Initial import

git-svn-id: http://moon:8086/svn/vhdl/trunk@2 cc03376c-175c-47c8-b038-4cd826a8556b

lib/CPUs/JCpu/src/core/chipram.vhd

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+--------------------------------------------------------------------------
+-- Project: JCPU, a portable 8-bit RISC CPU written in VHDL
+-- This file: On-chip RAM
+--
+-- Copyright (C) 2007 J. Ahrensfeld
+--
+-- This program is free software: you can redistribute it and/or modify
+-- it under the terms of the GNU General Public License as published by
+-- the Free Software Foundation, either version 3 of the License, or
+-- (at your option) any later version.
+--
+-- This program is distributed in the hope that it will be useful,
+-- but WITHOUT ANY WARRANTY; without even the implied warranty of
+-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+-- GNU General Public License for more details.
+--
+-- You should have received a copy of the GNU General Public License
+-- along with this program.  If not, see <http://www.gnu.org/licenses/>.
+--
+-- For questions and ideas, please contact the author at jens@jayfield.org
+--
+--------------------------------------------------------------------------
+
+library IEEE;
+use IEEE.STD_LOGIC_1164.ALL;
+use IEEE.numeric_std.ALL;
+
+use work.cpu_pkg.all;
+
+entity chipram is
+	Generic (
+		addr_width : integer := 3;
+		data_width : integer := 8
+	);
+	Port (
+		clka		: in  STD_LOGIC;
+		clkb		: in  STD_LOGIC;
+		en_a		: in  STD_LOGIC;
+		en_b		: in  STD_LOGIC;
+		we_a		: in  STD_LOGIC;
+		we_b		: in  STD_LOGIC;
+		addr_a		: in  unsigned (addr_width-1 downto 0);
+		addr_b		: in  unsigned (addr_width-1 downto 0);
+		din_a		: in  unsigned (data_width-1 downto 0);
+		din_b		: in  unsigned (data_width-1 downto 0);
+		dout_a		: out unsigned (data_width-1 downto 0);
+		dout_b		: out unsigned (data_width-1 downto 0)
+	);
+end chipram;
+
+architecture Behavioral of chipram is
+
+	constant depth : integer := 2**addr_width;
+	type RAMtype is array (0 to depth-1) of unsigned (data_width-1 downto 0);
+	shared variable RAM : RAMtype;
+	
+begin
+
+process (clka)
+begin
+if clka'event and clka = '1' then
+	if en_a = '1' then
+		if we_a = '1' then
+			RAM(to_integer(addr_a)) := din_a;
+		end if;
+		dout_a <= RAM(to_integer(addr_a));
+	end if;
+end if;
+end process;
+
+process (clkb)
+begin
+if clkb'event and clkb = '1' then
+	if en_b = '1' then
+		if we_b = '1' then
+			RAM(to_integer(addr_b)) := din_b;
+		end if;
+		dout_b <= RAM(to_integer(addr_b));
+	end if;
+end if;
+end process;
+
+
+end Behavioral;
+