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arniml |
------------------------------------------------------------------------------
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--
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-- The Program memory controller.
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--
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arniml |
-- $Id: t400_pmem_ctrl.vhd,v 1.3 2006-05-28 15:32:40 arniml Exp $
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arniml |
--
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-- Copyright (c) 2006 Arnim Laeuger (arniml@opencores.org)
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--
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-- All rights reserved
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--
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-- Redistribution and use in source and synthezised forms, with or without
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-- modification, are permitted provided that the following conditions are met:
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--
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-- Redistributions of source code must retain the above copyright notice,
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-- this list of conditions and the following disclaimer.
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--
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-- Redistributions in synthesized form must reproduce the above copyright
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-- notice, this list of conditions and the following disclaimer in the
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-- documentation and/or other materials provided with the distribution.
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--
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-- Neither the name of the author nor the names of other contributors may
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-- be used to endorse or promote products derived from this software without
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-- specific prior written permission.
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--
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-- THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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-- AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
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-- THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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-- PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE
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-- LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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-- CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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-- SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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-- INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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-- CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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-- ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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-- POSSIBILITY OF SUCH DAMAGE.
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--
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-- Please report bugs to the author, but before you do so, please
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-- make sure that this is not a derivative work and that
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-- you have the latest version of this file.
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--
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-- The latest version of this file can be found at:
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-- http://www.opencores.org/cvsweb.shtml/t400/
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--
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-------------------------------------------------------------------------------
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library ieee;
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use ieee.std_logic_1164.all;
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use work.t400_opt_pack.all;
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use work.t400_pack.all;
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entity t400_pmem_ctrl is
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generic (
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opt_type_g : integer := t400_opt_type_420_c
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);
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port (
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-- System Interface -------------------------------------------------------
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ck_i : in std_logic;
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ck_en_i : in boolean;
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por_i : in boolean;
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res_i : in boolean;
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a_i : in dw_t;
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m_i : in dw_t;
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-- Control Interface ------------------------------------------------------
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op_i : in pc_op_t;
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dec_data_i : in dec_data_t;
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-- Stack Interface --------------------------------------------------------
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pc_o : out pc_t;
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pc_i : in pc_t;
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-- Program Memory Interface -----------------------------------------------
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pm_addr_o : out pc_t
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);
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end t400_pmem_ctrl;
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library ieee;
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use ieee.numeric_std.all;
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arniml |
-- pragma translate_off
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use work.tb_pack.tb_pc_s;
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-- pragma translate_on
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architecture rtl of t400_pmem_ctrl is
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signal pc_q : pc_t;
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signal last_pc_s : pc_t;
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begin
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-----------------------------------------------------------------------------
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-- Determine last program counter address
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-----------------------------------------------------------------------------
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last_pc_s <= to_unsigned(16#1ff#, pc_t'length)
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when opt_type_g = t400_opt_type_410_c else
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to_unsigned(16#3ff#, pc_t'length);
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-----------------------------------------------------------------------------
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-- Process pc
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--
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-- Purpose:
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-- Implements the program counter.
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--
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pc: process (ck_i, por_i)
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begin
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if por_i then
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pc_q <= (others => '0');
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elsif ck_i'event and ck_i = '1' then
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if res_i then
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-- synchronous reset upon external reset event
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pc_q <= (others => '0');
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elsif ck_en_i then
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-- determine PC update mode
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case op_i is
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-- increment program counter ----------------------------------------
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when PC_INC_PC =>
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if pc_q = last_pc_s then
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-- roll over
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pc_q <= (others => '0');
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else
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pc_q <= pc_q + 1;
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end if;
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-- Load lower 6 bits from program memory data -----------------------
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when PC_LOAD_6 =>
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pc_q(5 downto 0) <= unsigned(dec_data_i(5 downto 0));
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-- Load lower 7 bits from program memory data -----------------------
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when PC_LOAD_7 =>
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pc_q(6 downto 0) <= unsigned(dec_data_i(6 downto 0));
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-- Load lower 8 bits from program memory data -----------------------
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when PC_LOAD_8 =>
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pc_q(7 downto 0) <= unsigned(dec_data_i(7 downto 0));
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-- Load all bits from program memory data ---------------------------
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when PC_LOAD =>
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pc_q <= unsigned(dec_data_i);
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-- pop program counter from stack -----------------------------------
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when PC_POP =>
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pc_q <= pc_i;
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-- update program counter for LQID instruction ----------------------
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when PC_LOAD_A_M =>
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pc_q(7 downto 4) <= unsigned(a_i);
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pc_q(3 downto 0) <= unsigned(m_i);
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-- load interrupt vector --------------------------------------------
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when PC_INT =>
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if opt_type_g = t400_opt_type_420_c then
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-- load address 0x100, i.e. skip first instruction at
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-- vector address 0x0ff which has to be a NOP :-)
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pc_q <= (8 => '1', others => '0');
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end if;
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when others =>
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null;
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end case;
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end if;
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end if;
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end process pc;
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--
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-----------------------------------------------------------------------------
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-- pragma translate_off
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-- instrument interrupt testbench
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tb_pc_s <= pc_q;
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-- pragma translate_on
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-----------------------------------------------------------------------------
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-- Output mapping
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-----------------------------------------------------------------------------
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pc_o <= pc_q;
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pm_addr_o <= pc_q;
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end rtl;
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-------------------------------------------------------------------------------
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-- File History:
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--
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-- $Log: not supported by cvs2svn $
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arniml |
-- Revision 1.2 2006/05/27 19:16:52 arniml
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-- interrupt functionality added
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--
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-- Revision 1.1.1.1 2006/05/06 01:56:45 arniml
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-- import from local CVS repository, LOC_CVS_0_1
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--
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arniml |
-------------------------------------------------------------------------------
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