verilog写ahb仲裁电路

以下是一个简单的AHB仲裁电路的Verilog代码：

module ahb_arbiter (
  input HCLK,
  input HRESETn,
  input [3:0] HSEL,
  input [3:0] HREADY,
  output reg HGRANT,
  output reg [3:0] HMASTER
);

reg [3:0] req_priority;

always @(posedge HCLK or negedge HRESETn) begin
  if (!HRESETn) begin
    HGRANT <= 0;
    req_priority <= 4'b0000;
    HMASTER <= 4'b0000;
  end else begin
    if (HGRANT) begin
      // If a master has already been granted bus access, keep granting it
      HMASTER <= HMASTER;
    end else begin
      // Check the highest priority request
      case (req_priority)
        4'b0001: HMASTER <= 4'b0001;
        4'b0010: HMASTER <= 4'b0010;
        4'b0100: HMASTER <= 4'b0100;
        4'b1000: HMASTER <= 4'b1000;
        default: HMASTER <= 4'b0000;
      endcase

      // Grant the bus access to the highest priority master
      if (HREADY[HMASTER] && HSEL[HMASTER]) begin
        HGRANT <= 1;
      end
    end

    // Update the priority levels based on the ready signals
    if (HREADY[req_priority] && HSEL[req_priority]) begin
      req_priority <= 4'b0001;
    end else if (HREADY[req_priority+1] && HSEL[req_priority+1]) begin
      req_priority <= 4'b0010;
    end else if (HREADY[req_priority+2] && HSEL[req_priority+2]) begin
      req_priority <= 4'b0100;
    end else if (HREADY[req_priority+3] && HSEL[req_priority+3]) begin
      req_priority <= 4'b1000;
    end
  end
end

endmodule

这个仲裁电路支持4个主设备，每个设备都有一个HSEL输入和一个HREADY输入。HSEL信号指示一个主设备是否正在请求总线访问，而HREADY信号指示它是否准备好进行访问。仲裁器将根据请求的优先级选择一个主设备，并将HGRANT输出高电平以授权总线访问。HMASTER输出指示被授权访问总线的主设备。