typedef struct __ENC_CB
{
    U08 phs_sample_period;

    U16 A_window;
    U16 B_window;

    U16 A_sum;
    U16 B_sum;

    U08 A_mask;
    U08 B_mask;

    U08 Current;
    U08 Previous;

    U08 State;

} ENC_CB;

ENC_CB ENC;

/* =================== */

void adsf (void)
{
    port = ENC_PORT;

    if (++ENC.phs_sample_period > (ENC_PHS_SAMPLE_PERIOD_VAL - 1))
    {
        ENC.phs_sample_period = 0;

        if (port & ENC_A_PIN)
        {
            ENC.A_sum++;
            ENC.A_window |= ENC.A_mask;
        }
        else
        {
            if (ENC.A_sum > 0)
                ENC.A_sum--;
            ENC.A_window &= ~ENC.A_mask;
        }

        ENC.A_mask <<= 1;
        if (ENC.A_mask == 0)
            ENC.A_mask = 1;

        if ((ENC.A_window & ENC.A_mask) &&
            (ENC.A_sum > 0)
           )
            ENC.A_sum--;

        if (port & ENC_B_PIN)
        {
            ENC.B_sum++;
            ENC.B_window |= ENC.B_mask;
        }
        else
        {
            if (ENC.B_sum > 0)
                ENC.B_sum--;
            ENC.B_window &= ~ENC.B_mask;
        }

        ENC.B_mask <<= 1;
        if (ENC.B_mask == 0)
            ENC.B_mask = 1;

        if ((ENC.B_window & ENC.B_mask) &&
            (ENC.B_sum > 0)
           )
            ENC.B_sum--;

        ENC.Current = ENC.Previous;

        if      (ENC.A_sum > 5)  ENC.Current |=  0x01;
        else if (ENC.A_sum < 2)  ENC.Current &= ~0x01;

        if      (ENC.B_sum > 5)  ENC.Current |=  0x02;
        else if (ENC.B_sum < 2)  ENC.Current &= ~0x02;

        if (!ENC.Current)
        {
            if (ENC.Previous == 0x01)
                ENC.State |= ENC_EVENT_UP;
            if (ENC.Previous == 0x02)
                ENC.State |= ENC_EVENT_DW;
        }

        ENC.Previous = ENC.Current;
    }
}