//    A simple 32-bit by 32-word memory model
//    ECE 313 Fall 2002

module mem32(clk, mem_read, mem_write, address, data_in, data_out);
  input  clk, mem_read, mem_write;
  input  [31:0] address, data_in;
  output [31:0] data_out;
  reg    [31:0] data_out;

  parameter BASE_ADDRESS = 25'd0; // address that applies to this memory - change if desired

  reg [31:0] mem_array [0:31];
  wire [4:0] mem_offset;
  wire address_select;

  assign mem_offset = address[6:2];  // drop 2 LSBs to get word offset

  assign address_select = (address[31:7] == BASE_ADDRESS);  // address decoding

  always @(mem_read or address_select or mem_offset or mem_array[mem_offset])
  begin

    if (mem_read == 1'b1 && address_select == 1'b1)
    begin
      if ((address % 4) != 0)
          $display($time, " rom32 error: unaligned address %d", address);
      data_out = mem_array[mem_offset];
      $display($time, " reading data: Mem[%h] => %h", address, data_out);
    end
      else data_out = 32'hxxxxxxxx;
  end

  // for WRITE operations
  always @(posedge clk)
  begin
    if (mem_write == 1'b1 && address_select == 1'b1)
    begin
      $display($time, " writing data: Mem[%h] <= %h", address,data_in);
      mem_array[mem_offset] <= data_in;
    end
  end

  // initialize with some arbitrary values

  integer i;
  initial begin
    for (i=0; i<7; i=i+1) mem_array[i] = i;
  end
endmodule