Notes on the scheduler in sched.c: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 'sched.c' provides an very simplistic multi-threading scheduler. See the example, function 'sched(...)', in the same file for its API usage. Until an exhaustive testing can be done, the implementation cannot qualify as that of production quality. It works with the example in 'sched.c', it may or may not work in other cases. Limitations: ~~~~~~~~~~~~ - There are NO primitives for thread synchronization (locking, notify etc). - Only the GPRs and FPRs context is saved during a thread context switch. Other registers on the PowerPC processor (60x, 7xx, 7xxx etc) are NOT saved. - The scheduler is NOT transparent to the user. The user applications must invoke thread_yield() to allow other threads to scheduler. - There are NO priorities, and the scheduling policy is round-robin based. - There are NO capabilities to collect thread CPU usage, scheduler stats, thread status etc. - The semantics are somewhat based on those of pthreads, but NOT the same. - Only seven threads are allowed. These can be easily increased by changing "#define MAX_THREADS" depending on the available memory. - The stack size of each thread is 8KBytes. This can be easily increased depending on the requirement and the available memory, by increasing "#define STK_SIZE". - Only one master/parent thread is allowed, and it cannot be stopped or deleted. Any given thread is NOT allowed to stop or delete itself. - There NOT enough safety checks as are probably in the other threads implementations. - There is no parent-child relationship between threads. Only one thread may thread_join, preferably the master/parent thread. (C) 2003 Arun Dharankar