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[/] [bluespec-h264/] [trunk/] [src_fpga/] [mkSatCounter.bsv] - Rev 100
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// 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