diff --git a/src/json.hpp b/src/json.hpp
index a6e5e44e..1fd3b916 100644
--- a/src/json.hpp
+++ b/src/json.hpp
@@ -6262,36 +6262,35 @@ class basic_json
}
}
- template<typename T, typename std::enable_if<sizeof(T) == 1, int>::type = 0>
- static constexpr T get_from_vector(const std::vector<uint8_t>& vec, const size_t current_idx)
+ /*
+ Precondition:
+
+ vec: | | | a | b | c | d | | | T: | | | | |
+ ^ ^ ^ ^
+ current_index idx ptr sizeof(T)
+
+
+ Postcondition:
+
+ vec: | | | a | b | c | d | | | T: | d | c | b | a |
+ ^ ^ ^
+ | idx ptr
+ current_index
+
+
+ Code from <http://stackoverflow.com/a/41031865/266378>
+ */
+ template<typename T>
+ static T get_from_vector(const std::vector<uint8_t>& vec, const size_t current_index)
{
- return static_cast<T>(vec[current_idx + 1]);
- }
- template<typename T, typename std::enable_if<sizeof(T) == 2, int>::type = 0>
- static constexpr T get_from_vector(const std::vector<uint8_t>& vec, const size_t current_idx)
- {
- return static_cast<T>((static_cast<T>(vec[current_idx + 1]) << 010) +
- static_cast<T>(vec[current_idx + 2]));
- }
- template<typename T, typename std::enable_if<sizeof(T) == 4, int>::type = 0>
- static constexpr T get_from_vector(const std::vector<uint8_t>& vec, const size_t current_idx)
- {
- return static_cast<T>((static_cast<T>(vec[current_idx + 1]) << 030) +
- (static_cast<T>(vec[current_idx + 2]) << 020) +
- (static_cast<T>(vec[current_idx + 3]) << 010) +
- static_cast<T>(vec[current_idx + 4]));
- }
- template<typename T, typename std::enable_if<sizeof(T) == 8, int>::type = 0>
- static constexpr T get_from_vector(const std::vector<uint8_t>& vec, const size_t current_idx)
- {
- return static_cast<T>((static_cast<T>(vec[current_idx + 1]) << 070) +
- (static_cast<T>(vec[current_idx + 2]) << 060) +
- (static_cast<T>(vec[current_idx + 3]) << 050) +
- (static_cast<T>(vec[current_idx + 4]) << 040) +
- (static_cast<T>(vec[current_idx + 5]) << 030) +
- (static_cast<T>(vec[current_idx + 6]) << 020) +
- (static_cast<T>(vec[current_idx + 7]) << 010) +
- static_cast<T>(vec[current_idx + 8]));
+ T result;
+ uint8_t* ptr = reinterpret_cast<uint8_t*>(&result);
+ size_t idx = current_index + 1 + sizeof(T);
+ while (idx > current_index)
+ {
+ *ptr++ = vec[--idx];
+ }
+ return result;
}
static void to_msgpack_internal(const basic_json& j, std::vector<uint8_t>& v)
@@ -7173,7 +7172,13 @@ class basic_json
{
idx += 2; // skip two content bytes
- // code from RFC 7049, Appendix D
+ // code from RFC 7049, Appendix D, Figure 3:
+ // As half-precision floating-point numbers were only added to IEEE
+ // 754 in 2008, today's programming platforms often still only have
+ // limited support for them. It is very easy to include at least
+ // decoding support for them even without such support. An example
+ // of a small decoder for half-precision floating-point numbers in
+ // the C language is shown in Figure 3.
const int half = (v[current_idx + 1] << 8) + v[current_idx + 2];
const int exp = (half >> 10) & 0x1f;
const int mant = half & 0x3ff;
diff --git a/src/json.hpp.re2c b/src/json.hpp.re2c
index 95a5027e..4859d946 100644
--- a/src/json.hpp.re2c
+++ b/src/json.hpp.re2c
@@ -6262,36 +6262,35 @@ class basic_json
}
}
- template<typename T, typename std::enable_if<sizeof(T) == 1, int>::type = 0>
- static constexpr T get_from_vector(const std::vector<uint8_t>& vec, const size_t current_idx)
+ /*
+ Precondition:
+
+ vec: | | | a | b | c | d | | | T: | | | | |
+ ^ ^ ^ ^
+ current_index idx ptr sizeof(T)
+
+
+ Postcondition:
+
+ vec: | | | a | b | c | d | | | T: | d | c | b | a |
+ ^ ^ ^
+ | idx ptr
+ current_index
+
+
+ Code from <http://stackoverflow.com/a/41031865/266378>
+ */
+ template<typename T>
+ static T get_from_vector(const std::vector<uint8_t>& vec, const size_t current_index)
{
- return static_cast<T>(vec[current_idx + 1]);
- }
- template<typename T, typename std::enable_if<sizeof(T) == 2, int>::type = 0>
- static constexpr T get_from_vector(const std::vector<uint8_t>& vec, const size_t current_idx)
- {
- return static_cast<T>((static_cast<T>(vec[current_idx + 1]) << 010) +
- static_cast<T>(vec[current_idx + 2]));
- }
- template<typename T, typename std::enable_if<sizeof(T) == 4, int>::type = 0>
- static constexpr T get_from_vector(const std::vector<uint8_t>& vec, const size_t current_idx)
- {
- return static_cast<T>((static_cast<T>(vec[current_idx + 1]) << 030) +
- (static_cast<T>(vec[current_idx + 2]) << 020) +
- (static_cast<T>(vec[current_idx + 3]) << 010) +
- static_cast<T>(vec[current_idx + 4]));
- }
- template<typename T, typename std::enable_if<sizeof(T) == 8, int>::type = 0>
- static constexpr T get_from_vector(const std::vector<uint8_t>& vec, const size_t current_idx)
- {
- return static_cast<T>((static_cast<T>(vec[current_idx + 1]) << 070) +
- (static_cast<T>(vec[current_idx + 2]) << 060) +
- (static_cast<T>(vec[current_idx + 3]) << 050) +
- (static_cast<T>(vec[current_idx + 4]) << 040) +
- (static_cast<T>(vec[current_idx + 5]) << 030) +
- (static_cast<T>(vec[current_idx + 6]) << 020) +
- (static_cast<T>(vec[current_idx + 7]) << 010) +
- static_cast<T>(vec[current_idx + 8]));
+ T result;
+ uint8_t* ptr = reinterpret_cast<uint8_t*>(&result);
+ size_t idx = current_index + 1 + sizeof(T);
+ while (idx > current_index)
+ {
+ *ptr++ = vec[--idx];
+ }
+ return result;
}
static void to_msgpack_internal(const basic_json& j, std::vector<uint8_t>& v)