Memory block management functions

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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.

 #include "memb.h"
 
 MEMB(cmem, 20, 8);

 int main(int argc, char *argv[]) {
    char *ptr;
    
    memb_init(&cmem);

    ptr = memb_alloc(&cmem);

    if(ptr != NULL) {
       do_something(ptr);
    } else {
       printf("Could not allocate memory.\n");
    }

    if(memb_free(&cmem, ptr) == 0) {
       printf("Deallocation succeeded.\n");
    }
 }

Files
file	memb.h
	Memory block allocation routines.
file	memb.c
	Memory block allocation routines.
Defines
#define	MEMB(name, size, num)
	Declare a memory block.
Functions
void	memb_init (struct memb_blocks *m)
	Initialize a memory block that was declared with MEMB().
char *	memb_alloc (struct memb_blocks *m)
	Allocate a memory block from a block of memory declared with MEMB().
char	memb_ref (struct memb_blocks *m, char *ptr)
	Increase the reference count for a memory chunk.
char	memb_free (struct memb_blocks *m, void *ptr)
	Deallocate a memory block from a memory block previously declared with MEMB().

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Define Documentation

#define MEMB (  name, size, num   )

Value: static char MEMB_CONCAT(name,_memb_mem)[(size + 1) * num]; \ static struct memb_blocks name = {size, num, 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.

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Function Documentation

char * 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().

char memb_ref (  struct memb_blocks *  m, char *  ptr )

Increase the reference count for a memory chunk. Note: No sanity checks are currently made. Parameters: m  m A memory block previosly declared with MEMB(). ptr  A pointer to the memory chunk for which the reference count should be increased. Returns: The new reference count.

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