uart全功能实现.实现如下函数: U_Open, U_Close, U_GetBytes, U_PutBytes, U_GetBytesAvail, U_GetTxRoomLeft, U_PutISRBytes, U_GetTxISRRoomLeft, U_Purge, U_SetOwner, U_SetFlowCtrl, U_ConfigEscape, U_SetDCBConfig, U_CtrlDCD, U_CtrlBreak, U_ClrRxBuffer, U_ClrTxBuffer, U_SetBaudRate, U_SendISRData, U_SendData, U_GetOwnerID, U_SetAutoBaud_Div, /*TY adds these to expand flexibility 2004/10/15*/ U_Register_TX_cb, U_Register_RX_cb, /*TY adds these to let virtual COM port can retrive exception log 2005/3/8*/ U_GetUARTByte, U_PutUARTByte, U_PutUARTBytes, /*for virtual com port to return DCB configuration*/ U_ReadDCBConfig, U_CtrlRI, U_CtrlDTR, U_ReadHWStatus
