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--
-- PIC16xx compatible microcontroller core
--
-- Version : 0221
--
-- Copyright (c) 2001-2002 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 :
--	Registers implemented in this entity are INDF, PCL, STATUS, FSR, (PCLATH)
--	other registers must be implemented externally including GPR
--
-- File history :
--
 
library IEEE;
use IEEE.std_logic_1164.all;
use IEEE.numeric_std.all;
 
entity PPX_RAM is
	generic(
		Bottom		: integer;
		Top			: integer;
		AddrWidth	: integer
	);
	port(
		Clk			: in std_logic;
		CS			: in std_logic;
		Wr			: in std_logic;
		Addr		: in std_logic_vector(AddrWidth - 1 downto 0);
		Data_In		: in std_logic_vector(7 downto 0);
		Data_Out	: out std_logic_vector(7 downto 0)
	);
end PPX_RAM;
 
architecture rtl of PPX_RAM is
 
	type RAM_Image is array (Top downto 0) of std_logic_vector(7 downto 0);
	signal	RAM			: RAM_Image;
	signal	AddrRd		: std_logic_vector(AddrWidth - 1 downto 0);
	signal	AddrWr		: std_logic_vector(AddrWidth - 1 downto 0);
 
begin
 
	process (Clk)
	begin
		if Clk'event and Clk = '1' then
			AddrRd <= Addr;
			AddrWr <= Addr;
			if CS = '1' and Wr = '1' then
				RAM(to_integer(unsigned(AddrWr))) <= Data_In;
			end if;
		end if;
	end process;
 
	Data_Out <= RAM(to_integer(unsigned(AddrRd)))
-- pragma translate_off
		when to_integer(unsigned(AddrRd)) >= Bottom and to_integer(unsigned(AddrRd)) <= Top else "--------"
-- pragma translate_on
	;
 
end;