Mercurial > pygar
comparison modules/bluespec/Pygar/core/BranchPred.bsv @ 8:74716e9a81cc pygar svn.9
[svn r9] Pygar now has the proper directory structure to play nicely with awb. Also, the apm file for audio-core willcompile successfully.
| author | rlm |
|---|---|
| date | Fri, 23 Apr 2010 02:32:05 -0400 |
| parents | |
| children |
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| 7:7393cd19371e | 8:74716e9a81cc |
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| 1 import RegFile::*; | |
| 2 import ProcTypes::*; | |
| 3 import FIFO::*; | |
| 4 | |
| 5 typedef Maybe#(Addr) BrPred; | |
| 6 typedef Bit#(4) BPindx; | |
| 7 | |
| 8 typedef struct {Addr brpc; Addr nextpc;} BrPair deriving (Bits,Eq); | |
| 9 | |
| 10 typedef union tagged | |
| 11 { | |
| 12 BrPair Valid; | |
| 13 void Invalid; | |
| 14 } CBranchPath deriving(Bits, Eq); // have the cache start out invalid and add valid values. | |
| 15 | |
| 16 interface BranchPred; | |
| 17 method BrPred get(Addr pres); //returns a maybe type that is invalid if no predition | |
| 18 method Action upd(Addr pres, Addr next); | |
| 19 endinterface | |
| 20 | |
| 21 module mkBranchPred(BranchPred); | |
| 22 | |
| 23 //state variables | |
| 24 RegFile#(BPindx, CBranchPath) bcache <- mkRegFileFull(); // cache to hold 16 (based on BPindx) | |
| 25 | |
| 26 method Action upd(Addr pres, Addr next); | |
| 27 BrPair brp; | |
| 28 brp = BrPair {brpc:pres, nextpc:next}; | |
| 29 bcache.upd(pres[5:2], tagged Valid brp); | |
| 30 endmethod | |
| 31 | |
| 32 method BrPred get(Addr prespc); | |
| 33 BPindx rd = prespc[5:2]; | |
| 34 let cbp = bcache.sub(rd); | |
| 35 if (cbp matches tagged Valid .bp &&& bp.brpc == prespc) //make sure that the read value was actually put there and the full address matches | |
| 36 return tagged Valid bp.nextpc; | |
| 37 else return Invalid; | |
| 38 endmethod | |
| 39 | |
| 40 endmodule | |
| 41 |