Merge branch 'dev' into ppu-interface

1 files changed, 53 insertions, 0 deletions

diff --git a/basys3/basys3.srcs/er_ram.vhd b/basys3/basys3.srcs/er_ram.vhd
new file mode 100644
index 0000000..66f905b
--- /dev/null
+++ b/basys3/basys3.srcs/er_ram.vhd
@@ -0,0 +1,53 @@
+library ieee;
+library work;
+use ieee.std_logic_1164.all;
+use ieee.numeric_std.all;
+
+entity er_ram is -- exposed register RAM
+	generic(
+		ADDR_W : natural := 2; -- ADDR line width
+		DATA_W : natural := 2; -- DATA line width
+		ADDR_LOW : natural := 16#0000#; -- starting address
+		ADDR_RANGE : natural := 16#0002#); -- amount of valid addresses after ADDR_LOW
+	port(
+		CLK : in std_logic; -- clock
+		RST : in std_logic; -- async memory clear
+		WEN : in std_logic; -- write enable
+		ADDR : in std_logic_vector(ADDR_W-1 downto 0); -- address line
+		DATA : in std_logic_vector(DATA_W-1 downto 0); -- data input
+		REG : out std_logic_vector((ADDR_RANGE*DATA_W)-1 downto 0)); -- exposed register output
+end er_ram;
+
+architecture Behavioral of er_ram is
+	component er_ram_mod
+		generic(
+			W : natural := DATA_W; -- module data width
+			ADDR_W : natural := ADDR_W; -- address width
+			ADDR_M : std_logic_vector(ADDR_W-1 downto 0) := (others => '0')); -- address match
+		port(
+			CLK : in std_logic; -- clock
+			RST : in std_logic; -- async memory clear
+			WEN : in std_logic; -- write enable
+			ADDR : in std_logic_vector(ADDR_W-1 downto 0);
+			DATA : in std_logic_vector(W-1 downto 0); -- data
+			REG : out std_logic_vector(W-1 downto 0)); -- direct register out
+	end component;
+	signal INT_REG : std_logic_vector((ADDR_RANGE*DATA_W)-1 downto 0);
+begin
+	REG <= INT_REG;
+
+	registers : for idx in 0 to ADDR_RANGE - 1 generate
+		reg : component er_ram_mod
+			generic map(
+				W => DATA_W,
+				ADDR_W => ADDR_W,
+				ADDR_M => std_logic_vector(to_unsigned(ADDR_LOW + idx, ADDR_W)))
+			port map(
+				CLK => CLK,
+				RST => RST,
+				WEN => WEN,
+				ADDR => ADDR,
+				DATA => DATA,
+				REG => INT_REG(idx*DATA_W+DATA_W-1 downto idx*DATA_W));
+	end generate;
+end Behavioral;