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Discussion and tips


I have got some mail about the speed and the size of the resulting patch
file.
Some of you found the patch file size much shorter than of other patchers,
some of you not, and almost all want a faster compare program.


Since version 3 we should not have to speak about speed any more. I have
not yet seen a program that can do such a search faster.

Of course not all Amiga users have 512 MB memory yet. But with Amithlon or
UAE this is no problem, and so I think, the search based on a three-dimensional
array is useful in the 68k version of GCompare too. If you don't have this
memory, then nevertheless you can use the program, it works just slower.


Because it is impossible to develop a format of the patch file with always
the shortest result (because the file size depends on the distance of the
matching data and the way to address it) GCompare has four algorithms.

The optimizer (activated with AUTO) selects the best format, but this takes
four times of computing time.

The results of the DEEP mode depends on the compared files. In much cases
DEEP produces the same results.


If you want not wait for the optimizer then I suggest you MODE 3 (the default mode).
In the most cases this provides a good result.


If you compare the results of GCompare with the results of other programs,
you should do this with compressed versions of the patch files too. GCompare
has no built in compression (different from other compare programs with run
length encoding), because I think all distribution files will always be
compressed before they are published and double compressing would decrease
the effectivity.


GCompare searches matching data in the patch file too if it already exists.
The more patches of different versions of the same program the patch file
contains, the more effective the resulting patch file will be, compared with
single patch files.

If the versions differ not much, then you should store the changes from one
version to the next in the patch file and run GPatch in the recursive mode.
So the patch file will be very small.



GPatch can not handle the old GCompare file formats (I want a small patch
program). If you need an older GPatch, then use one of the included versions
1.4, 1.6 or 2.6. from the drawer bin/old.

If GPatch detects an old patch file then it tells you which version you need.