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i8244_charset_rom.vhd
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i8244_charset_rom.vhd
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-------------------------------------------------------------------------------
--
-- i8244 Video Display Controller
--
-- $Id: i8244_charset_rom.vhd,v 1.5 2007/02/05 22:08:59 arnim Exp $
--
-- Built-in charater set ROM
--
-------------------------------------------------------------------------------
--
-- Copyright (c) 2007, Arnim Laeuger (arnim.laeuger@gmx.net)
--
-- 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.
--
-------------------------------------------------------------------------------
library ieee;
use ieee.std_logic_1164.all;
entity i8244_charset_rom is
port (
clk_i : in std_logic;
rom_addr_i : in std_logic_vector(8 downto 0);
rom_en_i : in std_logic;
rom_data_o : out std_logic_vector(7 downto 0)
);
end i8244_charset_rom;
library ieee;
use ieee.numeric_std.all;
architecture rtl of i8244_charset_rom is
subtype payload_t is natural range 0 to 255;
type rom_cont_t is array (natural range 0 to 511) of
payload_t;
constant rom_cont_c : rom_cont_t := (
16#7C#,16#C6#,16#C6#,16#C6#,16#C6#,16#C6#,16#7C#,16#00#,
16#18#,16#38#,16#18#,16#18#,16#18#,16#18#,16#3C#,16#00#,
16#3C#,16#66#,16#0C#,16#18#,16#30#,16#60#,16#7E#,16#00#,
16#7C#,16#C6#,16#06#,16#3C#,16#06#,16#C6#,16#7C#,16#00#,
16#CC#,16#CC#,16#CC#,16#FE#,16#0C#,16#0C#,16#0C#,16#00#,
16#FE#,16#C0#,16#C0#,16#7C#,16#06#,16#C6#,16#7C#,16#00#,
16#7C#,16#C6#,16#C0#,16#FC#,16#C6#,16#C6#,16#7C#,16#00#,
16#FE#,16#06#,16#0C#,16#18#,16#30#,16#60#,16#C0#,16#00#,
16#7C#,16#C6#,16#C6#,16#7C#,16#C6#,16#C6#,16#7C#,16#00#,
16#7C#,16#C6#,16#C6#,16#7E#,16#06#,16#C6#,16#7C#,16#00#,
16#00#,16#18#,16#18#,16#00#,16#18#,16#18#,16#00#,16#00#,
16#18#,16#7E#,16#58#,16#7E#,16#1A#,16#7E#,16#18#,16#00#,
16#00#,16#00#,16#00#,16#00#,16#00#,16#00#,16#00#,16#00#,
16#3C#,16#66#,16#0C#,16#18#,16#18#,16#00#,16#18#,16#00#,
16#C0#,16#C0#,16#C0#,16#C0#,16#C0#,16#C0#,16#FE#,16#00#,
16#FC#,16#C6#,16#C6#,16#FC#,16#C0#,16#C0#,16#C0#,16#00#,
16#00#,16#18#,16#18#,16#7E#,16#18#,16#18#,16#00#,16#00#,
16#C6#,16#C6#,16#C6#,16#D6#,16#FE#,16#EE#,16#C6#,16#00#,
16#FE#,16#C0#,16#C0#,16#F8#,16#C0#,16#C0#,16#FE#,16#00#,
16#FC#,16#C6#,16#C6#,16#FC#,16#D8#,16#CC#,16#C6#,16#00#,
16#7E#,16#18#,16#18#,16#18#,16#18#,16#18#,16#18#,16#00#,
16#C6#,16#C6#,16#C6#,16#C6#,16#C6#,16#C6#,16#7C#,16#00#,
16#3C#,16#18#,16#18#,16#18#,16#18#,16#18#,16#3C#,16#00#,
16#7C#,16#C6#,16#C6#,16#C6#,16#C6#,16#C6#,16#7C#,16#00#,
16#7C#,16#C6#,16#C6#,16#C6#,16#DE#,16#CC#,16#76#,16#00#,
16#7C#,16#C6#,16#C0#,16#7C#,16#06#,16#C6#,16#7C#,16#00#,
16#FC#,16#C6#,16#C6#,16#C6#,16#C6#,16#C6#,16#FC#,16#00#,
16#FE#,16#C0#,16#C0#,16#F8#,16#C0#,16#C0#,16#C0#,16#00#,
16#7C#,16#C6#,16#C0#,16#C0#,16#CE#,16#C6#,16#7E#,16#00#,
16#C6#,16#C6#,16#C6#,16#FE#,16#C6#,16#C6#,16#C6#,16#00#,
16#06#,16#06#,16#06#,16#06#,16#06#,16#C6#,16#7C#,16#00#,
16#C6#,16#CC#,16#D8#,16#F0#,16#D8#,16#CC#,16#C6#,16#00#,
16#38#,16#6C#,16#C6#,16#C6#,16#FE#,16#C6#,16#C6#,16#00#,
16#7E#,16#06#,16#0C#,16#18#,16#30#,16#60#,16#7E#,16#00#,
16#C6#,16#C6#,16#6C#,16#38#,16#6C#,16#C6#,16#C6#,16#00#,
16#7C#,16#C6#,16#C0#,16#C0#,16#C0#,16#C6#,16#7C#,16#00#,
16#C6#,16#C6#,16#C6#,16#C6#,16#C6#,16#6C#,16#38#,16#00#,
16#FC#,16#C6#,16#C6#,16#FC#,16#C6#,16#C6#,16#FC#,16#00#,
16#C6#,16#EE#,16#FE#,16#D6#,16#C6#,16#C6#,16#C6#,16#00#,
16#00#,16#00#,16#00#,16#00#,16#00#,16#38#,16#38#,16#00#,
16#00#,16#00#,16#00#,16#7E#,16#00#,16#00#,16#00#,16#00#,
16#00#,16#66#,16#3C#,16#18#,16#3C#,16#66#,16#00#,16#00#,
16#00#,16#18#,16#00#,16#7E#,16#00#,16#18#,16#00#,16#00#,
16#00#,16#00#,16#7C#,16#00#,16#7C#,16#00#,16#00#,16#00#,
16#66#,16#66#,16#66#,16#3C#,16#18#,16#18#,16#18#,16#00#,
16#C6#,16#E6#,16#F6#,16#FE#,16#DE#,16#CE#,16#C6#,16#00#,
16#03#,16#06#,16#0C#,16#18#,16#30#,16#60#,16#C0#,16#00#,
16#FF#,16#FF#,16#FF#,16#FF#,16#FF#,16#FF#,16#FF#,16#00#,
16#CE#,16#DB#,16#DB#,16#DB#,16#DB#,16#DB#,16#CE#,16#00#,
16#00#,16#00#,16#3C#,16#7E#,16#7E#,16#7E#,16#3C#,16#00#,
16#1C#,16#1C#,16#18#,16#1E#,16#18#,16#18#,16#1C#,16#00#,
16#1C#,16#1C#,16#18#,16#1E#,16#18#,16#34#,16#26#,16#00#,
16#38#,16#38#,16#18#,16#78#,16#18#,16#2C#,16#64#,16#00#,
16#38#,16#38#,16#18#,16#78#,16#18#,16#18#,16#38#,16#00#,
16#00#,16#18#,16#0C#,16#FE#,16#0C#,16#18#,16#00#,16#00#,
16#18#,16#3C#,16#7E#,16#FF#,16#FF#,16#18#,16#18#,16#00#,
16#03#,16#07#,16#0F#,16#1F#,16#3F#,16#7F#,16#FF#,16#00#,
16#C0#,16#E0#,16#F0#,16#F8#,16#FC#,16#FE#,16#FF#,16#00#,
16#38#,16#38#,16#12#,16#FE#,16#B8#,16#28#,16#6C#,16#00#,
16#C0#,16#60#,16#30#,16#18#,16#0C#,16#06#,16#03#,16#00#,
16#00#,16#00#,16#0C#,16#08#,16#08#,16#FF#,16#7E#,16#00#,
16#00#,16#03#,16#63#,16#FF#,16#FF#,16#18#,16#08#,16#00#,
16#00#,16#00#,16#00#,16#10#,16#38#,16#FF#,16#7E#,16#00#,
16#00#,16#00#,16#00#,16#06#,16#6E#,16#FF#,16#7E#,16#00#);
signal addr_q : std_logic_vector(rom_addr_i'range);
begin
-----------------------------------------------------------------------------
-- Process seq
--
-- Purpose:
-- Implements the address register.
--
seq: process (clk_i)
begin
if rising_edge(clk_i) then
if rom_en_i = '1' then
addr_q <= rom_addr_i;
end if;
end if;
end process seq;
--
-----------------------------------------------------------------------------
-----------------------------------------------------------------------------
-- Process rom_data
--
-- Purpose:
-- Does the ROM array look-up
--
rom_data: process (addr_q)
variable idx_v : natural range 0 to 511;
variable dat_v : std_logic_vector(7 downto 0);
begin
idx_v := to_integer(unsigned(addr_q));
rom_data_o <= std_logic_vector(to_unsigned(rom_cont_c(idx_v), 8));
end process rom_data;
--
-----------------------------------------------------------------------------
end rtl;