Memory block management functions

Data Structures
struct	memb_blocks
Files
file	memb.c
file	memb.h
Defines
#define	MEMB_CONCAT2(s1, s2)   s1##s2
#define	MEMB_CONCAT(s1, s2)   MEMB_CONCAT2(s1, s2)
#define	MEMB(name, structure, num)
Functions
void	memb_init (struct memb_blocks *m)
void *	memb_alloc (struct memb_blocks *m)
char	memb_free (struct memb_blocks *m, void *ptr)

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Detailed Description

The memory block allocation routines provide a simple yet powerful set of functions for managing a set of memory blocks of fixed size. A set of memory blocks is statically declared with the MEMB() macro. Memory blocks are allocated from the declared memory by the memb_alloc() function, and are deallocated with the memb_free() function.

Note:

Because of namespace clashes only one MEMB() can be declared per C module, and the name scope of a MEMB() memory block is local to each C module.

The following example shows how to declare and use a memory block called "cmem" which has 8 chunks of memory with each memory chunk being 20 bytes large.

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Define Documentation

#define MEMB	(	name,
		structure,
		num		)

Value:

static char MEMB_CONCAT(name,_memb_count)[num]; \
        static structure MEMB_CONCAT(name,_memb_mem)[num]; \
        static struct memb_blocks name = {sizeof(structure), num, \
                                          MEMB_CONCAT(name,_memb_count), \
                                          (void *)MEMB_CONCAT(name,_memb_mem)}

Declare a memory block.

This macro is used to staticall declare a block of memory that can be used by the block allocation functions. The macro statically declares a C array with a size that matches the specified number of blocks and their individual sizes.

Example:

MEMB(connections, sizeof(struct connection), 16);

Parameters:

	name	The name of the memory block (later used with memb_init(), memb_alloc() and memb_free()).
	size	The size of each memory chunk, in bytes.
	num	The total number of memory chunks in the block.

#define MEMB_CONCAT	(	s1,
		s2		)	MEMB_CONCAT2(s1, s2)

#define MEMB_CONCAT2	(	s1,
		s2		)	s1##s2

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Function Documentation

void * memb_alloc

(

struct memb_blocks *

m

)

Allocate a memory block from a block of memory declared with MEMB().

Parameters:

m

A memory block previosly declared with MEMB().

char memb_free	(	struct memb_blocks *	m,
		void *	ptr
	)

Deallocate a memory block from a memory block previously declared with MEMB().

Parameters:

	m	m A memory block previosly declared with MEMB().
	ptr	A pointer to the memory block that is to be deallocated.

Returns:

The new reference count for the memory block (should be 0 if successfully deallocated) or -1 if the pointer "ptr" did not point to a legal memory block.

void memb_init

(

struct memb_blocks *

m

)

Initialize a memory block that was declared with MEMB().

Parameters:

m

A memory block previosly declared with MEMB().