115 lines
2.2 KiB
C++
115 lines
2.2 KiB
C++
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#include "math_tools.hh"
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#define DEBUG 1
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namespace LibCryptAffinity {
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int MathTools::pgcd(int a, int b){
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int fa = a;
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int fb = b;
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int pgcd;
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int rest;
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int tmp;
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while(b > 0){
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if (a<b){ tmp = a; a=b; b=tmp; }
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rest = a%b;
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//pDEBUG("MathTools::pgcd","%d - %d -> %d\n", a,b,rest);
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a = b;
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b = rest;
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}
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pDEBUG("MathTools::pgcd","%d - %d -> %d\n", fa,fb,a);
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return a;
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}
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int MathTools::ppcm(int a, int b){
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}
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std::vector<int> MathTools::pgcd_real(int * reste, int * quotient, int * coef_first, int * coef_second, int pas){
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std::vector<int> result;
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int nreste = reste[0] % reste[1];
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int nquotient;
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int ncf, ncs; // coef first , coef sec
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if (nreste == 0){
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result.push_back(reste[1]);
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if (pas % 2 == 0) {
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result.push_back(coef_first[1]);
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result.push_back(-coef_second[1]);
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} else {
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result.push_back(-coef_first[1]);
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result.push_back(coef_second[1]);
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}
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return result;
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} else {
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nquotient = reste[1] / nreste;
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ncf = quotient[1] * coef_first[1] + coef_first[0];
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ncs = quotient[1] * coef_second[1] + coef_second[0];
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reste[0] = reste[1];
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reste[1] = nreste;
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quotient[0] = quotient[1];
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quotient[1] = nquotient;
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coef_first[0] = coef_first[1];
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coef_first[1] = ncf;
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coef_second[0] = coef_second[1];
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coef_second[1] = ncs;
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return pgcd_real(reste, quotient, coef_first, coef_second, pas+1);
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}
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}
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std::vector<int> MathTools::pgcd_mod(int a, int b){
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int reste[2];
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int quotient[2];
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int coef_first[2];
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int coef_second[2];
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int i;
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//init
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reste[0] = a;
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reste[1] = b;
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quotient[0] = 0;
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quotient[1] = a / b;
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coef_first[0] = 1;
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coef_first[1] = 0;
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coef_second[0] = 0;
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coef_second[1] = 1;
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return this->pgcd_real(reste, quotient, coef_first, coef_second, 1);
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}
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int MathTools::inverse(int a, int modulo){
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std::vector<int> pgcd_vec;
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int ca, cm, cpgcd;
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pgcd_vec = this->pgcd_mod(a, modulo);
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ca = pgcd_vec[1];
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cm = pgcd_vec[2];
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cpgcd = pgcd_vec[0];
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if (cpgcd != 1) {
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// crash
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pDEBUG("MathTools::inverse","CRASHHHHHH");
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} else {
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while (ca < 0){
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ca = (ca + modulo);
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}
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// ca est positif;
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ca = ca % modulo;
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}
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return ca;
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}
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}
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#undef DEBUG
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