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POx86 equivalent for LWARX and STWCX
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copied!<p>I'm looking for an equivalent of LWARX and STWCX (as found on the PowerPC processors) or a way to implement similar functionality on the x86 platform. Also, where would be the best place to find out about such things (i.e. good articles/web sites/forums for lock/wait-free programing).</p> <hr> <p><strong>Edit</strong><br> I think I might need to give more details as it is being assumed that I'm just looking for a CAS (compare and swap) operation. What I'm trying to do is implement a lock-free reference counting system with smart pointers that can be accessed and changed by multiple threads. I basically need a way to implement the following function on an x86 processor.</p> <pre>int* IncrementAndRetrieve(int **ptr) { int val; int *pval; do { // fetch the pointer to the value pval = *ptr; // if its NULL, then just return NULL, the smart pointer // will then become NULL as well if(pval == NULL) return NULL; // Grab the reference count val = lwarx(pval); // make sure the pointer we grabbed the value from // is still the same one referred to by 'ptr' if(pval != *ptr) continue; // Increment the reference count via 'stwcx' if any other threads // have done anything that could potentially break then it should // fail and try again } while(!stwcx(pval, val + 1)); return pval; } </pre> <p>I really need something that mimics LWARX and STWCX fairly accurately to pull this off (I can't figure out a way to do this with the CompareExchange, swap or add functions I've so far found for the x86).</p> <p>Thanks</p>

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