in MavLinkCom/common_utils/json.hpp [6898:7150]
static void to_cbor_internal(const basic_json& j, std::vector<uint8_t>& v)
{
switch (j.type())
{
case value_t::null:
{
v.push_back(0xf6);
break;
}
case value_t::boolean:
{
v.push_back(j.m_value.boolean ? 0xf5 : 0xf4);
break;
}
case value_t::number_integer:
{
if (j.m_value.number_integer >= 0)
{
// CBOR does not differentiate between positive signed
// integers and unsigned integers. Therefore, we used the
// code from the value_t::number_unsigned case here.
if (j.m_value.number_integer <= 0x17)
{
add_to_vector(v, 1, j.m_value.number_integer);
}
else if (j.m_value.number_integer <= std::numeric_limits<uint8_t>::max())
{
v.push_back(0x18);
// one-byte uint8_t
add_to_vector(v, 1, j.m_value.number_integer);
}
else if (j.m_value.number_integer <= std::numeric_limits<uint16_t>::max())
{
v.push_back(0x19);
// two-byte uint16_t
add_to_vector(v, 2, j.m_value.number_integer);
}
else if (j.m_value.number_integer <= std::numeric_limits<uint32_t>::max())
{
v.push_back(0x1a);
// four-byte uint32_t
add_to_vector(v, 4, j.m_value.number_integer);
}
else
{
v.push_back(0x1b);
// eight-byte uint64_t
add_to_vector(v, 8, j.m_value.number_integer);
}
}
else
{
// The conversions below encode the sign in the first
// byte, and the value is converted to a positive number.
const auto positive_number = -1 - j.m_value.number_integer;
if (j.m_value.number_integer >= -24)
{
v.push_back(static_cast<uint8_t>(0x20 + positive_number));
}
else if (positive_number <= std::numeric_limits<uint8_t>::max())
{
// int 8
v.push_back(0x38);
add_to_vector(v, 1, positive_number);
}
else if (positive_number <= std::numeric_limits<uint16_t>::max())
{
// int 16
v.push_back(0x39);
add_to_vector(v, 2, positive_number);
}
else if (positive_number <= std::numeric_limits<uint32_t>::max())
{
// int 32
v.push_back(0x3a);
add_to_vector(v, 4, positive_number);
}
else
{
// int 64
v.push_back(0x3b);
add_to_vector(v, 8, positive_number);
}
}
break;
}
case value_t::number_unsigned:
{
if (j.m_value.number_unsigned <= 0x17)
{
v.push_back(static_cast<uint8_t>(j.m_value.number_unsigned));
}
else if (j.m_value.number_unsigned <= 0xff)
{
v.push_back(0x18);
// one-byte uint8_t
add_to_vector(v, 1, j.m_value.number_unsigned);
}
else if (j.m_value.number_unsigned <= 0xffff)
{
v.push_back(0x19);
// two-byte uint16_t
add_to_vector(v, 2, j.m_value.number_unsigned);
}
else if (j.m_value.number_unsigned <= 0xffffffff)
{
v.push_back(0x1a);
// four-byte uint32_t
add_to_vector(v, 4, j.m_value.number_unsigned);
}
else if (j.m_value.number_unsigned <= 0xffffffffffffffff)
{
v.push_back(0x1b);
// eight-byte uint64_t
add_to_vector(v, 8, j.m_value.number_unsigned);
}
break;
}
case value_t::number_float:
{
// Double-Precision Float
v.push_back(0xfb);
const auto* helper = reinterpret_cast<const uint8_t*>(&(j.m_value.number_float));
for (size_t i = 0; i < 8; ++i)
{
v.push_back(helper[7 - i]);
}
break;
}
case value_t::string:
{
const auto N = j.m_value.string->size();
if (N <= 0x17)
{
v.push_back(0x60 + static_cast<uint8_t>(N)); // 1 byte for string + size
}
else if (N <= 0xff)
{
v.push_back(0x78); // one-byte uint8_t for N
add_to_vector(v, 1, N);
}
else if (N <= 0xffff)
{
v.push_back(0x79); // two-byte uint16_t for N
add_to_vector(v, 2, N);
}
else if (N <= 0xffffffff)
{
v.push_back(0x7a); // four-byte uint32_t for N
add_to_vector(v, 4, N);
}
// LCOV_EXCL_START
else if (N <= 0xffffffffffffffff)
{
v.push_back(0x7b); // eight-byte uint64_t for N
add_to_vector(v, 8, N);
}
// LCOV_EXCL_STOP
// append string
std::copy(j.m_value.string->begin(), j.m_value.string->end(),
std::back_inserter(v));
break;
}
case value_t::array:
{
const auto N = j.m_value.array->size();
if (N <= 0x17)
{
v.push_back(0x80 + static_cast<uint8_t>(N)); // 1 byte for array + size
}
else if (N <= 0xff)
{
v.push_back(0x98); // one-byte uint8_t for N
add_to_vector(v, 1, N);
}
else if (N <= 0xffff)
{
v.push_back(0x99); // two-byte uint16_t for N
add_to_vector(v, 2, N);
}
else if (N <= 0xffffffff)
{
v.push_back(0x9a); // four-byte uint32_t for N
add_to_vector(v, 4, N);
}
// LCOV_EXCL_START
else if (N <= 0xffffffffffffffff)
{
v.push_back(0x9b); // eight-byte uint64_t for N
add_to_vector(v, 8, N);
}
// LCOV_EXCL_STOP
// append each element
for (const auto& el : *j.m_value.array)
{
to_cbor_internal(el, v);
}
break;
}
case value_t::object:
{
const auto N = j.m_value.object->size();
if (N <= 0x17)
{
v.push_back(0xa0 + static_cast<uint8_t>(N)); // 1 byte for object + size
}
else if (N <= 0xff)
{
v.push_back(0xb8);
add_to_vector(v, 1, N); // one-byte uint8_t for N
}
else if (N <= 0xffff)
{
v.push_back(0xb9);
add_to_vector(v, 2, N); // two-byte uint16_t for N
}
else if (N <= 0xffffffff)
{
v.push_back(0xba);
add_to_vector(v, 4, N); // four-byte uint32_t for N
}
// LCOV_EXCL_START
else if (N <= 0xffffffffffffffff)
{
v.push_back(0xbb);
add_to_vector(v, 8, N); // eight-byte uint64_t for N
}
// LCOV_EXCL_STOP
// append each element
for (const auto& el : *j.m_value.object)
{
to_cbor_internal(el.first, v);
to_cbor_internal(el.second, v);
}
break;
}
default:
{
break;
}
}
}