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MFIFO.bsv
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MFIFO.bsv
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//----------------------------------------------------------------------//
// The MIT License
//
// Copyright (c) 2008 Abhinav Agarwal, Alfred Man Cheuk Ng
// Contact: abhiag@gmail.com
//
// 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.
//----------------------------------------------------------------------//
import FIFOF::*;
import RWire::*;
// -------------------------------------------------------------------
// MFIFO Interface: a fifo allow to the value of the first element to be modified
// -------------------------------------------------------------------
interface MFIFO#(numeric type sz, type a);
method Action enq(a in);
method Action deq();
method Action clear();
interface Reg#(a) first;
endinterface
interface MFIFOF#(numeric type sz, type a);
method Action enq(a in);
method Action deq();
method Action clear();
method Bool notEmpty();
method Bool notFull();
interface Reg#(a) first;
endinterface
// ---------------------------------------------------------
// MFIFO module
// ---------------------------------------------------------
// a mfifof of size 1
module mkMFIFOF1 (MFIFOF#(1,a))
provisos (Bits#(a,a_sz));
Reg#(Maybe#(a)) buffer <- mkReg(tagged Invalid);
RWire#(a) upW <- mkRWire();
RWire#(Bit#(0)) deqW <- mkRWire();
rule writeBuffer(isValid(upW.wget())
|| isValid(deqW.wget()));
if (isValid(deqW.wget()))
buffer <= tagged Invalid;
else
buffer <= tagged Valid fromMaybe(?,upW.wget());
endrule
method Action enq(a in) if (!isValid(buffer));
buffer <= tagged Valid in;
endmethod
method Action deq() if (isValid(buffer));
deqW.wset(?);
endmethod
method Action clear();
buffer <= tagged Invalid;
endmethod
method Bool notEmpty();
return isValid(buffer);
endmethod
method Bool notFull();
return !isValid(buffer);
endmethod
interface Reg first;
method Action _write(a in) if (isValid(buffer));
upW.wset(in);
endmethod
method a _read() if (buffer matches tagged Valid .val);
return val;
endmethod
endinterface
endmodule
// a mfifof of size > 1
module mkMFIFOF (MFIFOF#(sz,a))
provisos (Add#(2,xxA,sz), // sz >= 2
Bits#(a,a_sz));
Reg#(Maybe#(a)) buffer <- mkReg(tagged Invalid);
FIFOF#(a) fifo <- mkSizedFIFOF(valueOf(sz)-1);
RWire#(a) upW <- mkRWire();
RWire#(Bit#(0)) deqW <- mkRWire();
let isNotEmpty = isValid(buffer) || fifo.notEmpty;
rule writeBuffer(True);
if (isValid(deqW.wget()))
buffer <= tagged Invalid;
else
if (isValid(upW.wget()))
buffer <= tagged Valid fromMaybe(?,upW.wget());
else
if (!isValid(buffer))
buffer <= tagged Valid fifo.first();
if (!isValid(buffer))
fifo.deq();
endrule
method Action enq(a in);
fifo.enq(in);
endmethod
method Action deq() if (isNotEmpty);
deqW.wset(?);
endmethod
method Action clear();
fifo.clear();
buffer <= tagged Invalid;
endmethod
method Bool notEmpty();
return isNotEmpty;
endmethod
method Bool notFull();
return fifo.notFull();
endmethod
interface Reg first;
method Action _write(a in) if (isNotEmpty);
upW.wset(in);
endmethod
method a _read() if (isNotEmpty);
return isValid(buffer) ? fromMaybe(?,buffer) : fifo.first();
endmethod
endinterface
endmodule
// a mfifo of size 1
module mkMFIFO1 (MFIFO#(1,a))
provisos (Bits#(a,a_sz));
MFIFOF#(1,a) fifo <- mkMFIFOF1();
method Action enq(a in) = fifo.enq(in);
method Action deq() = fifo.deq();
method Action clear() = fifo.clear();
interface Reg first = fifo.first;
endmodule
// a mfifo of size > 1
module mkMFIFO (MFIFO#(sz,a))
provisos (Add#(2,xxA,sz), // sz >= 2
Bits#(a,a_sz));
MFIFOF#(sz,a) fifo <- mkMFIFOF();
method Action enq(a in) = fifo.enq(in);
method Action deq() = fifo.deq();
method Action clear() = fifo.clear();
interface Reg first = fifo.first;
endmodule
// ---------------------------------------------------------
// MFIFO Test module
// ---------------------------------------------------------
//(* synthesize *)
(* execution_order = "updOrDeqFIFO, enqFIFO, incrCounter" *)
module mkMFIFOTest(Empty);
Reg#(Bit#(16)) counter <- mkReg(0);
MFIFO#(10,Bit#(16)) fifo <- mkMFIFO();
Reg#(Bit#(16)) fstElm = fifo.first;
rule enqFIFO(True);
$display("enq fifo: %d",counter);
fifo.enq(counter);
endrule
rule updOrDeqFIFO(True);
if ((counter & 16'h0007) == 16'h0007)
begin
$display("deq fifo: %d",fstElm);
fifo.deq();
end
else
begin
$display("update fifo: %d = %d * 3",fstElm * 3,fstElm);
fstElm <= fstElm * 3;
end
endrule
rule incrCounter(True);
$display("cycle: %d",counter);
$display("----------------------------------------------------------");
if (counter == 1000)
$finish();
counter <= counter + 1;
endrule
endmodule