casting?

[audinue]

Btw, I want to explicitely 'hide' my structure.

Let say I have a structure:

typedef struct
{
    void *base;
    unsigned short initialSize;
    unsigned short increment;
    unsigned int allocated;
    unsigned int elementSize;

} _MEMORY_POOL, *_PMEMORY_POOL;

and a typedef:

typedef void *MEMORY_POOL;

void *_pcheck(MEMORY_POOL p, unsigned int offset)
{
    if(offset >= ((_PMEMORY_POOL)p)->allocated)
        if((((_PMEMORY_POOL)p)->base = realloc(((_PMEMORY_POOL)p)->base, (((_PMEMORY_POOL)p)->allocated = ++((_PMEMORY_POOL)p)->increment * ((_PMEMORY_POOL)p)->initialSize) * ((_PMEMORY_POOL)p)->elementSize)) == NULL)
            abort();

    return ((_PMEMORY_POOL)p)->base;
}

Is it a good idea to do something like this?