bigint::bigvalue_t bigint::do_bigmult(const bigvalue_t& left, const bigvalue_t& right) {
bigvalue_t prod;
prod.resize(left.size() + right.size());
int carry = 0;
int d = 0;
for(int i = left.size()-1; i != -1; --i) {
carry = 0;
for(int j = right.size()-1; j != -1; --j) {
d = (prod.at((left.size()-1 -i) + (right.size()-1 - j))) + (left.at(i) * right.at(j)) + carry;
//cout << (prod.at((left.size()-1 - i) + (right.size()-1 - j))) << " new ";
//cout << (left.at(i) * right.at(j)) << " old ";
//cout << carry << "carry" << endl;
//cout << d << endl;
//cout << d%10 << "<--insert"<<endl;
//cout << d/10 << " carry" << endl;
prod.at((left.size()-1 - i) + (right.size()-1 - j)) = d % 10;
carry = d/10;
}
if(carry != 0) {
//cout << carry << "<- insert c"<<endl;
prod.at((right.size()-1) - -1) = carry;
}
}
//trim
return prod;
}
bigvalue_t do_bigmul(const bigvalue_t& left, const bigvalue_t& right){
int carry = 0;
digit_t digit = 0;
bigvalue_t prod;
prod.reserve(left.size() + right.size());
for (size_t i=0; i<left.size(); ++i) {
carry = 0;
for (size_t j=0; j<right.size(); ++j) {
digit = prod.at(i+j) + left.at(i)*right.at(j) + carry;
prod.at(i+j) = digit % 10;
carry = digit / 10;
}
prod.at(i+right.size()) = carry;
}
return prod;
}