Add CUDA support to from_chars for integers

.github/workflows/ci.yml

@@ -765,3 +765,62 @@ jobs:
 
       - name: Run tests
         run: ci/build.sh
+
+
+  cuda-cmake-test:
+    strategy:
+      fail-fast: false
+
+    runs-on: gpu-runner-1
+
+    steps:
+      - uses: Jimver/cuda-toolkit@v0.2.25
+        id: cuda-toolkit
+        with:
+          cuda: '12.8.0'
+          method: 'network'
+          sub-packages: '["nvcc"]'
+
+      - name: Output CUDA information
+        run: |
+          echo "Installed cuda version is: ${{steps.cuda-toolkit.outputs.cuda}}"+
+          echo "Cuda install location: ${{steps.cuda-toolkit.outputs.CUDA_PATH}}"
+          nvcc -V
+      - uses: actions/checkout@v4
+
+      - name: Install Packages
+        run: |
+          sudo apt-get install -y cmake make
+      - name: Setup Boost
+        run: |
+          echo GITHUB_REPOSITORY: $GITHUB_REPOSITORY
+          LIBRARY=${GITHUB_REPOSITORY#*/}
+          echo LIBRARY: $LIBRARY
+          echo "LIBRARY=$LIBRARY" >> $GITHUB_ENV
+          echo GITHUB_BASE_REF: $GITHUB_BASE_REF
+          echo GITHUB_REF: $GITHUB_REF
+          REF=${GITHUB_BASE_REF:-$GITHUB_REF}
+          REF=${REF#refs/heads/}
+          echo REF: $REF
+          BOOST_BRANCH=develop && [ "$REF" == "master" ] && BOOST_BRANCH=master || true
+          echo BOOST_BRANCH: $BOOST_BRANCH
+          cd ..
+          git clone -b $BOOST_BRANCH --depth 1 https://github.com/boostorg/boost.git boost-root
+          cd boost-root
+          mkdir -p libs/$LIBRARY
+          cp -r $GITHUB_WORKSPACE/* libs/$LIBRARY
+          git submodule update --init tools/boostdep
+          python3 tools/boostdep/depinst/depinst.py --git_args "--jobs 3" $LIBRARY
+      - name: Configure
+        run: |
+          cd ../boost-root
+          mkdir __build__ && cd __build__
+          cmake -DBOOST_INCLUDE_LIBRARIES=$LIBRARY -DBUILD_TESTING=ON -DCMAKE_CUDA_COMPILER=/usr/local/cuda/bin/nvcc -DBOOST_CHARCONV_ENABLE_CUDA=1 -DCMAKE_CUDA_ARCHITECTURES="75;86" -DCUDA_TOOLKIT_ROOT_DIR=/usr/local/cuda-12.8 -DCMAKE_CUDA_STANDARD=17 ..
+      - name: Build tests
+        run: |
+          cd ../boost-root/__build__
+          cmake --build . --target tests -j $(nproc)
+      - name: Run tests
+        run: |
+          cd ../boost-root/__build__
+          ctest --output-on-failure --no-tests=error

include/boost/charconv/detail/config.hpp

@@ -20,7 +20,7 @@
 #endif
 
 // Use 128-bit integers and suppress warnings for using extensions
-#if defined(BOOST_HAS_INT128)
+#if defined(BOOST_HAS_INT128) && !defined(__NVCC__)
 #  define BOOST_CHARCONV_HAS_INT128
 #  define BOOST_CHARCONV_INT128_MAX  static_cast<boost::int128_type>((static_cast<boost::uint128_type>(1) << 127) - 1)
 #  define BOOST_CHARCONV_INT128_MIN  (-BOOST_CHARCONV_INT128_MAX - 1)
@@ -201,5 +201,10 @@ static_assert(std::is_same<long double, __float128>::value, "__float128 should b
 
 #endif
 
+#ifdef __NVCC__
+#  define BOOST_CHARCONV_HOST_DEVICE __host__ __device__
+#else
+#  define BOOST_CHARCONV_HOST_DEVICE
+#endif
 
 #endif // BOOST_CHARCONV_DETAIL_CONFIG_HPP

include/boost/charconv/detail/from_chars_integer_impl.hpp

@@ -22,6 +22,8 @@
 
 namespace boost { namespace charconv { namespace detail {
 
+#ifndef __NVCC__
+
 static constexpr unsigned char uchar_values[] =
      {255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
       255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
@@ -83,9 +85,33 @@ static constexpr double log_2_table[] =
     0.193426403617
 };
 
+#endif // __NVCC__
+
 // Convert characters for 0-9, A-Z, a-z to 0-35. Anything else is 255
-constexpr unsigned char digit_from_char(char val) noexcept
+BOOST_CHARCONV_HOST_DEVICE constexpr unsigned char digit_from_char(const char val) noexcept
 {
+    #ifdef __NVCC__
+
+    constexpr unsigned char uchar_values[] =
+    {255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
+     255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
+     255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
+       0,   1,   2,   3,   4,   5,   6,   7,   8,   9, 255, 255, 255, 255, 255, 255,
+     255,  10,  11,  12,  13,  14,  15,  16,  17,  18,  19,  20,  21,  22,  23,  24,
+      25,  26,  27,  28,  29,  30,  31,  32,  33,  34,  35, 255, 255, 255, 255, 255,
+     255,  10,  11,  12,  13,  14,  15,  16,  17,  18,  19,  20,  21,  22,  23,  24,
+      25,  26,  27,  28,  29,  30,  31,  32,  33,  34,  35, 255, 255, 255, 255, 255,
+     255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
+     255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
+     255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
+     255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
+     255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
+     255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
+     255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
+     255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255};
+
+    #endif // __NVCC__
+
     return uchar_values[static_cast<unsigned char>(val)];
 }
 
@@ -111,9 +137,75 @@ constexpr unsigned char digit_from_char(char val) noexcept
 
 #endif
 
+#ifdef __NVCC__
+
+template <typename T>
+__host__ __device__ constexpr T get_max_value()
+{
+    using UT = typename std::make_unsigned<T>::type;
+    return std::is_signed<T>::value
+        ? static_cast<T>(static_cast<UT>(-1) >> 1)
+        : static_cast<T>(static_cast<UT>(-1));
+}
+
+#else
+
+template <typename T>
+constexpr T get_max_value()
+{
+    return (std::numeric_limits<T>::max)();
+}
+
+#endif
+
 template <typename Integer, typename Unsigned_Integer>
-BOOST_CXX14_CONSTEXPR from_chars_result from_chars_integer_impl(const char* first, const char* last, Integer& value, int base) noexcept
+BOOST_CHARCONV_HOST_DEVICE BOOST_CXX14_CONSTEXPR from_chars_result from_chars_integer_impl(const char* first, const char* last, Integer& value, int base) noexcept
 {
+    #ifdef __NVCC__
+
+    constexpr double log_2_table[] =
+    {
+        0.0,
+        0.0,
+        1.0,
+        0.630929753571,
+        0.5,
+        0.430676558073,
+        0.386852807235,
+        0.356207187108,
+        0.333333333333,
+        0.315464876786,
+        0.301029995664,
+        0.289064826318,
+        0.278942945651,
+        0.270238154427,
+        0.262649535037,
+        0.255958024810,
+        0.25,
+        0.244650542118,
+        0.239812466568,
+        0.235408913367,
+        0.231378213160,
+        0.227670248697,
+        0.224243824218,
+        0.221064729458,
+        0.218104291986,
+        0.215338279037,
+        0.212746053553,
+        0.210309917857,
+        0.208014597677,
+        0.205846832460,
+        0.203795047091,
+        0.201849086582,
+        0.2,
+        0.198239863171,
+        0.196561632233,
+        0.194959021894,
+        0.193426403617
+    };
+
+    #endif // __NVCC__
+
     Unsigned_Integer result = 0;
     Unsigned_Integer overflow_value = 0;
     Unsigned_Integer max_digit = 0;
@@ -155,8 +247,8 @@ BOOST_CXX14_CONSTEXPR from_chars_result from_chars_integer_impl(const char* firs
         else
         #endif
         {
-            overflow_value = static_cast<Unsigned_Integer>((std::numeric_limits<Integer>::max)());
-            max_digit = static_cast<Unsigned_Integer>((std::numeric_limits<Integer>::max)());
+            overflow_value = static_cast<Unsigned_Integer>(get_max_value<Integer>());
+            max_digit = static_cast<Unsigned_Integer>(get_max_value<Integer>());
         }
 
         if (is_negative)
@@ -181,8 +273,8 @@ BOOST_CXX14_CONSTEXPR from_chars_result from_chars_integer_impl(const char* firs
         else
         #endif
         {
-            overflow_value = (std::numeric_limits<Unsigned_Integer>::max)();
-            max_digit = (std::numeric_limits<Unsigned_Integer>::max)();
+            overflow_value = get_max_value<Unsigned_Integer>();
+            max_digit = get_max_value<Unsigned_Integer>();
         }
     }
 
@@ -310,7 +402,7 @@ BOOST_CXX14_CONSTEXPR from_chars_result from_chars_integer_impl(const char* firs
 
 // Only from_chars for integer types is constexpr (as of C++23)
 template <typename Integer>
-BOOST_CHARCONV_GCC5_CONSTEXPR from_chars_result from_chars(const char* first, const char* last, Integer& value, int base = 10) noexcept
+BOOST_CHARCONV_HOST_DEVICE BOOST_CHARCONV_GCC5_CONSTEXPR from_chars_result from_chars(const char* first, const char* last, Integer& value, int base = 10) noexcept
 {
     using Unsigned_Integer = typename std::make_unsigned<Integer>::type;
     return detail::from_chars_integer_impl<Integer, Unsigned_Integer>(first, last, value, base);
@@ -325,10 +417,12 @@ BOOST_CHARCONV_GCC5_CONSTEXPR from_chars_result from_chars128(const char* first,
 }
 #endif
 
+#ifndef __NVCC__
 BOOST_CHARCONV_GCC5_CONSTEXPR from_chars_result from_chars128(const char* first, const char* last, uint128& value, int base = 10) noexcept
 {
     return from_chars_integer_impl<uint128, uint128>(first, last, value, base);
 }
+#endif
 
 }}} // Namespaces
 

include/boost/charconv/detail/from_chars_result.hpp

@@ -5,6 +5,7 @@
 #ifndef BOOST_CHARCONV_DETAIL_FROM_CHARS_RESULT_HPP
 #define BOOST_CHARCONV_DETAIL_FROM_CHARS_RESULT_HPP
 
+#include <boost/charconv/detail/config.hpp>
 #include <system_error>
 
 namespace boost { namespace charconv {
@@ -22,17 +23,17 @@ struct from_chars_result_t
     // ERANGE = result_out_of_range
     std::errc ec;
 
-    friend constexpr bool operator==(const from_chars_result_t<UC>& lhs, const from_chars_result_t<UC>& rhs) noexcept
+    BOOST_CHARCONV_HOST_DEVICE friend constexpr bool operator==(const from_chars_result_t<UC>& lhs, const from_chars_result_t<UC>& rhs) noexcept
     {
         return lhs.ptr == rhs.ptr && lhs.ec == rhs.ec;
     }
 
-    friend constexpr bool operator!=(const from_chars_result_t<UC>& lhs, const from_chars_result_t<UC>& rhs) noexcept
+    BOOST_CHARCONV_HOST_DEVICE friend constexpr bool operator!=(const from_chars_result_t<UC>& lhs, const from_chars_result_t<UC>& rhs) noexcept
     {
         return !(lhs == rhs); // NOLINT : Expression can not be simplified since this is the definition
     }
 
-    constexpr explicit operator bool() const noexcept { return ec == std::errc{}; }
+    BOOST_CHARCONV_HOST_DEVICE constexpr explicit operator bool() const noexcept { return ec == std::errc{}; }
 };
 using from_chars_result = from_chars_result_t<char>;
 

include/boost/charconv/from_chars.hpp

@@ -19,48 +19,48 @@ namespace boost { namespace charconv {
 
 // integer overloads
 
-BOOST_CHARCONV_GCC5_CONSTEXPR from_chars_result from_chars(const char* first, const char* last, bool& value, int base = 10) noexcept = delete;
-BOOST_CHARCONV_GCC5_CONSTEXPR from_chars_result from_chars(const char* first, const char* last, char& value, int base = 10) noexcept
+BOOST_CHARCONV_HOST_DEVICE BOOST_CHARCONV_GCC5_CONSTEXPR from_chars_result from_chars(const char* first, const char* last, bool& value, int base = 10) noexcept = delete;
+BOOST_CHARCONV_HOST_DEVICE BOOST_CHARCONV_GCC5_CONSTEXPR from_chars_result from_chars(const char* first, const char* last, char& value, int base = 10) noexcept
 {
     return detail::from_chars(first, last, value, base);
 }
-BOOST_CHARCONV_GCC5_CONSTEXPR from_chars_result from_chars(const char* first, const char* last, signed char& value, int base = 10) noexcept
+BOOST_CHARCONV_HOST_DEVICE BOOST_CHARCONV_GCC5_CONSTEXPR from_chars_result from_chars(const char* first, const char* last, signed char& value, int base = 10) noexcept
 {
     return detail::from_chars(first, last, value, base);
 }
-BOOST_CHARCONV_GCC5_CONSTEXPR from_chars_result from_chars(const char* first, const char* last, unsigned char& value, int base = 10) noexcept
+BOOST_CHARCONV_HOST_DEVICE BOOST_CHARCONV_GCC5_CONSTEXPR from_chars_result from_chars(const char* first, const char* last, unsigned char& value, int base = 10) noexcept
 {
     return detail::from_chars(first, last, value, base);
 }
-BOOST_CHARCONV_GCC5_CONSTEXPR from_chars_result from_chars(const char* first, const char* last, short& value, int base = 10) noexcept
+BOOST_CHARCONV_HOST_DEVICE BOOST_CHARCONV_GCC5_CONSTEXPR from_chars_result from_chars(const char* first, const char* last, short& value, int base = 10) noexcept
 {
     return detail::from_chars(first, last, value, base);
 }
-BOOST_CHARCONV_GCC5_CONSTEXPR from_chars_result from_chars(const char* first, const char* last, unsigned short& value, int base = 10) noexcept
+BOOST_CHARCONV_HOST_DEVICE BOOST_CHARCONV_GCC5_CONSTEXPR from_chars_result from_chars(const char* first, const char* last, unsigned short& value, int base = 10) noexcept
 {
     return detail::from_chars(first, last, value, base);
 }
-BOOST_CHARCONV_GCC5_CONSTEXPR from_chars_result from_chars(const char* first, const char* last, int& value, int base = 10) noexcept
+BOOST_CHARCONV_HOST_DEVICE BOOST_CHARCONV_GCC5_CONSTEXPR from_chars_result from_chars(const char* first, const char* last, int& value, int base = 10) noexcept
 {
     return detail::from_chars(first, last, value, base);
 }
-BOOST_CHARCONV_GCC5_CONSTEXPR from_chars_result from_chars(const char* first, const char* last, unsigned int& value, int base = 10) noexcept
+BOOST_CHARCONV_HOST_DEVICE BOOST_CHARCONV_GCC5_CONSTEXPR from_chars_result from_chars(const char* first, const char* last, unsigned int& value, int base = 10) noexcept
 {
     return detail::from_chars(first, last, value, base);
 }
-BOOST_CHARCONV_GCC5_CONSTEXPR from_chars_result from_chars(const char* first, const char* last, long& value, int base = 10) noexcept
+BOOST_CHARCONV_HOST_DEVICE BOOST_CHARCONV_GCC5_CONSTEXPR from_chars_result from_chars(const char* first, const char* last, long& value, int base = 10) noexcept
 {
     return detail::from_chars(first, last, value, base);
 }
-BOOST_CHARCONV_GCC5_CONSTEXPR from_chars_result from_chars(const char* first, const char* last, unsigned long& value, int base = 10) noexcept
+BOOST_CHARCONV_HOST_DEVICE BOOST_CHARCONV_GCC5_CONSTEXPR from_chars_result from_chars(const char* first, const char* last, unsigned long& value, int base = 10) noexcept
 {
     return detail::from_chars(first, last, value, base);
 }
-BOOST_CHARCONV_GCC5_CONSTEXPR from_chars_result from_chars(const char* first, const char* last, long long& value, int base = 10) noexcept
+BOOST_CHARCONV_HOST_DEVICE BOOST_CHARCONV_GCC5_CONSTEXPR from_chars_result from_chars(const char* first, const char* last, long long& value, int base = 10) noexcept
 {
     return detail::from_chars(first, last, value, base);
 }
-BOOST_CHARCONV_GCC5_CONSTEXPR from_chars_result from_chars(const char* first, const char* last, unsigned long long& value, int base = 10) noexcept
+BOOST_CHARCONV_HOST_DEVICE BOOST_CHARCONV_GCC5_CONSTEXPR from_chars_result from_chars(const char* first, const char* last, unsigned long long& value, int base = 10) noexcept
 {
     return detail::from_chars(first, last, value, base);
 }

test/CMakeLists.txt

@@ -6,8 +6,24 @@ include(BoostTestJamfile OPTIONAL RESULT_VARIABLE HAVE_BOOST_TEST)
 
 if(HAVE_BOOST_TEST)
 
-# https://crascit.com/2015/03/28/enabling-cxx11-in-cmake/
-set(CMAKE_CXX_EXTENSIONS OFF)
-boost_test_jamfile(FILE Jamfile LINK_LIBRARIES Boost::charconv Boost::core Boost::assert)
+    enable_testing()
+
+    if(BOOST_CHARCONV_ENABLE_CUDA)
+
+        message(STATUS "Building Boost.charconv with CUDA")
+
+        find_package(CUDA REQUIRED)
+        enable_language(CUDA)
+        set(CMAKE_CUDA_EXTENSIONS OFF)
+
+        boost_test_jamfile(FILE cuda_jamfile LINK_LIBRARIES Boost::charconv Boost::core Boost::assert ${CUDA_LIBRARIES} INCLUDE_DIRECTORIES ${CUDA_INCLUDE_DIRS} )
+
+    else()
+
+        # https://crascit.com/2015/03/28/enabling-cxx11-in-cmake/
+        set(CMAKE_CXX_EXTENSIONS OFF)
+        boost_test_jamfile(FILE Jamfile LINK_LIBRARIES Boost::charconv Boost::core Boost::assert)
+
+    endif()
 
 endif()