include/mempool.h File Reference

Memory pool allocator. More...

#include <types.h>

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Data Structures
struct	mem_pool
	Memory pool. More...
Functions
void	mem_pool_init (struct mem_pool *pool, void *start, size_t size, size_t objsize, unsigned int align_order)
	Initialize a memory pool.
void	mem_pool_init_physmem (struct mem_pool *mempool, struct physmem_pool *phys_pool, unsigned int nr_objects, size_t objsize, unsigned int align_order)
	Initialize a memory pool using the physmem allocator.
void *	mem_pool_alloc (struct mem_pool *pool)
	Allocate an object from a memory pool.
void	mem_pool_free (struct mem_pool *pool, const void *obj)
	Free an object previously allocated from a memory pool.

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Detailed Description

Memory pool allocator.

A memory pool contains a number of objects of the same size that can be allocated in constant time. This is useful for allocating request structures, etc.

Memory pool objects are managed in Last-In-First-Out (LIFO) order to maximize the chances of allocating a cache-hot object.

See also:

dmapool.h

• Compiler: IAR EWAVR32 and GNU GCC for AVR32
• Supported devices: All AVR32 devices with a USBB module can be used.
• AppNote:

Author:

Atmel Corporation: http://www.atmel.com
Support and FAQ: http://support.atmel.no/

Definition in file mempool.h.

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Function Documentation

void* mem_pool_alloc

(

struct mem_pool *

pool

)

Allocate an object from a memory pool.

Parameters:

pool

The memory pool from which the object is allocated.

Returns:

A pointer to the newly allocated object, or NULL if the pool is exhausted.

Definition at line 170 of file mempool.c.

References assert, cpu_irq_restore(), cpu_irq_save(), and mem_pool::freelist.

Referenced by usb_req_alloc().

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void mem_pool_free	(	struct mem_pool *	pool,
		const void *	obj
	)

Free an object previously allocated from a memory pool.

The caller is responsible for making sure obj was originally allocated from pool. If an object is freed into a different pool, the integrity of the pool can no longer be guaranteed.

Note:

The object ceases to exist the moment this function is called, so even though this function casts away the const qualifier internally, it doesn't technically modify the object. Having the const qualifier there allows callers to keep const pointers to objects which are never modified after initialization.

Parameters:

	pool	The memory pool which the object belongs to.
	obj	The object to be freed.

Definition at line 202 of file mempool.c.

References assert, cpu_irq_restore(), cpu_irq_save(), and mem_pool::freelist.

Referenced by usb_req_free().

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void mem_pool_init	(	struct mem_pool *	pool,
		void *	start,
		size_t	size,
		size_t	objsize,
		unsigned int	align_order
	)

Initialize a memory pool.

This function will initialize a memory pool, populating its freelist with objects tightly packed into the specified memory range.

All objects in the pool are guaranteed to be aligned to a multiple of bytes. For example, if align_order is 4, each object will start on a 16-byte boundary.

Parameters:

	pool	The memory pool to be initialized.
	start	The memory area to be used for object storage.
	size	The size of the memory area in bytes.
	objsize	The size of each object in bytes.
	align_order	log2 of the minimum object alignment in bytes.

Precondition:

objsize must be larger than the size of a pointer.

size must be large enough to hold at least one object.

Definition at line 88 of file mempool.c.

References assert, dbg_printf, mem_pool::freelist, and round_up().

Referenced by mem_pool_init_physmem().

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void mem_pool_init_physmem	(	struct mem_pool *	mempool,
		struct physmem_pool *	phys_pool,
		unsigned int	nr_objects,
		size_t	objsize,
		unsigned int	align_order
	)

Initialize a memory pool using the physmem allocator.

This function will grab enough physical memory for nr_objects and use this to initialize mempool.

Parameters:

	mempool	The memory pool to be initialized.
	phys_pool	The physical memory pool from which to grab memory
	nr_objects	The number of objects in the pool
	objsize	The size of each object in bytes.
	align_order	log2 of the minimum object alignment in bytes.

Precondition:

nr_objects must be at least one.

There must be enough available memory in phys_pool.

objsize must be larger than the size of a pointer.

See also:

mem_pool_init()

Definition at line 139 of file mempool.c.

References assert, mem_pool_init(), PHYS_MAP_WRBACK, PHYS_MAP_WRBUF, physmem_alloc(), PHYSMEM_ALLOC_ERR, physmem_map(), and round_up().

Referenced by usb_init().

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