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git-svn-id: http://moon:8086/svn/vhdl/trunk@882 cc03376c-175c-47c8-b038-4cd826a8556b

lib/emac/src/crc32.vhd

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+LIBRARY IEEE;
+USE IEEE.STD_LOGIC_1164.ALL;
+USE IEEE.NUMERIC_STD.ALL;
+use std.textio.all; --  Imports the standard textio package.
+
+use work.utils_pkg.all; --  Imports the standard textio package.
+
+ENTITY crc32 IS
+	Port
+	(
+		rst			: in  STD_LOGIC;
+		clk			: in  STD_LOGIC;
+		din_vld		: in  STD_LOGIC;
+		din			: in  unsigned(7 downto 0);
+		crc32_vld	: out STD_LOGIC;
+		crc32_out	: out unsigned(31 downto 0)
+		
+	);
+END crc32;
+
+ARCHITECTURE behavior OF crc32 IS
+
+	type crc_table_t is array (0 to 15) of unsigned(31 downto 0);
+	
+	constant crc_table	: crc_table_t :=
+	(
+		X"4DBDF21C", X"500AE278", X"76D3D2D4", X"6B64C2B0",
+		X"3B61B38C", X"26D6A3E8", X"000F9344", X"1DB88320",
+		X"A005713C", X"BDB26158", X"9B6B51F4", X"86DC4190",
+		X"D6D930AC", X"CB6E20C8", X"EDB71064", X"F0000000"
+	);
+	
+	signal crc0		: unsigned(31 downto 0);
+	signal crc1		: unsigned(31 downto 0);
+	signal crc2		: unsigned(31 downto 0);
+	
+--------------------------------------------------------------------------
+begin
+
+	crc1	<= X"0" & crc0(31 downto 4) xor crc_table(to_integer(crc0(3 downto 0) xor din(3 downto 0)));
+	crc2	<= X"0" & crc1(31 downto 4) xor crc_table(to_integer(crc1(3 downto 0) xor din(7 downto 4)));
+	
+	crc32_out	<= crc0;
+	
+--------------------------------------------------------------------------
+process(clk)
+begin
+	if rising_edge(clk) then
+		crc32_vld	<= not rst and din_vld;
+		if rst = '1' then
+			crc0		<= (others => '0');
+		elsif din_vld = '1' then	
+			crc0		<= crc2;
+		end if;
+	end if;
+end process;
+
+--------------------------------------------------------------------------
+end behavior;