text: /*
   * Copyright (c) 2015, Freescale Semiconductor, Inc.
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without modification,
   * are permitted provided that the following conditions are met:
   *
   * o Redistributions of source code must retain the above copyright notice, this list
   *   of conditions and the following disclaimer.
   *
   * o Redistributions in binary form must reproduce the above copyright notice, this
   *   list of conditions and the following disclaimer in the documentation and/or
   *   other materials provided with the distribution.
   *
   * o Neither the name of Freescale Semiconductor, Inc. nor the names of its
   *   contributors may be used to endorse or promote products derived from this
   *   software without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
   * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
   * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
   * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
   * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
   * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
   * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
   * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
   * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   */
  #ifndef _FSL_UART_H_
  #define _FSL_UART_H_
  
  #include "fsl_common.h"
  
  /*!
   * @addtogroup uart
   * @{
   */
  
  /*! @file*/
  
  /*******************************************************************************
   * Definitions
   ******************************************************************************/
  /*! @brief UART driver version */
  #define FSL_UART_DRIVER_VERSION (MAKE_VERSION(2, 0, 0)) /*!< Version 2.0.0. */
  
  /*! @brief Error codes for the UART driver. */
  enum _uart_status
  {
      kStatus_UART_TxBusy = MAKE_STATUS(kStatusGroup_UART, 0),              /*!< Transmitter is busy. */
      kStatus_UART_RxBusy = MAKE_STATUS(kStatusGroup_UART, 1),              /*!< Receiver is busy. */
      kStatus_UART_TxIdle = MAKE_STATUS(kStatusGroup_UART, 2),              /*!< UART transmitter is idle. */
      kStatus_UART_RxIdle = MAKE_STATUS(kStatusGroup_UART, 3),              /*!< UART receiver is idle. */
      kStatus_UART_TxWatermarkTooLarge = MAKE_STATUS(kStatusGroup_UART, 4), /*!< TX FIFO watermark too large  */
      kStatus_UART_RxWatermarkTooLarge = MAKE_STATUS(kStatusGroup_UART, 5), /*!< RX FIFO watermark too large  */
      kStatus_UART_FlagCannotClearManually =
          MAKE_STATUS(kStatusGroup_UART, 6),                                /*!< UART flag can't be manually cleared. */
      kStatus_UART_Error = MAKE_STATUS(kStatusGroup_UART, 7),               /*!< Error happens on UART. */
      kStatus_UART_RxRingBufferOverrun = MAKE_STATUS(kStatusGroup_UART, 8), /*!< UART RX software ring buffer overrun. */
      kStatus_UART_RxHardwareOverrun = MAKE_STATUS(kStatusGroup_UART, 9),   /*!< UART RX receiver overrun. */
      kStatus_UART_NoiseError = MAKE_STATUS(kStatusGroup_UART, 10),         /*!< UART noise error. */
      kStatus_UART_FramingError = MAKE_STATUS(kStatusGroup_UART, 11),       /*!< UART framing error. */
      kStatus_UART_ParityError = MAKE_STATUS(kStatusGroup_UART, 12),        /*!< UART parity error. */
      kStatus_UART_BaudrateNotSupport = MAKE_STATUS(kStatusGroup_UART, 13), /*!< Baudrate is not support in current clock source */
  };
  
  /*! @brief UART parity mode. */
  typedef enum _uart_parity_mode
  {
      kUART_ParityDisabled = 0x0U, /*!< Parity disabled */
      kUART_ParityEven = 0x2U,     /*!< Parity enabled, type even, bit setting: PE|PT = 10 */
      kUART_ParityOdd = 0x3U,      /*!< Parity enabled, type odd,  bit setting: PE|PT = 11 */
  } uart_parity_mode_t;
  
  /*! @brief UART stop bit count. */
  typedef enum _uart_stop_bit_count
  {
      kUART_OneStopBit = 0U, /*!< One stop bit */
      kUART_TwoStopBit = 1U, /*!< Two stop bits */
  } uart_stop_bit_count_t;
  
  /*!
   * @brief UART interrupt configuration structure, default settings all disabled.
   *
   * This structure contains the settings for all of the UART interrupt configurations.
   */
  enum _uart_interrupt_enable
  {
  #if defined(FSL_FEATURE_UART_HAS_LIN_BREAK_DETECT) && FSL_FEATURE_UART_HAS_LIN_BREAK_DETECT
      kUART_LinBreakInterruptEnable = (UART_BDH_LBKDIE_MASK), /*!< LIN break detect interrupt. */
  #endif
      kUART_RxActiveEdgeInterruptEnable = (UART_BDH_RXEDGIE_MASK),   /*!< RX active edge interrupt. */
      kUART_TxDataRegEmptyInterruptEnable = (UART_C2_TIE_MASK << 8), /*!< Transmit data register empty interrupt. */
      kUART_TransmissionCompleteInterruptEnable = (UART_C2_TCIE_MASK << 8), /*!< Transmission complete interrupt. */
      kUART_RxDataRegFullInterruptEnable = (UART_C2_RIE_MASK << 8),         /*!< Receiver data register full interrupt. */
      kUART_IdleLineInterruptEnable = (UART_C2_ILIE_MASK << 8),             /*!< Idle line interrupt. */
      kUART_RxOverrunInterruptEnable = (UART_C3_ORIE_MASK << 16),           /*!< Receiver overrun interrupt. */
      kUART_NoiseErrorInterruptEnable = (UART_C3_NEIE_MASK << 16),          /*!< Noise error flag interrupt. */
      kUART_FramingErrorInterruptEnable = (UART_C3_FEIE_MASK << 16),        /*!< Framing error flag interrupt. */
      kUART_ParityErrorInterruptEnable = (UART_C3_PEIE_MASK << 16),         /*!< Parity error flag interrupt. */
  #if defined(FSL_FEATURE_UART_HAS_FIFO) && FSL_FEATURE_UART_HAS_FIFO
      kUART_RxFifoOverflowInterruptEnable = (UART_CFIFO_TXOFE_MASK << 24),  /*!< TX FIFO overflow interrupt. */
      kUART_TxFifoOverflowInterruptEnable = (UART_CFIFO_RXUFE_MASK << 24),  /*!< RX FIFO underflow interrupt. */
      kUART_RxFifoUnderflowInterruptEnable = (UART_CFIFO_RXUFE_MASK << 24), /*!< RX FIFO underflow interrupt. */
  #endif
  };
  
  /*!
   * @brief UART status flags.
   *
   * This provides constants for the UART status flags for use in the UART functions.
   */
  enum _uart_flags
  {
      kUART_TxDataRegEmptyFlag = (UART_S1_TDRE_MASK),     /*!< TX data register empty flag. */
      kUART_TransmissionCompleteFlag = (UART_S1_TC_MASK), /*!< Transmission complete flag. */
      kUART_RxDataRegFullFlag = (UART_S1_RDRF_MASK),      /*!< RX data register full flag. */
      kUART_IdleLineFlag = (UART_S1_IDLE_MASK),           /*!< Idle line detect flag. */
      kUART_RxOverrunFlag = (UART_S1_OR_MASK),            /*!< RX overrun flag. */
      kUART_NoiseErrorFlag = (UART_S1_NF_MASK),           /*!< RX takes 3 samples of each received bit.
                                                               If any of these samples differ, noise flag sets */
      kUART_FramingErrorFlag = (UART_S1_FE_MASK),         /*!< Frame error flag, sets if logic 0 was detected
                                                               where stop bit expected */
      kUART_ParityErrorFlag = (UART_S1_PF_MASK),          /*!< If parity enabled, sets upon parity error detection */
  #if defined(FSL_FEATURE_UART_HAS_LIN_BREAK_DETECT) && FSL_FEATURE_UART_HAS_LIN_BREAK_DETECT
      kUART_LinBreakFlag = (UART_S2_LBKDIF_MASK << 8), /*!< LIN break detect interrupt flag, sets when
                                                                      LIN break char detected and LIN circuit enabled */
  #endif
      kUART_RxActiveEdgeFlag = (UART_S2_RXEDGIF_MASK << 8), /*!< RX pin active edge interrupt flag,
                                                                           sets when active edge detected */
      kUART_RxActiveFlag = (UART_S2_RAF_MASK << 8),         /*!< Receiver Active Flag (RAF),
                                                                           sets at beginning of valid start bit */
  #if defined(FSL_FEATURE_UART_HAS_EXTENDED_DATA_REGISTER_FLAGS) && FSL_FEATURE_UART_HAS_EXTENDED_DATA_REGISTER_FLAGS
      kUART_NoiseErrorInRxDataRegFlag = (UART_ED_NOISY_MASK << 16),    /*!< Noisy bit, sets if noise detected. */
      kUART_ParityErrorInRxDataRegFlag = (UART_ED_PARITYE_MASK << 16), /*!< Paritye bit, sets if parity error detected. */
  #endif
  #if defined(FSL_FEATURE_UART_HAS_FIFO) && FSL_FEATURE_UART_HAS_FIFO
      kUART_TxFifoEmptyFlag = (UART_SFIFO_TXEMPT_MASK << 24),   /*!< TXEMPT bit, sets if TX buffer is empty */
      kUART_RxFifoEmptyFlag = (UART_SFIFO_RXEMPT_MASK << 24),   /*!< RXEMPT bit, sets if RX buffer is empty */
      kUART_TxFifoOverflowFlag = (UART_SFIFO_TXOF_MASK << 24),  /*!< TXOF bit, sets if TX buffer overflow occurred */
      kUART_RxFifoOverflowFlag = (UART_SFIFO_RXOF_MASK << 24),  /*!< RXOF bit, sets if receive buffer overflow */
      kUART_RxFifoUnderflowFlag = (UART_SFIFO_RXUF_MASK << 24), /*!< RXUF bit, sets if receive buffer underflow */
  #endif
  };
  
  /*! @brief UART configuration structure. */
  typedef struct _uart_config
  {
      uint32_t baudRate_Bps;         /*!< UART baud rate  */
      uart_parity_mode_t parityMode; /*!< Parity mode, disabled (default), even, odd */
  #if defined(FSL_FEATURE_UART_HAS_STOP_BIT_CONFIG_SUPPORT) && FSL_FEATURE_UART_HAS_STOP_BIT_CONFIG_SUPPORT
      uart_stop_bit_count_t stopBitCount; /*!< Number of stop bits, 1 stop bit (default) or 2 stop bits  */
  #endif
  #if defined(FSL_FEATURE_UART_HAS_FIFO) && FSL_FEATURE_UART_HAS_FIFO
      uint8_t txFifoWatermark; /*!< TX FIFO watermark */
      uint8_t rxFifoWatermark; /*!< RX FIFO watermark */
  #endif
      bool enableTx; /*!< Enable TX */
      bool enableRx; /*!< Enable RX */
  } uart_config_t;
  
  /*! @brief UART transfer structure. */
  typedef struct _uart_transfer
  {
      uint8_t *data;   /*!< The buffer of data to be transfer.*/
      size_t dataSize; /*!< The byte count to be transfer. */
  } uart_transfer_t;
  
  /* Forward declaration of the handle typedef. */
  typedef struct _uart_handle uart_handle_t;
  
  /*! @brief UART transfer callback function. */
  typedef void (*uart_transfer_callback_t)(UART_Type *base, uart_handle_t *handle, status_t status, void *userData);
  
  /*! @brief UART handle structure. */
  struct _uart_handle
  {
      uint8_t *volatile txData;   /*!< Address of remaining data to send. */
      volatile size_t txDataSize; /*!< Size of the remaining data to send. */
      size_t txDataSizeAll;       /*!< Size of the data to send out. */
      uint8_t *volatile rxData;   /*!< Address of remaining data to receive. */
      volatile size_t rxDataSize; /*!< Size of the remaining data to receive. */
      size_t rxDataSizeAll;       /*!< Size of the data to receive. */
  
      uint8_t *rxRingBuffer;              /*!< Start address of the receiver ring buffer. */
      size_t rxRingBufferSize;            /*!< Size of the ring buffer. */
      volatile uint16_t rxRingBufferHead; /*!< Index for the driver to store received data into ring buffer. */
      volatile uint16_t rxRingBufferTail; /*!< Index for the user to get data from the ring buffer. */
  
      uart_transfer_callback_t callback; /*!< Callback function. */
      void *userData;                    /*!< UART callback function parameter.*/
  
      volatile uint8_t txState; /*!< TX transfer state. */
      volatile uint8_t rxState; /*!< RX transfer state */
  };
  
  /*******************************************************************************
   * API
   ******************************************************************************/
  
  #if defined(__cplusplus)
  extern "C" {
  #endif /* _cplusplus */
  
  /*!
   * @name Initialization and deinitialization
   * @{
   */
  
  /*!
   * @brief Initializes a UART instance with user configuration structure and peripheral clock.
   *
   * This function configures the UART module with the user-defined settings. The user can configure the configuration
   * structure and also get the default configuration by using the UART_GetDefaultConfig() function.
   * Example below shows how to use this API to configure UART.
   * @code
   *  uart_config_t uartConfig;
   *  uartConfig.baudRate_Bps = 115200U;
   *  uartConfig.parityMode = kUART_ParityDisabled;
   *  uartConfig.stopBitCount = kUART_OneStopBit;
   *  uartConfig.txFifoWatermark = 0;
   *  uartConfig.rxFifoWatermark = 1;
   *  UART_Init(UART1, &uartConfig, 20000000U);
   * @endcode
   *
   * @param base UART peripheral base address.
   * @param config Pointer to user-defined configuration structure.
   * @param srcClock_Hz UART clock source frequency in HZ.
   * @retval kStatus_UART_BaudrateNotSupport Baudrate is not support in current clock source.
   * @retval kStatus_Success Status UART initialize succeed
   */
  status_t UART_Init(UART_Type *base, const uart_config_t *config, uint32_t srcClock_Hz);
  
  /*!
   * @brief Deinitializes a UART instance.
   *
   * This function waits for TX complete, disables TX and RX, and disables the UART clock.
   *
   * @param base UART peripheral base address.
   */
  void UART_Deinit(UART_Type *base);
  
  /*!
   * @brief Gets the default configuration structure.
   *
   * This function initializes the UART configuration structure to a default value. The default
   * values are:
   *   uartConfig->baudRate_Bps = 115200U;
   *   uartConfig->bitCountPerChar = kUART_8BitsPerChar;
   *   uartConfig->parityMode = kUART_ParityDisabled;
   *   uartConfig->stopBitCount = kUART_OneStopBit;
   *   uartConfig->txFifoWatermark = 0;
   *   uartConfig->rxFifoWatermark = 1;
   *   uartConfig->enableTx = false;
   *   uartConfig->enableRx = false;
   *
   * @param config Pointer to configuration structure.
   */
  void UART_GetDefaultConfig(uart_config_t *config);
  
  /*!
   * @brief Sets the UART instance baud rate.
   *
   * This function configures the UART module baud rate. This function is used to update
   * the UART module baud rate after the UART module is initialized by the UART_Init.
   * @code
   *  UART_SetBaudRate(UART1, 115200U, 20000000U);
   * @endcode
   *
   * @param base UART peripheral base address.
   * @param baudRate_Bps UART baudrate to be set.
   * @param srcClock_Hz UART clock source freqency in HZ.
   * @retval kStatus_UART_BaudrateNotSupport Baudrate is not support in current clock source.
   * @retval kStatus_Success Set baudrate succeed
   */
  status_t UART_SetBaudRate(UART_Type *base, uint32_t baudRate_Bps, uint32_t srcClock_Hz);
  
  /* @} */
  
  /*!
   * @name Status
   * @{
   */
  
  /*!
   * @brief Get UART status flags.
   *
   * This function get all UART status flags, the flags are returned as the logical
   * OR value of the enumerators @ref _uart_flags. To check specific status,
   * compare the return value with enumerators in @ref _uart_flags.
   * For example, to check whether the TX is empty:
   * @code
   *     if (kUART_TxDataRegEmptyFlag & UART_GetStatusFlags(UART1))
   *     {
   *         ...
   *     }
   * @endcode
   *
   * @param base UART peripheral base address.
   * @return UART status flags which are ORed by the enumerators in the _uart_flags.
   */
  uint32_t UART_GetStatusFlags(UART_Type *base);
  
  /*!
   * @brief Clears status flags with the provided mask.
   *
   * This function clears UART status flags with a provided mask. Automatically cleared flag
   * can't be cleared by this function.
   * Some flags can only be cleared or set by hardware itself. These flags are:
   *    kUART_TxDataRegEmptyFlag, kUART_TransmissionCompleteFlag, kUART_RxDataRegFullFlag,
   *    kUART_RxActiveFlag, kUART_NoiseErrorInRxDataRegFlag, kUART_ParityErrorInRxDataRegFlag,
   *    kUART_TxFifoEmptyFlag,kUART_RxFifoEmptyFlag
   *
   * @param base UART peripheral base address.
   * @param mask The status flags to be cleared, it is logical OR value of @ref _uart_flags.
   * @retval kStatus_UART_FlagCannotClearManually The flag can't be cleared by this function but
   *         it is cleared automatically by hardware.
   * @retval kStatus_Success Status in the mask are cleared.
   */
  status_t UART_ClearStatusFlags(UART_Type *base, uint32_t mask);
  
  /* @} */
  
  /*!
   * @name Interrupts
   * @{
   */
  
  /*!
   * @brief Enables UART interrupts according to the provided mask.
   *
   * This function enables the UART interrupts according to the provided mask. The mask
   * is a logical OR of enumeration members. See @ref _uart_interrupt_enable.
   * For example, to enable TX empty interrupt and RX full interrupt:
   * @code
   *     UART_EnableInterrupts(UART1,kUART_TxDataRegEmptyInterruptEnable | kUART_RxDataRegFullInterruptEnable);
   * @endcode
   *
   * @param base UART peripheral base address.
   * @param mask The interrupts to enable. Logical OR of @ref _uart_interrupt_enable.
   */
  void UART_EnableInterrupts(UART_Type *base, uint32_t mask);
  
  /*!
   * @brief Disables the UART interrupts according to the provided mask.
   *
   * This function disables the UART interrupts according to the provided mask. The mask
   * is a logical OR of enumeration members. See @ref _uart_interrupt_enable.
   * For example, to disable TX empty interrupt and RX full interrupt:
   * @code
   *     UART_DisableInterrupts(UART1,kUART_TxDataRegEmptyInterruptEnable | kUART_RxDataRegFullInterruptEnable);
   * @endcode
   *
   * @param base UART peripheral base address.
   * @param mask The interrupts to disable. Logical OR of @ref _uart_interrupt_enable.
   */
  void UART_DisableInterrupts(UART_Type *base, uint32_t mask);
  
  /*!
   * @brief Gets the enabled UART interrupts.
   *
   * This function gets the enabled UART interrupts. The enabled interrupts are returned
   * as the logical OR value of the enumerators @ref _uart_interrupt_enable. To check
   * specific interrupts enable status, compare the return value with enumerators
   * in @ref _uart_interrupt_enable.
   * For example, to check whether TX empty interrupt is enabled:
   * @code
   *     uint32_t enabledInterrupts = UART_GetEnabledInterrupts(UART1);
   *
   *     if (kUART_TxDataRegEmptyInterruptEnable & enabledInterrupts)
   *     {
   *         ...
   *     }
   * @endcode
   *
   * @param base UART peripheral base address.
   * @return UART interrupt flags which are logical OR of the enumerators in @ref _uart_interrupt_enable.
   */
  uint32_t UART_GetEnabledInterrupts(UART_Type *base);
  
  /* @} */
  
  #if defined(FSL_FEATURE_UART_HAS_DMA_SELECT) && FSL_FEATURE_UART_HAS_DMA_SELECT
  /*!
   * @name DMA Control
   * @{
   */
  
  /*!
   * @brief Gets the UART data register address.
   *
   * This function returns the UART data register address, which is mainly used by DMA/eDMA.
   *
   * @param base UART peripheral base address.
   * @return UART data register address which are used both by transmitter and receiver.
   */
  static inline uint32_t UART_GetDataRegisterAddress(UART_Type *base)
  {
      return (uint32_t) & (base->D);
  }
  
  /*!
   * @brief Enables or disables the UART transmitter DMA request.
   *
   * This function enables or disables the transmit data register empty flag, S1[TDRE], to generate the DMA requests.
   *
   * @param base UART peripheral base address.
   * @param enable True to enable, false to disable.
   */
  static inline void UART_EnableTxDMA(UART_Type *base, bool enable)
  {
      if (enable)
      {
  #if (defined(FSL_FEATURE_UART_IS_SCI) && FSL_FEATURE_UART_IS_SCI)
          base->C4 |= UART_C4_TDMAS_MASK;
  #else
          base->C5 |= UART_C5_TDMAS_MASK;
  #endif
          base->C2 |= UART_C2_TIE_MASK;
      }
      else
      {
  #if (defined(FSL_FEATURE_UART_IS_SCI) && FSL_FEATURE_UART_IS_SCI)
          base->C4 &= ~UART_C4_TDMAS_MASK;
  #else
          base->C5 &= ~UART_C5_TDMAS_MASK;
  #endif
          base->C2 &= ~UART_C2_TIE_MASK;
      }
  }
  
  /*!
   * @brief Enables or disables the UART receiver DMA.
   *
   * This function enables or disables the receiver data register full flag, S1[RDRF], to generate DMA requests.
   *
   * @param base UART peripheral base address.
   * @param enable True to enable, false to disable.
   */
  static inline void UART_EnableRxDMA(UART_Type *base, bool enable)
  {
      if (enable)
      {
  #if (defined(FSL_FEATURE_UART_IS_SCI) && FSL_FEATURE_UART_IS_SCI)
          base->C4 |= UART_C4_RDMAS_MASK;
  #else
          base->C5 |= UART_C5_RDMAS_MASK;
  #endif
          base->C2 |= UART_C2_RIE_MASK;
      }
      else
      {
  #if (defined(FSL_FEATURE_UART_IS_SCI) && FSL_FEATURE_UART_IS_SCI)
          base->C4 &= ~UART_C4_RDMAS_MASK;
  #else
          base->C5 &= ~UART_C5_RDMAS_MASK;
  #endif
          base->C2 &= ~UART_C2_RIE_MASK;
      }
  }
  
  /* @} */
  #endif /* FSL_FEATURE_UART_HAS_DMA_SELECT */
  
  /*!
   * @name Bus Operations
   * @{
   */
  
  /*!
   * @brief Enables or disables the UART transmitter.
   *
   * This function enables or disables the UART transmitter.
   *
   * @param base UART peripheral base address.
   * @param enable True to enable, false to disable.
   */
  static inline void UART_EnableTx(UART_Type *base, bool enable)
  {
      if (enable)
      {
          base->C2 |= UART_C2_TE_MASK;
      }
      else
      {
          base->C2 &= ~UART_C2_TE_MASK;
      }
  }
  
  /*!
   * @brief Enables or disables the UART receiver.
   *
   * This function enables or disables the UART receiver.
   *
   * @param base UART peripheral base address.
   * @param enable True to enable, false to disable.
   */
  static inline void UART_EnableRx(UART_Type *base, bool enable)
  {
      if (enable)
      {
          base->C2 |= UART_C2_RE_MASK;
      }
      else
      {
          base->C2 &= ~UART_C2_RE_MASK;
      }
  }
  
  /*!
   * @brief Writes to the TX register using a blocking method.
   *
   * This function polls the TX register, waits for the TX register to be empty or for the TX FIFO
   * to have room and writes data to the TX buffer.
   *
   * @note This function does not check whether all the data has been sent out to the bus.
   * Before disabling the TX, check kUART_TransmissionCompleteFlag to ensure that the TX is
   * finished.
   *
   * @param base UART peripheral base address.
   * @param data Start address of the data to write.
   * @param length Size of the data to write.
   */
  void UART_WriteBlocking(UART_Type *base, const uint8_t *data, size_t length);
  
  /*!
   * @brief Writes to the TX register.
   *
   * This function writes data to the TX register directly. The upper layer must ensure
   * that the TX register is empty or TX FIFO has empty room before calling this function.
   *
   * @param base UART peripheral base address.
   * @param data The byte to write.
   */
  static inline void UART_WriteByte(UART_Type *base, uint8_t data)
  {
      base->D = data;
  }
  
  /*!
   * @brief Read RX data register using a blocking method.
   *
   * This function polls the RX register, waits for the RX register to be full or for RX FIFO to
   * have data and read data from the TX register.
   *
   * @param base UART peripheral base address.
   * @param data Start address of the buffer to store the received data.
   * @param length Size of the buffer.
   */
  void UART_ReadBlocking(UART_Type *base, uint8_t *data, size_t length);
  
  /*!
   * @brief Reads the RX register directly.
   *
   * This function reads data from the TX register directly. The upper layer must
   * ensure that the RX register is full or that the TX FIFO has data before calling this function.
   *
   * @param base UART peripheral base address.
   * @return The byte read from UART data register.
   */
  static inline uint8_t UART_ReadByte(UART_Type *base)
  {
      return base->D;
  }
  
  /* @} */
  
  /*!
   * @name Transactional
   * @{
   */
  
  /*!
   * @brief Initializes the UART handle.
   *
   * This function initializes the UART handle which can be used for other UART
   * transactional APIs. Usually, for a specified UART instance,
   * call this API once to get the initialized handle.
   *
   * @param base UART peripheral base address.
   * @param handle UART handle pointer.
   * @param callback The callback function.
   * @param userData The parameter of the callback function.
   */
  void UART_CreateHandle(UART_Type *base, uart_handle_t *handle, uart_transfer_callback_t callback, void *userData);
  
  /*!
   * @brief Sets up the RX ring buffer.
   *
   * This function sets up the RX ring buffer to a specific UART handle.
   *
   * When the RX ring buffer is used, data received are stored into the ring buffer even when the
   * user doesn't call the UART_ReceiveNonBlocking() API. If there is already data received
   * in the ring buffer, the user can get the received data from the ring buffer directly.
   *
   * @note When using the RX ring buffer, one byte is reserved for internal use. In other
   * words, if @p ringBufferSize is 32, then only 31 bytes are used for saving data.
   *
   * @param base UART peripheral base address.
   * @param handle UART handle pointer.
   * @param ringBuffer Start address of the ring buffer for background receiving. Pass NULL to disable the ring buffer.
   * @param ringBufferSize size of the ring buffer.
   */
  void UART_StartRingBuffer(UART_Type *base, uart_handle_t *handle, uint8_t *ringBuffer, size_t ringBufferSize);
  
  /*!
   * @brief Aborts the background transfer and uninstalls the ring buffer.
   *
   * This function aborts the background transfer and uninstalls the ring buffer.
   *
   * @param base UART peripheral base address.
   * @param handle UART handle pointer.
   */
  void UART_StopRingBuffer(UART_Type *base, uart_handle_t *handle);
  
  /*!
   * @brief Transmits a buffer of data using the interrupt method.
   *
   * This function sends data using an interrupt method. This is a non-blocking function, which
   * returns directly without waiting for all data to be written to the TX register. When
   * all data is written to the TX register in the ISR, the UART driver calls the callback
   * function and passes the @ref kStatus_UART_TxIdle as status parameter.
   *
   * @note The kStatus_UART_TxIdle is passed to the upper layer when all data is written
   * to the TX register. However it does not ensure that all data are sent out. Before disabling the TX,
   * check the kUART_TransmissionCompleteFlag to ensure that the TX is finished.
   *
   * @param base UART peripheral base address.
   * @param handle UART handle pointer.
   * @param xfer UART transfer structure. See  #uart_transfer_t.
   * @retval kStatus_Success Successfully start the data transmission.
   * @retval kStatus_UART_TxBusy Previous transmission still not finished, data not all written to TX register yet.
   */
  status_t UART_SendNonBlocking(UART_Type *base, uart_handle_t *handle, uart_transfer_t *xfer);
  
  /*!
   * @brief Aborts the interrupt driven data transmit.
   *
   * This function aborts the interrupt driven data sending. The user can get the remainBytes to find out
   * how many bytes are still not sent out.
   *
   * @param base UART peripheral base address.
   * @param handle UART handle pointer.
   */
  void UART_AbortSend(UART_Type *base, uart_handle_t *handle);
  
  /*!
   * @brief Get the number of bytes that have been written to UART TX register.
   *
   * This function gets the number of bytes that have been written to UART TX
   * register by interrupt method.
   *
   * @param base UART peripheral base address.
   * @param handle UART handle pointer.
   * @param count Send bytes count.
   * @retval kStatus_NoTransferInProgress No send in progress.
   * @retval kStatus_InvalidArgument Parameter is invalid.
   * @retval kStatus_Success Get successfully through the parameter \p count;
   */
  status_t UART_GetSendCount(UART_Type *base, uart_handle_t *handle, uint32_t *count);
  
  /*!
   * @brief Receives a buffer of data using an interrupt method.
   *
   * This function receives data using an interrupt method. This is a non-blocking function, which
   *  returns without waiting for all data to be received.
   * If the RX ring buffer is used and not empty, the data in the ring buffer is copied and
   * the parameter @p receivedBytes shows how many bytes are copied from the ring buffer.
   * After copying, if the data in the ring buffer is not enough to read, the receive
   * request is saved by the UART driver. When the new data arrives, the receive request
   * is serviced first. When all data is received, the UART driver notifies the upper layer
   * through a callback function and passes the status parameter @ref kStatus_UART_RxIdle.
   * For example, the upper layer needs 10 bytes but there are only 5 bytes in the ring buffer.
   * The 5 bytes are copied to the xfer->data and this function returns with the
   * parameter @p receivedBytes set to 5. For the left 5 bytes, newly arrived data is
   * saved from the xfer->data[5]. When 5 bytes are received, the UART driver notifies the upper layer.
   * If the RX ring buffer is not enabled, this function enables the RX and RX interrupt
   * to receive data to the xfer->data. When all data is received, the upper layer is notified.
   *
   * @param base UART peripheral base address.
   * @param handle UART handle pointer.
   * @param xfer UART transfer structure, refer to #uart_transfer_t.
   * @param receivedBytes Bytes received from the ring buffer directly.
   * @retval kStatus_Success Successfully queue the transfer into transmit queue.
   * @retval kStatus_UART_RxBusy Previous receive request is not finished.
   */
  status_t UART_ReceiveNonBlocking(UART_Type *base, uart_handle_t *handle, uart_transfer_t *xfer, size_t *receivedBytes);
  
  /*!
   * @brief Aborts the interrupt-driven data receiving.
   *
   * This function aborts the interrupt-driven data receiving. The user can get the remainBytes to know
   * how many bytes not received yet.
   *
   * @param base UART peripheral base address.
   * @param handle UART handle pointer.
   */
  void UART_AbortReceive(UART_Type *base, uart_handle_t *handle);
  
  /*!
   * @brief Get the number of bytes that have been received.
   *
   * This function gets the number of bytes that have been received.
   *
   * @param base UART peripheral base address.
   * @param handle UART handle pointer.
   * @param count Receive bytes count.
   * @retval kStatus_NoTransferInProgress No receive in progress.
   * @retval kStatus_InvalidArgument Parameter is invalid.
   * @retval kStatus_Success Get successfully through the parameter \p count;
   */
  status_t UART_GetReceiveCount(UART_Type *base, uart_handle_t *handle, uint32_t *count);
  
  /*!
   * @brief UART IRQ handle function.
   *
   * This function handles the UART transmit and receive IRQ request.
   *
   * @param base UART peripheral base address.
   * @param handle UART handle pointer.
   */
  void UART_HandleIRQ(UART_Type *base, uart_handle_t *handle);
  
  /*!
   * @brief UART Error IRQ handle function.
   *
   * This function handle the UART error IRQ request.
   *
   * @param base UART peripheral base address.
   * @param handle UART handle pointer.
   */
  void UART_HandleErrorIRQ(UART_Type *base, uart_handle_t *handle);
  
  /* @} */
  
  #if defined(__cplusplus)
  }
  #endif
  
  /*! @}*/
  
  #endif /* _FSL_UART_H_ */
  