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Amiga Plus 1996 #6
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1996-07-27
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This are short notes about the Amiga version of Unrar 2.01 .
(The only differences between 2.00 and 2.01 are a small (yet important) bugfix
and shorter executables.)
*************
* Copyright *
*************
Unrar, its code and algoritm are (C)opyright by Eugene Roshal.
The Amiga port is (C)opyright Andrea Vallinotto.
This software is FREEWARE, but cannot be used in any commercial production or
for any commercial use.
In any event, nor Andrea or Eugene cannot be held resposible for damage of any
kind resulting from the use of this program.
Contact addresse are in Aminet readme!
***************
* Amiga Stuff *
***************
This port has basically the same functions and features of the Un*x and DOS
versions, with some slight changes for Amiga-friendliness.
There are two versions, one for each class of processors (68000, 68020)
Just copy to a directory of your search path the one that suit you best.
I didn't include the '040 specific version because on my 40Mhz '040, the 68020
version runs faster!
Note for 68060 owners: '060 lacks an 64-bit integer math instruction, which is
emulated via software. The emulation is usually slower than using a 32 bit only
routine. I don't know if the compiled code of Unrar uses this instruction
directly, and have no way to test it. I suggest you try all three versions and
see which is faster.
There is not a real documentation, type "Unrar" alone for a summary of the
avaible commands/switches. There's just one thing to note: since Un*x pattern
matching is emulated via software, you can use '*' to select every file, but NOT
Amiga-Dos '#?' .
As of this version, the only true 'tipical Amiga' features are:
- correct (Amiga-Dos) return error codes.
- locale-aware character conversion from lowercase to uppercase.
Note that since there isn't an Amiga version of the main program (RAR), the
protection bits shown with command 'l' are those of the OS used for archiving,
either MSDOS (and relatives...) or Un*x .
Also, the code is indeed quite slow. This is for two main reasons:
1) the DOS version of RAR is assembler optimized, while Unrar Amiga is written
in C.
2) when encrypting, RAR stores data is little-endian mode, because of its Intel
origin. The big-endian versions (like this Amiga port) have to swap each
longword, resulting in a high overhead.
***********
* History *
***********
I ported the first version of Unrar to allow a correct behaviour in AmigaDos
enviromnents. Then I made a second version , with some slight
modifications/fixes.
When RAR 2.00 made his debut, I received many requests for a version that could
handle the new packing methods. Since, contrary to Unrar 1, there were no public
source code, I had to ask Andrey Spasibozhko, the conctact address of the author,
to supply me for the new source. He was very kind with me, and sent me the
source along, few days later, with a fix for big-endian machines.
**********
* Thanks *
**********
Millions of thanks to Eugene Roshal and Andrey Spasibozhko for suppling me with
the sources.
Zillions of thanks to Juergen 'Socrates' Zeschky for a bugreport of version 2.00
Thanks also to:
the GCC and libnix authors, for the wonderful and freeware GCC system.
Sergio Lorenzetti for some help he was about to give but never did.
Port done with Amiga GCC 2.7.0 .