const int BASE64 = 64;

std::string result;

result.reserve(length);

while (value != 0U) {

result.push_back(chars[value % BASE64]);

value /= BASE64;

}

while ((int)result.size() != length) {

result.push_back('0');

}

std::reverse(result.begin(), result.end());

return result;

std::string::size_type zeros = string.find_first_not_of('0');

unsigned result = 0;

if (zeros != std::string::npos) {

for (std::string::const_iterator i = string.begin() + zeros; i != string.end(); ++i) {

result *= 64;

const char* character = strchr(chars, *i);

if (character == nullptr) {

throw IfcParse::IfcException("Failed to decode GlobalId");

}

result += (unsigned)(character - chars);

}

}

return result;

std::string result;

result.reserve(22);

result += base64(value[0], 2);

for (unsigned i = 1; i < 16; i += 3) {

result += base64((value[i] << 16) + (value[i + 1] << 8) + value[i + 2], 4);

}

return result;

v.push_back((unsigned char)from_base64(s.substr(0, 2)));

for (unsigned i = 0; i < 5; ++i) {

unsigned d = from_base64(s.substr(2 + 4 * i, 4));

for (unsigned j = 0; j < 3; ++j) {

v.push_back((d >> (8 * (2 - j))) % 256);

}

}