Re: LZ: Delete Strings in ASM?


[Prev][Next][Index][Thread]

Re: LZ: Delete Strings in ASM?



Mel Tsai wrote:
> 
> On Tue, 24 Sep 1996 19:08:35 -0500, you wrote:
> >JEGblkbelt@aol.com wrote:
> >>
> >> Is it possible to delete a ASM program from another ASM program?  Is there a
> >> ROM call for this or something.  How does the calc do it? Any help would be
> >> apprieciated.
> >>
> >> -James
> >no there isn't and no there isnt.
> >PCoMP
> >Visit Maximus Productions home page at: http://www.ntsource.com/~pcomp
> >
> 
> Actually, it is possible.  The program would be complex, however.  You
> would first need to make sure your program was located in a lower
> memory position, otherwise it may get moved and all of a sudden the
> program crashes (I'm not sure when this will occur).  One solution
> would be to move your program to the graph memory, move programs, and
> then go back to your main program.  Probably the most difficult
> aspect, however, is knowing which variables you must update, i.e. free
> memory, vat and memory pointers, checksum, and of course moving the
> entire memory down.  One thing I did notice is that the ROM doesn't
> totally delete a file.  I deleted a zshell program, loaded hexview,
> and fragments of the program were still in memory.  I'm not sure what
> exactly happens.
> 
> -Mel


I'm pretty sure it deletes the program from the vat, moves that stuff 
up(cause the vat's upside down) while changing mem pointers, and only 
moves the actual mem if it was sandwiched between two other variables, to 
make it as far down as possible.  I wouldn't try deleting variables in 
your program, though.  There also must be a rom call, but it hasn't been 
found on all rom versions, and probably hard to find hidden in there 
somewhere


<pre>
-- 
Compliments of:
_-_-_-_-_-_-_-_
  Alan Bailey
  mailto:bailala@mw.sisna.com
  IRC:Abalone
  Web:http://www.mw.sisna.com/users/bailala/home.htm
</pre>


References: