---------------------------------------------------------------------
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---------------------------------------------------------------------
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-- TITLE: Random Access Memory
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-- TITLE: Random Access Memory
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-- AUTHOR: Steve Rhoads (rhoadss@yahoo.com)
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-- AUTHOR: Steve Rhoads (rhoadss@yahoo.com)
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-- DATE CREATED: 4/21/01
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-- DATE CREATED: 4/21/01
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-- FILENAME: ram.vhd
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-- FILENAME: ram.vhd
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-- PROJECT: Plasma CPU core
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-- PROJECT: Plasma CPU core
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-- COPYRIGHT: Software placed into the public domain by the author.
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-- COPYRIGHT: Software placed into the public domain by the author.
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-- Software 'as is' without warranty. Author liable for nothing.
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-- Software 'as is' without warranty. Author liable for nothing.
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-- DESCRIPTION:
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-- DESCRIPTION:
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-- Implements the RAM, reads the executable from either "code.txt",
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-- Implements the RAM, reads the executable from either "code.txt",
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-- or for Altera "code[0-3].hex".
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-- or for Altera "code[0-3].hex".
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-- Modified from "The Designer's Guide to VHDL" by Peter J. Ashenden
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-- Modified from "The Designer's Guide to VHDL" by Peter J. Ashenden
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---------------------------------------------------------------------
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---------------------------------------------------------------------
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library ieee;
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library ieee;
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use ieee.std_logic_1164.all;
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use ieee.std_logic_1164.all;
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use ieee.std_logic_misc.all;
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use ieee.std_logic_misc.all;
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use ieee.std_logic_arith.all;
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use ieee.std_logic_arith.all;
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use ieee.std_logic_textio.all;
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use ieee.std_logic_textio.all;
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use std.textio.all;
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use std.textio.all;
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use ieee.std_logic_unsigned.all;
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use ieee.std_logic_unsigned.all;
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use work.mlite_pack.all;
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use work.mlite_pack.all;
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entity ram is
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entity ram is
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generic(memory_type : string := "GENERIC");
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generic(memory_type : string := "GENERIC");
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port(clk : in std_logic;
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port(clk : in std_logic;
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mem_byte_sel : in std_logic_vector(3 downto 0);
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mem_byte_sel : in std_logic_vector(3 downto 0);
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mem_write : in std_logic;
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mem_write : in std_logic;
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mem_address : in std_logic_vector(31 downto 0);
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mem_address : in std_logic_vector(31 downto 0);
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mem_data : inout std_logic_vector(31 downto 0));
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mem_data_w : in std_logic_vector(31 downto 0);
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mem_data_r : out std_logic_vector(31 downto 0));
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end; --entity ram
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end; --entity ram
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architecture logic of ram is
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architecture logic of ram is
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constant ADDRESS_WIDTH : natural := 13;
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signal clk_inv : std_logic;
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signal mem_sel : std_logic;
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signal mem_sel : std_logic;
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signal read_enable : std_logic;
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signal read_enable : std_logic;
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signal write_byte_enable : std_logic_vector(3 downto 0);
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signal write_byte_enable : std_logic_vector(3 downto 0);
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begin
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begin
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clk_inv <= not clk;
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mem_sel <= '1' when mem_address(30 downto 16) = ZERO(30 downto 16) else
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mem_sel <= '1' when mem_address(30 downto 16) = ZERO(30 downto 16) else
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'0';
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'0';
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read_enable <= mem_sel and not mem_write;
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read_enable <= mem_sel and not mem_write;
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write_byte_enable <= mem_byte_sel when mem_sel = '1' else
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write_byte_enable <= mem_byte_sel when mem_sel = '1' else
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"0000";
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"0000";
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generic_ram:
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generic_ram:
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if memory_type = "GENERIC" generate
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if memory_type = "GENERIC" generate
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ram_proc: process(clk, mem_byte_sel, mem_write,
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ram_proc: process(clk, mem_byte_sel, mem_write,
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mem_address, mem_data, mem_sel)
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mem_address, mem_data_w, mem_sel)
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variable mem_size : natural := 8192;
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variable data : std_logic_vector(31 downto 0);
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variable data : std_logic_vector(31 downto 0);
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subtype word is std_logic_vector(mem_data'length-1 downto 0);
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subtype word is std_logic_vector(mem_data_w'length-1 downto 0);
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type storage_array is
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type storage_array is
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array(natural range 0 to 8191) of word;
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array(natural range 0 to mem_size-1) of word;
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variable storage : storage_array;
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variable storage : storage_array;
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variable index : natural := 0;
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variable index : natural := 0;
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file load_file : text is in "code.txt";
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file load_file : text is in "code.txt";
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variable hex_file_line : line;
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variable hex_file_line : line;
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begin
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begin
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--load in the ram executable image
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--load in the ram executable image
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if index = 0 then
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if index = 0 then
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while not endfile(load_file) loop
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while not endfile(load_file) loop
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--The following two lines had to be commented out for synthesis
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readline(load_file, hex_file_line);
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readline(load_file, hex_file_line);
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hread(hex_file_line, data);
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hread(hex_file_line, data);
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storage(index) := data;
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storage(index) := data;
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index := index + 1;
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index := index + 1;
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end loop;
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end loop;
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--assert false report "done reading code" severity note;
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--assert false report "done reading code" severity note;
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end if;
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end if;
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index := conv_integer(mem_address(mem_address'length-1 downto 2));
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index := conv_integer(mem_address(ADDRESS_WIDTH-1 downto 2));
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data := storage(index);
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data := storage(index);
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if mem_sel = '1' then
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if mem_sel = '1' then
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if mem_write = '0' then
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if mem_write = '0' then
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mem_data <= data;
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mem_data_r <= data;
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end if;
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end if;
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if mem_byte_sel(0) = '1' then
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if mem_byte_sel(0) = '1' then
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data(7 downto 0) := mem_data(7 downto 0);
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data(7 downto 0) := mem_data_w(7 downto 0);
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end if;
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end if;
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if mem_byte_sel(1) = '1' then
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if mem_byte_sel(1) = '1' then
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data(15 downto 8) := mem_data(15 downto 8);
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data(15 downto 8) := mem_data_w(15 downto 8);
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end if;
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end if;
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if mem_byte_sel(2) = '1' then
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if mem_byte_sel(2) = '1' then
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data(23 downto 16) := mem_data(23 downto 16);
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data(23 downto 16) := mem_data_w(23 downto 16);
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end if;
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end if;
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if mem_byte_sel(3) = '1' then
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if mem_byte_sel(3) = '1' then
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data(31 downto 24) := mem_data(31 downto 24);
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data(31 downto 24) := mem_data_w(31 downto 24);
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end if;
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end if;
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end if;
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end if;
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if rising_edge(clk) then
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if rising_edge(clk) then
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if mem_write = '1' then
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if mem_write = '1' then
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storage(index) := data;
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storage(index) := data;
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end if;
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end if;
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end if;
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end if;
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end process;
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end process;
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end generate; --generic_ram
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end generate; --generic_ram
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altera_ram:
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altera_ram:
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if memory_type = "ALTERA" generate
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if memory_type = "ALTERA" generate
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lpm_ram_io_component0 : lpm_ram_io
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--Quartus II does not allow asynchronous RAM to be initialized
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--since the RAM may see glitches on the write enable during powerup.
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--Making lpm_address_control="REGISTERED" makes the RAM synchronous
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--but then the reads are delayed by a clock cycle.
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--Inverting the RAM clock appears to solve the clock cycle delay problem.
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lpm_ram_io_component0 : lpm_ram_dq
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GENERIC MAP (
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GENERIC MAP (
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intended_device_family => "UNUSED",
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intended_device_family => "UNUSED",
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lpm_width => 8,
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lpm_width => 8,
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lpm_widthad => 11,
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lpm_widthad => ADDRESS_WIDTH-2,
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lpm_indata => "REGISTERED",
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lpm_indata => "REGISTERED",
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lpm_address_control => "UNREGISTERED",
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lpm_address_control => "REGISTERED",
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lpm_outdata => "UNREGISTERED",
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lpm_outdata => "UNREGISTERED",
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lpm_file => "code0.hex",
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lpm_file => "code0.hex",
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use_eab => "ON",
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use_eab => "ON",
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lpm_type => "LPM_RAM_DQ")
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lpm_type => "LPM_RAM_DQ")
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PORT MAP (
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PORT MAP (
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outenab => read_enable,
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data => mem_data_w(31 downto 24),
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address => mem_address(12 downto 2),
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address => mem_address(ADDRESS_WIDTH-1 downto 2),
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inclock => clk,
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inclock => clk_inv,
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we => write_byte_enable(3),
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we => write_byte_enable(3),
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dio => mem_data(31 downto 24));
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q => mem_data_r(31 downto 24));
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lpm_ram_io_component1 : lpm_ram_io
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lpm_ram_io_component1 : lpm_ram_dq
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GENERIC MAP (
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GENERIC MAP (
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intended_device_family => "UNUSED",
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intended_device_family => "UNUSED",
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lpm_width => 8,
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lpm_width => 8,
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lpm_widthad => 11,
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lpm_widthad => ADDRESS_WIDTH-2,
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lpm_indata => "REGISTERED",
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lpm_indata => "REGISTERED",
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lpm_address_control => "UNREGISTERED",
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lpm_address_control => "REGISTERED",
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lpm_outdata => "UNREGISTERED",
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lpm_outdata => "UNREGISTERED",
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lpm_file => "code1.hex",
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lpm_file => "code1.hex",
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use_eab => "ON",
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use_eab => "ON",
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lpm_type => "LPM_RAM_DQ")
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lpm_type => "LPM_RAM_DQ")
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PORT MAP (
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PORT MAP (
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outenab => read_enable,
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data => mem_data_w(23 downto 16),
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address => mem_address(12 downto 2),
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address => mem_address(ADDRESS_WIDTH-1 downto 2),
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inclock => clk,
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inclock => clk_inv,
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we => write_byte_enable(2),
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we => write_byte_enable(2),
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dio => mem_data(23 downto 16));
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q => mem_data_r(23 downto 16));
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lpm_ram_io_component2 : lpm_ram_io
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lpm_ram_io_component2 : lpm_ram_dq
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GENERIC MAP (
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GENERIC MAP (
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intended_device_family => "UNUSED",
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intended_device_family => "UNUSED",
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lpm_width => 8,
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lpm_width => 8,
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lpm_widthad => 11,
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lpm_widthad => ADDRESS_WIDTH-2,
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lpm_indata => "REGISTERED",
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lpm_indata => "REGISTERED",
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lpm_address_control => "UNREGISTERED",
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lpm_address_control => "REGISTERED",
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lpm_outdata => "UNREGISTERED",
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lpm_outdata => "UNREGISTERED",
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lpm_file => "code2.hex",
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lpm_file => "code2.hex",
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use_eab => "ON",
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use_eab => "ON",
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lpm_type => "LPM_RAM_DQ")
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lpm_type => "LPM_RAM_DQ")
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PORT MAP (
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PORT MAP (
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outenab => read_enable,
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data => mem_data_w(15 downto 8),
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address => mem_address(12 downto 2),
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address => mem_address(ADDRESS_WIDTH-1 downto 2),
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inclock => clk,
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inclock => clk_inv,
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we => write_byte_enable(1),
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we => write_byte_enable(1),
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dio => mem_data(15 downto 8));
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q => mem_data_r(15 downto 8));
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lpm_ram_io_component3 : lpm_ram_io
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lpm_ram_io_component3 : lpm_ram_dq
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GENERIC MAP (
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GENERIC MAP (
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intended_device_family => "UNUSED",
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intended_device_family => "UNUSED",
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lpm_width => 8,
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lpm_width => 8,
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lpm_widthad => 11,
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lpm_widthad => ADDRESS_WIDTH-2,
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lpm_indata => "REGISTERED",
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lpm_indata => "REGISTERED",
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lpm_address_control => "UNREGISTERED",
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lpm_address_control => "REGISTERED",
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lpm_outdata => "UNREGISTERED",
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lpm_outdata => "UNREGISTERED",
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lpm_file => "code3.hex",
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lpm_file => "code3.hex",
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use_eab => "ON",
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use_eab => "ON",
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lpm_type => "LPM_RAM_DQ")
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lpm_type => "LPM_RAM_DQ")
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PORT MAP (
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PORT MAP (
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outenab => read_enable,
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data => mem_data_w(7 downto 0),
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address => mem_address(12 downto 2),
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address => mem_address(ADDRESS_WIDTH-1 downto 2),
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inclock => clk,
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inclock => clk_inv,
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we => write_byte_enable(0),
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we => write_byte_enable(0),
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dio => mem_data(7 downto 0));
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q => mem_data_r(7 downto 0));
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end generate; --altera_ram
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end generate; --altera_ram
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end; --architecture logic
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end; --architecture logic
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