btb.h

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/*
        Copyright (C) 1997 CFU Corporation

        File: btb.h
        Description: branch target buffer
        Author: Chao-yinig Fu
        Date: Oct. 27, 2000

        ^..^
        (00)

         $__$
        <~00~>
         (oo)
          ||

        ```````
        C ^|^ D
         \ O /
*/

#ifndef INCLUDED_BTB_H
#define INCLUDED_BTB_H

#include <stdio.h>
#include <assert.h>

class BTB
{
public:
        BTB():_tag(NULL) {}

        // b => block size
        // e => number of entry
        // s => set associtivity
        BTB(int b, int e,int s):_b(b),_e(e),_s(s)
        {
                _num_of_entry=1<<_e;
                _num_of_entry_per_set=1<<_s;
                _index_mask=(1<<(_e-_s))-1;

                _tag=new int[_num_of_entry];
                _time=new int[_num_of_entry];
                _slot=new int[_num_of_entry];
                _target=new int[_num_of_entry];

                for(int i=0;i<_num_of_entry;i++)
                {
                        _tag[i]=-1;
                        _slot[i]=0;
                        _target[i]=0;
                        _time[i]=0;
                }

                //show(stderr);
                //exit(0);
        }

        void show(FILE *f)
        {
                fprintf(f,"=== BTB ===");
                fprintf(f,"_b=%d\n",_b);
                fprintf(f,"_e=%d\n",_e);
                fprintf(f,"_s=%d\n",_s);
                fprintf(f,"_num_of_entry=%d\n",_num_of_entry);
                fprintf(f,"_num_of_entry_per_set=%d\n",_num_of_entry_per_set);
                fprintf(f,"_index_mask=%d\n",_index_mask);
        }

        ~BTB() 
        {
                delete []_tag;
                delete []_slot;
                delete []_target;
                delete []_time;
        }

        void predict(int ip,int slot,bool &find_btb,int &target);
        void update(int ip,int slot,int target,int global_cycle);
        

private:
        int _b;         // operation size are the 2^_b bytes
        int _e;         // 2^_c => number of entry
        int _s;         // 2^_s => set associativity
        int _num_of_entry;      // number of entry
        int _num_of_entry_per_set;      // number of entry per set
        int _index_mask;        // mask for finding index

        int *_tag;      // store the tag of this op
        int *_slot;     // store the slot information of this op
        int *_target;   // store the value for prediction
        int *_time;     // store the time array
};

#endif // INCLUDED_BRANCH_H

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