编写一段共性缓存RTL代码

以下是一段共性缓存RTL代码的示例：

module cache (
  input wire clk,
  input wire rst_n,
  input wire [31:0] addr_in,
  input wire [31:0] data_in,
  input wire we_in,
  output wire [31:0] data_out,
  input wire [31:0] addr_out
);

  // Parameters
  parameter CACHE_SIZE = 1024;  // Cache size in bytes
  parameter CACHE_LINE_SIZE = 32;  // Cache line size in bytes
  parameter CACHE_ASSOCIATIVITY = 4;  // Cache associativity
  parameter CACHE_NUM_SETS = CACHE_SIZE / (CACHE_LINE_SIZE * CACHE_ASSOCIATIVITY);  // Number of sets in cache
  parameter CACHE_INDEX_WIDTH = $clog2(CACHE_NUM_SETS);  // Width of index field
  parameter CACHE_TAG_WIDTH = 32 - CACHE_INDEX_WIDTH - $clog2(CACHE_LINE_SIZE);  // Width of tag field

  // Internal signals
  wire [CACHE_TAG_WIDTH-1:0] tag_in;
  wire [CACHE_INDEX_WIDTH-1:0] index_in;
  wire [CACHE_TAG_WIDTH-1:0] tag_out;
  wire [CACHE_INDEX_WIDTH-1:0] index_out;
  wire [CACHE_LINE_SIZE-1:0] data_out_internal;
  reg [CACHE_TAG_WIDTH-1:0] tag_array [0:CACHE_NUM_SETS-1][0:CACHE_ASSOCIATIVITY-1];
  reg [CACHE_LINE_SIZE-1:0] data_array [0:CACHE_NUM_SETS-1][0:CACHE_ASSOCIATIVITY-1];
  reg [CACHE_ASSOCIATIVITY-1:0] valid_array [0:CACHE_NUM_SETS-1];
  wire [CACHE_ASSOCIATIVITY-1:0] hit_index;
  wire hit;

  // Extract tag and index from address
  assign tag_in = addr_in[CACHE_TAG_WIDTH+CACHE_INDEX_WIDTH-1:CACHE_INDEX_WIDTH];
  assign index_in = addr_in[CACHE_TAG_WIDTH+CACHE_INDEX_WIDTH-1:CACHE_TAG_WIDTH];

  // Check for hit in cache
  assign hit = valid_array[index_out][hit_index] && (tag_out == tag_in);
  
  // Extract tag and index from output address
  assign tag_out = addr_out[CACHE_TAG_WIDTH+CACHE_INDEX_WIDTH-1:CACHE_INDEX_WIDTH];
  assign index_out = addr_out[CACHE_TAG_WIDTH+CACHE_INDEX_WIDTH-1:CACHE_TAG_WIDTH];
  
  // Write to cache
  always @(posedge clk) begin
    if (!rst_n) begin
      // Reset cache
      for (int i=0; i<CACHE_NUM_SETS; i=i+1) begin
        for (int j=0; j<CACHE_ASSOCIATIVITY; j=j+1) begin
          tag_array[i][j] <= 0;
          data_array[i][j] <= 0;
        end
        valid_array[i] <= 0;
      end
    end else if (we_in) begin
      // Write data to cache
      if (hit) begin
        // Update existing line
        data_array[index_out][hit_index] <= data_in;
      end else begin
        // Replace existing line or select empty line
        int replace_index = CACHE_ASSOCIATIVITY;
        for (int i=0; i<CACHE_ASSOCIATIVITY; i=i+1) begin
          if (!valid_array[index_out][i]) begin
            // Found empty line
            replace_index = i;
            break;
          end
        end
        if (replace_index == CACHE_ASSOCIATIVITY) begin
          // No empty line found, replace LRU line
          replace_index = 0;
          for (int i=1; i<CACHE_ASSOCIATIVITY; i=i+1) begin
            if (valid_array[index_out][i] && (valid_array[index_out][i-1] == 0 || $time - valid_array[index_out][i] < $time - valid_array[index_out][i-1])) begin
              replace_index = i;
            end
          end
        end
        tag_array[index_out][replace_index] <= tag_in;
        data_array[index_out][replace_index] <= data_in;
        valid_array[index_out][replace_index] <= $time;
      end
    end
  end

  // Read from cache
  assign data_out_internal = data_array[index_out][hit_index];
  assign data_out = hit ? data_out_internal : 32'h00000000;

  // Find hit index
  assign hit_index = 0;
  for (int i=0; i<CACHE_ASSOCIATIVITY; i=i+1) begin
    if (valid_array[index_out][i] && tag_array[index_out][i] == tag_out) begin
      hit_index = i;
    end
  end

endmodule

此模块实现了一个具有指定大小、行大小和关联度的缓存。输入地址和数据用于读写缓存，而输出数据则根据是否命中来决定。此外，此模块还包含了一些内部信号和参数，例如标记、索引、缓存数组、有效位和更新策略。这个实现仅仅是一个示例，实际实现需要视具体需求而定。