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dpram.vhd
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dpram.vhd
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library IEEE;
use IEEE.STD_LOGIC_1164.all;
use IEEE.STD_LOGIC_ARITH.all;
use IEEE.STD_LOGIC_UNSIGNED.all;
--
-- Copyright (C) 2007, Peter C. Wallace, Mesa Electronics
-- http://www.mesanet.com
--
-- This program is is licensed under a disjunctive dual license giving you
-- the choice of one of the two following sets of free software/open source
-- licensing terms:
--
-- * GNU General Public License (GPL), version 2.0 or later
-- * 3-clause BSD License
--
--
-- The GNU GPL License:
--
-- 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 2 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, write to the Free Software
-- Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
--
--
-- The 3-clause BSD License:
--
-- Redistribution and use in source and binary 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 binary 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 Mesa Electronics nor the names of its
-- contributors may be used to endorse or promote products
-- derived from this software without specific prior written
-- permission.
--
--
-- Disclaimer:
--
-- 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
-- COPYRIGHT OWNER 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.
--
use work.log2.all;
entity dpram is
generic (
width : integer;
depth : integer
);
port (
addra: in std_logic_vector((log2(depth) -1) downto 0);
addrb: in std_logic_vector((log2(depth) -1) downto 0);
clk: in std_logic;
dina: in std_logic_vector(width-1 downto 0);
douta: out std_logic_vector(width-1 downto 0);
doutb: out std_logic_vector(width-1 downto 0);
wea: in std_logic);
end ;
architecture syn of dpram is
type ram_type is array (0 to depth-1) of std_logic_vector(width-1 downto 0);
signal RAM : ram_type;
signal daddra: std_logic_vector((log2(depth) -1) downto 0);
signal daddrb: std_logic_vector((log2(depth) -1) downto 0);
begin
adpram: process (clk)
begin
if (clk'event and clk = '1') then
if (wea = '1') then
RAM(conv_integer(addra)) <= dina;
end if;
daddra <= addra;
daddrb <= addrb;
end if; -- clk
end process;
douta <= RAM(conv_integer(daddra));
doutb <= RAM(conv_integer(daddrb));
end;