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SMS_MiSTer/rtl/VM2413/outputmemory.vhd
birdybro 26247dd359 Update edge detection method from VHDL 87 to VHDL 93 (#131)
Technically, `Clk’event and clk = ‘1’` can result in non-`0` triggers (e.g. `1`, `U`, `H`, `X`, `Z`, `W`, etc...), whereas `rising_edge(clk)` does not.
2022-07-07 16:00:25 +08:00

87 lines
2.7 KiB
VHDL

--
-- OutputMemory.vhd
--
-- Copyright (c) 2006 Mitsutaka Okazaki (brezza@pokipoki.org)
-- All rights reserved.
--
-- Redistribution and use of this source code or any derivative works, are
-- permitted provided that the following conditions are met:
--
-- 1. Redistributions of source code must retain the above copyright notice,
-- this list of conditions and the following disclaimer.
-- 2. 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.
-- 3. Redistributions may not be sold, nor may they be used in a commercial
-- product or activity 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 COPYRIGHT OWNER OR
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-- PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
-- OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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--
--
library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;
use WORK.VM2413.ALL;
entity OutputMemory is port (
clk : in std_logic;
reset : in std_logic;
wr : in std_logic;
addr : in SLOT_TYPE;
wdata : in SIGNED_LI_TYPE;
rdata : out SIGNED_LI_TYPE;
addr2 : in SLOT_TYPE;
rdata2 : out SIGNED_LI_TYPE
);
end OutputMemory;
architecture RTL of OutputMemory is
type SIGNED_LI_ARRAY_TYPE is array (0 to 18) of SIGNED_LI_VECTOR_TYPE;
signal data_array : SIGNED_LI_ARRAY_TYPE;
attribute ramstyle : string;
attribute ramstyle of data_array : signal is "logic";
begin
process(clk, reset)
variable init_ch : integer range 0 to 18;
begin
if (reset = '1') then
init_ch := 0;
elsif rising_edge(clk) then
if init_ch /= 18 then
data_array(init_ch) <= (others=>'0');
init_ch := init_ch + 1;
elsif wr='1' then
data_array(conv_integer(addr)) <= CONV_SIGNED_LI_VECTOR(wdata);
end if;
rdata <= CONV_SIGNED_LI(data_array(conv_integer(addr)));
rdata2 <= CONV_SIGNED_LI(data_array(conv_integer(addr2)));
end if;
end process;
end RTL;