Managed memory allocator

The managed memory allocator is a fragmentation-free memory manager.

It keeps the allocated memory free from fragmentation by compacting the memory when blocks are freed. A program that uses the managed memory module cannot be sure that allocated memory stays in place. Therefore, a level of indirection is used: access to allocated memory must always be done using a special macro.

Note

This module has not been heavily tested.

Data Structures
struct	mmem

Files
file	mmem.c
	Implementation of the managed memory allocator
file	mmem.h
	Header file for the managed memory allocator

Macros
#define	MMEM_PTR(m)
	Get a pointer to the managed memory. More...
#define	MMEM_SIZE   4096

Functions
	LIST (mmemlist)
int	mmem_alloc (struct mmem *m, unsigned int size)
	Allocate a managed memory block. More...
void	mmem_free (struct mmem *m)
	Deallocate a managed memory block. More...
void	mmem_init (void)
	Initialize the managed memory module. More...

Variables
unsigned int	avail_memory
static char	memory [MMEM_SIZE]

#define MMEM_PTR

(

m

)

Get a pointer to the managed memory.

Parameters

m	A pointer to the struct mmem

Returns

A pointer to the memory block, or NULL if memory could not be allocated.

Author

Adam Dunkels

        This macro is used to get a pointer to a memory block
        allocated with mmem_alloc().

#define MMEM_SIZE   4096

Referenced by mmem_alloc(), mmem_free(), and mmem_init().

LIST

(

mmemlist

)

int mmem_alloc	(	struct mmem *	m,
		unsigned int	size
	)

Allocate a managed memory block.

Parameters

m	A pointer to a struct mmem.
size	The size of the requested memory block

Returns

Non-zero if the memory could be allocated, zero if memory was not available.

Author

Adam Dunkels

        This function allocates a chunk of managed memory. The
        memory allocated with this function must be deallocated
        using the mmem_free() function.

        \note This function does NOT return a pointer to the
        allocated memory, but a pointer to a structure that
        contains information about the managed memory. The
        macro MMEM_PTR() is used to get a pointer to the
        allocated memory.

References avail_memory, list_add(), memory, MMEM_SIZE, ptr, and size.

void mmem_free

(

struct mmem *

m

)

Deallocate a managed memory block.

Parameters

m	A pointer to the managed memory block

Author

Adam Dunkels

        This function deallocates a managed memory block that
        previously has been allocated with mmem_alloc().

References avail_memory, list_remove(), memory, MMEM_SIZE, n, next, NULL, ptr, and size.

void mmem_init

(

void

)

Initialize the managed memory module.

Author

Adam Dunkels

        This function initializes the managed memory module and
        should be called before any other function from the
        module.

References avail_memory, list_init(), and MMEM_SIZE.

unsigned int avail_memory

Referenced by mmem_alloc(), mmem_free(), and mmem_init().

char memory[MMEM_SIZE]

static

Referenced by mmem_alloc(), and mmem_free().