Merge pull request #93 from antonblanchard/fifo-fix

Remove shared variable from fifo, and reformat
jtag-port
Anton Blanchard 5 years ago committed by GitHub
commit 854c93f970
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@ -7,85 +7,85 @@ use ieee.std_logic_1164.all;
--! @brief A generic FIFO module. --! @brief A generic FIFO module.
--! Adopted from the FIFO module in <https://github.com/skordal/smallthings>. --! Adopted from the FIFO module in <https://github.com/skordal/smallthings>.
entity pp_fifo is entity pp_fifo is
generic( generic(
DEPTH : natural := 64; DEPTH : natural := 64;
WIDTH : natural := 32 WIDTH : natural := 32
); );
port( port(
-- Control lines: -- Control lines:
clk : in std_logic; clk : in std_logic;
reset : in std_logic; reset : in std_logic;


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


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


architecture behaviour of pp_fifo is architecture behaviour of pp_fifo is


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


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


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


begin begin


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


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


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


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


end architecture behaviour; end architecture behaviour;

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