predictor.h

#ifndef _PREDICTOR_H_
#define _PREDICTOR_H_

#include "utils.h"
#include "tracer.h"
#include <bitset>

#define NUMTAGTABLES 4


/////////////////////////////////////////////////////////////
/////////////////////////////////////////////////////////////
// Each entry in the tag Pred Table
struct TagEntry 
{
    INT32 ctr;
    UINT32 tag;
    INT32 usefulBits;
};

// Folded History implementation ... from ghr (geometric length) -> compressed(target)
struct CompressedHist
{
 /// Objective is to convert geomLengt of GHR into tagPredLog which is of length equal to the index of the corresponding bank
    // It can be also used for tag when the final length would be the Tag
    UINT32 geomLength;
    UINT32 targetLength;
    UINT32 compHist;
      
    void updateCompHist(bitset<131> ghr)
    {
        
        /*bitset<131> temp;;
        int numFolds = geomLength / targetLength;
        //int remainder = (ghr.size()) % compLength;
        int mask = (1 << targetLength) - 1;
        int geometricMask = (1 << geomLength) - 1;
        temp = ghr;
        
        temp = temp & geometricMask;
        UINT32 remainder = 0;
        UINT32 comphistfolds[numFolds];
        
        for(int i=0; i < numFolds; i++)
        {    
            comphistfolds[i] = temp & mask;
            temp = temp >> targetLength;
            
        }
        remainder = temp & mask;
        
        for(int i = 0; i< numFolds; i++)
        {
            compHist ^= comphistfolds[i];
        }
        compHist ^= remainder;*/
        // easier way below... see PPM paper Figure 2
        // creating important masks
        int mask = (1 << targetLength) - 1;
        int mask1 = ghr[geomLength] << (geomLength % targetLength);
        int mask2 = (1 << targetLength);
            compHist  = (compHist << 1) + ghr[0];
            compHist ^= ((compHist & mask2) >> targetLength);
            compHist ^= mask1;
            compHist &= mask;  
         
    }    
};
class PREDICTOR{

  // The state is defined for Gshare, change for your design

 private:
  bitset<131> GHR;           // global history register
  // 16 bit path history
  int PHR;
  // Bimodal
  UINT32  *bimodal;          // pattern history table
  UINT32  historyLength; // history length
  UINT32  numBimodalEntries; // entries in pht 
  UINT32  bimodalLog;
  //Tagged Predictors
  TagEntry *tagPred[NUMTAGTABLES];
  UINT32 numTagPredEntries;
  UINT32 tagPredLog;
  UINT32 geometric[NUMTAGTABLES];
  //Compressed Buffers
  CompressedHist indexComp[NUMTAGTABLES];
  CompressedHist tagComp[2][NUMTAGTABLES]; 
 
  // Predictions need to be global ?? recheck
  bool primePred;
  bool altPred;
  int primeBank;
  int altBank;
  // index had to be made global else recalculate for update
  UINT32 indexTagPred[NUMTAGTABLES];
  UINT32 tag[NUMTAGTABLES];
  UINT32 clock;
  int clock_flip;
  INT32 altBetterCount;
public:

  // The interface to the four functions below CAN NOT be changed

  PREDICTOR(void);
  bool    GetPrediction(UINT32 PC);  
  void    UpdatePredictor(UINT32 PC, bool resolveDir, bool predDir, UINT32 branchTarget);
  void    TrackOtherInst(UINT32 PC, OpType opType, UINT32 branchTarget);
  
  // Contestants can define their own functions below

};


  

    /***********************************************************/
#endif