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Jun 7 09

Deflektor remake for Nintendo DS

by sigmaris

Here is a project I’ve been working on for a few weeks to learn more about DS homebrew coding. It’s a remake of Deflektor, an old puzzle game that I played on the Amiga. I’ve tried to keep the retro feel of the original while updating it to use the touchscreen interface.

ss2ss1

The aim is to rotate the mirrors (mirror) to reflect the laser beam from the source (source) to blow up all the triggers (trigger) and then enter the target (target). Rotate the mirrors by tapping on them and then dragging to align the mirror at a particular angle. You start with an amount of energy which is constantly declining (the green bar). Directing the beam into a spike (spike) or reflecting the beam back to the source will cause it to overload (represented by the red bar). If the source is overloaded too much or if you run out of energy, you lose a life. There are also rotating blocks which only allow the beam to pass at a certain angle (angleblocker), teleports (teleport) which work in pairs, and blocks which randomize the beam direction (random). In addition, in some levels there are gremlins which roam about the board and mess with your stuff. You can get rid of them by tapping on them repeatedly.

There are a few things I’d like to add to the game, like highscore saving and a level editor, which might appear if I have time to work on it. For now it comes with all the levels from the original game. You can download it here. Any comments, bug reports, etc are welcome!

Apr 5 09

DesMuME for Mac OS X with GDB stub support

by sigmaris

I’ve built a Mac (Intel) binary of DesMuME, from the latest SVN code, with a patch to enable masscat’s GDB stub. With it you can load a homebrew rom, connect to DesMuME with the copy of GDB that’s provided with devkitARM, and start debugging your homebrew code while it’s running in the emulator. For more details check out this post on the official forums.

The binary can be found here, and the modified parts of the source code can be downloaded here. Please let me know if you find any bugs related to using the GDB stub – I’ve tested it a bit and most features seem to work, but this is the first time I’ve worked on the DesMuME code and I may have overlooked something. I take no responsibility for bugs in the unmodified Mac version of DesMuME though 😉

How to use it:

Currently the only method of specifying the debugger ports to use is on the command line. So, open up Terminal.app and run DesMuME from there, like so:

orange:~ sigmaris$ /path/to/DeSmuME.app/Contents/MacOS/DeSmuME -arm9gdb 20000

Note the single dash before the argument. This will start the ARM9 stub listening on port 20000. You can also use -arm7gdb to start the ARM7 stub. You can omit either of the arm9gdb or arm7gdb arguments and it won’t start the respective GDB stubs at all. If startup was successful you should see log messages like this on the console:

2009-04-05 22:32:41.896 DeSmuME[29404:10b] Using ARM9 GDB port 20000

Then go to the DesMuME window, set up a FAT image if necessary, and load your homebrew ROM. You’ll notice it doesn’t start immediately but just shows a white screen. It is waiting for GDB to connect, so go ahead and start it up (I assume you have devkitPRO installed in /usr/local)

orange:~ sigmaris$ /usr/local/devkitPRO/devkitARM/bin/arm-eabi-gdb homebrew.elf

You should point gdb to the compiled ELF file of the homebrew ROM that you loaded earlier. You should see the (gdb) prompt, now tell GDB to connect to the DesMuME stub:

(gdb) target remote :20000
Remote debugging using :20000
0x02000000 in _start ()
(gdb)

If you see the above output, you’re ready to start debugging. For example, set a breakpoint on a function that you use in your homebrew program, and then enter ‘cont’ to tell DesMuME to continue running the program. You should see your program run up to the breakpoint and then stop, and GDB will print a message saying it encountered the breakpoint. You can now examine the state of local variables, print a backtrace, or step line-by-line through your code.

Hopefully this will be useful for some homebrew DS developers on the Mac. Unfortunately, even with the GDB stub in place, DesMuME doesn’t catch many of the errors that would trip you up on a real DS like writes to invalid memory and other similar errors. But being able to jump in anywhere and examine the running state of your code is a step forward from just using tons of iprintf() calls 😉