2014-05-31 Doom Windowing

Found some time today to look at some things.  First thing to address is that since putting in the windowing code, Doom has failed to load and caused a recursive crash.  While I haven't actually tracked the cause of this, it only happens if I compile using my Debug_Map configuration (a build configuration in the project which outputs the link map during the build, useful for debugging).  It's probably something related to output directories or something, but I can work around it for now.

Before now, I had a special routine in the kernel library which accepted the kind of bitmap that Doom outputted and drew it to the screen.  With the windowing system progressed, this has been slightly modified to accept a pointer to the window structure as well.  Now, Doom calls OpenWindow() to create a window,  then calls this DrawBitmap() function each frame to actually put the bitmap onto it.  This new version of the DrawBitmap() function currently uses SetPixel() to draw each pixel on the screen one-at-a-time, which isn't fast, but should allow me to get things running and debugged more easily.

At the moment, the windowing system doesn't handle windows overlapping one another, or moving them, but there's plenty to do before worrying about minor things like that.  I also broke the USB Mass Storage driver at some point, so I had to track two small bugs in this before I could test this on real hardware.  I hadn't reset the USB port before calling SetAddress() against device 0, and I hadn't reset the transfer descriptor CurrentPage property between calls.

With these bits in place, Doom is running in a window on the screen, and is outputting the console text to the console window.

It's not fast, and it's not dithered currently, but it's working and running the Doom demos (I nearly know the demos off by heart now).

A few things stand out from this image which aren't quite correct

1. The window title text for the Doom window is actually drawing over the Console window for some reason.
2. The console text doesn't scroll, so when it gets to the bottom, it just overwrites the last line.
3. Many other things :)