🚀 go-pugleaf

johna@mobdig.ncal.mobdig.com (John Antypas) writes:

>Here's one for the DOS veterans...

>In my Microsoft C (or Borland) program, I allocate memory via malloc et al.
>in small model.  The set of statements proceeds roughly as follows:
>ptr1 = malloc(SIZEA);
>...
>ptr2 = malloc(SIZEB);
>...
>ptr3 = malloc(SIZEC);
>...
>if (_memavl() < MIN_SIZE) { error code here }
>...
>free(ptr2);
>...
>if (_memavl() < MIN_SIZE) { error code here }
>...

>What SHOULD happen is DOS should report that SIZEA+SIZEC bytes of 
>memory are no longer available.  Instead it reports SIZEA+SIZEB+SIZEC
>are used (or rather that top-SIZEA-SIZEB-SIZEC are available).
>This may be correct for a heap, but it causes trouble for me.  
>I can't be sure the heap will 'unwind' in the order wound.

>Is there any way to find the actual amount of memory available for
>allocation at any moment that takes into account the memory just
>allocated or freed?  By the way, I'm not wed to using malloc/free,
>if anything else works, let me know?

When DOS frees memory of SIZEB, it is left with SIZEA | free | SIZEC | free
and so the _contiguous_ memory available starts after SIZEC.

Misha.