text: /**
   * Copyright (c) 2012 - 2018, Nordic Semiconductor ASA
   * 
   * All rights reserved.
   * 
   * Redistribution and use in source and binary forms, with or without modification,
   * are permitted provided that the following conditions are met:
   * 
   * 1. Redistributions of source code must retain the above copyright notice, this
   *    list of conditions and the following disclaimer.
   * 
   * 2. Redistributions in binary form, except as embedded into a Nordic
   *    Semiconductor ASA integrated circuit in a product or a software update for
   *    such product, 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.
   * 
   * 3. Neither the name of Nordic Semiconductor ASA nor the names of its
   *    contributors may be used to endorse or promote products derived from this
   *    software without specific prior written permission.
   * 
   * 4. This software, with or without modification, must only be used with a
   *    Nordic Semiconductor ASA integrated circuit.
   * 
   * 5. Any software provided in binary form under this license must not be reverse
   *    engineered, decompiled, modified and/or disassembled.
   * 
   * THIS SOFTWARE IS PROVIDED BY NORDIC SEMICONDUCTOR ASA "AS IS" AND ANY EXPRESS
   * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   * OF MERCHANTABILITY, NONINFRINGEMENT, AND FITNESS FOR A PARTICULAR PURPOSE ARE
   * DISCLAIMED. IN NO EVENT SHALL NORDIC SEMICONDUCTOR ASA 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 ANCS_TX_BUFFER_H__
  #define ANCS_TX_BUFFER_H__
  
  #include "nrf_ble_ancs_c.h"
  
  /** @file
   *
   * @addtogroup ble_ancs_c
   * @{
   */
  
  #define TX_BUFFER_MASK                   0x07                     //!< TX buffer mask. Must be a mask of contiguous zeroes followed by a contiguous sequence of ones: 000...111.
  #define TX_BUFFER_SIZE                   (TX_BUFFER_MASK + 1)     //!< Size of the send buffer, which is 1 bigger than the mask.
  #define WRITE_MESSAGE_LENGTH             20                       //!< Length of the write message for the CCCD/control point.
  
  /**@brief ANCS request types.
   */
  typedef enum
  {
      READ_REQ = 1,  /**< Type identifying that this TX message is a read request. */
      WRITE_REQ      /**< Type identifying that this TX message is a write request. */
  } tx_request_t;
  
  
  /**@brief Structure for writing a message to the central, thus the Control Point or CCCD.
   */
  typedef struct
  {
    uint8_t                  gattc_value[WRITE_MESSAGE_LENGTH]; //!< The message to write.
    ble_gattc_write_params_t gattc_params;                      //!< GATTC parameters for this message.
  } write_params_t;
  
  
  /**@brief Data to be transmitted to the connected master.
   */
  typedef struct
  {
    uint16_t          conn_handle;  //!< Connection handle to be used when transmitting this message.
    tx_request_t type;         //!< Type of this message (read or write message).
      union
      {
        uint16_t       read_handle;    //!< Read request message.
        write_params_t write_req; //!< Write request message.
      } req;
  } tx_message_t;
  
  /**@brief Function for clearing the TX buffer.
   *
   * @details Always call this function before using the TX buffer.
  */
  void tx_buffer_init(void);
  
  /**@brief Function for moving the pointer of the ring buffer to the next element.
  */
  void tx_buffer_insert(tx_message_t * p_msg);
  
  /**@brief Function for passing any pending request from the buffer to the stack.
  */
  void tx_buffer_process(void);
  
  /** @} */
  
  #endif // ANCS_TX_BUFFER_H__
  
  