So, I’ve built simple cothreading routines using setjmp in C that I
can use for multitasking. Cool. As it stands, it is limited to
cooperative multitasking, but if I could invoke it from an ALARM
signal set on a periodic timer, and get information about where the
program was interrupted, I could implement pre-emptive multitasking.
So, is it possible to get information about the area that a program
was interrupted to invoke the signal handler? Yes, but it is somewhat
nonstandard and implementation-specific. Use sigaction() with
SA_SIGINFO to request ucontext_t, which is where you retrieve this
information.
20190724/DuckDuckGo unix get information about area in program where
signal occurred
20190724/DuckDuckGo linux how to get instruction where signal
interrupted
20190724/https://stackoverflow.com/questions/34989829/linux-signal-handling-how-to-get-address-of-interrupted-instruction
Basically, I’m reinventing “green threads,” but with the goal of doing so in a tiny, minimalistic implementation.