The Smartphone Age is a great time to learn chess!

I'm excited to report that the portable chess problem has been solved, and the solution is called a "smartphone" (aka iPhone 3GS). As a result, there is no reason not to learn this fabulous game.

My reintroduction to the game was made by my iPhone courtesy of Deep Green, but only really deepened with Shredder Chess (a total steal at $7.99 - the desktop version starts at $50) particularly thanks to the puzzle feature. "Puzzles" are generally mid-game problems with solutions from 1 to 8 moves in length. They are fantastic "aha!" teaching moments, and they are fun to solve. I've learned more about forks, time, and pinning from these puzzles than in years of casual play. I can apply these lessons directly to my normal games.

• Click here to get a sense of a shredder chess puzzle (updated daily).
• Click here to play against shredder free online.

The great innovation here is two fold. First, portable computer chess finally has found a great platform: the smart phone. Most people's interest in chess isn't high enough to justify a separate device, which have been sold for years. But it's enough to sustain an app on a phone you carry anyway. Forget Doodle Jump - play chess when you're waiting around for something! The second innovation is Shredder Chess' concept of a Chess puzzle.

Chess puzzles highlight the beautiful parts of a chess game. Openings are about memory and style, end games about mathematical certainty. But mid-game situations are where that big advantage is won or lost, and so where the game is won or lost even if it takes another 30 moves to knock over the king.

Shredder's software execution is all but perfect, particularly the ability to play the puzzle then switching to play the position against the computer, allowing you to test out alternate theories from both sides. That is, the solution to the puzzle is only the start. You can regress the game and ask the all-important question: I beat my opponent this time. How could he have avoided this fate?

Without a single word, these puzzles say so much! What a perfect way to learn the game: rather than memorize and apply the insights of masters, this method encourages you to make your own insights, which in turn makes the game in a very rewarding game of discovery rather than a boring game of regurgitation or application of theory. The insight of masters are invaluable, but to really appreciate them you must have your own framework of understanding. (Many Go teachers say that you should play at least 100 games of Go, before studying theory for this very reason.)

I should add that while you generally don't have to play out the puzzle game to it's end, I often do, as my end game is (was?) a big weakness. I might be up a queen and still lose in my rush to end it. But now I really understand the significance of a passed pawn and the slipperiness of the King and the need to be thoughtful and careful even when you have an enormous power advantage. Carelessness kills.

I can't say enough about Shredder on the iPhone, but there is one thing missing: openings. Very few of the puzzles occur in the opening, and most of those take advantage of fairly obvious opponent mistakes. Shredder has a cool feature where it identifies and names your opening. But it would be nice if it had an "opening drill" feature to help you memorize openings (and understand their implications for the rest of the game).

Not to take away anything from the amazing and innovative new kinds of games like Flight Control, Doodle Jump, Angry Birds, or Spider but why not kill two birds with one stone (or two stones with one bird, if you play Angry Birds). Chess is an aristocratic game of kings. It's good for the brain and a lot of fun, and perfect on this platform.

Kinda tempted to build a gaming computer

A cheap, good gaming PC for $430. Really, just to play Portal 2, Counter Strike:Source, and maybe some old stand-by's like Supreme Commander and Ultima III in the Apple IIe emulator. (It may be a $60 card but it will drive my 30" Cinema at full resolution.)

Best Buy Bodhisattva

I'm not sure who the author really is, but it's a beautiful piece of writing, and a wonderful story about the intersection of gaming and enlightenment.

Best Buy Bodhisattva

It's also a very interesting site for some of my friends, "gamerswithjobs.com". Probably a more LOTRO than a WoW crowd, I reckon.

Thinkpad Accelerometer with Java JNI

Man I have a lot of things to do. But I can't help thinking about my aunt tilting the laptop for Crayon physics. It turns out that the accelerometer on the Thinkpad can actually be accessed:

1. C# code [fritjers.net] and a very nice version from bsuter.[stanford.edu]
   
2. Perl code [thinkwiki.org]
3. More C# code with a writeup.
   

Shocking that IBM doesn't have a Java library for it! Well, I got a bit excited that I might be the first to write the code...of course, I've never written JNI code before in my life. I've heard its tricky, and I know it complicates deployment (I've had to package and deploy JNI code before). So it seems that Sun's JNI programmers guide is the place to go. I skimmed it and came to this section on wrapping existing native libraries. It's pretty hairy, especially compared to the perl code, but hey this is Java right?

Undaunted I downloaded the example code from the book, thinking I could just compile the CFuntion, etc classes and be on my way. I fire up Cygwin, discover I don't have gcc or make installed - which was easily corrected. (And I noticed that an ocaml compiler was available, so I installed it too for giggles.)

I run into my first roadblock - make goes into infinite recursion and I have to kill the process. I read the makefile. It appears that the win32 makefiles provided with the distro are written for nmake - Microsoft's rewrite of gnu make. I'd never heard of it before. (Good heavens, how many make clones does the world really need?)

Probably the easiest thing to do would be to just install Visual Studio, if I had the disk space (I have a bigger drive on order, actually). If I knew make better I could edit the makefile for compatibility. But I suspect there may be other things in the codebase that require VS. Or I could scrap my original plan and write custom "one-to-one mapping" code, and hope that gcc will cut the mustard. That might be worth a shot (and more educational) while I wait for my new hard drive.

So I gave HelloWorld a shot. Alas, it didn't work (using the command line "gcc -I$JAVA_HOME/include -I$JAVA_HOME/include/win32 HelloWorld.c") - the parser didn't like the header files. What I really need is a version of this book for Cygwin, as I don't have the expertise to figure it out myself. The internet to the rescue! (Hmm and he mentions SWIG. Interesting.)

Well I was damn close. "gcc -mno-cygwin -I$JAVA_HOME/include -I$JAVA_HOME/include/win32 -Wl,--add-stdcall-alias -shared -o HelloWorld.dll HelloWorld.c" did the trick.

(Note that when I first tried to run I got a "java.lang.UnsupportedClassVersionError: Bad version number in .class file". A "which java" in cygwin showed that I was running a JRE in "/cygdrive/c/WINDOWS/system32/java" while compiling with a different one. So I just ran it with the right JRE and it worked! "$JAVA_HOME/bin/java HelloWorld". There are lots of ways to fix cygwin systematically - I'll probably make the change globally to the PATH in /etc/.bashrc)

I don't hold JNI itself responsible for this learning curve of mine - I don't do C/C++ development in Cygwin (or out of it), and that's caused the majority of the trouble. It's true that I think it *should* be possible to drag a DLL into a tool and have it's functions exposed in whatever language you like, automatically.

After reading the mindprod JNI article (which I should have done first - Roedy Green really gets into this stuff and is generous with his knowledge) I think the biggest thing holding me back is not having the source to sensor.dll source code. There are several "SharedStub" pre-compiled libraries out there (JNative, JNIWrapper - commercial) which claim to avoid writing and compiling any C (at least under Windows and Linux). SWIG claims to avoid writing any C - but you have to compile it (and it's not clear how you compile for Windows vs. Linux). The super cool thing about SWIG is once you write the ".i" file you can generate bindings for 13 different languages, not just Java. I might even get inspiration from how Eclipse generates JNI for SWT (something called JNIGeneratorAppUI). I discovered that the Shared Stub C code from the Sun book is on the site repackaged and distrubuted with a normal make file! Perhaps that's the code that JNative is based on?

One problem I cannot solve is figuring out which functions "sensors.dll" exposes. Static or dynamic, all of these JNI methods basically require a header file to work with. Seems to me a library would be pretty up-front about the functions it exposes. A tool to generate SWIG .i files from a dll would be pretty cool - if overkill. If that's not available, then a tool that generates .h files from a .dll.



If only this data was available via a port or a file handle! Oddly, the file handle method is the one used in C# and Perl. I don't really understand it though. Ironically, Mark Smith at IBM started a project to make accelerometer data available in Linux and is now open source. (This is ironic for two reasons: first, that the Linux form would be easier to use with Java, and second that Mark had to reverse-engineer his own companies software - but come to think of it that happens all the time.)

[Update: According to MSDN, that strange path-like structure is a "communication resource handle" on which there are several possible operations. These operations are fully documented (for example the CreateFile function).

Oddly, I noticed similar path strings in Windows Services. Take this executable path: "C:\bin\Tomcat 5.5\bin\tomcat5.exe" //RS//Tomcat5. My guess is this is an internal attempt to avoid running tomcat twice, similar to using a PID file. But that's probably not what it is since tomcat won't start again because of port conflicts - a sort of port PID.

Here's another - "C:\bin\Tomcat 5.5\bin\tomcat5w.exe" //MS//Tomcat5 (for monitoring tomcat)

Scrap theory in action

Crayon Physics is a lot of fun on the tablet - too bad it's so short (only 7 levels). The amazing thing is that, to Petri Purho, this is "scrap". (see my earlier post on scrap theory)

This guy Petri Purho is releasing a game a month and writing about it on his blog. He was interviewed about it, and apparently it's just a hobby. But a serious one!

Damn, that's inspiring.