From 35312cb5fd4b23a7fef16246b87f28efdf4a2dba Mon Sep 17 00:00:00 2001
From: Matt Borland <matt@mattborland.com>
Date: Thu, 8 Jun 2023 13:27:28 +0200
Subject: [PATCH] Add overload for emulated128 in num_digits

---
 .../charconv/detail/integer_search_trees.hpp    | 11 +++++++++++
 test/test_num_digits.cpp                        | 17 +++++++++++++++++
 2 files changed, 28 insertions(+)

diff --git a/include/boost/charconv/detail/integer_search_trees.hpp b/include/boost/charconv/detail/integer_search_trees.hpp
index 0609646..52c5189 100644
--- a/include/boost/charconv/detail/integer_search_trees.hpp
+++ b/include/boost/charconv/detail/integer_search_trees.hpp
@@ -9,6 +9,7 @@
 // https://graphics.stanford.edu/~seander/bithacks.html
 
 #include <boost/charconv/detail/config.hpp>
+#include <boost/charconv/detail/emulated128.hpp>
 #include <limits>
 #include <array>
 #include <cstdint>
@@ -156,6 +157,16 @@ BOOST_CHARCONV_CXX14_CONSTEXPR int num_digits(std::uint64_t x) noexcept
     return 1;
 }
 
+BOOST_CHARCONV_CXX14_CONSTEXPR int num_digits(uint128 x) noexcept
+{
+    if (x.high != 0)
+    {
+        return num_digits(x.high) + 19;
+    }
+
+    return num_digits(x.low);
+}
+
 #ifdef BOOST_CHARCONV_HAS_INT128
 static constexpr std::array<std::uint64_t, 20> powers_of_10 =
 {{
diff --git a/test/test_num_digits.cpp b/test/test_num_digits.cpp
index 58198cf..ebd604d 100644
--- a/test/test_num_digits.cpp
+++ b/test/test_num_digits.cpp
@@ -3,6 +3,7 @@
 // https://www.boost.org/LICENSE_1_0.txt
 
 #include <boost/charconv/detail/integer_search_trees.hpp>
+#include <boost/charconv/detail/emulated128.hpp>
 #include <boost/charconv/config.hpp>
 #include <boost/core/lightweight_test.hpp>
 #include <type_traits>
@@ -57,6 +58,20 @@ void test()
     BOOST_TEST_EQ(boost::charconv::detail::num_digits(val), std::numeric_limits<T>::digits10 + 1);
 }
 
+void test_emulated128()
+{
+    using namespace boost::charconv::detail;
+
+    uint128 v1 {0, 1234};
+    BOOST_TEST_EQ(num_digits(v1), 4);
+
+    uint128 v2 {1234, 0};
+    BOOST_TEST_EQ(num_digits(v2), 23);
+
+    uint128 v3 {UINT64_MAX, UINT64_MAX};
+    BOOST_TEST_EQ(num_digits(v3), 39);
+}
+
 int main()
 {
     test<char>();
@@ -78,5 +93,7 @@ int main()
     test128<boost::uint128_type>();
     #endif
 
+    test_emulated128();
+
     return boost::report_errors();
 }