Subversion Repositories mips789

/******************************************************************

 *                                                                *

 *    Author: Liwei                                               *

 *                                                                *

 *    This file is part of the "mips789" project.                 *

 *    Downloaded from:                                            *

 *    http://www.opencores.org/pdownloads.cgi/list/mips789        *

 *                                                                *

 *    If you encountered any problem, please contact me via       *

 *    Email:mcupro@opencores.org  or mcupro@163.com               *

 *                                                                *

 ******************************************************************/

`include "mips789_defs.v"

module ext(

        input [31:0] ins_i ,

        output reg [31:0] res ,

        input [2:0]ctl

    );

    wire [25:0] instr25_0;

    assign instr25_0 = ins_i[25:0] ;

    wire[15:0] sign = {

            instr25_0[15],instr25_0[15],instr25_0[15],instr25_0[15],

            instr25_0[15],instr25_0[15],instr25_0[15],instr25_0[15],

            instr25_0[15],instr25_0[15],instr25_0[15],instr25_0[15],

            instr25_0[15],instr25_0[15],instr25_0[15],instr25_0[15]};

    always @ (*)

    case (ctl)

        `EXT_SIGN    :res ={sign,instr25_0[15:0]};//sign

        `EXT_UNSIGN  :res ={16'b0,instr25_0[15:0]};//zeroext

        `EXT_J       :res ={4'b0,instr25_0[25:0],2'b0};//jmp

        `EXT_B       :res ={sign[13:0],instr25_0[15:0],2'B0};//brach

        `EXT_SA      :res ={27'b0,instr25_0[10:6]} ;//sll,srl

        `EXT_S2H     :res ={instr25_0[15:0],16'B0};//shift to high

        default: res=0;

    endcase

endmodule

module compare (

        input [31:0] s,

        input [31:0] t,

        input [2:0]ctl,

        output reg res

    );

    always @ (*)

    case  (ctl)

        `CMP_BEQ:   res = (s==t);

        `CMP_BNE:   res = (s!=t);

        `CMP_BLTZ:  res = s[31];

        `CMP_BGTZ:  res = ~s[31] && (|s[30:0]);

        `CMP_BLEZ:  res = s[31] |(~|s);

        `CMP_BGEZ:  res = ~s[31];

        default res=1'B0;

    endcase

endmodule

module pc_gen(

        input [2:0]ctl,

        output reg   [31:0]pc_next,

        input [3:0] pc_prectl,

        input check,

        input [31:0]s,

        input [31:0]pc,

        input [31:0]zz_spc,

        input [31:0]imm,

        input [31:0]irq

    );

    wire [32:0] br_addr = pc + imm ;

    always @ (*)

        if(pc_prectl == `PC_IGN )

        begin

            case (ctl)

                `PC_RET         :       pc_next = zz_spc ;

                `PC_J           :       pc_next ={pc[31:28],imm[27:0]};

                `PC_JR          :       pc_next = s;

                `PC_BC          :       pc_next = (check)?({br_addr[31:0]}):(pc+4);

                `PC_NEXT        :       pc_next = pc+ 4 ;

                default                 pc_next = pc + 4;

            endcase

        end

        else

        begin

            case (pc_prectl)

                `PC_KEP         : pc_next=pc;

                `PC_IRQ         : pc_next=irq;

                `PC_RST         : pc_next='d0;

                default           pc_next =0;

            endcase

        end

endmodule

module reg_array(

        data,

        wraddress,

        rdaddress_a,

        rdaddress_b,

        wren,

        clock,

        qa,

        qb,

        rd_clk_cls

    );

    input       [31:0]  data;

    input       [4:0]  wraddress;

    input       [4:0]  rdaddress_a;

    input       [4:0]  rdaddress_b;

    reg [31:0]  r_data;

    reg [4:0]  r_wraddress;

    reg [4:0]  r_rdaddress_a;

    reg [4:0]  r_rdaddress_b;

    input rd_clk_cls;

    input       wren;

    reg r_wren;

    input       clock;

    output      [31:0]  qa;

    output      [31:0]  qb;

    reg [31:0]reg_bank[0:31];

    integer i;

    initial

    begin

        for(i=0;i<32;i=i+1)

            reg_bank[i]=0;

    end

    assign qa=(r_rdaddress_a==0)?0:

           ((r_wraddress==r_rdaddress_a)&&(1==r_wren))?r_data:

           reg_bank[r_rdaddress_a];

    assign qb=(r_rdaddress_b==0)?0:

           ((r_wraddress==r_rdaddress_b)&&(1==r_wren))?r_data:

           reg_bank[r_rdaddress_b];

    always@(posedge clock)

        if (~rd_clk_cls)

        begin

            r_rdaddress_a <=rdaddress_a;

            r_rdaddress_b<=rdaddress_b;

        end

    always@(posedge clock)

    begin

        r_data <=data;

        r_wraddress<=wraddress;

        r_wren<=wren;

    end

    always@(posedge clock)

        if (r_wren)

            reg_bank[r_wraddress] <= r_data ;

endmodule