Monday, July 27, 2015

Entering the .NET world

At this point, I'd say my C++ proficiency is at a point where I can confidently state that I am "decent" at it, and by that I mean I can fumble my way through it! But in all seriousness, I've utilized several different aspects of C++, from parallelism/concurrency, to memory management, to graphical display, and so on, with several years of experience, to where I can say that I feel comfortable using it now. I still very much am a beginner, in that I have so much more to learn, but at least now I can manage to not be completely lost whenever I come across a C++ article or blog post covering an interesting facet of the language.

PreviewLite, a simple image viewer for Windows using C# and Windows Presentation Foundation (WPF).

Over the past month I've been reading up on C# and the .NET framework. Along the way, I wrote a script for the LeagueSharp League of Legends bot and recently started another project. In the above picture, you can see what the program looks like. To use, go to File->Open and select the image you want to see, and then use the buttons to see other images in the folder.

PreviewLite Github:

It's a very simple program, but I wanted to start out with something simple to get my feet wet. I don't expect to invest too much time learning Windows Presentation Foundation (it's easy to get into, but with a lot of features if you want to invest the time learning), as my interest lies more in back-end development, specifically ASP.NET. I've been reading Pro C# 5.0 and the .NET 4.5 Framework and am getting close to finishing in the next week or two. The book covers most of what C# has to offer, including the major components of the .NET framework, including ADO.NET and ASP.NET.

From what I've read, I'm really liking the Entity Framework, which provides a way to use objects that seamlessly translate into database entries, to create easy to use and persistent objects in your program. This is in contrast to traditional database APIs that require you to manually define the tables and their entries. I was able to follow a Microsoft tutorial to create a basic ASP.NET based web store that used Entities for its products, and was pleasantly surprised at how simple it is. I'm excited to learn more and have another idea for my next C# project!

P.S. I gave my website a recent face-lift, so check it out!

Sunday, July 5, 2015

Game Boy Emulator: Project Update

I'm excited to announce two big things! First, the emulator can now play most Game Boy games with minimal issues! Secondly, the emulator is now open source on github! Go check it out at the following link,

Github Repository:

Above are some screenshots of the emulator in action (The Legend of Zelda: Link's Awakening, Pokemon Red, and Super Mario Land 2: 6 Golden Coins). As of now two apparent issues occur: First, upon first starting the game, graphical glitches occur. Second, the timing is off which is most obvious with the scanline, which is out of sync and causes a slight graphical glitch. While the instruction test ROM works fine, the instruction timing ROM fails.

Additionally, even basic interface features are missing. The big issue that was holding me up for the past week was an issue where some games would randomly crash when trying to load a new section of the game. When checking the logger for my emulator and comparing the assembly instructions and memory state against BGB's emulator output, I was finding that the ROM was reading from the wrong memory bank. Unfortunately, nothing in the memory bank controller code looked wrong. I ended up having to log the entire output of the emulator up to the point of the crash, which included the register data, program counter, and some other relevant data, and stepping through BGB's emulator, instruction by instruction, until I could find the discrepancy which took about an hour to do. Eventually, I saw a point where the vertical blanking interrupt vector would trigger and set the wrong memory bank. It was only for a few instructions and not something I expected, but when the LCD is disabled, the current horizontal line stops incrementing. This isn't in any of the documentation I came across, so I'm guessing it's just assumed that you would know this. Unfortunately, I didn't make the assumption but thankfully the problem is now fixed.

While there is still a lot more work to be done (including adding more memory controller support), I'm glad to say that the emulator works on most of the games and works well! It's awesome seeing my favorite games from my childhood running in my own homegrown emulator.