From:	James W Sager Iii <sager+@andrew.cmu.edu>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Allegro datfiles was:re: Compiler Optimizations
Date:	Sat, 21 Mar 1998 09:51:53 -0500
Organization:	Junior, MCS Undeclared, Carnegie Mellon, Pittsburgh, PA
Lines:	32
Message-ID:	<0p4xE9q00WB_07il00@andrew.cmu.edu>
NNTP-Posting-Host:	po8.andrew.cmu.edu
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

>> B) I am unsure of whether the .dat file loads itself fully into memory.     
>> Since my game is a slow paced RPG, I have no need for all the BITMAPs       
>> to be in the memory, and there are ALOT of BITMAPs appx 1000+. I have       
>> other devious uses for the memory...                                        
                                                                              
>Remember about virtual memory.  Even if the entire datafile were loaded,      
>it would be paged out until actually used.  The only overhead would be    

>in loading the file in the first place.  As it is, I believe that             
>Allegro only loads those portions of a datafile that you actually             
>request.                                                                      
                                                                              
The problem is that I'm kinda confused...
My plan was to put all the images into one big file and only pull out a
few out at a time to
put in memory. Allegro will use the cwsdpmi thing to simulate ALOT of
ram, but after a certain
point(memory on chips are used, the hard drive is used and a noticable
slow down occurs
using memory.  On my game, I malloc out a bunch of 40kb levels from one
to a hundred or more...
Malloc is weird in that it will only go up to the extended memory, and
not hit the hard drive.
My questions are:
  	A: If I load up 8 meg of images in a .dat file, and there is exactly
8 meg of 
extended memory: Will I be able to malloc out 4 meg of levels? 
        B: If it doesn't crash, will the game be slowed down because it
has to access the hard
drive at unknown times because its using virtual memory?

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