- added cordic

git-svn-id: http://moon:8086/svn/vhdl/trunk@1412 cc03376c-175c-47c8-b038-4cd826a8556b

projects/cordic/src/cordic_rom.vhd

@@ -0,0 +1,80 @@
+--------------------------------------------------------------------------------
+-- Company: 
+-- Engineer:
+--
+-- Create Date:    12:37:26 10/02/05
+-- Design Name:    
+-- Module Name:    coeff_rom - Behavioral
+-- Project Name:   
+-- Target Device:  
+-- Tool versions:  
+-- Description:
+--
+-- Dependencies:
+-- 
+-- Revision:
+-- Revision 0.01 - File Created
+-- Additional Comments:
+-- 
+--------------------------------------------------------------------------------
+library IEEE;
+USE ieee.std_logic_1164.ALL;
+USE ieee.numeric_std.ALL;
+
+library work;
+use work.fixed_ja.all;
+use work.cordic_pkg.all;
+
+---- Uncomment the following library declaration if instantiating
+---- any Xilinx primitives in this code.
+--library UNISIM;
+--use UNISIM.VComponents.all;
+
+entity rom_arctan is
+	Generic 
+	(
+	        nbits : integer := 8;
+	        nbits_int : integer := 0
+	);
+	Port 
+	(
+			addr : in unsigned(6 downto 0);
+			dout : out sfixed_t
+	);
+end rom_arctan;
+
+architecture Behavioral of rom_arctan is
+
+subtype word_t is sfixed_t(sproto(nbits, nbits_int)'high downto sproto(nbits, nbits_int)'low);
+type rom_t is array (natural range <>) of word_t;
+
+-------------------------------------------------------------------------------
+function rom_gen(nstages : integer; round_mode : round_mode_t) return rom_t is
+variable rom : rom_t (0 to nstages-1);
+variable word : word_t;
+begin
+
+	for i in 0 to nstages-1 loop
+		word := to_sfixed(arctan_tbl(i), word, round_mode);
+		rom(i) := word;
+	end loop;
+	
+	return rom;
+end rom_gen;
+
+-------------------------------------------------------------------------------
+-- Create ROM
+constant arctan_rom : rom_t (0 to max_iteration-1) := rom_gen(max_iteration, cordic_round_mode);
+
+-------------------------------------------------------------------------------
+
+begin
+
+-- ROM implementation
+rom_arctan: process(addr)
+begin
+	dout <= arctan_rom(to_integer(addr));
+end process;
+
+-------------------------------------------------------------------------------
+end Behavioral;