-- ****
-- T80(b) core. In an effort to merge and maintain bug fixes ....
--
--
-- Ver 300 started tidyup
-- MikeJ March 2005
-- Latest version from www.fpgaarcade.com (original www.opencores.org)
--
-- ****
--
-- T80 Registers, technology independent
--
-- Version : 0244
--
-- Copyright (c) 2002 Daniel Wallner (jesus@opencores.org)
--
-- All rights reserved
--
-- Redistribution and use in source and synthezised forms, with or without
-- modification, are permitted provided that the following conditions are met:
--
-- Redistributions of source code must retain the above copyright notice,
-- this list of conditions and the following disclaimer.
--
-- Redistributions in synthesized form must reproduce the above copyright
-- notice, this list of conditions and the following disclaimer in the
-- documentation and/or other materials provided with the distribution.
--
-- Neither the name of the author nor the names of other contributors may
-- be used to endorse or promote products derived from this software without
-- specific prior written permission.
--
-- THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
-- AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
-- THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
-- PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE
-- LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
-- CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
-- SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
-- INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
-- CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
-- ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
-- POSSIBILITY OF SUCH DAMAGE.
--
-- Please report bugs to the author, but before you do so, please
-- make sure that this is not a derivative work and that
-- you have the latest version of this file.
--
-- The latest version of this file can be found at:
-- http://www.opencores.org/cvsweb.shtml/t51/
--
-- Limitations :
--
-- File history :
--
-- 0242 : Initial release
--
-- 0244 : Changed to single register file
--
library IEEE;
use IEEE.std_logic_1164.all;
use IEEE.numeric_std.all;
entity T80_Reg is
port(
Clk : in std_logic;
CEN : in std_logic;
WEH : in std_logic;
WEL : in std_logic;
AddrA : in std_logic_vector(2 downto 0);
AddrB : in std_logic_vector(2 downto 0);
AddrC : in std_logic_vector(2 downto 0);
DIH : in std_logic_vector(7 downto 0);
DIL : in std_logic_vector(7 downto 0);
DOAH : out std_logic_vector(7 downto 0);
DOAL : out std_logic_vector(7 downto 0);
DOBH : out std_logic_vector(7 downto 0);
DOBL : out std_logic_vector(7 downto 0);
DOCH : out std_logic_vector(7 downto 0);
DOCL : out std_logic_vector(7 downto 0)
);
end T80_Reg;
architecture rtl of T80_Reg is
type Register_Image is array (natural range <>) of std_logic_vector(7 downto 0);
signal RegsH : Register_Image(0 to 7);
signal RegsL : Register_Image(0 to 7);
begin
process (Clk)
begin
if Clk'event and Clk = '1' then
if CEN = '1' then
if WEH = '1' then
RegsH(to_integer(unsigned(AddrA))) <= DIH;
end if;
if WEL = '1' then
RegsL(to_integer(unsigned(AddrA))) <= DIL;
end if;
end if;
end if;
end process;
DOAH <= RegsH(to_integer(unsigned(AddrA)));
DOAL <= RegsL(to_integer(unsigned(AddrA)));
DOBH <= RegsH(to_integer(unsigned(AddrB)));
DOBL <= RegsL(to_integer(unsigned(AddrB)));
DOCH <= RegsH(to_integer(unsigned(AddrC)));
DOCL <= RegsL(to_integer(unsigned(AddrC)));
end;