Here's a little synopsis to get people up to speed.
In the original game there was a function that was attached to interrupt 28. In hexadecimal this is 1C, which is why I call it the 1Ch thread. How the interrupt originally worked was every 55 milliseconds game control was taken away and the interrupt would update various variables and things on the screen. Then it would give control back to the main game again. ROE is funny because it doesn't really have a "main loop" like you would assume. The game is screen based and each screen has it's own input loop. When the input is captured the state of the screen is changed. The "master" loop is actually the interrupt that runs independently of the screens.
Because interrupts are not available and I couldn't use a program loop to poll events, I decided to use a thread that just woke up every 55 milliseconds, did it's thing and went to sleep. The original interrupt was controlled by globals that directed what parts would run. I used the same variables to control my thread.
Everything seemed to work fine. My first hurdle was to gracefully kill the running thread at shutdown. Normally just returning from the function killed the thread, but I set mine up to run forever in a while() loop. Because the thread also contained allegro drawing functions, when I shut down allegro on exit, the thread would crash. Using a no control global I was able to get the game to exit gracefully. Look OK so far.
|The thread is corrupting my blits :(|
I'm going to need to implement a mutex, which is a thing I learned today, so that I can politely wait until the drawing surface is clear so I can write to it with my thread. How fun.
I knew that was going to be hard. I was warned about using a thread too. I didn't exactly think it would cause everything to blow up in my face though.