Subversion Repositories bluespec-h264

// The MIT License

// Copyright (c) 2006-2007 Massachusetts Institute of Technology

// Permission is hereby granted, free of charge, to any person obtaining a copy

// of this software and associated documentation files (the "Software"), to deal

// in the Software without restriction, including without limitation the rights

// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell

// copies of the Software, and to permit persons to whom the Software is

// furnished to do so, subject to the following conditions:

// The above copyright notice and this permission notice shall be included in

// all copies or substantial portions of the Software.

// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE

// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,

// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN

// THE SOFTWARE.

package mkSatCounter;

interface SatCounter#(numeric type bits);

  method Action up();

  method Action down();

  method Bit#(bits) value();

endinterface

module mkSatCounter#(Bit#(bits) init) (SatCounter#(bits));

  Reg#(Bit#(bits)) counter <- mkReg(init);

  RWire#(Bit#(0)) up_called <- mkRWire();

  RWire#(Bit#(0)) down_called <- mkRWire();

  rule update;

    if(up_called.wget matches tagged Valid .x)

      begin

        if(down_called.wget matches tagged Invalid)

          if(counter != ~0)

            counter <= counter + 1;

      end

    else

        if(down_called.wget matches tagged Valid .x)

            if(counter != 0)

               counter <= counter - 1;

  endrule

  method Action up();

    up_called.wset(0);

  endmethod

  method Action down();

    down_called.wset(0);

  endmethod

  method Bit#(bits) value();

    return counter;

  endmethod

endmodule

endpackage