class local_update : public branch_update
{
public:
        unsigned int index;
};

class local_predictor : public branch_predictor
{
public:
#define HISTORY_LENGTH  15
#define TABLE_BITS  15
    branch_info bi;
    unsigned int history;
    unsigned char tab[1<<TABLE_BITS];
    local_update u;

    local_predictor (void) : history(0)
    {
        memset (tab, 0, sizeof (tab));
    }

    branch_update *predict (branch_info & b)
    {
        bi = b;
        if (b.br_flags & BR_CONDITIONAL)
        {
            u.index = (history << (TABLE_BITS - HISTORY_LENGTH)) ^ (b.address & ((1<<TABLE_BITS)-1));
            u.direction_prediction (tab[u.index] >> 1);
        }
        else
        {
            u.direction_prediction (true);
        }
        u.target_prediction (0);
        return &u;
    }

    void update (branch_update *u, bool taken, unsigned int target)
    {
        if (bi.br_flags & BR_CONDITIONAL)
        {
            unsigned char *c = &tab[((local_update*)u)->index];
            if (taken)
            {
                if (*c < 3)
                    (*c)++;
            }
            else
            {
                if (*c > 0)
                    (*c)--;
            }

            history <<= 1;              //Bit shift _history_ to the left one to make room for the new result
            history |= taken;           //Put the result (1 or 0) in the least significant bit of history (right bit)
            history &= (1<<HISTORY_LENGTH)-1;
        }
    }
};