Memory Object module

Functions for controlling a memory object. More...

Modules
	Linked memory allocator module configuration

Macros
#define	NRF_MEMOBJ_STD_HEADER_SIZE   sizeof(uint32_t)
#define	NRF_MEMOBJ_POOL_DEF(_name, _chunk_size, _pool_size)
	Macro for creating an nrf_memobj pool. More...

Typedefs
typedef nrf_balloc_t	nrf_memobj_pool_t
	Pool of memory objects.
typedef void *	nrf_memobj_t
	Memory object handle.

Functions
ret_code_t	nrf_memobj_pool_init (nrf_memobj_pool_t const *p_pool)
	Function for initializing the memobj pool instance. More...
nrf_memobj_t *	nrf_memobj_alloc (nrf_memobj_pool_t const *p_pool, size_t size)
	Function for allocating a memobj with a requested size. More...
void	nrf_memobj_get (nrf_memobj_t const *p_obj)
	Function for indicating that a memory object is used and cannot be freed. More...
void	nrf_memobj_put (nrf_memobj_t *p_obj)
	Function for indicated that memory object is no longer used by the module and can be freed if no other module is using it. More...
void	nrf_memobj_free (nrf_memobj_t *p_obj)
	Function for forcing freeing of the memory object. More...
void	nrf_memobj_write (nrf_memobj_t *p_obj, void *p_data, size_t len, size_t offset)
	Function for writing data to the memory object. More...
void	nrf_memobj_read (nrf_memobj_t *p_obj, void *p_data, size_t len, size_t offset)
	Function for reading data from the memory object. More...

Detailed Description

Functions for controlling a memory object.

Macro Definition Documentation

#define NRF_MEMOBJ_POOL_DEF	(		_name,
			_chunk_size,
			_pool_size
	)

Value:

STATIC_ASSERT((_chunk_size) > sizeof(uint32_t)); \
 NRF_BALLOC_DEF(_name, ((_chunk_size)+NRF_MEMOBJ_STD_HEADER_SIZE), (_pool_size))

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.

Parameters

_name	Name of the instance.
_chunk_size	Size of a single chunk.
_pool_size	Number of chunks in the pool.

#define NRF_MEMOBJ_STD_HEADER_SIZE   sizeof(uint32_t)

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.

 _____________________        _____________________          _____________________
|                     |      |                     |        |                     |
|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

Function Documentation

nrf_memobj_t* nrf_memobj_alloc	(	nrf_memobj_pool_t const *	p_pool,
		size_t	size
	)

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: nrf_memobj_write and nrf_memobj_read.

Parameters

[in]	p_pool	Pointer to the memobj pool instance structure.
[in]	size	Data size of requested object.

Returns

Pointer to a memory object or NULL if the requested size cannot be allocated.

void nrf_memobj_free

(

nrf_memobj_t *

p_obj

)

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.

Parameters

[in]

p_obj

Pointer to memory object.

void nrf_memobj_get

(

nrf_memobj_t const *

p_obj

)

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. nrf_memobj_put function decrements the counter.

Parameters

[in]

p_obj

Pointer to memory object.

ret_code_t nrf_memobj_pool_init

(

nrf_memobj_pool_t const *

p_pool

)

Function for initializing the memobj pool instance.

This function initializes the pool.

Parameters

[in]

p_pool

Pointer to the memobj pool instance structure.

Returns

NRF_SUCCESS on success, otherwise an error code.

void nrf_memobj_put

(

nrf_memobj_t *

p_obj

)

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.

Parameters

[in]

p_obj

Pointer to memory object.

void nrf_memobj_read	(	nrf_memobj_t *	p_obj,
		void *	p_data,
		size_t	len,
		size_t	offset
	)

Function for reading data from the memory object.

Parameters

[in]	p_obj	Pointer to memory object.
[in]	p_data	Pointer to the destination buffer.
[in]	len	Amount of data to be read from the memory object.
[in]	offset	Offset.

void nrf_memobj_write	(	nrf_memobj_t *	p_obj,
		void *	p_data,
		size_t	len,
		size_t	offset
	)

Function for writing data to the memory object.

Parameters

[in]	p_obj	Pointer to memory object.
[in]	p_data	Pointer to data to be written to the memory object.
[in]	len	Amount of data to be written to the memory object.
[in]	offset	Offset.