CNum::Counter CNum::Counter::pow(const Counter &rhs) const {
assert(isNormalized());
if (*this == 0 && rhs == 0)
throw;
if (*this == 0)
return 0;
if (rhs == 0)
return 1;
// *this >=1 && rhs >=1 here
// Do repeated square algorithm
const Unit SQ_SIZE = rhs.bitSize();
assert(SQ_SIZE >= 1);
std::vector<Counter> sq(SQ_SIZE);
sq[0] = *this;
for (Unit i = 1; i < SQ_SIZE; ++i) {
sq[i] = sq[i - 1] * sq[i - 1];
}
Counter rv(1);
for (Unit i = 0; i < SQ_SIZE; ++i) {
if (rhs.isSet(i)) {
rv *= sq[i];
}
}
return rv;
}
