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POthe stack and vtable [re]location
 

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    <p><strong>NOTE:</strong> To understand my question, you <em>might</em> need to know about my project and the problem. If not, skip right to the "QUESTION" section at the bottom.<br/><br/></p> <p><hr/><strong>PROJECT</strong><br/><br/> I'm working on a writing a C++ class that enables its parent to act like synchronous/blocking threads by having Pause() and Resume(). <br/><br/> Here's an example of how it would work.</p> <pre><code>class BlockingThread : public BlockingThreadBase // all the Asm magic happens in BlockingThreadBase { void StartStopHere(void) // called upon the first Resume() call (pure virtual in base) { printf("1"); Pause(); printf("3"); Pause(); printf("5"); Pause(); } }; int main(void) { BlockingThread obj; obj.Resume(); printf("2"); obj.Resume(); printf("4"); obj.Resume(); printf("6"); return 0; } // OUTPUT: 123456 </code></pre> <p>I've tried true threading and several novel ideas but they ended up too slow to transfer between code locations <strong>21 million times per second.</strong></p> <p>My latest idea is use chunks of the stack (stack buffers) to create the illusion of multiple stacks. When obj1.Resume() is called, it would return to location of its personal stack, <code>New #1 Stack</code>, execute until Pause() and then return to the previous stack location it was at.</p> <p><hr/><strong>ILLUSTRATIONS</strong><br/><br/></p> <p>How the stack would look without any<code>BlockingThread</code> objects in main().</p> <pre><code> _________________ | Normal | Stack | | Stack | Buffer | |________|________| </code></pre> <p>How a<code>BlockingThread</code> object in main() would look like on the stack.</p> <pre><code> ___________________________________ | Normal | Stack | New #1 | Stack | | Stack | Buffer | Stack | Buffer | |________|________|________|________| </code></pre> <p>How <strong>two</strong><code>BlockingThread</code> objects in main() would look like on the stack.</p> <pre><code> _____________________________________________________ | Normal | Stack | New #1 | Stack | New #2 | Stack | | Stack | Buffer | Stack | Buffer | Stack | Buffer | |________|________|________|________|________|________| </code></pre> <p><hr/><strong>PROBLEM</strong><br/><br/></p> <p>When moving to a "new" stack, and then calling obj.Resume() (from main) which in turn call StartStopHere() causes a segfault at the point of calling StartStopHere(). GDB says <code>can't find linker symbol for virtual table for 'BlockingThreadBase' value</code> when I try to get the value of a member variable from BlockingThreadBase. This is why I suspect it has the same problem when trying to find the location of StartStopHere() when it's called.</p> <p><hr/><strong>QUESTION</strong><br/><br/></p> <p>(ignore the italics words if you didn't read the other sections)</p> <p>How can I find [<em>and move or copy</em>] the vtable (or its location if that's what's stored) of the class in the [<em>normal</em>] stack [<em>to a new stack</em>]?</p>
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    1. COhow is the BlockingThreadBase implemented?
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    2. COMaybe you are looking for Coroutines? http://en.wikipedia.org/wiki/Coroutines
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    3. COalso very interesting but still not an answer to my question.
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