//---------------------------------------------------------------------------
static ulong cmd_transmit = 0L;

#define BIT_START    BIT0
#define BIT_STOP    BIT10
static             int bkey;
static volatile int bcnt;

//---------------------------------------------------------------------------
// ps2_int_handler()
// INT driven service routine that collects 11 bits that make up a scan code
// sent by a PS2 encoder.
//---------------------------------------------------------------------------
__irq __arm void ps2_isr_handler(void)
{
    if( cmd_transmit )
    {   switch( bcnt )
        {    // TX --------------------------

    case 11:
            bcnt = cmd_transmit = 0;          // End transmit;
            break;

    default:              // Transmit Start + Body + parity + Stop
            if( cmd_transmit & (1<<(bcnt-1)) )
                PS2_DATA_HI();
            else
                PS2_DATA_LO();
   case 0:
            bcnt++;
        }
    }
    else
    {    // RX --------------------------
        if( IOxPIN & PxB_DATA_INP )
            bkey |= (1<<bcnt);

        if( bcnt < 10 )
            bcnt++;
        else
        {    // 11bits is received - Decode the key
            if( ( bkey & (BIT_START|BIT_STOP) ) == BIT_STOP )
            {    bkey >>= 1;
                xQueueSendFromISR( ATSCAN_handle, &bkey, 0 );
            }
            else
                status_word |= STW_AT_ERROR_DETECTED;
            bcnt = bkey = 0;
        }
    }
    EXTINT = PS2_EINT2;            // Clear the EXT interrupt flag
    VICVectAddr    = 0;             // Dummy write to signal end of interrupt
}