Subversion Repositories openrisc_2011-10-31

//////////////////////////////////////////////////////////////////////

////                                                              ////

////  Generic Double-Port Synchronous RAM                         ////

////                                                              ////

////  This file is part of memory library available from          ////

////  http://www.opencores.org/cvsweb.shtml/generic_memories/     ////

////                                                              ////

////  Description                                                 ////

////  This block is a wrapper with common double-port             ////

////  synchronous memory interface for different                  ////

////  types of ASIC and FPGA RAMs. Beside universal memory        ////

////  interface it also provides behavioral model of generic      ////

////  double-port synchronous RAM.                                ////

////  It should be used in all OPENCORES designs that want to be  ////

////  portable accross different target technologies and          ////

////  independent of target memory.                               ////

////                                                              ////

////  Author(s):                                                  ////

////      - Michael Unneback, unneback@opencores.org              ////

////                                                              ////

//////////////////////////////////////////////////////////////////////

////                                                              ////

//// Copyright (C) 2000 Authors and OPENCORES.ORG                 ////

////                                                              ////

//// This source file may be used and distributed without         ////

//// restriction provided that this copyright statement is not    ////

//// removed from the file and that any derivative work contains  ////

//// the original copyright notice and the associated disclaimer. ////

////                                                              ////

//// This source file is free software; you can redistribute it   ////

//// and/or modify it under the terms of the GNU Lesser General   ////

//// Public License as published by the Free Software Foundation; ////

//// either version 2.1 of the License, or (at your option) any   ////

//// later version.                                               ////

////                                                              ////

//// This source is distributed in the hope that it will be       ////

//// useful, but WITHOUT ANY WARRANTY; without even the implied   ////

//// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR      ////

//// PURPOSE.  See the GNU Lesser General Public License for more ////

//// details.                                                     ////

////                                                              ////

//// You should have received a copy of the GNU Lesser General    ////

//// Public License along with this source; if not, download it   ////

//// from http://www.opencores.org/lgpl.shtml                     ////

////                                                              ////

//////////////////////////////////////////////////////////////////////

//

// CVS Revision History

//

// $Log: or1200_dpram_32x32.v,v $

// Revision 2.0  2010/06/30 11:00:00  ORSoC

// New 

//

// synopsys translate_off

`include "timescale.v"

// synopsys translate_on

`include "or1200_defines.v"

module or1200_dpram

  (

   // Generic synchronous double-port RAM interface

   clk_a, ce_a, addr_a, do_a,

   clk_b, ce_b, we_b, addr_b, di_b

   );

   //

   // Default address and data buses width

   //

   parameter aw = 5;

   parameter dw = 32;

   //

   // Generic synchronous double-port RAM interface

   //

   input                        clk_a;  // Clock

   input                        ce_a;   // Chip enable input

   input [aw-1:0]                addr_a; // address bus inputs

   output [dw-1:0]               do_a;   // output data bus

   input                        clk_b;  // Clock

   input                        ce_b;   // Chip enable input

   input                        we_b;   // Write enable input

   input [aw-1:0]                addr_b; // address bus inputs

   input [dw-1:0]                di_b;   // input data bus

   //

   // Internal wires and registers

   //

   //

   // Generic double-port synchronous RAM model

   //

   //

   // Generic RAM's registers and wires

   //

   reg [dw-1:0]          mem [(1<<aw)-1:0] /*synthesis syn_ramstyle = "no_rw_check"*/;    // RAM content

   reg [aw-1:0]          addr_a_reg;             // RAM address registered

   // Function to access GPRs (for use by Verilator). No need to hide this one

   // from the simulator, since it has an input (as required by IEEE 1364-2001).

   function [31:0] get_gpr;

      // verilator public

      input [aw-1:0]             gpr_no;

      get_gpr = { mem[gpr_no*32 + 31], mem[gpr_no*32 + 30],

                  mem[gpr_no*32 + 29], mem[gpr_no*32 + 28],

                  mem[gpr_no*32 + 27], mem[gpr_no*32 + 26],

                  mem[gpr_no*32 + 25], mem[gpr_no*32 + 24],

                  mem[gpr_no*32 + 23], mem[gpr_no*32 + 22],

                  mem[gpr_no*32 + 21], mem[gpr_no*32 + 20],

                  mem[gpr_no*32 + 19], mem[gpr_no*32 + 18],

                  mem[gpr_no*32 + 17], mem[gpr_no*32 + 16],

                  mem[gpr_no*32 + 15], mem[gpr_no*32 + 14],

                  mem[gpr_no*32 + 13], mem[gpr_no*32 + 12],

                  mem[gpr_no*32 + 11], mem[gpr_no*32 + 10],

                  mem[gpr_no*32 +  9], mem[gpr_no*32 +  8],

                  mem[gpr_no*32 +  7], mem[gpr_no*32 +  6],

                  mem[gpr_no*32 +  5], mem[gpr_no*32 +  4],

                  mem[gpr_no*32 +  3], mem[gpr_no*32 +  2],

                  mem[gpr_no*32 +  1], mem[gpr_no*32 +  0] };

   endfunction // get_gpr

   //

   // Data output drivers

   //

   //assign do_a = (oe_a) ? mem[addr_a_reg] : {dw{1'b0}};

   assign do_a = mem[addr_a_reg];

   //

   // RAM read

   //

   always @(posedge clk_a)

     if (ce_a)

       addr_a_reg <= #1 addr_a;

   //

   // RAM write

   //

   always @(posedge clk_b)

     if (ce_b & we_b)

       mem[addr_b] <= #1 di_b;

endmodule // or1200_dpram