
if rising_edge(clk) then
if reset = '1' then
prev_op <= FIFO_POP;
else
if push = '1' and pop = '1' then
prev_op <= FIFO_POP;
elsif push = '1' then
prev_op <= FIFO_PUSH;
elsif pop = '1' then
prev_op <= FIFO_POP;
end if;
end if;
end if;
end process set_prev_op;
set_prev_op: process(clk)
begin
if rising_edge(clk) then
if reset = '1' then
prev_op <= FIFO_POP;
else
if push = '1' and pop = '1' then
prev_op <= FIFO_POP;
elsif push = '1' then
prev_op <= FIFO_PUSH;
elsif pop = '1' then
prev_op <= FIFO_POP;
end if;
end if;
end if;
end process set_prev_op;

end architecture behaviour;

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