256个组，每个组4个cache行，有读写两种请求，用lru替换算法实现替换 verilog实现

下面是一个基于 LRU 替换算法的 256 组、每组 4 个缓存行的 Verilog 缓存实现，支持读写两种请求：

module Cache (
    input [31:0] addr,
    input [31:0] data_in,
    input wr_en,
    input rd_en,
    output reg [31:0] data_out
);

    parameter NUM_SETS = 256;
    parameter NUM_LINES = 4;
    parameter NUM_WORDS = 8;
    parameter TAG_WIDTH = 20;

    reg [TAG_WIDTH-1:0] tag [NUM_SETS-1:0][NUM_LINES-1:0];
    reg [NUM_WORDS*8-1:0] data [NUM_SETS-1:0][NUM_LINES-1:0];
    reg [NUM_LINES-1:0] lru [NUM_SETS-1:0];
    wire [NUM_WORDS*8-1:0] data_out_wire;
    assign data_out = (rd_en) ? data_out_wire : 0;

    always @ (posedge clk) begin
        if (wr_en) begin
            int set_index = addr[NUM_SETS+1:3];
            int line_index = 0;
            int lru_line = 0;
            int lru_count = 0;
            for (int i = 0; i < NUM_LINES; i = i + 1) begin
                if (tag[set_index][i] == addr[TAG_WIDTH+NUM_SETS+2:NUM_SETS+3]) begin
                    line_index = i;
                    break;
                end
                if (lru[set_index][i] > lru_count) begin
                    lru_count = lru[set_index][i];
                    lru_line = i;
                end
            end
            if (line_index != 0) begin
                tag[set_index][line_index] = addr[TAG_WIDTH+NUM_SETS+2:NUM_SETS+3];
                data[set_index][line_index] = data_in;
                lru[set_index][line_index] = 0;
                for (int i = 0; i < NUM_LINES; i = i + 1) begin
                    if (i != line_index) begin
                        lru[set_index][i] = lru[set_index][i] + 1;
                    end
                end
            end else begin
                tag[set_index][lru_line] = addr[TAG_WIDTH+NUM_SETS+2:NUM_SETS+3];
                data[set_index][lru_line] = data_in;
                lru[set_index][lru_line] = 0;
                for (int i = 0; i < NUM_LINES; i = i + 1) begin
                    if (i != lru_line) begin
                        lru[set_index][i] = lru[set_index][i] + 1;
                    end
                end
            end
        end
        if (rd_en) begin
            int set_index = addr[NUM_SETS+1:3];
            for (int i = 0; i < NUM_LINES; i = i + 1) begin
                if (tag[set_index][i] == addr[TAG_WIDTH+NUM_SETS+2:NUM_SETS+3]) begin
                    data_out_wire = data[set_index][i];
                    lru[set_index][i] = 0;
                    for (int j = 0; j < NUM_LINES; j = j + 1) begin
                        if (i != j) begin
                            lru[set_index][j] = lru[set_index][j] + 1;
                        end
                    end
                    break;
                end
            end
        end
    end

endmodule

这个实现和前面的实现非常相似，但是增加了对读请求的支持。当读请求到达时，它会查找与地址匹配的缓存行，并返回该行的数据。同时，它会使用 LRU 计数器更新缓存行的状态。注意，这个实现是为了说明 LRU 替换算法而设计的，它可能需要根据实际需求进行修改。