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/** @file
 *
 * @defgroup memory_pool Memory pool
 * @{
 * @ingroup app_common
 *
 * @brief Memory pool implementation
 *
 * Memory pool implementation, based on circular buffer data structure, which supports asynchronous 
 * processing of RX data. The current default implementation supports 1 TX buffer and 4 RX buffers.
 * The memory managed by the pool is allocated from static storage instead of heap. The internal 
 * design of the circular buffer implementing the RX memory layout is illustrated in the picture 
 * below. 
 *
 * @image html memory_pool.png "Circular buffer design"
 *
 * The expected call order for the RX APIs is as follows:
 * - hci_mem_pool_rx_produce
 * - hci_mem_pool_rx_data_size_set
 * - hci_mem_pool_rx_extract
 * - hci_mem_pool_rx_consume
 *
 * @warning If the above mentioned expected call order is violated the end result can be undefined.
 *
 * \par Component specific configuration options
 *
 * The following compile time configuration options are available to suit various implementations:
 * - TX_BUF_SIZE TX buffer size in bytes. 
 * - RX_BUF_SIZE RX buffer size in bytes. 
 * - RX_BUF_QUEUE_SIZE RX buffer element size.
 */
 
#ifndef HCI_MEM_POOL_H__
#define HCI_MEM_POOL_H__

#include <stdint.h>
#include "nrf_error.h"

/**@brief Function for opening the module.
 *
 * @retval NRF_SUCCESS          Operation success. 
 */
uint32_t hci_mem_pool_open(void);

/**@brief Function for closing the module.
 *
 * @retval NRF_SUCCESS          Operation success. 
 */
uint32_t hci_mem_pool_close(void);

/**@brief Function for allocating requested amount of TX memory.
 *
 * @param[out] pp_buffer        Pointer to the allocated memory.
 *
 * @retval NRF_SUCCESS          Operation success. Memory was allocated.
 * @retval NRF_ERROR_NO_MEM     Operation failure. No memory available for allocation.
 * @retval NRF_ERROR_NULL       Operation failure. NULL pointer supplied.  
 */
uint32_t hci_mem_pool_tx_alloc(void ** pp_buffer);
 
/**@brief Function for freeing previously allocated TX memory.
 *
 * @note Memory management follows the FIFO principle meaning that free() order must match the 
 *       alloc(...) order, which is the reason for omitting exact memory block identifier as an 
 *       input parameter.
 *
 * @retval NRF_SUCCESS          Operation success. Memory was freed.
 */
uint32_t hci_mem_pool_tx_free(void);
 
/**@brief Function for producing a free RX memory block for usage.
 *
 * @note Upon produce request amount being 0, NRF_SUCCESS is returned.   
 *
 * @param[in]  length           Amount, in bytes, of free memory to be produced.
 * @param[out] pp_buffer        Pointer to the allocated memory.
 *
 * @retval NRF_SUCCESS          Operation success. Free RX memory block produced.
 * @retval NRF_ERROR_NO_MEM     Operation failure. No suitable memory available for allocation.
 * @retval NRF_ERROR_DATA_SIZE  Operation failure. Request size exceeds limit.  
 * @retval NRF_ERROR_NULL       Operation failure. NULL pointer supplied.   
 */
uint32_t hci_mem_pool_rx_produce(uint32_t length, void ** pp_buffer);

/**@brief Function for setting the length of the last produced RX memory block.
 *
 * @warning If call to this API is omitted the end result is that the following call to 
 *          mem_pool_rx_extract will return incorrect data in the p_length output parameter.
 *
 * @param[in]  length           Amount, in bytes, of actual memory used.
 *
 * @retval NRF_SUCCESS          Operation success. Length was set.
 */
uint32_t hci_mem_pool_rx_data_size_set(uint32_t length);
 
/**@brief Function for extracting a packet, which has been filled with read data, for further 
 * processing.
 *
 * @param[out] pp_buffer        Pointer to the packet data.
 * @param[out] p_length         Length of packet data in bytes.  
 *
 * @retval NRF_SUCCESS          Operation success. 
 * @retval NRF_ERROR_NO_MEM     Operation failure. No packet available to extract.
 * @retval NRF_ERROR_NULL       Operation failure. NULL pointer supplied.    
 */
uint32_t hci_mem_pool_rx_extract(uint8_t ** pp_buffer, uint32_t * p_length);
 
/**@brief Function for freeing previously extracted packet, which has been filled with read data.
 *
 * @param[in] p_buffer             Pointer to consumed buffer.
 *
 * @retval NRF_SUCCESS             Operation success. 
 * @retval NRF_ERROR_NO_MEM        Operation failure. No packet available to free. 
 * @retval NRF_ERROR_INVALID_ADDR  Operation failure. Not a valid pointer. 
 */
uint32_t hci_mem_pool_rx_consume(uint8_t * p_buffer);
 
#endif // HCI_MEM_POOL_H__
 
/** @} */