Mercurial > pygar

     1 /// The MIT License

     2 

     3 // Copyright (c) 2009 Massachusetts Institute of Technology

     4 

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

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

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

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

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

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

    11 

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

    13 // all copies or substantial portions of the Software.

    14 

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

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

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

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

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

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

    21 // THE SOFTWARE.

    22 

    23 import Connectable::*;

    24 import GetPut::*;

    25 import ClientServer::*;

    26 import RegFile::*;

    27 import BRegFile::*;

    28 import FIFO::*;

    29 import FIFOF::*;

    30 import SFIFO::*;

    31 import RWire::*;

    32 

    33 import BFIFO::*;

    34 import MemTypes::*;

    35 import ProcTypes::*;

    36 import BranchPred::*;

    37 import PathTypes::*;

    38 

    39 import Trace::*;

    40 

    41 interface ProcStats;

    42   interface Get#(Stat) num_cycles;

    43   interface Get#(Stat) num_inst;

    44 endinterface

    45 

    46 interface CPUToHost;

    47   method Bit#(32) cpuToHost(int req);

    48 endinterface

    49 

    50 interface Proc;

    51 

    52   // Interface from processor to caches

    53   interface Client#(DataReq,DataResp) dmem_client;

    54   interface Client#(InstReq,InstResp) imem_client;

    55 

    56   // Interface for enabling/disabling statistics on the rest of the core

    57   interface Get#(Bool) statsEn_get;

    58 

    59   // Interface for collecting statistics.

    60   interface ProcStats stats;

    61 

    62   // Interface to host

    63   interface CPUToHost tohost;

    64 

    65 endinterface

    66 

    67 

    68 typedef enum { PCgen, Exec, Writeback } Stage deriving(Eq,Bits);

    69 

    70 //-----------------------------------------------------------

    71 // Register file module

    72 //-----------------------------------------------------------

    73 

    74 interface BRFile;

    75    method Action   wr( Rindx rindx, Bit#(32) data );

    76    method Bit#(32) rd1( Rindx rindx );

    77    method Bit#(32) rd2( Rindx rindx );

    78 endinterface

    79 

    80 module mkBRFile( BRFile );

    81    

    82    RegFile#(Rindx,Bit#(32)) rfile <- mkBRegFile();

    83    

    84    method Action wr( Rindx rindx, Bit#(32) data );

    85       rfile.upd( rindx, data );

    86    endmethod

    87    

    88    method Bit#(32) rd1( Rindx rindx );

    89       return ( rindx == 0 ) ? 0 : rfile.sub(rindx);

    90    endmethod

    91    

    92    method Bit#(32) rd2( Rindx rindx );

    93       return ( rindx == 0 ) ? 0 : rfile.sub(rindx);

    94    endmethod

    95 

    96 endmodule

    97 

    98 //-----------------------------------------------------------

    99 // Helper functions

   100 //-----------------------------------------------------------

   101 

   102 function Bit#(32) slt( Bit#(32) val1, Bit#(32) val2 );

   103    return zeroExtend( pack( signedLT(val1,val2) ) );

   104 endfunction

   105 

   106 function Bit#(32) sltu( Bit#(32) val1, Bit#(32) val2 );

   107    return zeroExtend( pack( val1 < val2 ) );

   108 endfunction

   109 

   110 function Bit#(32) rshft( Bit#(32) val );

   111    return zeroExtend(val[4:0]);

   112 endfunction

   113 

   114 

   115 //-----------------------------------------------------------

   116 // Find funct for wbQ

   117 //-----------------------------------------------------------

   118 function Bool findwbf(Rindx fVal, WBResult cmpVal);

   119   case (cmpVal) matches   

   120      tagged WB_ALU  {data:.res, dest:.rd} :

   121 	return (fVal == rd);

   122      tagged WB_Load .rd  :

   123 	return (fVal == rd);

   124      tagged WB_Store .st :

   125 	return False;

   126      tagged WB_Host .x   :

   127 	return False;

   128   endcase

   129 endfunction

   130 

   131      

   132 //-----------------------------------------------------------

   133 // Stall funct for wbQ

   134 //-----------------------------------------------------------

   135 function Bool stall(Instr inst, SFIFO#(WBResult, Rindx) f);

   136    case (inst) matches

   137       	 // -- Memory Ops ------------------------------------------------      

   138       tagged LW .it :

   139 	 return f.find(it.rbase);

   140       tagged SW {rsrc:.dreg, rbase:.addr, offset:.o} :

   141 	 return (f.find(addr) ||  f.find2(dreg));

   142 

   143 	 // -- Simple Ops ------------------------------------------------      

   144       tagged ADDIU .it : return f.find(it.rsrc);

   145       tagged SLTI  .it : return f.find(it.rsrc);

   146       tagged SLTIU .it : return f.find(it.rsrc);

   147       tagged ANDI  .it : return f.find(it.rsrc);

   148       tagged ORI   .it : return f.find(it.rsrc);

   149       tagged XORI  .it : return f.find(it.rsrc);

   150       

   151       tagged LUI   .it : return f.find(it.rdst);  //this rds/wrs itself

   152       tagged SLL   .it : return f.find(it.rsrc);

   153       tagged SRL   .it : return f.find(it.rsrc);

   154       tagged SRA   .it : return f.find(it.rsrc);

   155       tagged SLLV  .it : return (f.find(it.rsrc) || f.find(it.rshamt));

   156       tagged SRLV  .it : return (f.find(it.rsrc) || f.find(it.rshamt));

   157       tagged SRAV  .it : return (f.find(it.rsrc) || f.find(it.rshamt));

   158       tagged ADDU  .it : return (f.find(it.rsrc1) || f.find2(it.rsrc2));

   159       tagged SUBU  .it : return (f.find(it.rsrc1) || f.find2(it.rsrc2));

   160       tagged AND   .it : return (f.find(it.rsrc1) || f.find2(it.rsrc2));

   161       tagged OR    .it : return (f.find(it.rsrc1) || f.find2(it.rsrc2));

   162       tagged XOR   .it : return (f.find(it.rsrc1) || f.find2(it.rsrc2));

   163       tagged NOR   .it : return (f.find(it.rsrc1) || f.find2(it.rsrc2));

   164       tagged SLT   .it : return (f.find(it.rsrc1) || f.find2(it.rsrc2));

   165       tagged SLTU  .it : return (f.find(it.rsrc1) || f.find2(it.rsrc2));

   166    

   167 

   168       // -- Branches --------------------------------------------------

   169     

   170       tagged BLEZ  .it : return (f.find(it.rsrc));

   171       tagged BGTZ  .it : return (f.find(it.rsrc));

   172       tagged BLTZ  .it : return (f.find(it.rsrc));

   173       tagged BGEZ  .it : return (f.find(it.rsrc));

   174       tagged BEQ   .it : return (f.find(it.rsrc1) || f.find2(it.rsrc2));

   175       tagged BNE   .it : return (f.find(it.rsrc1) || f.find2(it.rsrc2));

   176       

   177       // -- Jumps -----------------------------------------------------

   178       

   179       tagged J     .it : return False;

   180       tagged JR    .it : return f.find(it.rsrc);

   181       tagged JALR  .it : return f.find(it.rsrc);

   182       tagged JAL   .it : return False;

   183       

   184       // -- Cop0 ------------------------------------------------------

   185       

   186       tagged MTC0  .it : return f.find(it.rsrc);      

   187       tagged MFC0  .it : return False; 

   188 

   189       // -- Illegal ---------------------------------------------------

   190 

   191       default : return False;

   192 

   193     endcase

   194 endfunction

   195 //-----------------------------------------------------------

   196 // Reference processor

   197 //-----------------------------------------------------------

   198 

   199 

   200 (* doc = "synthesis attribute ram_style mkProc distributed;" *)

   201 (* synthesize *)

   202 module  mkProc( Proc );

   203 

   204    //-----------------------------------------------------------

   205    // State

   206 

   207    // Standard processor state

   208    

   209    Reg#(Addr)  pc    <- mkReg(32'h00001000);

   210    Reg#(Epoch) epoch <- mkReg(0);

   211    Reg#(Stage) stage <- mkReg(PCgen);

   212    BRFile      rf    <- mkBRFile;

   213 

   214    // Branch Prediction

   215    BranchPred               bp <- mkBranchPred();

   216    FIFO#(PCStat)        execpc <- mkLFIFO();

   217    

   218    // Pipelines

   219    FIFO#(PCStat)           pcQ <-mkSizedFIFO(3);

   220    SFIFO#(WBResult, Rindx) wbQ <-mkSFIFO(findwbf);

   221 

   222    Reg#(Bit#(32)) cp0_tohost   <- mkReg(0);

   223    Reg#(Bit#(32)) cp0_fromhost <- mkReg(0);

   224    Reg#(Bool)     cp0_statsEn  <- mkReg(False);

   225 

   226    // Memory request/response state

   227    

   228    FIFO#(InstReq)  instReqQ    <- mkBFIFO1();

   229    FIFO#(InstResp) instRespQ   <- mkFIFO();

   230 

   231    FIFO#(DataReq)  dataReqQ    <- mkBFIFO1();

   232    FIFO#(DataResp) dataRespQ   <- mkFIFO();

   233 

   234    // Statistics state

   235    Reg#(Stat) num_cycles <- mkReg(0);

   236    Reg#(Stat) num_inst <- mkReg(0);

   237 

   238    //-----------------------------------------------------------

   239    // Rules

   240 

   241    (* descending_urgency = "exec, pcgen" *)

   242    rule pcgen; //( stage == PCgen );

   243       let pc_plus4 = pc + 4;

   244 

   245       traceTiny("mkProc", "pc",pc);

   246       traceTiny("mkProc", "pcgen","P");

   247       instReqQ.enq( LoadReq{ addr:pc, tag:epoch} );

   248       

   249       let next_pc = bp.get(pc);

   250       if (next_pc matches tagged Valid .npc) 

   251 	begin

   252 	   pcQ.enq(PCStat {qpc:pc, qnxtpc:npc, qepoch:epoch});

   253 	   pc <= npc;

   254 	end

   255      else

   256 	 begin

   257 	   pcQ.enq(PCStat {qpc:pc, qnxtpc:pc_plus4, qepoch:epoch});

   258 	   pc <= pc_plus4;

   259 	 end

   260       

   261    endrule

   262 

   263    rule discard (instRespQ.first() matches tagged LoadResp .ld

   264 					      &&& ld.tag != epoch);

   265       traceTiny("mkProc", "stage", "D");

   266       instRespQ.deq();

   267    endrule

   268 

   269    (* conflict_free = "exec, writeback" *)		      

   270    rule exec (instRespQ.first() matches tagged LoadResp.ld

   271 	      &&& (ld.tag == epoch)

   272 	      &&& unpack(ld.data) matches .inst

   273               &&& !stall(inst, wbQ));

   274 

   275       // Some abbreviations

   276       let sext = signExtend;

   277       let zext = zeroExtend;

   278       let sra  = signedShiftRight;

   279       

   280       // Get the instruction

   281       

   282       instRespQ.deq();

   283       Instr inst 

   284       = case ( instRespQ.first() ) matches

   285 	   tagged LoadResp  .ld : return unpack(ld.data);

   286 	   tagged StoreResp .st : return ?;

   287 	endcase;

   288 

   289       // Get the PC info

   290       let instrpc = pcQ.first().qpc;

   291       let pc_plus4 = instrpc + 4;

   292       

   293       Bool branchTaken = False;

   294       Addr newPC = pc_plus4;

   295 

   296       // Tracing

   297       traceTiny("mkProc", "exec","X");

   298       traceTiny("mkProc", "exInstTiny",inst);

   299       traceFull("mkProc", "exInstFull",inst);

   300 

   301       case ( inst ) matches

   302 

   303 	 // -- Memory Ops ------------------------------------------------      

   304 

   305 	 tagged LW .it : 

   306 	    begin

   307                Addr addr = rf.rd1(it.rbase) + sext(it.offset);

   308                dataReqQ.enq( LoadReq{ addr:addr, tag:zeroExtend(it.rdst) } );

   309                wbQ.enq(tagged WB_Load it.rdst);

   310 	    end

   311 

   312 	 tagged SW .it : 

   313 	    begin

   314                Addr addr = rf.rd1(it.rbase) + sext(it.offset);

   315                dataReqQ.enq( StoreReq{ tag:0, addr:addr, data:rf.rd2(it.rsrc) } );

   316                wbQ.enq(tagged WB_Store);

   317 	    end

   318 

   319 	 // -- Simple Ops ------------------------------------------------      

   320 

   321 	 tagged ADDIU .it : 

   322 	    begin

   323 	       Bit#(32) result = rf.rd1(it.rsrc) + sext(it.imm);

   324 	       wbQ.enq(tagged WB_ALU {data:result, dest:it.rdst});

   325 	    end

   326 	 tagged SLTI  .it : wbQ.enq(tagged WB_ALU {dest:it.rdst, data:slt( rf.rd1(it.rsrc), sext(it.imm) )});

   327 	 tagged SLTIU .it : wbQ.enq(tagged WB_ALU {dest:it.rdst, data:sltu( rf.rd1(it.rsrc), sext(it.imm) ) });

   328 	 tagged ANDI  .it : 

   329 	    begin

   330 	       Bit#(32) zext_it_imm = zext(it.imm);

   331 	       wbQ.enq(tagged WB_ALU {dest:it.rdst, data:(rf.rd1(it.rsrc) & zext_it_imm)} );

   332 	    end

   333 	 tagged ORI   .it : 

   334 	    begin

   335 	       Bit#(32) zext_it_imm = zext(it.imm);

   336 	       wbQ.enq(tagged WB_ALU {dest:it.rdst, data:(rf.rd1(it.rsrc) | zext_it_imm)} );

   337 	    end

   338 	 tagged XORI  .it : 

   339 	    begin

   340 	       Bit#(32) zext_it_imm = zext(it.imm);

   341 	       wbQ.enq(tagged WB_ALU {dest: it.rdst, data:(rf.rd1(it.rsrc) ^ zext_it_imm )});

   342 	    end

   343 	 tagged LUI   .it : 

   344 	    begin

   345 	       Bit#(32) zext_it_imm = zext(it.imm);

   346 	       wbQ.enq(tagged WB_ALU {dest: it.rdst, data:(zext_it_imm << 32'd16) });

   347 	    end

   348 	 

   349 	 tagged SLL   .it : 

   350 	    begin

   351 	       Bit#(32) zext_it_shamt = zext(it.shamt);

   352 	       wbQ.enq(tagged WB_ALU {dest: it.rdst, data:(rf.rd1(it.rsrc) << zext_it_shamt )} );

   353 	    end

   354 	 tagged SRL   .it : 

   355 	    begin

   356 	       Bit#(32) zext_it_shamt = zext(it.shamt);

   357 	       wbQ.enq(tagged WB_ALU {dest: it.rdst, data:(rf.rd1(it.rsrc) >> zext_it_shamt )});

   358 	    end

   359 	 tagged SRA   .it : 

   360 	    begin

   361 	       Bit#(32) zext_it_shamt = zext(it.shamt);

   362 	       wbQ.enq(tagged WB_ALU {dest: it.rdst, data:sra( rf.rd1(it.rsrc), zext_it_shamt )});

   363 	    end

   364 	 tagged SLLV  .it : wbQ.enq(tagged WB_ALU {dest: it.rdst, data:(rf.rd1(it.rsrc) << rshft(rf.rd2(it.rshamt)) )});

   365 	 tagged SRLV  .it : wbQ.enq(tagged WB_ALU {dest: it.rdst, data:(rf.rd1(it.rsrc) >> rshft(rf.rd2(it.rshamt)) )} );

   366 	 tagged SRAV  .it : wbQ.enq(tagged WB_ALU {dest: it.rdst, data:sra( rf.rd1(it.rsrc), rshft(rf.rd2(it.rshamt)) ) });

   367 	 tagged ADDU  .it : wbQ.enq(tagged WB_ALU {dest: it.rdst, data:(rf.rd1(it.rsrc1) + rf.rd2(it.rsrc2) )} );

   368 	 tagged SUBU  .it : wbQ.enq(tagged WB_ALU {dest: it.rdst, data:(rf.rd1(it.rsrc1) - rf.rd2(it.rsrc2) )} );

   369 	 tagged AND   .it : wbQ.enq(tagged WB_ALU {dest: it.rdst, data:(rf.rd1(it.rsrc1) & rf.rd2(it.rsrc2) )} );

   370 	 tagged OR    .it : wbQ.enq(tagged WB_ALU {dest: it.rdst, data:(rf.rd1(it.rsrc1) | rf.rd2(it.rsrc2) )} );

   371 	 tagged XOR   .it : wbQ.enq(tagged WB_ALU {dest: it.rdst, data:(rf.rd1(it.rsrc1) ^ rf.rd2(it.rsrc2) )} );

   372 	 tagged NOR   .it : wbQ.enq(tagged WB_ALU {dest: it.rdst, data:(~(rf.rd1(it.rsrc1) | rf.rd2(it.rsrc2)) )} );

   373 	 tagged SLT   .it : wbQ.enq(tagged WB_ALU {dest: it.rdst, data:slt( rf.rd1(it.rsrc1), rf.rd2(it.rsrc2) ) });

   374 	 tagged SLTU  .it : wbQ.enq(tagged WB_ALU {dest: it.rdst, data:sltu( rf.rd1(it.rsrc1), rf.rd2(it.rsrc2) ) });

   375 

   376 	 // -- Branches --------------------------------------------------

   377 

   378 	 tagged BLEZ  .it : 

   379             if ( signedLE( rf.rd1(it.rsrc), 0 ) )

   380 	       begin

   381 		  newPC = pc_plus4 + (sext(it.offset) << 2);

   382 		  branchTaken = True;

   383 	       end

   384 

   385 	 tagged BGTZ  .it : 

   386             if ( signedGT( rf.rd1(it.rsrc), 0 ) ) 

   387                begin 

   388 		  newPC = pc_plus4 + (sext(it.offset) << 2);

   389 		  branchTaken = True;

   390 	       end

   391 

   392 	 tagged BLTZ  .it : 

   393             if ( signedLT( rf.rd1(it.rsrc), 0 ) )

   394                begin 

   395 		  newPC = pc_plus4 + (sext(it.offset) << 2);

   396 		  branchTaken = True;

   397 	       end

   398 		  

   399 	 tagged BGEZ  .it : 

   400             if ( signedGE( rf.rd1(it.rsrc), 0 ) )

   401                begin 

   402 		  newPC = pc_plus4 + (sext(it.offset) << 2);		  

   403 		  branchTaken = True;

   404 	       end

   405 

   406       tagged BEQ   .it : 

   407         if ( rf.rd1(it.rsrc1) == rf.rd2(it.rsrc2) )

   408           begin 

   409 	     newPC = pc_plus4 + (sext(it.offset) << 2);

   410 	     branchTaken = True;

   411 	  end

   412 

   413       tagged BNE   .it : 

   414         if ( rf.rd1(it.rsrc1) != rf.rd2(it.rsrc2) )

   415           begin 

   416 	     newPC = pc_plus4 + (sext(it.offset) << 2);

   417 	     branchTaken = True;

   418 	  end

   419 

   420       // -- Jumps -----------------------------------------------------

   421       

   422       tagged J     .it : 

   423         begin 

   424 	   newPC = { pc_plus4[31:28], it.target, 2'b0 };

   425 	   branchTaken = True;

   426 	end

   427       

   428       tagged JR    .it : 

   429         begin 

   430 	   newPC = rf.rd1(it.rsrc);

   431 	   branchTaken = True;

   432 	end

   433 

   434       tagged JAL   .it : 

   435        begin

   436           wbQ.enq(tagged WB_ALU {dest:31, data:pc_plus4 });

   437           newPC = { pc_plus4[31:28], it.target, 2'b0 };		  

   438 	  branchTaken = True;

   439        end

   440 

   441       tagged JALR  .it : 

   442        begin

   443           wbQ.enq(tagged WB_ALU {dest:it.rdst, data:pc_plus4 });

   444           newPC = rf.rd1(it.rsrc);

   445 	  branchTaken = True;

   446        end

   447 

   448       // -- Cop0 ------------------------------------------------------

   449       

   450       tagged MTC0  .it : 

   451 	 begin

   452             case ( it.cop0dst )

   453 	       5'd10 : cp0_statsEn <= unpack(truncate(rf.rd1(it.rsrc)));

   454 	       5'd21 : cp0_tohost  <= truncate(rf.rd1(it.rsrc));

   455 	       default :

   456 	       $display( " RTL-ERROR : %m : Illegal MTC0 cop0dst register!" );

   457 	    endcase

   458 	    wbQ.enq(tagged WB_Host 0); //no idea wwhat this actually should be.

   459 	 end

   460 

   461 //this is host stuff?

   462       tagged MFC0  .it :

   463 	 begin

   464             case ( it.cop0src )

   465 	    // not actually an ALU instruction but don't have the format otherwise

   466                5'd10 : wbQ.enq(tagged WB_ALU {dest:it.rdst, data:zext(pack(cp0_statsEn)) });

   467                5'd20 : wbQ.enq(tagged WB_ALU {dest:it.rdst, data:cp0_fromhost });

   468                5'd21 : wbQ.enq(tagged WB_ALU {dest:it.rdst, data:cp0_tohost   });

   469               default : 

   470                 $display( " RTL-ERROR : %m : Illegal MFC0 cop0src register!" );

   471             endcase

   472 	end

   473 

   474       // -- Illegal ---------------------------------------------------

   475 

   476       default : 

   477         $display( " RTL-ERROR : %m : Illegal instruction !" );

   478 

   479     endcase

   480 

   481 //evaluate branch prediction

   482      Addr ppc = pcQ.first().qnxtpc; //predicted branch

   483      if (ppc != newPC) //prediction wrong

   484        begin

   485 	  epoch <= pcQ.first().qepoch + 1;

   486 	  bp.upd(instrpc, newPC); //update branch predictor

   487 	  pcQ.clear();

   488 	  pc <= newPC;

   489        end

   490      else

   491 	pcQ.deq();

   492 

   493     if ( cp0_statsEn )

   494       num_inst <= num_inst+1;

   495 

   496   endrule

   497 

   498   rule writeback; // ( stage == Writeback );

   499      traceTiny("mkProc", "writeback","W");

   500      

   501 

   502     // get what to do off the writeback queue

   503      wbQ.deq();

   504      case (wbQ.first()) matches

   505 	tagged WB_ALU {data:.res, dest:.rdst} : rf.wr(rdst, res);

   506 	tagged WB_Load .regWr : 

   507 	   begin

   508 	      dataRespQ.deq();

   509 	      if (dataRespQ.first() matches tagged LoadResp .ld)

   510 		rf.wr(truncate(ld.tag), ld.data); // no need to use Rindx from queue?  Duplicate?

   511 	   end

   512 	tagged WB_Store : dataRespQ.deq();

   513 	tagged WB_Host .dat : noAction;

   514      endcase

   515            

   516   endrule

   517 

   518   rule inc_num_cycles;

   519     if ( cp0_statsEn )

   520       num_cycles <= num_cycles+1;

   521   endrule

   522 

   523 

   524 //-----------------------------------------------------------

   525 // My Adds

   526 //-----------------------------------------------------------

   527 

   528   //-----------------------------------------------------------

   529   // Methods

   530 

   531   interface Client imem_client;

   532     interface Get request  = toGet(instReqQ);

   533     interface Put response = toPut(instRespQ);

   534   endinterface

   535 

   536   interface Client dmem_client;

   537     interface Get request  = toGet(dataReqQ);

   538     interface Put response = toPut(dataRespQ);

   539   endinterface

   540 

   541   interface Get statsEn_get = toGet(asReg(cp0_statsEn));

   542 

   543   interface ProcStats stats;

   544     interface Get num_cycles = toGet(asReg(num_cycles));

   545     interface Get num_inst = toGet(asReg(num_inst));

   546   endinterface

   547 

   548   interface CPUToHost tohost;

   549     method Bit#(32) cpuToHost(int req);

   550       return (case (req)

   551        0: cp0_tohost;

   552        1: pc;

   553        2: zeroExtend(pack(stage));

   554       endcase);

   555     endmethod

   556   endinterface

   557 

   558 endmodule

   559
author	punk
date	Tue, 13 Apr 2010 17:34:33 -0400
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