目录
一、实验目的
1. 理解MIPS处理器指令格式及功能。
2. 掌握lw, sw, beq, bne, lui, j, jal指令格式与功能。
3. 掌握ModelSim和ISE\Vivado工具软件。
4. 掌握基本的测试代码编写和FPGA开发板使用方法。
二、实验环境
1. 装有ModelSim和ISE\Vivado的计算机。
2. Sword\Basys3\EGo1实验系统。
三、实验原理
MIPS 32位处理器的指令格式分为R型、I型和J型。R型为寄存器型，即两个源操作数和目的操作数都是寄存器性。I型为操作数含有立即数。而J型特指转移类型指令，如图1所示。
如图2所示，本次实验将实现实验挑选剩余部分MIPS处理器指令进行实现。主要是部分R型和J型指令。指令的格式如图2所示，指令的功能参考资料1（李亚民. 计算机原理与设计：Verilog HDL版）。
如图3所示为按照单指令周期设计MIPS处理器内部结构。所有控制信号及字段均标注出来。另外，每条指令周期都包含2个clk，即PC模块用1个clk，Regfile和DataMem模块用1个clk，也可以说是由2个时钟构成的指令流水线。为了便于今后的扩展，将MIPS处理器进行了分阶段设计，这样结构更清晰，也有利于流水线的设计。随着后续指令的不断添加，处理器内部结构设计也会进行相应的调整，但时序部分应保持不变。
四、实验任务
1. 用Verilog HDL设计32位MIPS处理指令实现,参照图3的MIPS内部结构示意图，先编写基本实现代码，即能实现j和jal指令的取指令和执行指令，在Modelsim上仿真测试。
2. 参照图2，将设计的MIPS处理器改造为分阶段实现方案，注意每条指令周期平均只包含1个时钟周期。
3.编写指令存储测试文件，在Modelsim上调试通过。
代码
`define RstEnable 1'b1
`define RstDisable 1'b0
`define RomEnable 1'b1
`define RomDisable 1'b0
`define Zero 0
`define Valid 1'b1
`define Invalid 1'b0
//I
`define Inst_ori 6'b001101
`define Inst_addi 6'b001000
`define Inst_andi 6'b001100
`define Inst_xori 6'b001110
`define Inst_lui 6'b001111
`define Inst_subi 6'b001001
//R
`define Inst_r 6'b000000
`define Inst_add 6'b100000
`define Inst_sub 6'b100010
`define Inst_and 6'b100100
`define Inst_or 6'b100101
`define Inst_xor 6'b100110
`define Inst_sll 6'b000000
`define Inst_srl 6'b000010
`define Inst_sra 6'b000011
//J
`define Inst_j 6'b000010
`define Inst_jal 6'b000011
`define Inst_jr 6'b001000
`define Inst_beq 6'b000100
`define Inst_bne 6'b000101
`define Nop 6'b000000
`define Or 6'b000001
`define Add 6'b000010
`define And 6'b000011
`define Xor 6'b000100
`define Lui 6'b000101
`define Sub 6'b000110
`define Sll 6'b000111
`define Srl 6'b001000
`define Sra 6'b001001
`define J 6'b001010
`define Jal 6'b001011
`define Beq 6'b001100
`define Bne 6'b001101
`define Jr 6'b001110`include "define.v"
module EX(
input wire rst,
input wire [5:0] op,
input wire [31:0] regaData,
input wire [31:0] regbData,
input wire regcWrite_i,
input wire [4:0]regcAddr_i,
output reg [31:0] regcData,
output wire regcWrite,
output wire [4:0] regcAddr
);
always@(*)
if(rst == `RstEnable)
regcData = `Zero;
else
begin
case(op)
`Or:
regcData = regaData | regbData;
`Add:
regcData = regaData + regbData;
`And:
regcData = regaData & regbData;
`Xor:
regcData = regaData ^ regbData;
`Lui:
regcData = regaData;
/*`Lui:
regcData = regaData | regbData;
*/
`Sub:
regcData = regaData - regbData;
`Sll:
regcData = regbData << regaData;
`Srl:
regcData = regbData >> regaData;
`Sra:
regcData = ($signed(regbData)) >>> regaData;
`J:
regcData = `Zero;
`Jr:
regcData = `Zero;
`Jal:
regcData = regbData;
`Beq:
regcData = `Zero;
`Bne:
regcData = `Zero;
default:
regcData = `Zero;
endcase
end
assign regcWrite = regcWrite_i;
assign regcAddr = regcAddr_i;
endmodule
`include "define.v";
module ID (
input wire rst,
input wire [31:0] pc, //J
input wire [31:0] inst,
input wire [31:0] regaData_i,
input wire [31:0] regbData_i,
output reg [5:0] op,
output reg [31:0] regaData,
output reg [31:0] regbData,
output reg regaRead,
output reg regbRead,
output reg regcWrite,
output reg [4:0] regaAddr,
output reg [4:0] regbAddr,
output reg [4:0] regcAddr,
output reg [31:0] jAddr, //J
output reg jCe//J
);
wire [5:0] inst_op = inst[31:26];
reg [31:0] imm;
//R
wire[5:0] func = inst[5:0];
//J
wire [31:0] npc = pc + 4;
always@(*)
if(rst == `RstEnable)
begin
op = `Nop;
regaRead = `Invalid;
regbRead = `Invalid;
regcWrite = `Invalid;
regaAddr = `Zero;
regbAddr = `Zero;
regcAddr = `Zero;
imm = `Zero;
jCe = `Invalid;//J
jAddr = `Zero;//J
end
else
begin
jCe = `Invalid;//J
jAddr = `Zero;//J
case(inst_op)
`Inst_ori:
begin
op = `Or;
regaRead = `Valid;
regbRead = `Invalid;
regcWrite = `Valid;
regaAddr = inst[25:21];
regbAddr = `Zero;
regcAddr = inst[20:16];
imm = {16'h0, inst[15:0]};
end
`Inst_andi:
begin
op = `And;
regaRead = `Valid;
regbRead = `Invalid;
regcWrite = `Valid;
regaAddr = inst[25:21];
regbAddr = `Zero;
regcAddr = inst[20:16];
imm = {16'h0, inst[15:0]};
end
`Inst_xori:
begin
op = `Xor;
regaRead = `Valid;
regbRead = `Invalid;
regcWrite = `Valid;
regaAddr = inst[25:21];
regbAddr = `Zero;
regcAddr = inst[20:16];
imm = {16'h0, inst[15:0]};
end
`Inst_addi:
begin
op = `Add;
regaRead = `Valid;
regbRead = `Invalid;
regcWrite = `Valid;
regaAddr = inst[25:21];
regbAddr = `Zero;
regcAddr = inst[20:16];
imm = {
{16{inst[15]}}, inst[15:0]};
end
`Inst_subi:
begin
op = `Sub;
regaRead = `Valid;
regbRead = `Invalid;
regcWrite = `Valid;
regaAddr = inst[25:21];
regbAddr = `Zero;
regcAddr = inst[20:16];
imm = {
{16{inst[15]}}, inst[15:0]};
end
`Inst_lui:
begin
op = `Lui;
regaRead = `Invalid;
regbRead = `Invalid;
regcWrite = `Valid;
regaAddr = `Zero;
regbAddr = `Zero;
regcAddr = inst[20:16];
imm = {inst[15:0],16'h0};
end
`Inst_r:
case(func)
`Inst_add:
begin
op = `Add;
regaRead = `Valid;
regbRead = `Valid;
regcWrite = `Valid;
regaAddr = inst[25:21];
regbAddr = inst[20:16];
regcAddr = inst[15:11];
imm = `Zero;
end
`Inst_or:
begin
op = `Or;
regaRead = `Valid;
regbRead = `Valid;
regcWrite = `Valid;
regaAddr = inst[25:21];
regbAddr = inst[20:16];
regcAddr = inst[15:11];
imm = `Zero;
end
`Inst_sub:
begin
op = `Sub;
regaRead = `Valid;
regbRead = `Valid;
regcWrite = `Valid;
regaAddr = inst[25:21];
regbAddr = inst[20:16];
regcAddr = inst[15:11];
imm = `Zero;
end
`Inst_and:
begin
op = `And;
regaRead = `Valid;
regbRead = `Valid;
regcWrite = `Valid;
regaAddr = inst[25:21];
regbAddr = inst[20:16];
regcAddr = inst[15:11];
imm = `Zero;
end
`Inst_xor:
begin
op = `Xor;
regaRead = `Valid;
regbRead = `Valid;
regcWrite = `Valid;
regaAddr = inst[25:21];
regbAddr = inst[20:16];
regcAddr = inst[15:11];
imm = `Zero;
end
`Inst_sll:
begin
op = `Sll;
regaRead = `Invalid;
regbRead = `Valid;
regcWrite = `Valid;
regaAddr = `Zero;
regbAddr = inst[20:16];
regcAddr = inst[15:11];
imm = {27'b0,inst[10:6]};
end
`Inst_srl:
begin
op = `Srl;
regaRead = `Invalid;
regbRead = `Valid;
regcWrite = `Valid;
regaAddr = `Zero;
regbAddr = inst[20:16];
regcAddr = inst[15:11];
imm = {27'b0,inst[10:6]};
end
`Inst_sra:
begin
op = `Sra;
regaRead = `Invalid;
regbRead = `Valid;
regcWrite = `Valid;
regaAddr = `Zero;
regbAddr = inst[20:16];
regcAddr = inst[15:11];
imm = {27'b0,inst[10:6]};
end
`Inst_jr:
begin
op = `Jr;
regaRead = `Valid;//rs
regbRead = `Invalid;
regcWrite = `Invalid;
regaAddr = inst[25:21];
regbAddr = `Zero;
regcAddr = `Zero;
jAddr = regaData;
jCe = `Valid;
imm = `Zero;
end
default:
begin
regaRead = `Invalid;
regbRead = `Invalid;
regcWrite = `Invalid;
regaAddr = `Zero;
regbAddr = `Zero;
regcAddr = `Zero;
imm = `Zero;
end
endcase
//J
`Inst_j:
begin
op = `J;
regaRead = `Invalid;
regbRead = `Invalid;
regcWrite = `Invalid;
regaAddr = `Zero;
regbAddr = `Zero;
regcAddr = `Zero;
jAddr = {npc[31:28], inst[25:0], 2'b00};
jCe = `Valid;
imm = `Zero;
end
`Inst_jal:
begin
op = `Jal;
regaRead = `Invalid;
regbRead = `Invalid;
regcWrite = `Valid;
regaAddr = `Zero;
regbAddr = `Zero;
regcAddr = 5'b11111;
jAddr = {npc[31:28], inst[25:0], 2'b00};
jCe = `Valid;
imm = npc;
end
//J
`Inst_beq:
begin
op = `Beq;
regaRead = `Valid;
regbRead = `Valid;
regcWrite = `Invalid;
regaAddr = inst[25:21];
regbAddr = inst[20:16];
regcAddr = `Zero;
jAddr = npc+{
{14{inst[15]}},inst[15:0],2'b00};
jCe=(regaData==regbData)?`Valid:`Invalid;
/* if(regaData==regbData)
jCe = `Valid;
else
jCe = `Invalid;*/
imm = `Zero;
end
`Inst_bne:
begin
op = `Bne;
regaRead = `Valid;
regbRead = `Valid;
regcWrite = `Invalid;
regaAddr = inst[25:21];
regbAddr = inst[20:16];
regcAddr = `Zero;
jAddr = npc+{
{14{inst[15]}},inst[15:0],2'b00};
jCe=(regaData!=regbData)?`Valid:`Invalid;
/* if(regaData!=regbData)
jCe = `Valid;
else
jCe = `Invalid;
*/
imm = `Zero;
end
default:
begin
op = `Nop;
regaRead = `Invalid;
regbRead = `Invalid;
regcWrite = `Invalid;
regaAddr = `Zero;
regbAddr = `Zero;
regcAddr = `Zero;
imm = `Zero;
end
endcase
end
always@(*)
if(rst == `RstEnable)
regaData = `Zero;
else if(regaRead == `Valid)
regaData = regaData_i;
else
regaData = imm;
always@(*)
if(rst == `RstEnable)
regbData = `Zero;
else if(regbRead == `Valid)
regbData = regbData_i;
else
regbData = imm;
endmodule
`include "define.v"
module IF(
input wire clk,
input wire rst,
input wire [31:0] jAddr,//J
input wire jCe,//J
output reg ce,
output reg [31:0] pc
);
always@(*)
if(rst == `RstEnable)
ce = `RomDisable;
else
ce = `RomEnable;
/* always@(posedge clk)
if(ce == `RomDisable)
pc = `Zero;
else
pc = pc + 4;
*/
always@(posedge clk)
if(ce == `RomDisable)
pc = `Zero;
else if(jCe == `Valid)//J
pc = jAddr;
else
pc = pc + 4;
endmodule
`include "define.v"
module MIPS(
input wire clk,
input wire rst,
input wire [31:0] instruction,
output wire romCe,
output wire [31:0] instAddr
);
wire [31:0] regaData_regFile, regbData_regFile;
wire [31:0] regaData_id, regbData_id;
wire [31:0] regcData_ex;
wire [5:0] op;
wire regaRead, regbRead;
wire [4:0] regaAddr, regbAddr;
wire regcWrite_id, regcWrite_ex;
wire [4:0] regcAddr_id, regcAddr_ex;
//J
wire [31:0] jAddr;
wire jCe;
IF if0(
.clk(clk),
.rst(rst),
.jAddr(jAddr),//J
.jCe(jCe),//J
.ce(romCe),
.pc(instAddr)
);
ID id0(
.pc(instAddr),//J
.jAddr(jAddr),//J
.jCe(jCe),//J
.rst(rst),
.inst(instruction),
.regaData_i(regaData_regFile),
.regbData_i(regbData_regFile),
.op(op),
.regaData(regaData_id),
.regbData(regbData_id),
.regaRead(regaRead),
.regbRead(regbRead),
.regaAddr(regaAddr),
.regbAddr(regbAddr),
.regcWrite(regcWrite_id),
.regcAddr(regcAddr_id)
);
EX ex0(
.rst(rst),
.op(op),
.regaData(regaData_id),
.regbData(regbData_id),
.regcWrite_i(regcWrite_id),
.regcAddr_i(regcAddr_id),
.regcData(regcData_ex),
.regcWrite(regcWrite_ex),
.regcAddr(regcAddr_ex)
);
RegFile regfile0(
.clk(clk),
.rst(rst),
.we(regcWrite_ex),
.waddr(regcAddr_ex),
.wdata(regcData_ex),
.regaRead(regaRead),
.regbRead(regbRead),
.regaAddr(regaAddr),
.regbAddr(regbAddr),
.regaData(regaData_regFile),
.regbData(regbData_regFile)
);
endmodule
`include "define.v"
module RegFile(
input wire clk,
input wire rst,
input wire we,
input wire [4:0] waddr,
input wire [31:0] wdata,
input wire regaRead,
input wire regbRead,
input wire [4:0] regaAddr,
input wire [4:0] regbAddr,
output reg [31:0] regaData,
output reg [31:0] regbData
);
reg [31:0] reg32 [31 : 0];
always@(*)
if(rst == `RstEnable)
regaData = `Zero;
else if(regaAddr == `Zero)
regaData = `Zero;
else
regaData = reg32[regaAddr];
always@(*)
if(rst == `RstEnable)
regbData = `Zero;
else if(regbAddr == `Zero)
regbData = `Zero;
else
regbData = reg32[regbAddr];
always@(posedge clk)
if(rst != `RstEnable)
if((we == `Valid) && (waddr != `Zero))
reg32[waddr] = wdata;
else ;
endmodulemodule SoC(
input wire clk,
input wire rst
);
wire [31:0] instAddr;
wire [31:0] instruction;
wire romCe;
MIPS mips0(
.clk(clk),
.rst(rst),
.instruction(instruction),
.instAddr(instAddr),
.romCe(romCe)
);
InstMem instrom0(
.ce(romCe),
.addr(instAddr),
.data(instruction)
);
endmodule
`include "define.v"
module soc_tb;
reg clk;
reg rst;
initial
begin
clk = 0;
rst = `RstEnable;
#100
rst = `RstDisable;
#10000 $stop;
end
always #10 clk = ~ clk;
SoC soc0(
.clk(clk),
.rst(rst)
);
endmodule