Reuse basic_fp

Signed-off-by: Vladislav Shchapov <vladislav@shchapov.ru>

include/fmt/format.h

@@ -3116,71 +3116,62 @@ FMT_CONSTEXPR20 inline void format_dragon(basic_fp<uint128_t> value,
 }
 
 // Formats a floating-point number with snprintf using the hexfloat format.
-template <typename Float, FMT_ENABLE_IF(!is_double_double<Float>::value)>
+template <typename Float>
 FMT_CONSTEXPR20 void format_hexfloat(Float value, int precision,
                                      float_specs specs, buffer<char>& buf) {
   // float is passed as double to reduce the number of instantiations and to
   // simplify implementation.
   static_assert(!std::is_same<Float, float>::value, "");
-  static_assert(std::numeric_limits<Float>::digits <= 113, "unsupported FP");
 
   using info = dragonbox::float_info<Float>;
 
   // Assume Float is in the format [sign][exponent][significand].
   using carrier_uint = typename info::carrier_uint;
 
-  carrier_uint f;
-  int e;
-
-  constexpr auto num_significand_bits = detail::num_significand_bits<Float>();
-  const auto implicit_bit = carrier_uint(1) << num_significand_bits;
-  const auto significand_mask = implicit_bit - 1;
-  auto u = bit_cast<carrier_uint>(value);
-  f = static_cast<carrier_uint>(u & significand_mask);
-  auto biased_e =
-      static_cast<int>((u & exponent_mask<Float>()) >> num_significand_bits);
+  constexpr auto num_float_significand_bits =
+      detail::num_significand_bits<Float>();
 
-  if (biased_e == 0)
-    biased_e = 1;  // Subnormals use biased exponent 1 (min exponent).
-  else if (has_implicit_bit<Float>())
-    f += static_cast<carrier_uint>(implicit_bit);
-
-  e = biased_e - (1 << (info::exponent_bits - 1)) + 1;
+  basic_fp<carrier_uint> f(value);
+  f.e += num_float_significand_bits;
+  if (!has_implicit_bit<Float>()) --f.e;
 
   constexpr auto num_fraction_bits =
-      num_significand_bits + (has_implicit_bit<Float>() ? 1 : 0);
+      num_float_significand_bits + (has_implicit_bit<Float>() ? 1 : 0);
   constexpr auto num_xdigits = (num_fraction_bits + 3) / 4;
 
   constexpr auto leading_shift = ((num_xdigits - 1) * 4);
   const auto leading_mask = carrier_uint(0xF) << leading_shift;
   const auto leading_v =
-      static_cast<uint32_t>((f & leading_mask) >> leading_shift);
-  if (leading_v > 1) e -= (32 - FMT_BUILTIN_CLZ(leading_v) - 1);
+      static_cast<uint32_t>((f.f & leading_mask) >> leading_shift);
+  if (leading_v > 1) f.e -= (32 - FMT_BUILTIN_CLZ(leading_v) - 1);
 
   int print_xdigits = num_xdigits - 1;
   if (precision >= 0 && print_xdigits > precision) {
     const int shift = ((print_xdigits - precision - 1) * 4);
     const auto mask = carrier_uint(0xF) << shift;
-    const auto v = static_cast<uint32_t>((f & mask) >> shift);
+    const auto v = static_cast<uint32_t>((f.f & mask) >> shift);
 
     if (v >= 8) {
       const auto inc = carrier_uint(1) << (shift + 4);
-      f += inc;
-      f &= ~(inc - 1);
+      f.f += inc;
+      f.f &= ~(inc - 1);
     }
 
-    // long double overflow
-    if (!has_implicit_bit<Float>() && ((f & implicit_bit) == implicit_bit)) {
-      f >>= 4;
-      e += 4;
+    // Check long double overflow
+    if (!has_implicit_bit<Float>()) {
+      const auto implicit_bit = carrier_uint(1) << num_float_significand_bits;
+      if ((f.f & implicit_bit) == implicit_bit) {
+        f.f >>= 4;
+        f.e += 4;
+      }
     }
 
     print_xdigits = precision;
   }
 
   char xdigits[num_bits<carrier_uint>() / 4];
   detail::fill_n(xdigits, sizeof(xdigits), '0');
-  format_uint<4>(xdigits, f, num_xdigits, specs.upper);
+  format_uint<4>(xdigits, f.f, num_xdigits, specs.upper);
 
   // Remove zero tail
   while (print_xdigits > 0 && xdigits[print_xdigits] == '0') --print_xdigits;
@@ -3196,23 +3187,16 @@ FMT_CONSTEXPR20 void format_hexfloat(Float value, int precision,
   buf.push_back(specs.upper ? 'P' : 'p');
 
   uint32_t abs_e;
-  if (e < 0) {
+  if (f.e < 0) {
     buf.push_back('-');
-    abs_e = static_cast<uint32_t>(-e);
+    abs_e = static_cast<uint32_t>(-f.e);
   } else {
     buf.push_back('+');
-    abs_e = static_cast<uint32_t>(e);
+    abs_e = static_cast<uint32_t>(f.e);
   }
   format_decimal<char>(appender(buf), abs_e, detail::count_digits(abs_e));
 }
 
-template <typename Float, FMT_ENABLE_IF(is_double_double<Float>::value)>
-FMT_CONSTEXPR20 void format_hexfloat(Float value, int precision,
-                                     float_specs specs, buffer<char>& buf) {
-  static_assert(std::numeric_limits<double>::is_iec559, "unsupported FP");
-  format_hexfloat(static_cast<double>(value), precision, specs, buf);
-}
-
 template <typename Float>
 FMT_CONSTEXPR20 auto format_float(Float value, int precision, float_specs specs,
                                   buffer<char>& buf) -> int {