loopDetector.cpp

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#include "loopDetector.hh"
#include "ppbox.hh"
 
void loopDetector::listPossibleCycles (vector<int>& v)
{
    //cerr << "list possible cycles" << endl;
    Tree t = get(0);
    for (int i=1; i<=(fBuffersize/2); i++) {
        if (t == get(i)) { 
            //cout << "possible cycle at " << i << endl;
            v.push_back(i); 
        }
    }
}
 
bool loopDetector::detect (Tree t)
{
    //cerr << "detect " << t << endl;
    fPhase++;
    fBuffer[fPhase%fBuffersize] = t;
    if ((fPhase%fCheckperiod) == 0) {
        // list possible cycles
        vector<int> vc;
        listPossibleCycles(vc);
    
        // check each possible cycle
        //for (int i = vc.size(); i > 0;) {
        for (unsigned int i = 0; i < vc.size(); i++) {
            //i--;
            if (isCycle(vc[i])) {
                cerr    << "ERROR : the Faust compiler has detected an endless cycle of "
                        << vc[i]  
                        << " evaluations. Last evaluated expression : "
                        << fPhase << endl;
                exit(1);
                return true;
            }
        }       
    }
    return false;
}


bool loopDetector::isCycle(int period)
{
    //cerr << "check cycle " << period << endl;
    int n = fBuffersize/period; // number of periods
    for (int i=0; i<period; i++) {
        Tree x = get(i);
        for (int p=1; p<n; p++) {
            if (x != get(i+p*period)) return false;
        }
    }
    return true;
}