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-- Company: 

--

-- File: cp_DecodeControl.vhd

--

-- Description:

--      projet copyblaze

--      instruction decoding & Operational control

--

-- File history:

-- v1.0: 21/10/11: Creation

-- v2.0: 26/10/11: Add Wishbone instructions

--

-- Targeted device: ProAsic A3P250 VQFP100

-- Author: AbdAllah Meziti

--------------------------------------------------------------------------------

library ieee;

use ieee.std_logic_1164.all;

use ieee.numeric_std.all;

use     work.Usefull_Pkg.all;           -- Usefull Package

--------------------------------------------------------------------------------

-- Entity: cp_DecodeControl

--

-- Description:

--      

--      REMARQUE:

--

--      

-- History:

-- 21/10/11 AM: Creation

-- ---------------------

-- xx/xx/xx AM: 

--                              

--------------------------------------------------------------------------------

entity cp_DecodeControl is

        generic

        (

                GEN_WIDTH_INST          : positive := 18;

                GEN_WIDTH_PC            : positive := 10;

                GEN_DEPTH_BANC          : positive := 16;       -- Taille (en octet) du Banc Register

                GEN_DEPTH_SCRATCH       : positive := 64        -- Taille (en octet) du Scratch Pad

        );

        port (

        --------------------------------------------------------------------------------

        -- Signaux Fonctionels

        --------------------------------------------------------------------------------

                --Phase1_i                      : in std_ulogic;

                Phase2_i                        : in std_ulogic;

                IEvent_i                        : in std_ulogic;

                Instruction_i           : in std_ulogic_vector(GEN_WIDTH_INST-1 downto 0);

                Fetch_o                         : out std_ulogic;

                Input_o                         : out std_ulogic;

                Ouput_o                         : out std_ulogic;

                Jump_o                          : out std_ulogic;

                Call_o                          : out std_ulogic;

                Return_o                        : out std_ulogic;

                ReturnI_o                       : out std_ulogic;

                IEWrite_o                       : out std_ulogic;

                BancWrite_o                     : out std_ulogic;

                ScratchWrite_o          : out std_ulogic;

                OperationSelect_o       : out std_ulogic_vector(2 downto 0);

                FlagsWrite_o            : out std_ulogic;

                FlagsPush_o                     : out std_ulogic;

                FlagsPop_o                      : out std_ulogic;

                aaa_o                           : out std_ulogic_vector(GEN_WIDTH_PC-1 downto 0);

                kk_o                            : out std_ulogic_vector(7 downto 0);

                ss_o                            : out std_ulogic_vector(log2(GEN_DEPTH_SCRATCH)-1 downto 0);

                pp_o                            : out std_ulogic_vector(7 downto 0);

                SxPtr_o                         : out std_ulogic_vector(log2(GEN_DEPTH_BANC)-1 downto 0);

                SyPtr_o                         : out std_ulogic_vector(log2(GEN_DEPTH_BANC)-1 downto 0);

                OperandSelect_o         : out std_ulogic;

                ArithOper_o                     : out std_ulogic_vector(1 downto 0);

                LogicOper_o                     : out std_ulogic_vector(1 downto 0);

                ShiftBit_o                      : out std_ulogic_vector(2 downto 0);

                ShiftSens_o                     : out std_ulogic;

                ConditionCtrl_o         : out std_ulogic_vector(2 downto 0);

                IEValue_o                       : out std_ulogic;

                wbRdSing_o                      : out std_ulogic;

                wbWrSing_o                      : out std_ulogic

        );

end cp_DecodeControl;

--------------------------------------------------------------------------------

-- Architecture: RTL

-- of entity : cp_DecodeControl

--------------------------------------------------------------------------------

architecture rtl of cp_DecodeControl is

        --------------------------------------------------------------------------------

        -- Définition des fonctions

        --------------------------------------------------------------------------------

        --------------------------------------------------------------------------------

        -- Définition des constantes

        --------------------------------------------------------------------------------

        --------------------------------------------------------------------------------

        -- Définition des signaux interne

        --------------------------------------------------------------------------------

        signal  iInstruction            : std_ulogic_vector(GEN_WIDTH_INST-1 downto 0);

        alias   iInstructionCode        : std_ulogic_vector(4 downto 0) is iInstruction(17 downto 13);

        -- **** --

        -- PATH --

        -- **** --

        alias   iaaa                            : std_ulogic_vector(GEN_WIDTH_PC-1 downto 0)                     is iInstruction(GEN_WIDTH_PC-1 downto 0);

        alias   ikk                                     : std_ulogic_vector(7 downto 0)                                                  is iInstruction(7 downto 0);

        alias   iss                                     : std_ulogic_vector(log2(GEN_DEPTH_SCRATCH)-1 downto 0)  is iInstruction(log2(GEN_DEPTH_SCRATCH)-1 downto 0);

        alias   ipp                                     : std_ulogic_vector(7 downto 0)                                                  is iInstruction(7 downto 0);

        alias   iSxPtr                          : std_ulogic_vector(log2(GEN_DEPTH_BANC)-1 downto 0)     is iInstruction(8+log2(GEN_DEPTH_BANC)-1 downto 8);

        alias   iSyPtr                          : std_ulogic_vector(log2(GEN_DEPTH_BANC)-1 downto 0)     is iInstruction(4+log2(GEN_DEPTH_BANC)-1 downto 4);

        -- ******* --

        -- CONTROL --

        -- ******* --

        -- Alu

        signal  iOperationSelect        : std_ulogic_vector(2 downto 0);

        alias   iOperandSelect          : std_ulogic                                                                                    is iInstruction(12);

        alias   iArithOper                      : std_ulogic_vector(1 downto 0)                                          is iInstruction(14 downto 13);

        alias   iLogicOper                      : std_ulogic_vector(1 downto 0)                                          is iInstruction(14 downto 13);

        alias   iShiftBit                       : std_ulogic_vector(2 downto 0)                                          is iInstruction(2 downto 0);

        alias   iShiftSens                      : std_ulogic                                                                                    is iInstruction(3);

        -- Banc

        signal  iBancWrite                      : std_ulogic;

        -- Scratch

        signal  iScratchWrite           : std_ulogic;

        -- Flags

        signal  iFlagsWrite                     ,

                        iFlagsPush                      ,

                        iFlagsPop                       : std_ulogic;

        signal  iIEWrite                        : std_ulogic;

        signal  iAddSub                         ,

                        iCompare                        ,

                        iLoad                           ,

                        iLogic                          ,

                        iTest                           ,

                        iShift                          ,

                        iStore                          ,

                        iFetch                          ,

                        iInput                          ,

                        iOuput                          ,

                        iJump                           ,

                        iCall                           ,

                        iReturn                         ,

                        iReturnI                        ,

                        iSetInterrupt           ,

                        -- Wishbone instructions

                        iWBWrSing                       ,

                        iWBRdSing

                                                                : std_ulogic;

        -- Flow

        alias   iConditionCtrl          : std_ulogic_vector(2 downto 0)                                          is iInstruction(12 downto 10);

        -- Int          

        alias   iIEValue                        : std_ulogic                                                                                    is iInstruction(0);

        signal  iIEvent                         : std_ulogic;

        --------------------------------------------------------------------------------

        -- Déclaration des composants

        --------------------------------------------------------------------------------

begin

        --------------------------------------------------------------------------------

        -- DECODER

        --------------------------------------------------------------------------------

        iIEvent                 <=      IEvent_i;

        -- Preempte the instruction in case of interrupt event

        iInstruction    <=      (others => '1') when (iIEvent='1') else Instruction_i;

        --------------------------------------------------------------------------------

        -- INSTRUCTION DECODER

        --------------------------------------------------------------------------------

        -- Arithmetic Group

        iAddSub                 <=      '1' when ((iInstructionCode = '0' & x"C") or

                                                                  (iInstructionCode = '0' & x"D") or

                                                                  (iInstructionCode = '0' & x"E") or

                                                                  (iInstructionCode = '0' & x"F")) else '0';

        iCompare                <=      '1' when ( iInstructionCode = '0' & x"A" ) else '0';

        -- Logic Group

        iLoad                   <=      '1' when ( iInstructionCode = '0' & x"0" ) else '0';

        iLogic                  <=      '1' when ((iInstructionCode = '0' & x"5") or

                                                                  (iInstructionCode = '0' & x"6") or

                                                                  (iInstructionCode = '0' & x"7")) else '0';

        iTest                   <=      '1' when ( iInstructionCode = '0' & x"9" ) else '0';

        -- Shift and Rotate Group

        iShift                  <=      '1' when ( iInstructionCode = '1' & x"0" ) else '0';

        -- Storage Group

        iStore                  <=      '1' when ( iInstructionCode = '1' & x"7" ) else '0';

        iFetch                  <=      '1' when ( iInstructionCode = '0' & x"3" ) else '0';

        -- Input/Ouput Group

        iInput                  <=      '1' when ( iInstructionCode = '0' & x"2" ) else '0';

        iOuput                  <=      '1' when ( iInstructionCode = '1' & x"6" ) else '0';

        -- Program Control Group

        iJump                   <=      '1' when ( iInstructionCode = '1' & x"A" ) else '0';

        iCall                   <=      '1' when ( iInstructionCode = '1' & x"8" ) else '0';

        iReturn                 <=      '1' when ( iInstructionCode = '1' & x"5" ) else '0';

        -- Interrupt Group

        iReturnI                <=      '1' when ( iInstructionCode = '1' & x"C" ) else '0';

        -- TODO : The ENABLE INTERRUPT instruction must clear the "iIEvent" bit if is set while the interrupts are disabled.

        iSetInterrupt   <=      '1' when ( iInstructionCode = '1' & x"E" ) else '0';

        -- Reserved for extension 6

        -- STAR                 = '0' & "B"     

        -- TESTCY               = '0' & "7"

        -- COMPARECY    = '0' & "F"

        -- REGBANK              = '1' & "B"

        -- OUTPUTK              = '1' & "5"

        -- CALL@                = '1' & "2"

        -- LOAD&RETURN  = '1' & "0"

        -- HWBUILD              = '0' & "A"

        -- Wishbone instructions

        iWBRdSing               <=      '1' when ( iInstructionCode = '0' & x"1" ) else '0';

        iWBWrSing               <=      '1' when ( iInstructionCode = '0' & x"4" ) else '0';

        --------------------------------------------------------------------------------

        -- CONTROL SIGNAL

        --------------------------------------------------------------------------------

        -- Flow

        iIEWrite                <=      (Phase2_i and (iSetInterrupt or iReturnI));

        -- Banc

        iBancWrite              <=      (Phase2_i and (iAddSub or iLoad or iLogic or iShift or iFetch or iInput));

        -- Scratch

        iScratchWrite   <=      (Phase2_i and (iStore));

        -- Alu

        iOperationSelect        <=      "000"   when (iShift='1')                                               else

                                                        "001"   when (iLogic='1'        or iTest='1')           else

                                                        "010"   when (iAddSub='1'       or iCompare='1')        else

                                                        "011"   when (iLoad='1')                                                else

                                                        "111";

        -- Flags

        iFlagsWrite             <= (Phase2_i and (iAddSub or iCompare or iLogic or iTest or iShift));

        iFlagsPush              <= (Phase2_i and (IEvent_i));

        iFlagsPop               <= (Phase2_i and (iReturnI));

        --------------------------------------------------------------------------------

        -- Outputs

        --------------------------------------------------------------------------------

        Fetch_o                         <= iFetch                       ;

        Input_o                         <= iInput                       ;

        Ouput_o                         <= iOuput                       ;

        Jump_o                          <= iJump                        ;

        Call_o                          <= iCall                        ;

        Return_o                        <= iReturn                      ;

        ReturnI_o                       <= iReturnI                     ;

        IEWrite_o                       <= iIEWrite                     ;

        BancWrite_o                     <= iBancWrite           ;

        ScratchWrite_o          <= iScratchWrite        ;

        OperationSelect_o       <= iOperationSelect     ;

        FlagsWrite_o            <= iFlagsWrite          ;

        FlagsPush_o                     <= iFlagsPush           ;

        FlagsPop_o                      <= iFlagsPop            ;

        aaa_o                           <= iaaa                         ;

        kk_o                            <= ikk                          ;

        ss_o                            <= iss                          ;

        pp_o                            <= ipp                          ;

        SxPtr_o                         <= iSxPtr                       ;

        SyPtr_o                         <= iSyPtr                       ;

        OperandSelect_o         <= iOperandSelect       ;

        ArithOper_o                     <= iArithOper           ;

        LogicOper_o                     <= iLogicOper           ;

        ShiftBit_o                      <= iShiftBit            ;

        ShiftSens_o                     <= iShiftSens           ;

        ConditionCtrl_o         <= iConditionCtrl       ;

        IEValue_o                       <= iIEValue                     ;

        wbRdSing_o                      <= iWBRdSing            ;

        wbWrSing_o                      <= iWBWrSing            ;

end rtl;