nRF51 SDK: Memory pool

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Memory pool
SDK Common Libraries

Memory pool implementation. More...

## Modules

| Memory Pool Internal
| Memory pool internal definitions.

## Functions

uint32_t | hci_mem_pool_open (void)
| Function for opening the module. More...
uint32_t | hci_mem_pool_close (void)
| Function for closing the module. More...
uint32_t | hci_mem_pool_tx_alloc (void **pp_buffer)
| Function for allocating requested amount of TX memory. More...
uint32_t | hci_mem_pool_tx_free (void)
| Function for freeing previously allocated TX memory. More...
uint32_t | hci_mem_pool_rx_produce (uint32_t length, void **pp_buffer)
| Function for producing a free RX memory block for usage. More...
uint32_t | hci_mem_pool_rx_data_size_set (uint32_t length)
| Function for setting the length of the last produced RX memory block. More...
uint32_t | hci_mem_pool_rx_extract (uint8_t **pp_buffer, uint32_t *p_length)
| Function for extracting a packet, which has been filled with read data, for further processing. More...
uint32_t | hci_mem_pool_rx_consume (uint8_t *p_buffer)
| Function for freeing previously extracted packet, which has been filled with read data. More...

## Detailed Description

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.

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.

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.

## Function Documentation

uint32_t hci_mem_pool_close | ( | void |  | ) |

Function for closing the module.

Return values

  NRF_SUCCESS | Operation success.

uint32_t hci_mem_pool_open | ( | void |  | ) |

Function for opening the module.

Return values

  NRF_SUCCESS | Operation success.

uint32_t hci_mem_pool_rx_consume | ( | uint8_t * | p_buffer | ) |

Function for freeing previously extracted packet, which has been filled with read data.

Parameters

  [in] | p_buffer | Pointer to consumed buffer.

Return values

  NRF_SUCCESS | Operation success.
  NRF_ERROR_NO_MEM | Operation failure. No packet available to free.
  NRF_ERROR_INVALID_ADDR | Operation failure. Not a valid pointer.

uint32_t hci_mem_pool_rx_data_size_set | ( | uint32_t | length | ) |

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.

Parameters

  [in] | length | Amount, in bytes, of actual memory used.

Return values

  NRF_SUCCESS | Operation success. Length was set.

uint32_t hci_mem_pool_rx_extract | ( | uint8_t ** | pp_buffer,
|  | uint32_t * | p_length
| ) |  |

Function for extracting a packet, which has been filled with read data, for further processing.

Parameters

  [out] | pp_buffer | Pointer to the packet data.
  [out] | p_length | Length of packet data in bytes.

Return values

  NRF_SUCCESS | Operation success.
  NRF_ERROR_NO_MEM | Operation failure. No packet available to extract.
  NRF_ERROR_NULL | Operation failure. NULL pointer supplied.

uint32_t hci_mem_pool_rx_produce | ( | uint32_t | length,
|  | void ** | pp_buffer
| ) |  |

Function for producing a free RX memory block for usage.

Note
  Upon produce request amount being 0, NRF_SUCCESS is returned.

Parameters

  [in] | length | Amount, in bytes, of free memory to be produced.
  [out] | pp_buffer | Pointer to the allocated memory.

Return values

  NRF_SUCCESS | Operation success. Free RX memory block produced.
  NRF_ERROR_NO_MEM | Operation failure. No suitable memory available for allocation.
  NRF_ERROR_DATA_SIZE | Operation failure. Request size exceeds limit.
  NRF_ERROR_NULL | Operation failure. NULL pointer supplied.

uint32_t hci_mem_pool_tx_alloc | ( | void ** | pp_buffer | ) |

Function for allocating requested amount of TX memory.

Parameters

  [out] | pp_buffer | Pointer to the allocated memory.

Return values

  NRF_SUCCESS | Operation success. Memory was allocated.
  NRF_ERROR_NO_MEM | Operation failure. No memory available for allocation.
  NRF_ERROR_NULL | Operation failure. NULL pointer supplied.

uint32_t hci_mem_pool_tx_free | ( | void |  | ) |

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.

Return values

  NRF_SUCCESS | Operation success. Memory was freed.