Subversion Repositories minimips_superscalar

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

--                                                                      --

--                                                                      --

-- miniMIPS Superscalar Processor : Execution stage                     --

-- based on miniMIPS Processor                                          --

--                                                                      --

--                                                                      --

-- Author : Miguel Cafruni                                              --

-- miguel_cafruni@hotmail.com                                           --

--                                                      December 2018   --

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

library IEEE;

use IEEE.std_logic_1164.all;

use IEEE.numeric_std.all;

library work;

use work.pack_mips.all;

use work.alu;

entity pps_ex is

port(

    clock : in std_logic;

    clock2 : in std_logic;

    reset : in std_logic;

    stop_all : in std_logic;            -- Unconditionnal locking of outputs

    stop_all2 : in std_logic; -- 07-08-2018

    clear : in std_logic;               -- Clear the pipeline stage

    -- Datas from DI stage

    DI_bra : in std_logic;              -- Branch instruction

    DI_link : in std_logic;             -- Branch with link

    DI_op1 : in bus32;                  -- Operand 1 for alu

    DI_op2 : in bus32;                  -- Operand 2 for alu

    DI_code_ual : in alu_ctrl_type;     -- Alu operation

    DI_offset : in bus32;               -- Offset for address calculation

    DI_adr_reg_dest : in adr_reg_type;  -- Destination register address for the result

    DI_ecr_reg : in std_logic;          -- Effective writing of the result

    DI_mode : in std_logic;             -- Address mode (relative to pc ou index by a register)

    DI_op_mem : in std_logic;           -- Memory operation

    DI_r_w : in std_logic;              -- Type of memory operation (read or write)

    DI_adr : in bus32;                  -- Instruction address

    DI_exc_cause : in bus32;            -- Potential cause exception

    DI_level : in level_type;           -- Availability stage of the result for bypassing

    DI_it_ok : in std_logic;            -- Allow hardware interruptions

    EX2_data_hilo : in bus64;--resultado da multiplicacao do pieline2

    EX_data_hilo : out bus64;

    -- Synchronous outputs to MEM stage

    EX_adr : out bus32;                 -- Instruction address

    EX_bra_confirm : out std_logic;     -- Branch execution confirmation

    EX_data_ual : out bus32;            -- Ual result

    EX_adresse : out bus32;             -- Address calculation result

    EX_adresse_p1p2 : out bus32;        -- resultado do calculo do endereco do desvio + 4 para pipe 2

    EX_adr_reg_dest : out adr_reg_type; -- Destination register for the result

    EX_ecr_reg : out std_logic;         -- Effective writing of the result

    EX_op_mem : out std_logic;          -- Memory operation needed

    EX_r_w : out std_logic;             -- Type of memory operation (read or write)

    EX_exc_cause : out bus32;           -- Potential cause exception

    EX_level : out level_type;          -- Availability stage of result for bypassing

    EX_it_ok : out std_logic            -- Allow hardware interruptions

);

end entity;

architecture rtl of pps_ex is

component alu

    port (

        clock : in bus1;

        reset : in bus1;

        op1 : in bus32;                 -- Operand 1

        op2 : in bus32;                 -- Operand 2

        ctrl : in alu_ctrl_type;        -- Operation

        hilo_p2 : in bus64;

        hilo_p1p2 : out bus64;

        res : out bus32;                -- Result

        overflow : out bus1             -- Overflow

    );

    end component;

    signal res_ual         : bus32;      -- Alu result output

    signal base_adr        : bus32;      -- Output of the address mode mux selection

    signal pre_ecr_reg     : std_logic;  -- Output of mux selection for writing command to register

    signal pre_data_ual    : bus32;      -- Mux selection of the data to write

    signal pre_bra_confirm : std_logic;  -- Result of the test in alu when branch instruction

    signal pre_exc_cause   : bus32;      -- Preparation of the exception detection signal

    signal overflow_ual    : std_logic;  -- Dectection of the alu overflow

    signal ex_address_p1p2   : bus32;

    signal hilo_p1p2_s : bus64;

begin

    -- Alu instantiation

    U1_alu : alu port map (clock => clock, reset => reset, op1=>DI_op1, op2=>DI_op2, ctrl=>DI_code_ual,

                                res=>res_ual, overflow=>overflow_ual, hilo_p2=>EX2_data_hilo, hilo_p1p2=>hilo_p1p2_s);

    -- Calculation of the future outputs

    base_adr <= DI_op1 when DI_mode='0' else DI_adr; -- *** base_adr = DI_op1 = 0 na instrucao JAL ***

    pre_ecr_reg <= DI_ecr_reg when DI_link='0' else pre_bra_confirm;

    pre_data_ual <= res_ual when DI_link='0' else bus32(unsigned(DI_adr) + 8); --***Endereco de retorno (link address) gravado pela instrucao JAL no registrador D_31, que depois sera usado pela intrucao de retorno da rotina, JR.***

    pre_bra_confirm <= DI_bra and res_ual(0);

    pre_exc_cause <= DI_exc_cause when DI_exc_cause/=IT_NOEXC else

                     IT_OVERF when overflow_ual='1' else

                     IT_NOEXC;

    -- Set the synchronous outputs

    process(clock) is

    begin

        if rising_edge(clock) then

            if reset='1' then

                EX_adr <= (others => '0');

                EX_bra_confirm <= '0';

                EX_data_ual <= (others => '0');

                EX_adresse <= (others => '0');

                EX_adr_reg_dest <= (others => '0');

                EX_ecr_reg <= '0';

                EX_op_mem <= '0';

                EX_r_w <= '0';

                EX_exc_cause <= IT_NOEXC;

                EX_level <= LVL_DI;

                EX_it_ok <= '0';

            elsif stop_all = '0' then

                if clear = '1' then -- Clear the stage

                    EX_adr <= DI_adr;

                    EX_bra_confirm <= '0';

                    EX_data_ual <= (others => '0');

                    EX_adresse <= (others => '0');

                    EX_adr_reg_dest <= (others => '0');

                    EX_ecr_reg <= '0';

                    EX_op_mem <= '0';

                    EX_r_w <= '0';

                    EX_exc_cause <= IT_NOEXC;

                    EX_level <= LVL_DI;

                    EX_it_ok <= '0';

                else -- Normal evolution 

                    EX_adr <= DI_adr;

                    EX_bra_confirm <= pre_bra_confirm;

                    EX_data_ual <= pre_data_ual;

                    EX_adr_reg_dest <= DI_adr_reg_dest;

                    EX_ecr_reg <= pre_ecr_reg;

                    EX_op_mem <= DI_op_mem;

                    EX_r_w <= DI_r_w;

                    EX_exc_cause <= pre_exc_cause;

                    EX_level <= DI_level;

                    EX_it_ok <= DI_it_ok;

                              EX_adresse <= bus32(unsigned(DI_offset) + unsigned(base_adr)); --*** base_adr = DI_op1 = 0 na instrucao JAL, para calcular o endereco alvo ***

                              ex_address_p1p2 <= bus32(unsigned(DI_offset) + unsigned(base_adr));

                end if;

            end if;

        end if;

        if falling_edge(clock2) then

                if reset = '1' then

                        EX_adresse_p1p2 <= (others => '0');

                        EX_data_hilo <= (others => '0');

                elsif stop_all2 = '0' then -- sinal stop_all do pipe 2

                        EX_data_hilo <= hilo_p1p2_s;

                        EX_adresse_p1p2 <= bus32(unsigned(ex_address_p1p2) + 4); --*** endereco alvo para o pipe 2 ***

                end if;

        end if;

    end process;

end architecture;