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--
-- Inferrable Synchronous SRAM for XST synthesis
--
-- Version : 0220
--
-- 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 :
-- 0208 : Initial release
-- 0218 : Fixed data out at write
-- 0220 : Added support for XST
library IEEE;
use IEEE.std_logic_1164.all;
use IEEE.numeric_std.all;
entity SSRAM is
generic(
AddrWidth : integer := 11;
DataWidth : integer := 8
);
port(
Clk : in std_logic;
CE_n : in std_logic;
WE_n : in std_logic;
A : in std_logic_vector(AddrWidth - 1 downto 0);
DIn : in std_logic_vector(DataWidth - 1 downto 0);
DOut : out std_logic_vector(DataWidth - 1 downto 0)
);
end SSRAM;
architecture behaviour of SSRAM is
type Memory_Image is array (natural range <>) of std_logic_vector(DataWidth - 1 downto 0);
signal RAM : Memory_Image(0 to 2 ** AddrWidth - 1);
signal A_r : std_logic_vector(AddrWidth - 1 downto 0);
begin
process (Clk)
begin
if Clk'event and Clk = '1' then
if (CE_n nor WE_n) = '1' then
RAM(to_integer(unsigned(A))) <= DIn;
end if;
A_r <= A;
end if;
end process;
DOut <= RAM(to_integer(unsigned(A_r)))
-- pragma translate_off
when not is_x(A_r) else (others => '-')
-- pragma translate_on
;
end;
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