GCompare / GPatch 1.4
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Author: Ralf Gruner, An der Sense 5a, D-02779 Großschönau, Germany
        ralf.gruner@t-online.de


GCompare generates patch files for the distribution of updates for any files.
GPatch applies these patches.

I know that there are already exist patch generators for Amiga. But I am
not owner of SAS C (I would be, if SAS would continue to sell it),
and the freeware version I found in Aminet crashes my machine.
So I have written a new patcher.

The features are:
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-The patch file can contain patches for any number of files.
 So you can distribute the update for a lot of versions in one file.
 If the directory structure of your product is unchanged, then the patcher
 will find the required patches without any additional actions of your update
 script.
 And you can put the patches for different files of your product in one
 patch file.

-The format of the patchfile is very high optimized. I do not know too many
 similar programs, but I think in the most cases it is the shortest available.

-To avoid corrupt files, the programs contain a very safe error checking
 (CRC32 signatures for all files). So you can be sure that the result of the
 patch process is perfect if no error messages appear.

Usage:
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GCompare and GPatch are shell commands.

Syntax:

 GCompare <old file> <new file> <patch file>

 GPatch <old file> <patch file> <new file>

If GCompare finds an existing <patch file>, then it appends the patches.

GPatch selects the matching patches by file size and CRC signature.

If the output contains no error messages, then the actions were successful.
Any fatal error produces a return code greater than 9.

GCompare needs enough free memory for old file, new file and the patch file.
If GCompare can allocate enough memory (10 times the filesize of the old
file), then it uses a fast search algorithm (lists), else it will use linear
search.

As GCompare example I have included scripts for a fictive program.
The old versions of this program "MyProgram" are in "Archive". The patches
for the program and a manual "MyProgram.readme" will be applied on the
distribution disk "MyProgram".

Distribution:
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GCompare and GPatch are freeware programs. You can use it for all your needs
without restrictions. Also use for commercial products is free.

If you want to see future updates of the programs, please send me an email
that you use the programs. There are some things to optimize, but if nobody
need them I can do other things.
Any comments are welcome.


Ralf

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Disclaimer
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THIS PROGRAM IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER
EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTY
OF FITNESS FOR A PARTICULAR PURPOSE.  THOUGH EVERY CARE HAS BEEN TAKEN TO
MAKE THIS PROGRAM SYSTEM-FRIENDLY AND BUGS-FREE, THE ENTIRE RISK AS TO THE
RESULTS, RELIABILITY AND PERFORMANCE OF THIS PROGRAM IS ASSUMED BY YOU.

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History:
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19.04.97: GCompare 1.0 / GPatch 1.0
Inital release.

21.04.97: GCompare 1.1 / GPatch 1.1
Bugfix. Better examples.

26.04.97: GCompare 1.2 / GPatch 1.2
Speed improvements.

01.05.97: GCompare 1.3 / GPatch 1.3
Bugfix (GPatch failed on the most files greater than 64KB).

11.05.97: GCompare 1.4 / GPatch 1.4
GCompare uses a faster search algorithm.