-------------------------------------------------------------------------------
-- Title : Single port RAM
-- Project : Memory Cores
-------------------------------------------------------------------------------
-- File : spmem.vhd
-- Author : Jamil Khatib (khatib@ieee.org)
-- Organization: OpenIPCore Project
-- Created : 1999/5/14
-- Last update : 2000/12/19
-- Platform :
-- Simulators : Modelsim 5.3XE/Windows98
-- Synthesizers: Leonardo/WindowsNT
-- Target :
-- Dependency : ieee.std_logic_1164,ieee.std_logic_unsigned
-------------------------------------------------------------------------------
-- Description: Single Port memory
-------------------------------------------------------------------------------
-- Copyright (c) 2000 Jamil Khatib
--
-- This VHDL design file is an open design; you can redistribute it and/or
-- modify it and/or implement it after contacting the author
-- You can check the draft license at
-- http://www.opencores.org/OIPC/license.shtml
-------------------------------------------------------------------------------
-- Revisions :
-- Revision Number : 1
-- Version : 0.1
-- Date : 12 May 1999
-- Modifier : Jamil Khatib (khatib@ieee.org)
-- Desccription : Created
-- Known bugs :
-- To Optimze :
-------------------------------------------------------------------------------
-- Revisions :
-- Revision Number : 2
-- Version : 0.2
-- Date : 19 Dec 2000
-- Modifier : Jamil Khatib (khatib@ieee.org)
-- Desccription : General review
-- Two versions are now available with reset and without
-- Default output can can be defined
-- Known bugs :
-- To Optimze :
-------------------------------------------------------------------------------
library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_unsigned.all;
-------------------------------------------------------------------------------
-- Single port Memory core with reset
entity Spmem_ent is
generic ( USE_RESET : boolean := true; -- use system reset
USE_CS : boolean := true; -- use chip select signal
DEFAULT_OUT : std_logic := 'Z'; -- Default output
ADD_WIDTH : integer := 3;
WIDTH : integer := 8);
port (
cs : std_logic; -- chip select
clk : in std_logic; -- write clock
reset : in std_logic; -- System Reset
add : in std_logic_vector(add_width -1 downto 0); -- Address
Data_In : in std_logic_vector(WIDTH -1 downto 0); -- input data
Data_Out : out std_logic_vector(WIDTH -1 downto 0); -- Output Data
WR : in std_logic); -- Read Write Enable
end Spmem_ent;
-------------------------------------------------------------------------------
-- This Architecture was tested on the ModelSim 5.2EE
-- The test vectors for model sim is included in vectors.do file
architecture spmem_beh of Spmem_ent is
type data_array is array (integer range <>) of std_logic_vector(WIDTH-1 downto 0);
-- Memory Type
signal data : data_array(0 to (2** add_width-1) ); -- Local data
procedure init_mem(signal memory_cell : inout data_array ) is
begin
for i in 0 to (2** add_width-1) loop
memory_cell(i) <= (others => '0');
end loop;
end init_mem;
begin -- spmem_beh
-------------------------------------------------------------------------------
-- Clocked Process with Reset
-------------------------------------------------------------------------------
Reset_ENABLED : if USE_RESET = true generate
-------------------------------------------------------------------------------
CS_ENABLED : if USE_CS = true generate
process (clk, reset)
begin -- PROCESS
-- activities triggered by asynchronous reset (active low)
if reset = '0' then
data_out <= (others => DEFAULT_OUT);
init_mem ( data);
-- activities triggered by rising edge of clock
elsif clk'event and clk = '1' then
if CS = '1' then
if WR = '0' then
data(conv_integer(add)) <= data_in;
data_out <= (others => DEFAULT_OUT);
else
data_out <= data(conv_integer(add));
end if;
else
data_out <= (others => DEFAULT_OUT);
end if;
end if;
end process;
end generate CS_ENABLED;
-------------------------------------------------------------------------------
CS_DISABLED : if USE_CS = false generate
process (clk, reset)
begin -- PROCESS
-- activities triggered by asynchronous reset (active low)
if reset = '0' then
data_out <= (others => DEFAULT_OUT);
init_mem ( data);
-- activities triggered by rising edge of clock
elsif clk'event and clk = '1' then
if WR = '0' then
data(conv_integer(add)) <= data_in;
data_out <= (others => DEFAULT_OUT);
else
data_out <= data(conv_integer(add));
end if;
end if;
end process;
end generate CS_DISABLED;
-------------------------------------------------------------------------------
end generate Reset_ENABLED;
-------------------------------------------------------------------------------
-------------------------------------------------------------------------------
-- Clocked Process without Reset
-------------------------------------------------------------------------------
Reset_DISABLED : if USE_RESET = false generate
-------------------------------------------------------------------------------
CS_ENABLED : if USE_CS = true generate
process (clk)
begin -- PROCESS
-- activities triggered by rising edge of clock
if clk'event and clk = '1' then
if cs = '1' then
if WR = '0' then
data(conv_integer(add)) <= data_in;
data_out <= (others => DEFAULT_OUT);
else
data_out <= data(conv_integer(add));
end if;
else
data_out <= (others => DEFAULT_OUT);
end if;
end if;
end process;
end generate CS_ENABLED;
-------------------------------------------------------------------------------
CS_DISABLED : if USE_CS = false generate
process (clk)
begin -- PROCESS
-- activities triggered by rising edge of clock
if clk'event and clk = '1' then
if WR = '0' then
data(conv_integer(add)) <= data_in;
data_out <= (others => DEFAULT_OUT);
else
data_out <= data(conv_integer(add));
end if;
end if;
end process;
end generate CS_DISABLED;
end generate Reset_DISABLED;
-------------------------------------------------------------------------------
end spmem_beh;
-------------------------------------------------------------------------------