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Editorial Team
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Asked: 2026-05-13T19:24:49+00:00

I’m trying to implement a simulation of a microcontroller. This simulation is not meant

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I’m trying to implement a simulation of a microcontroller. This simulation is not meant to do a clock cycle precise representation of one specific microcontroller but check the general correctness of the code.

I thought of having a “main thread” executing normal code and a second thread executing ISR code. Whenever an ISR needs to be run, the ISR thread suspends the “main thread”.

Of course, I want to have a feature to block interrupts.
I thought of solving this with a mutex that the ISR thread holds whenever it executes ISR code while the main thread holds it as long as “interrupts are blocked”.

A POR (power on reset) can then be implemented by not only suspending but killing the main thread (and starting a new one executing the POR function).

The windows API provides the necessary functions.
But it seems to be impossible to do the above with posix threads (on linux).

I don’t want to change the actual hardware independent microcontroller code. So inserting anything to check for pending interrupts is not an option.

Receiving interrupts at non well behaved points is desirable, as this also happens on microcontrollers (unless you block interrupts).

Is there a way to suspend another thread on linux? (Debuggers must use that option somehow, I think.)

Please, don’t tell me this is a bad idea. I know that is true in most circumstances. But the main code does not use standard libs or lock/mutexes/semaphores.

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1 Answer

  1. Editorial Team

    Somehow I think sending the other thread SIGSTOP works.

    However, you are far better off writing some thread communication involving senaogires.mutexes and global variables.

    You see, if you suspend the other thread in malloc() and you call malloc() -> deadlock.

    Did I mention that lots of C standard library functions, let alone other libraries you use, will call malloc() behind your back?

    EDIT:

    Hmmm, no standard library code. Maybe use setjmp/longjump() from signal handler to simulate the POR and a signal handier to simulate interrupt.

    TO THOSE WHO KEEP DOWNVOTING THIS: The answer was accepted for the contents after EDIT, which is a specific scenario that cannot be used in any other scenario.

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