Author: Tord Romstad
Date: 04:36:19 02/05/04
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On February 04, 2004 at 21:13:48, Thorsten Czub wrote: >i really wonder that there are so few chess programs for >risc-palm. > >so far only genius2 is adapted for risc-palm. >what a pity. Unfortunately, it is not so easy to port a chess engine to Palm OS, especially if you want to use ARM code. You cannot just compile your C source code and run the engine on a Palm. Palm OS 5 is a strange animal. The OS itself is ARM-native, but all applications are run as 68k apps with the help of an emulation layer. It is not possible to write a 100% ARM-native app for Palm OS 5. However, applications which need good performance can include what is called "ARMlets", which are small chunks of ARM code which can be called from the 68k app. Using ARMlets is kind of tricky. For instance, you cannot share global data between the 68k and the ARM parts of the program. You have to pass the data you want to share by a pointer. Another complication is that the bytes are ordered differently in ARM compared to 68k, which means that you have to shuffle the order of the bytes of all data passed to an ARMlet. In other words, if you want to port a chess program written in C to Palm OS and use ARMlets to speed up your code, you will probably be forced to rewrite big parts of your code and structure it very differently. The good news is that all these problems will probably disappear in Palm OS 6. Another problem is that the memory on handheld units is of course extremely limited compared to desktop machines. Programs which consume too much memory will be difficult to force. I'm afraid (though I am by no means sure) that Crafty will suffer from this problem, and that it therefore will not be the easiest engine to port. >please more programs. There will almost certainly be a Palm OS version of Gothmog at some stage, but I'm afraid it will be so weak that nobody except me will ever want to use it. :-) Tord
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