🚀 go-pugleaf

A general question (re memory management under DOS).

If I allocate a pointer to 64K in Borland C.
unsigned char *ptr = farmalloc(0xFFFF);

The pointer has some segment, and the offset is always
4 (four).  This means that the last few bytes of data are
actually in the NEXT segment !!  If the pointer is declared
to be far, then these bytes roll to the bottom of the same
segment.

My question is twofold :

(1)  What does DOS do with these 4 extra bytes - are they
used by the memory manager of DOS (or, in an even weirder
scenario, is this a quirk of Borland C, and would not appear
in Microsoft C) ???

(2)  I need to have a 64K (EXACTLY) byte memory block in an
application, and would like to be aligned from the base of
the segment (i.e. an offset of 0 (zero) not 4 (four)), so
if I just say "ptr-=4", the pointer will now be at the base
of the segment, but..... is this inviting disaster ???

Does someone out there know the answers to this (what I
consider to be a) quirk ?



-- 
					What's the point in callin' shots
Brian Parkinson				This cue ain't straight in line
<parki@csri.toronto.edu.ca>		The cue-ball's made of styrofoam
					And no-one's got the time