text: /**
   * Copyright (c) 2017 - 2020, 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 NRF_MEMOBJ_H
  #define NRF_MEMOBJ_H
  
  /**
  * @defgroup nrf_memobj Memory Object module
  * @{
  * @ingroup app_common
  * @brief Functions for controlling a memory object.
  */
  #include <stdint.h>
  #include <stdlib.h>
  #include "sdk_errors.h"
  #include "nrf_balloc.h"
  
  #ifdef __cplusplus
  extern "C" {
  #endif
  
  /**
   * A memory object can consist of multiple chunks with the same size. Each object has a header part
   * and a data part. The first element in a memory object is memory object head which has a special header.
   * The remaining objects have a header of the same size.
   * 
  @verbatim
   _____________________        _____________________          _____________________
  |                     |      |                     |        |                     |
  |4 B  head header     |  --> |4 B    p_next        |------->|4 B  p_memobj_pool   |
  |_____________________|  |   |_____________________|        |_____________________|
  |                     |  |   |                     |        |                     |
  |4 B    p_next        |--|   |                     |        |                     |
  |_____________________|      |                     |  ....  |                     |
  |                     |      |        data         |        |        data         |
  |                     |      |                     |        |                     |
  |       data          |      |                     |        |                     |
  |                     |      |                     |        |                     |
  |_____________________|      |_____________________|        |_____________________|
           head                      mid_element                  last_element
  @endverbatim
   *
   */
  #define NRF_MEMOBJ_STD_HEADER_SIZE sizeof(uint32_t)
  
  /**
   * @brief Macro for creating an nrf_memobj pool.
   *
   * This macro declares an nrf_balloc object. The element in the pool contains a user-defined data part and
   * a memory object header.
   *
   * @param _name       Name of the instance.
   * @param _chunk_size Size of a single chunk.
   * @param _pool_size  Number of chunks in the pool.
   */
  #define NRF_MEMOBJ_POOL_DEF(_name, _chunk_size, _pool_size)                           \
      STATIC_ASSERT((_chunk_size) > sizeof(uint32_t));                                  \
      NRF_BALLOC_DEF(_name, ((_chunk_size)+NRF_MEMOBJ_STD_HEADER_SIZE), (_pool_size))
  
  /**
   * @brief Pool of memory objects.
   */
  typedef nrf_balloc_t nrf_memobj_pool_t;
  
  /**
   * @brief Memory object handle.
   */
  typedef void * nrf_memobj_t;
  
  /**
   * @brief Function for initializing the memobj pool instance.
   *
   * This function initializes the pool.
   *
   * @param[in] p_pool     Pointer to the memobj pool instance structure.
   *
   * @return  NRF_SUCCESS on success, otherwise an error code.
   */
  ret_code_t nrf_memobj_pool_init(nrf_memobj_pool_t const * p_pool);
  
  /**
   * @brief Function for allocating a memobj with a requested size.
   *
   * Fixed length elements in the pool are linked together to provide the amount of memory requested by
   * the user. If a memory object is successfully allocated, then the users can use the memory.
   * However, it is fragmented into multiple objects so it must be accessed through the API:
   * @ref nrf_memobj_write and @ref nrf_memobj_read.
   * 
   * @param[in] p_pool     Pointer to the memobj pool instance structure.
   * @param[in] size       Data size of requested object.
   *
   * @return  Pointer to a memory object or NULL if the requested size cannot be allocated.
   */
  nrf_memobj_t * nrf_memobj_alloc(nrf_memobj_pool_t const * p_pool,
                                  size_t size);
  
  /**
   * @brief Function for indicating that a memory object is used and cannot be freed.
   *
   * Memory object can be shared and reused between multiple modules and this mechanism ensures that
   * object is freed when no longer used by any module. Memory object has a counter which is incremented
   * whenever this function is called. @ref nrf_memobj_put function decrements the counter.
   *
   * @param[in] p_obj  Pointer to memory object.
   */
  void nrf_memobj_get(nrf_memobj_t const * p_obj);
  
  
  /**
   * @brief Function for indicated that memory object is no longer used by the module and can be freed
   * if no other module is using it.
   *
   * Memory object is returned to the pool if internal counter reaches 0 after decrementing. It means
   * that no other module is needing it anymore.
   *
   * @note Memory object holds pointer to the pool which was used to allocate it so it does not have
   * to be provided explicitly to this function.
   *
   * @param[in] p_obj  Pointer to memory object.
   */
  void nrf_memobj_put(nrf_memobj_t * p_obj);
  
  
  /**
   * @brief Function for forcing freeing of the memory object.
   *
   * @note This function should be use with caution because it can lead to undefined behavior of the
   * modules since modules using the memory object are not aware that it has been freed.
   *
   * @param[in] p_obj  Pointer to memory object.
   */
  void nrf_memobj_free(nrf_memobj_t * p_obj);
  
  /**
   * @brief Function for writing data to the memory object.
   *
   * @param[in]      p_obj  Pointer to memory object.
   * @param[in]      p_data Pointer to data to be written to the memory object.
   * @param[in]      len    Amount of data to be written to the memory object.
   * @param[in]      offset Offset.
   */
  void nrf_memobj_write(nrf_memobj_t * p_obj,
                        void *         p_data,
                        size_t         len,
                        size_t         offset);
  
  /**
   * @brief Function for reading data from the memory object.
   *
   * @param[in]     p_obj  Pointer to memory object.
   * @param[in]     p_data Pointer to the destination buffer.
   * @param[in]     len    Amount of data to be read from the memory object.
   * @param[in]     offset Offset.
   */
  void nrf_memobj_read(nrf_memobj_t * p_obj,
                       void *         p_data,
                       size_t         len,
                       size_t         offset);
  
  #ifdef __cplusplus
  }
  #endif
  
  #endif //NRF_MEMOBJ_H
  
  /** @} */
  