cpp_freertos::MemoryPool Class Reference

#include <mem_pool.hpp>

Collaboration diagram for cpp_freertos::MemoryPool:

Public Member Functions
	MemoryPool (int itemSize, int itemCount, int alignment)
	MemoryPool (int itemSize, void *preallocatedMemory, int preallocatedMemorySize, int alignment)
void	AddMemory (int itemCount)
void	AddMemory (void *preallocatedMemory, int preallocatedMemorySize)
void *	Allocate ()
void	Free (void *item)

Private Member Functions
void	CalculateValidAlignment ()
void	CalculateItemSize ()
	~MemoryPool ()

Private Attributes
Mutex *	Lock
int	ItemSize
int	Alignment
std::list< void * >	FreeItems

Detailed Description

Memory Pools are fixed size allocations to prevent fragmentation.

This is a new feature to FreeRTOS Wrappers and is not in and of itself a wrapper.

Memory Pools are thread safe, but cannot be used in ISR context. The OS must be running, because these use Mutexes to protect internal data structures.

Definition at line 140 of file mem_pool.hpp.

Constructor & Destructor Documentation

MemoryPool() [1/2]

MemoryPool::MemoryPool	(	int	itemSize,
		int	itemCount,
		int	alignment
	)

Constructor to create a Memory Pool.

This constructor uses the system malloc to actually obtain the memory.

Parameters

itemSize	How big is each item you want to allocate.
itemCount	How many items max do you want to allocate at once.
Alignment	Power of 2 value denoting on which address boundary the memory will be aligned to. Must be at least sizeof(unsigned char *).

Exceptions

MemoryPoolMallocException	on failure.
MemoryPoolBadAlignmentException	on failure.

Definition at line 96 of file cmem_pool.cpp.

MemoryPool() [2/2]

MemoryPool::MemoryPool	(	int	itemSize,
		void *	preallocatedMemory,
		int	preallocatedMemorySize,
		int	alignment
	)

Constructor to create a Memory Pool.

This constructor uses memory you pass in to actually create the pool. This constructor does not throw.

Parameters

itemSize	How big is each item you want to allocate.
preallocatedMemory	Pointer to the preallocated memory you are dedicating to this pool.
preallocatedMemorySize	How big is the buffer you are passing in.
Alignment	Power of 2 value denoting on which address boundary the memory will be aligned to. Must be at least sizeof(unsigned char *).

Exceptions

MemoryPoolBadAlignmentException

on failure.

Definition at line 125 of file cmem_pool.cpp.

~MemoryPool()

cpp_freertos::MemoryPool::~MemoryPool ( )

private

To correctly delete a Memory Pool, we'd have to guarantee that all allocations had been returned to us. We side step this issue by making the destructor private so it can't be accessed.

Member Function Documentation

AddMemory() [1/2]

void MemoryPool::AddMemory

(

int

itemCount

)

Allows you to add memory to a MemoryPool.

Items will be the same size as you initially asked for.

Parameters

itemCount

How many more items max do you want to allocate

Exceptions

MemoryPoolMallocException

on failure.

Definition at line 170 of file cmem_pool.cpp.

AddMemory() [2/2]

void MemoryPool::AddMemory	(	void *	preallocatedMemory,
		int	preallocatedMemorySize
	)

Allows you to add memory to a MemoryPool.

Items will be the same size as you initially asked for.

Parameters

preallocatedMemory	Pointer to the preallocated memory you are dedicating to this pool.
preallocatedMemorySize	How big is the buffer you are passing in.

Definition at line 192 of file cmem_pool.cpp.

Allocate()

void * MemoryPool::Allocate

(

)

Allocate an item from the pool.

Returns

Pointer of the memory or NULL if the pool is empty.

Definition at line 149 of file cmem_pool.cpp.

CalculateItemSize()

void MemoryPool::CalculateItemSize ( )

private

Calculate the true item size, based on alignment.

Definition at line 78 of file cmem_pool.cpp.

CalculateValidAlignment()

void MemoryPool::CalculateValidAlignment ( )

private

Adjusts and validates the alignment argument passed in the ctor.

Guarantee that the alignment is the size of a pointer.

Definition at line 49 of file cmem_pool.cpp.

Free()

void MemoryPool::Free

(

void *

item

)

Returns the item back to it's pool.

Note

There is no checking that the item is actually valid to be returned to this pool.

Definition at line 163 of file cmem_pool.cpp.

Member Data Documentation

Alignment

int cpp_freertos::MemoryPool::Alignment

private

The overall alignment of an item.

Definition at line 246 of file mem_pool.hpp.

FreeItems

std::list<void *> cpp_freertos::MemoryPool::FreeItems

private

All of the real work is done with STL lists.

Definition at line 251 of file mem_pool.hpp.

ItemSize

int cpp_freertos::MemoryPool::ItemSize

private

Save the item size for additions.

Definition at line 241 of file mem_pool.hpp.

Lock

Mutex* cpp_freertos::MemoryPool::Lock

private

Standard Mutex to allow thread safety.

Definition at line 236 of file mem_pool.hpp.

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The documentation for this class was generated from the following files:

• mem_pool.hpp
• cmem_pool.cpp