2011-07-13 - Threads and Processes

A few more tweaks to the Process subsystem today.  I've taken an old set of code that I was working on before this issue with Bochs not working came up, and I applied the fixes to make it work in Bochs to it.  After a little tweaking, it started to work and tick along correctly.

Tested a few threads as well (the character generator program that I developed previously) and it all seemed to work.  There is a slight issue with the display when scrolling which the semaphore should have fixed, but I think it's actually a render issue with Bochs.  The semaphore itself tested correctly.

The next step from here is to remove the Sleep(Time) code from the process system and implement a GetPid() function, Sleep(Pid) and Wake(Pid) to allow threads to control one another.  The Sleep(Time) will be reimplemented as a separate subsystem which will use its own thread (or even an interrupt handler) to wake a thread up once its timer has expired.

This should then give me the following functions:

• GetPid(): Returns the current Pid
• Sleep(Pid): Sets the given Pid to sleep
• Wake(Pid): Sets the given Pid to waiting
• Sleep(Time): Sleeps the thread for some time
• TickHandler(): Checks for threads needing waking and wakes them.

The Top command would be modified to display the Pid in the table, and command versions of Sleep() and Wake() will be added to allow thread control for testing and lolz.