OpenEuphoria

Re: allocated memory enlargement

• Posted by "Kat" <gertie at visionsix.com> Mar 27, 2004
• 532 views

On 26 Mar 2004, at 18:48, Allen Robnett wrote:

> 
> http://click.topica.com/caab4CEb1dd66b6816za/ Crazy Aaron Enterprises
> 
> 
> Tommy Carlier wrote:
> 
> >kat wrote
> >  
> >
> >>Er,, i ever thought i'd be asking this, but if i have a block of memory 
> >>allocated
> >>on windows, and i want to enlarge it without changing it contents, can i?
> >>How?
> >>
> >>Kat
> >>    
> >>
> >If you have allocated it with the Euphoria-function allocate, you could do it
> >like this:
> >
> >function resize_memblock(atom old_mem, integer old_size, integer new_size)
> >	atom new_mem 	if old_size = new_size then return old_mem end if 	new_mem =
> >allocate(new_size) 	if old_size < new_size then 		mem_copy(new_mem, old_mem,
> >old_size) 	else 		mem_copy(new_mem, old_mem, new_size) 	end if 	free(old_mem)
> >	return new_mem end function
> >
> >-- Using the function:
> >
> >pointer = resize_memblock(pointer, size, size + 1000) -- adds 1000 bytes 
> >to the memory block
> >  
> >
> I am very pleased to see this. Not being familiar with mem_copy, I had 
> wondered about a subject that Kat raised earlier regarding inserting a 
> new new record into a memory buffered file. mem_copy makes it easy to 
> make room for the new record. (if you are building the file in a 
> specific order, alphabetical, for instance.)

But the code above is not *expand* file, it's *making another new* file! 
Freeing the space the file occupies is definitely changing the contents of the 
existing space.

Try to do that on a 385 megabyte system when you need to do a few 
hundred inserts real fast in a 200 meg ramdisk. The OS will page the files to 
disk (if you are lucky, but dos won't page to virtual ram), and your speed will 
be slower than if you used a disk-based system in the first place. Nix may 
be faster than Windows in this regard.

Kat