Merge pull request #93 from antonblanchard/fifo-fix

Remove shared variable from fifo, and reformat

fpga/pp_fifo.vhd

@@ -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(
+    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;
 
 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
 
-	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;