1 //===========================================
  2 // Function : Asynchronous read write RAM 
  3 // Coder    : Deepak Kumar Tala
  4 // Date     : 1-Nov-2005
  5 //===========================================
  6 module ram_sp_ar_sw #(parameter DATA_WIDTH = 8,
  7                   parameter ADDR_WIDTH = 8,
  8                   parameter RAM_DEPTH = (1 << ADDR_WIDTH))(
  9 input  wire                  clk      , // Clock Input
 10 input  wire [ADDR_WIDTH-1:0] address  , // Address Input
 11 inout  wire [DATA_WIDTH-1:0] data     , // Data bi-directional
 12 input  wire                  cs       , // Chip Select
 13 input  wire                  we       , // Write Enable/Read Enable
 14 input  wire                  oe         // Output Enable
 15 ); 
 16 //--------------Internal variables---------------- 
 17 reg [DATA_WIDTH-1:0]   data_out ;
 18 // Use Associative array to save memory footprint
 19 typedef reg [ADDR_WIDTH-1:0] mem_addr;
 20 reg [DATA_WIDTH-1:0] mem [mem_addr];
 21 //--------------Code Starts Here------------------ 
 22 // Tri-State Buffer control 
 23 // output : When we = 0, oe = 1, cs = 1
 24 assign data = (cs && oe &&  ! we) ? data_out : 8'bz; 
 25 // Memory Write Block 
 26 // Write Operation : When we = 1, cs = 1
 27 always @ (posedge clk)
 28 begin : MEM_WRITE
 29    if ( cs && we ) begin
 30        mem[address] = data;
 31    end
 32 end
 33 // Memory Read Block 
 34 // Read Operation : When we = 0, oe = 1, cs = 1
 35 always @ (address or cs or we or oe)
 36 begin : MEM_READ
 37     if (cs &&  ! we && oe) begin
 38          data_out = mem[address];
 39     end
 40 end
 41 
 42 endmodule // End of Module ram_sp_ar_sw

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