(unsigned) __int128 formatter for GCC/Clang

Author: HenryAWE

include/papilio/core.hpp

@@ -4951,7 +4951,10 @@ inline constexpr std::basic_string_view<CharT> nan_name_upper = PAPILIO_TSTRING_
  * - none: Same as `d`.
  */
 template <std::integral T, typename CharT>
-requires(!char_like<T>)
+requires(
+    !char_like<T> &&
+    sizeof(T) <= sizeof(std::uintmax_t) // No extension like __int128
+)
 class int_formatter : public std_formatter_base
 {
 public:
@@ -6076,7 +6079,10 @@ class range_formatter
  * @throw format_error If the integer value is to big for a Unicode code point for `c` type.
  */
 PAPILIO_EXPORT template <std::integral T, typename CharT>
-requires(!std::same_as<T, bool> && !char_like<T>)
+requires(
+    !std::same_as<T, bool> && !char_like<T> &&
+    sizeof(T) <= sizeof(std::uintmax_t) // No extension like __int128
+)
 class formatter<T, CharT>
 {
 public:

include/papilio/formatter/int128.hpp

@@ -8,10 +8,19 @@
 
 #ifdef PAPILIO_STDLIB_MSVC_STL
 #    define PAPILIO_IMPL_INT128_MSVC_STL
-#    define PAPILIO_HAS_INT128 1
+#    define PAPILIO_HAS_INT128 "std::_Unsigned128/_Signed128"
+// 128-bit integer provided by MSVC STL
 #    include <__msvc_int128.hpp>
 #endif
 
+#ifndef PAPILIO_HAS_INT128
+#    ifdef __SIZEOF_INT128__
+// Built-in __int128 provided by GCC/Clang extension
+#        define PAPILIO_IMPL_INT128_EXT__INT128
+#        define PAPILIO_HAS_INT128 "(unsigned) __int128"
+#    endif
+#endif
+
 #include "../detail/prefix.hpp"
 
 namespace papilio
@@ -61,6 +70,51 @@ namespace detail
 
 #endif
 
+#ifdef PAPILIO_IMPL_INT128_EXT__INT128
+
+using int128_t = __int128;
+using uint128_t = unsigned __int128;
+
+namespace detail
+{
+    template <typename Int128>
+    struct int128_is_unsigned;
+
+    template <>
+    struct int128_is_unsigned<unsigned __int128> : std::false_type
+    {};
+
+    template <>
+    struct int128_is_unsigned<__int128> : std::true_type
+    {};
+
+    // Check if val < 0
+    constexpr bool i128_signbit(const __int128& val) noexcept
+    {
+        return static_cast<bool>(val >> 127);
+    }
+
+    constexpr __int128 i128_abs(const __int128& val) noexcept
+    {
+        if(PAPILIO_NS detail::i128_signbit(val))
+            return -val;
+        else
+            return val;
+    }
+
+    constexpr std::uint64_t i128_low64bit(const __int128& val) noexcept
+    {
+        return static_cast<std::uint64_t>(val & (~0uLL));
+    }
+
+    constexpr std::uint64_t u128_low64bit(const unsigned __int128& val) noexcept
+    {
+        return static_cast<std::uint64_t>(val & (~0uLL));
+    }
+} // namespace detail
+
+#endif
+
 #ifdef PAPILIO_HAS_INT128
 
 template <typename T>

test/test_format/int128.cpp

@@ -29,6 +29,27 @@ static constexpr papilio::int128_t i128_data_b()
     return tmp + 1;
 }
 
+#    endif
+
+#    ifdef PAPILIO_IMPL_INT128_EXT__INT128
+
+// == UINT64_MAX
+static constexpr papilio::int128_t i128_data_a()
+{
+    return static_cast<__int128>(
+        std::numeric_limits<std::uint64_t>::max()
+    );
+}
+
+// == UINT64_MAX + 1
+static constexpr papilio::int128_t i128_data_b()
+{
+    auto tmp = static_cast<__int128>(
+        std::numeric_limits<std::uint64_t>::max()
+    );
+    return tmp + 1;
+}
+
 #    endif
 } // namespace test_format
 
@@ -37,6 +58,7 @@ TEST(int128_formatter, int128)
     using namespace test_format;
     using namespace papilio;
 
+    static_assert(papilio::integral_128bit<papilio::int128_t>);
     static_assert(formattable<papilio::int128_t>);
 
     // UINT64_MAX
@@ -81,6 +103,27 @@ static constexpr papilio::uint128_t u128_data_b()
     return tmp + 1;
 }
 
+#    endif
+
+#    ifdef PAPILIO_IMPL_INT128_EXT__INT128
+
+// == UINT64_MAX
+static constexpr papilio::uint128_t u128_data_a()
+{
+    return static_cast<unsigned __int128>(
+        std::numeric_limits<std::uint64_t>::max()
+    );
+}
+
+// == UINT64_MAX + 1
+static constexpr papilio::uint128_t u128_data_b()
+{
+    auto tmp = static_cast<unsigned __int128>(
+        std::numeric_limits<std::uint64_t>::max()
+    );
+    return tmp + 1;
+}
+
 #    endif
 } // namespace test_format
 
@@ -89,6 +132,7 @@ TEST(int128_formatter, uint128)
     using namespace test_format;
     using namespace papilio;
 
+    static_assert(papilio::integral_128bit<papilio::uint128_t>);
     static_assert(formattable<papilio::uint128_t>);
 
     // UINT64_MAX

test/test_format/test_format.cpp

@@ -2,6 +2,7 @@
 #include "test_format.hpp"
 #include <papilio/print.hpp>
 #include <papilio/chrono/chrono_utility.hpp>
+#include <papilio/formatter/int128.hpp>
 #include <papilio_test/setup.hpp>
 
 namespace test_format
@@ -23,6 +24,10 @@ int main(int argc, char* argv[])
 {
     testing::InitGoogleTest(&argc, argv);
 
+#ifdef PAPILIO_HAS_INT128
+    papilio::println(std::cerr, "PAPILIO_HAS_INT128 = {:?}", PAPILIO_HAS_INT128);
+#endif
+
 #ifdef PAPILIO_HAS_LIB_STACKTRACE
     papilio::println(std::cerr, "PAPILIO_HAS_LIB_STACKTRACE = {:d}L", PAPILIO_HAS_LIB_STACKTRACE);
 #endif