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--

-- PIC16xx compatible microcontroller core

--

-- Version : 0224

--

-- 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/ppx16/

--

-- 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;

entity PPX_Ctrl is

        generic(

                InstructionLength : integer

        );

        port(

                Clk                     : in std_logic;

                Reset_n         : in std_logic;

                ROM_Data        : in std_logic_vector(InstructionLength - 1 downto 0);

                Inst            : in std_logic_vector(InstructionLength - 1 downto 0);

                Skip            : in std_logic;

                File_Wr         : out std_logic;

                W_Wr            : out std_logic;

                Imm_Op          : out std_logic;

                A2Res           : out std_logic;

                B2Res           : out std_logic;

                Push            : out std_logic;

                Pop                     : out std_logic;

                Goto            : out std_logic;

                IRet            : out std_logic;

                B_Skip          : out std_logic;

                Sleep           : out std_logic

        );

end PPX_Ctrl;

architecture rtl of PPX_Ctrl is

begin

        Imm_Op <= Inst(InstructionLength - 1);

        i12 : if InstructionLength = 12 generate

                B_Skip <= '1' when Inst(11 downto 10) = "10" else '0';

                Sleep <= '1' when ROM_Data(11 downto 0) = "000000000011" else '0';

                W_Wr <= '1' when Inst(11 downto 8) = "1000" or

                                        Inst(11 downto 10) = "11" or

                                        (Inst(11 downto 10) = "00" and Inst(5) = '0' and Inst(9 downto 6) /= "0000") else '0';

                IRet <= '0';

                process (Reset_n, Clk)

                begin

                        if Reset_n = '0' then

                                File_Wr <= '0';

                                Goto <= '0';

                                Push <= '0';

                                Pop <= '0';

                                A2Res <= '0';

                                B2Res <= '0';

                        elsif Clk'event and Clk = '1' then

                                File_Wr <= '0';

                                Goto <= '0';

                                Push <= '0';

                                Pop <= '0';

                                A2Res <= '0';

                                B2Res <= '0';

                                if Skip = '0' then

                                        if (ROM_Data(InstructionLength - 1 downto InstructionLength - 2) = "00" and

                                                ROM_Data(InstructionLength - 7) = '1') or

                                                ROM_Data(InstructionLength - 1 downto InstructionLength - 3) = "010" then

                                                File_Wr <= '1';

                                        end if;

                                        if ROM_Data(InstructionLength - 1 downto InstructionLength - 3) = "101" then

                                                Goto <= '1';

                                        end if;

                                        if ROM_Data(11 downto 8) = "1001" then -- CALL

                                                Push <= '1';

                                        end if;

                                        if ROM_Data(11 downto 8) = "1000" then -- RETLW

                                                Pop <= '1';

                                        end if;

                                        if ROM_Data(11 downto 6) = "001000" then

                                                -- MOVF

                                                A2Res <= '1';

                                        end if;

                                        if ROM_Data(11 downto 8) = "1100" or -- MOVLW

                                                ROM_Data(11 downto 8) = "1000" or -- RETLW

                                                ROM_Data(11 downto 6) = "000000" then -- MOVWF/TRIS/OPTION and some others

                                                B2Res <= '1';

                                        end if;

                                end if;

                        end if;

                end process;

        end generate;

        i14 : if InstructionLength = 14 generate

                B_Skip <= '1' when Inst(13 downto 12) = "10" or Inst(13 downto 10) = "1101" or

                                Inst(13 downto 1) = "0000000000100" else '0';

                Sleep <= '1' when ROM_Data(13 downto 0) = "00000001100011" else '0';

                W_Wr <= '1' when Inst(13 downto 12) = "11" or

                                        (Inst(13 downto 12) = "00" and Inst(7) = '0' and Inst(11 downto 8) /= "0000") else '0';

                IRet <= '1' when Inst(13 downto 0) = "00000000001001" else '0'; -- RETFIE

                process (Reset_n, Clk)

                begin

                        if Reset_n = '0' then

                                File_Wr <= '0';

                                Goto <= '0';

                                Push <= '0';

                                Pop <= '0';

                                A2Res <= '0';

                                B2Res <= '0';

                        elsif Clk'event and Clk = '1' then

                                File_Wr <= '0';

                                Goto <= '0';

                                Push <= '0';

                                Pop <= '0';

                                A2Res <= '0';

                                B2Res <= '0';

                                if Skip = '0' then

                                        if (ROM_Data(InstructionLength - 1 downto InstructionLength - 2) = "00" and

                                                ROM_Data(InstructionLength - 7) = '1') or

                                                ROM_Data(InstructionLength - 1 downto InstructionLength - 3) = "010" then

                                                File_Wr <= '1';

                                        end if;

                                        if ROM_Data(InstructionLength - 1 downto InstructionLength - 3) = "101" then

                                                Goto <= '1';

                                        end if;

                                        if ROM_Data(13 downto 11) = "100" then

                                                Push <= '1'; -- CALL

                                        end if;

                                        if ROM_Data(13 downto 10) = "1101" or -- RETLW

                                                ROM_Data(13 downto 1) = "0000000000100" then -- RETURN, RETFIE

                                                Pop <= '1';

                                        end if;

                                        if ROM_Data(13 downto 8) = "001000" then

                                                -- MOVF

                                                A2Res <= '1';

                                        end if;

                                        if ROM_Data(13 downto 10) = "1100" or -- MOVLW

                                                ROM_Data(13 downto 10) = "1101" or -- RETLW

                                                ROM_Data(13 downto 8) = "000000" then -- MOVWF/TRIS/OPTION and some others

                                                B2Res <= '1';

                                        end if;

                                end if;

                        end if;

                end process;

        end generate;

end;