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From: crystal@eleazar.dartmouth.edu (Richard Brittain)
Newsgroups: comp.os.msdos.programmer
Subject: Help in relocating a program in DOS memory
Message-ID: <1991Jun21.111320.3481@dartvax.dartmouth.edu>
Date: 21 Jun 91 11:13:20 GMT
Sender: news@dartvax.dartmouth.edu (The News Manager)
Organization: Dartmouth College, Hanover, NH
Lines: 26
Originator: crystal@eleazar.dartmouth.edu

Hello,
   I'm trying to make a small (actually tiny model) C program relocate
itself to the top of the 640k memory space in order to prevent fragmentation
later on.  What I naively tried was:
 - find out how big the current program is from the MCB
 - set the DOS allocation strategy to last-fit
 - allocate the same size block at the top of memory
 - deallocate my own environment since I don't need it
 - copy myself from here to there
 - deallocate myself
 - set all the segment registers equal to the new segment address + 100h

I crash and burn at the last two steps.  The program has no separately allocated
memory, is tiny model and has no hooked interrupts.  What else do I need to
do - any suggestions?
The better way to do this of course would be for DOS to respect the exe
header blocks saying how much memory a program needs and then allocate only
that much to it - I presume setting last-fit strategy before doing a spawn()
would then achieve what I'm trying to do.  Is there some magic flag to make
the exec service work like this ?

Thanks a lot,

Richard Brittain,

richard@einstein.dartmouth.edu