🚀 go-pugleaf

c51903@dm.uibk.ac.at (Meinhard Berger) wrote:

>to allocate bigger memory
>ALLOCATE( VAR a: ADDRESS; size: CARDINAL );
> allocates "size" BYTES from the heap
>HeapAllocate( Source: HeapRecPtr; VAR a: ADDRESS; size: CARDINAL );
> allocates "size" UNITS from the allocated heap "source".
> 
> ALLOCATEs limit is 64K
> HeapAllocate has a varying limit, as size depends on your
>  memory model, under large it is 16, so the limit is 1MB,
>  if its available of course. "source" is simply STORAGE.MainHeap
>  (2mk).

In case you found that hard to follow, it means the _unit_ of 'size'
varies according to the memory model. In small and medium models it's
a byte and in other models it's a paragraph (16 bytes). 

The total memory even in the large models will still be restricted to
what is left out of the 1Mb direct address space. STORAGE.MainHeap
will be pointing at what is available to the program in the DOS 640K
space. "Source" _could_ be some other area you have set up using
STORAGE.MakeHeap; e.g. "backfilled" RAM above 640K that your program
has determined is available. As you're unlikely to find as much as you
want up there, I wouldn't worry about that too much - it's just to
show that "source" could be another heap altogether.

With the TopSpeed DOS Extender, you get "huge" pointers and all the
attendant joys of managing a segmented address space in a protected
environment.

 
Martin Rand            | Tel: (44) 1703 252445 |
Highfield Software Ltd | Fax: (44) 1703 252445 |
Southampton, UK        |                       |