void rotate1D(DoubleCRT& d, long i, long amt,
const vector< vector< DoubleCRT > > & maskTable)
// rotate d in dimension i by amt
{
const FHEcontext& context = d.getContext();
const PAlgebra& al = context.zMstar;
// const PAlgebraModTwo& al2 = context.modTwo;
long ngens = al.numOfGens();
// long nslots = al.NSlots();
assert(i >= 0 && i < ngens);
long ord = al.OrderOf(i);
amt = amt % ord;
if (amt < 0) amt += ord;
if (amt == 0) return;
if (al.SameOrd(i)) {
// "native" rotation
long val = PowerMod(al.ZmStarGen(i), amt, al.M());
d.automorph(val);
}
else {
// more expensive "non-native" rotation
assert(maskTable[i].size() > 0);
long val = PowerMod(al.ZmStarGen(i), amt, al.M());
// long ival = InvMod(val, al.M());
long ival = PowerMod(al.ZmStarGen(i), amt-ord, al.M());
const DoubleCRT& m1 = maskTable[i].at(ord-amt);
DoubleCRT d1(d);
d1.Mul(m1, false);
d -= d1;
d.automorph(val);
d1.automorph(ival);
d += d1;
}
}
