// moduleni 2 dlouhych cisel (opet vyuzivajici stredoskolsky algoritmus)
LNum operator%(LNum & dividend, LNum & divisor) {
LNum quotient = dividend/divisor;
LNum multiple = quotient*divisor;
to_normal_form(multiple);
LNum result = dividend-multiple;
to_normal_form(result);
return result;
}
long_hash decode_mnemonic(const word_list& mnemonic,
const std::string& passphrase)
{
const auto sentence = join(mnemonic);
const std::string prefix(passphrase_prefix);
const auto salt = to_normal_form(prefix + passphrase);
return pkcs5_pbkdf2_hmac_sha512(to_data_chunk(sentence),
to_data_chunk(salt), hmac_iterations);
}
// celociselne deleni 2 dlouhych cisel (stredoskolsky algoritmus)
// -- viz http://courses.cs.vt.edu/~cs1104/BuildingBlocks/divide.030.html
LNum operator/(LNum & dividend, LNum & divisor) {
LNum quotient(1);
quotient[0] = 0;
to_normal_form(dividend);
to_normal_form(divisor);
// deleni nulou !!
if (divisor.get_size() == 1 && divisor[0] == 0) {
cout << "Division by zero!! Returning \"0\"!" << endl;
return quotient;
}
// deleni mensiho cisla vetsim -> podil == 0
if (dividend < divisor) {
LNum oh(1);
return oh;
}
// zarovnej delitel do leveho rohu delence
int lock = dividend.get_size() - divisor.get_size(); // zarazka zpracovavane
// cifry v dividendu
LNum portion = cut(dividend, lock, dividend.get_size()-1);
do {
if (!(portion<divisor)) {
portion = portion - divisor;
quotient.append(1);
} else {
quotient.append(0);
}
if (--lock >= 0) {
portion.append(dividend[lock]);
}
} while (lock >= 0);
to_normal_form(quotient);
return quotient;
}
// porovnani 2 dlouhych cisel: a<b ?
// nejprve dle #cifer; pak po cifrach od nejvyssi k nejnizsi mocnine
bool operator<(const LNum & num1, const LNum & num2) {
// zbavime se "0" na zacatku
LNum a = num1; to_normal_form(a);
LNum b = num2; to_normal_form(b);
if (a.get_size() < b.get_size()) { // ruzne pocty cifer
return true;
} else if (a.get_size() > b.get_size()) {
return false;
} else { // porovnavani po cifrach
for (int i = a.get_size()-1; i >= 0; i--) {
// i-ta cifra "a" mensi nez i-ta cifra "b": 0 < 1
if (a[i] < b[i]) {
return true;
}
// i-ta cifra "a" vetsi nez i-ta cifra "b": 1 > 0
else if (a[i] > b[i]) {
return false;
}
}
}
return false; // v tuhle chvili uz je a == b
}
