Re: No realloc

[roberto@... (Roberto Ierusalimschy)]

> I'm considering using Lua on a system offering no realloc(): only 
> malloc() and free().
> 
> What loss of performance could I expect by using realloc=free+malloc, 
> assuming the allocator is stupid enough not to immediately recycle the 
> same block when there is enough space?

Why don't you test? It is quite easy to change the allocation function not
to use realloc; something like this (untested):


void *l_alloc (void *ud, void *block, size_t oldsize, size_t size) {
  if (size == 0) {
    free(block);
    return NULL;
  }
  else {
    void *newblock = malloc(size);  /* alloc a new block */
    if (newblock == NULL) return NULL;
    if (block) {
      size_t commonsize = (oldsize < size) ? oldsize : size;
      memcpy(newblock, block, commonsize);
      free(block);
    }
    return newblock;
  }
}



-- Roberto