- 掌握MIPS R型、I型和J型指令的综合数据通路设计，掌握各种转移类指令的控制流和指令流的多路选通控制方法
- 掌握J型、I型和R型转移指令的指令格式和寻址方式，学习转移地址的产生方法，掌握无条件转移指令和条件转移指令的实现方法
- 编程实现MIPS的部分J型、I型和R型转移指令的功能
- 分析MIPS J型指令的特点，由6位OP字段和26位的address字段构成
- 分析转移指令的数据通路，转移地址的产生有三种方式，转移地址产生后，要送入PC，才能完成跳转
- R型指令还添加了一条无条件跳转指令，要在原来的PC模块判断R型指令的地方进行修改，不能在I型指令下判断，这样会产生冲突
- 对于条件转移指令beq和bne要使用ALU做减法，判断是否全为零，也就是用ZF判断是否转移
- J型指令可以接着I型指令的case结构写下来，与J型case结构无冲突
- 由于实验九和实验十想法十分接近，主要是控制信号的改变，及其译码模块的改变
- 涉及实验：具体用到的实验是多功能ALU设计实验、寄存器堆设计实验 、取指令与指令译码实验
- 代码展示
顶层模块
module CPU(clk,rst,OF,ZF,F,ALU_OP,M_R_Data,w_r_s,imm_s,rt_imm_s,Mem_Write,Write_Reg,PC,PC_s,clk_M,R_Data_B,Inst_code);
input clk,rst,clk_M;
output [31:0]Inst_code;
wire [5:0]op_code,funct;
wire [4:0]rs_addr,rt_addr,rd_addr,shamt;
output [31:0]F;
output OF,ZF;
output [31:0]M_R_Data;
output [2:0]ALU_OP;
wire [31:0]Mem_Addr;
wire [4:0]W_Addr;
output imm_s,rt_imm_s,Mem_Write,Write_Reg;
output [1:0]w_r_s;
wire [31:0]imm_data;
wire [31:0]R_Data_A;
output [31:0]R_Data_B;
wire [15:0]imm;
wire [31:0]ALU_B;
wire [31:0]W_Data;
output [1:0]PC_s;
wire [25:0]address;
wire [1:0]wr_data_s;
wire [31:0]PC_new;
output [31:0]PC;
PC pc1(clk,rst,Inst_code,PC_s,R_Data_A,address,PC,imm_data,PC_new);
assign op_code = Inst_code[31:26];
assign rs_addr = Inst_code[25:21];
assign rt_addr = Inst_code[20:16];
assign rd_addr = Inst_code[15:11];
assign shamt = Inst_code[10:6];
assign funct = Inst_code[5:0];
assign imm = Inst_code[15:0];
assign address = Inst_code[25:0];
OP_Func op(op_code,funct,Write_Reg,ALU_OP,w_r_s,imm_s,rt_imm_s,Mem_Write,wr_data_s,PC_s,ZF);
assign W_Addr = (w_r_s[1])?5'b11111:((w_r_s[0])?rt_addr:rd_addr);
assign imm_data = (imm_s)?{{16{imm[15]}},imm}:{{16{1'b0}},imm};
Fourth_experiment_first F1(rs_addr,rt_addr,Write_Reg,R_Data_A,R_Data_B,rst,~clk,W_Addr,W_Data);
assign ALU_B = (rt_imm_s)?imm_data:R_Data_B;
Third_experiment_first T1(OF,ZF,ALU_OP,R_Data_A,ALU_B,F);
RAM RAM_B (
.clka(clk_M), // input clka
.wea(Mem_Write), // input [0 : 0] wea
.addra(F[5:0]), // input [5 : 0] addra
.dina(R_Data_B), // input [31 : 0] dina
.douta(M_R_Data) // output [31 : 0] douta
);
assign W_Data = (wr_data_s[1])?PC_new:((wr_data_s[0])? M_R_Data:F);
endmodulePC（取指令模块）
module PC(clk,rst,Inst_code,PC_s,R_Data_A,address,PC,imm_data,PC_new);
input clk,rst;
input [1:0]PC_s;
input [31:0]R_Data_A;
input [25:0]address;
input [31:0]imm_data;
output reg[31:0]PC;
output [31:0]PC_new;
initial
PC = 32'h0000_0000;
output [31:0]Inst_code;
assign PC_new = PC +4;
Inst_Rom rom(
.clka(clk), // input clka
.addra(PC[7:2]), // input [5 : 0] addra
.douta(Inst_code) // output [31 : 0] douta
);
always@(negedge clk or posedge rst)
begin
if(rst)
begin PC <= 32'h0000_0000; end
else
begin
case (PC_s)
2'b00: PC <= PC_new;
2'b01: PC <= R_Data_A;
2'b10: PC <= PC_new + (imm_data<<2);
2'b11: PC <= {PC_new[31:28],address,2'b00};
endcase
end
end
endmodule
OP_Func（译码模块）
module OP_Func(op_code,funct,Write_Reg,ALU_OP,w_r_s,imm_s,rt_imm_s,Mem_Write,wr_data_s,PC_s,ZF);
input [5:0]op_code;
input [5:0]funct;
input ZF;
output reg[2:0]ALU_OP;
output reg Write_Reg;
output reg [1:0]wr_data_s;
output reg imm_s;
output reg rt_imm_s;
output reg Mem_Write;
output reg [1:0]w_r_s;
output reg [1:0]PC_s;
always@(*)
begin
Write_Reg=1;
ALU_OP=3'b100;
wr_data_s=0;
imm_s=0;
rt_imm_s=0;
Mem_Write=0;
w_r_s=0;
PC_s = 0;
if(op_code==6'b000000)
begin
case(funct)
6'b100000:begin ALU_OP=3'b100; end
6'b100010:begin ALU_OP=3'b101; end
6'b100100:begin ALU_OP=3'b000;end
6'b100101:begin ALU_OP=3'b001;end
6'b100110:begin ALU_OP=3'b010;end
6'b100111:begin ALU_OP=3'b011;end
6'b101011:begin ALU_OP=3'b110;end
6'b000100:begin ALU_OP=3'b111;end
6'b001000:begin Write_Reg=0;Mem_Write=0;PC_s = 2'b01; end
endcase
end
else
begin
case(op_code)
6'b001000:begin w_r_s=2'b01;imm_s=1;rt_imm_s=1;ALU_OP=3'b100;end
6'b001100:begin w_r_s=2'b01;rt_imm_s=1;ALU_OP=3'b000; end
6'b001110:begin w_r_s=2'b01;rt_imm_s=1;ALU_OP=3'b010;end
6'b001011:begin w_r_s=2'b01;rt_imm_s=1;ALU_OP=3'b110; end
6'b100011:begin w_r_s=2'b01;imm_s=1;rt_imm_s=1;wr_data_s=2'b01;ALU_OP=3'b100; end
6'b101011:begin imm_s=1;rt_imm_s=1;ALU_OP=3'b100;Write_Reg=0;Mem_Write=1; end
6'b000100:begin ALU_OP=3'b101;PC_s = (ZF)?2'b10:2'b00; Write_Reg = 1'b0;end
6'b000101:begin ALU_OP=3'b101;PC_s = (ZF)?2'b00:2'b10; Write_Reg = 1'b0;end
6'b000010:begin Write_Reg=0;PC_s = 2'b11; end
6'b000011:begin w_r_s=2'b10;wr_data_s=2'b10;PC_s = 2'b11; end
endcase
end
end
endmoduleFourth_experiment_first（寄存器堆模块）
module Fourth_experiment_first(R_Addr_A,R_Addr_B,Write_Reg,R_Data_A,R_Data_B,Reset,Clk,W_Addr,W_Data);
input [4:0]R_Addr_A,R_Addr_B,W_Addr;
input Write_Reg,Reset,Clk;
input[31:0] W_Data;
output [31:0] R_Data_A,R_Data_B;
reg [31:0] REG_Files[0:31];
integer i=0;
initial
for(i=0;i<32;i=i+1) REG_Files[i]<=0;
always @ (posedge Clk or posedge Reset)
begin
if(Reset)
begin
for(i=0;i<=31;i=i+1)
REG_Files[i]<=0;
end
else
begin
if(Write_Reg)
REG_Files[W_Addr]<=W_Data;
end
end
assign R_Data_A = REG_Files[R_Addr_A];
assign R_Data_B = REG_Files[R_Addr_B];
endmoduleThird_experiment_first（ALU模块）
module Third_experiment_first(OF,ZF,ALU_OP,A,B,F);
input [2:0]ALU_OP;
input [31:0]A,B;
output reg[31:0]F;
reg C32;
output reg OF;
output reg ZF;
always @(ALU_OP or A or B)
begin
OF = 0;
C32 = 0;
case(ALU_OP)
3'b000:F<=A&B;
3'b001:F<=A|B;
3'b010:F<=A^B;
3'b011:F<=A~^B;
3'b100:{C32,F}<=A+B;
3'b101:{C32,F}<=A-B;
3'b110:begin if(A<B) F<=32'h0000_0001;else F<=32'h0000_0000;end
3'b111:begin F<=B<<A;end
endcase
if(F==32'h0000_0000)
ZF<=1;
else
ZF<=0;
if(ALU_OP == 3'b100 || ALU_OP == 3'b101)
OF<=C32^F[31]^A[31]^B[31];
else
OF <=0;
end
endmodule数据.coe
memory_initialization_radix=16;
memory_initialization_vector=88888888,99999999,00010fff,20006789,FFFF0000,0000FFFF,88888888,99999999,
aaaaaaaa,bbbbbbbb,00000820,00632020,00010fff,20006789,FFFF0000,0000FFFF,88888888,99999999,aaaaaaaa,bbbbbbbb,00000820,00632020,00010fff,
20006789,FFFF0000,0000FFFF,88888888,99999999,aaaaaaaa,bbbbbbbb,00000820,00632020,00010fff,20006789,FFFF0000,0000FFFF,88888888,99999999,aaaaaaaa,bbbbbbbb,
00000820,00632020,00010fff,20006789,FFFF0000,0000FFFF,88888888,99999999,aaaaaaaa,bbbbbbbb,12345678,23456789,3456789a,6789abcd;程序机器码.coe
memory_initialization_radix=16;
memory_initialization_vector=00002020,20050014,2006000b,0c000004,00804020,00a04820,00c05020,8d0b0000,ad2b0000,21080001,21290001,214affff,1540fffa,03e00008;测试模块
module test;
// Inputs
reg clk;
reg rst;
reg clk_M;
// Outputs
wire OF;
wire ZF;
wire [31:0] F;
wire [2:0] ALU_OP;
wire [31:0] M_R_Data;
wire [1:0] w_r_s;
wire imm_s;
wire rt_imm_s;
wire Mem_Write;
wire Write_Reg;
wire [31:0] PC;
wire [1:0] PC_s;
wire [31:0] R_Data_B;
wire [31:0] Inst_code;
CPU uut (
.clk(clk),
.rst(rst),
.OF(OF),
.ZF(ZF),
.F(F),
.ALU_OP(ALU_OP),
.M_R_Data(M_R_Data),
.w_r_s(w_r_s),
.imm_s(imm_s),
.rt_imm_s(rt_imm_s),
.Mem_Write(Mem_Write),
.Write_Reg(Write_Reg),
.PC(PC),
.PC_s(PC_s),
.clk_M(clk_M),
.R_Data_B(R_Data_B),
.Inst_code(Inst_code)
);
always #4 clk_M = ~clk_M;
always #16 clk =~clk;
initial begin
clk = 0;
rst = 1;
clk_M = 0;
#2;
rst = 0;
end
endmodule汇编程序
main:
add $a0,$zero,$zero
addi $a1,$zero,20;
addi $a2,$zero,10;
jal BankMove
BankMove:
add $t0,$a0,$zero;
add $t1,$a1,$zero;
add $t2,$a2,$zero;
Loop1:lw $t3,0($t0);
sw $t3,0($t1);
addi $t0,$t0,1;
addi $t1,$t1,1;
addi $t2,$t2,-1;
bne $t2,$zero,Loop1;
jr $ra书上的机器码存在错误，读者可以自行对比，纠正机器码，博主用的汇编程序是将存储器1-10位搬到20-30位