diff --git a/CMakeLists.txt b/CMakeLists.txt
new file mode 100644
index 0000000..7e50013
--- /dev/null
+++ b/CMakeLists.txt
@@ -0,0 +1,241 @@
+#.rst
+# CMake configuration of libLBFGS project
+# ---------------------------------------
+#
+# This CMakeLists.txt defines some libLBFGS specific configuration variables
+# using a custom "subproject_define" command defined in the Subproject.cmake module.
+# The default values of these variables can be overridden either on the CMake
+# command-line using the -D option of the cmake command or in a super-project
+# which includes the libLBFGS source tree by setting the LBFGS_<varname>
+# CMake variables before adding the libLBFGS source directory via CMake's
+# add_subdirectory command. Only when the non-cached variable LBFGS_IS_SUBPROJECT
+# has a value equivalent to FALSE, these configuration variables are added to
+# the CMake cache so they can be edited in the CMake GUI. By default,
+# LBFGS_IS_SUBPROJECT is set to TRUE when the CMAKE_SOURCE_DIR is not identical
+# to the directory of this CMakeLists.txt  file, i.e., the top-level directory of
+# the libLBFGS project source tree.
+#
+# Example CMakeLists.txt of user project which requires separate libLBFGS
+# installation (possibly requires FindLBFGS.cmake module for distribution
+# packages of libLBFGS that do not include a LBFGSConfig.cmake file)::
+#
+#    cmake_minimum_required(VERSION 2.8.12 FATAL_ERROR)
+#
+#    project(Foo)
+#
+#    find_package(LBFGS REQUIRED)
+#
+#    add_executable(foo src/foo.cc)
+#    target_link_libraries(foo LBFGS::lib)
+#
+# Example CMakeLists.txt of super-project which contains libLBFGS source tree::
+#
+#    cmake_minimum_required(VERSION 2.8.12 FATAL_ERROR)
+#
+#    project(Foo)
+#
+#    set(LBFGS_USE_SSE ON)
+#    set(LBFGS_lib_TARGET_NAME liblbfgs)
+#    add_subdirectory(lbfgs)
+#    set_target_properties(liblbfgs PROPERTIES OUTPUT_NAME foolbfgs)
+#
+#    add_executable(foo src/foo.cc)
+#    target_link_libraries(foo liblbfgs)
+#    # or use the usual namespaced ALIAS target:
+#    #target_link_libraries(foo LBFGS::lib)
+#
+# Variables to configure the source files::
+#
+#    LBFGS_USE_DOUBLE  - Enable double precision floating point arithmetics. (default: ON)
+#    LBFGS_USE_SSE     - Enable SSE/SSE2 optimiations. (default: OFF)
+#    LBFGS_USE_IEEE754 - Enable optimization routines for IEEE754 floating point values. (default: ON)
+#
+# Variables to configure the build::
+#
+#    LBFGS_BUILD_SHARED_LIBS    - Enable build of shared libraries. (default: OFF)
+#    LBFGS_BUILD_EXAMPLES       - Enable build of example programs. (default: OFF)
+#    LBFGS_<target>_TARGET_NAME - Custom target name for target <target>, i.e., "lib" or "sample".
+#                                 By default, the target name is prefixed by "lbfgs_" if this project
+#                                 is configured as a subproject of another project.
+#    LBFGS_NO_ALIASES           - Do not add ALIAS targets LBFGS::lib and LBFGS::sample. (default: OFF)
+#
+# Variables to configure the installation::
+#
+#    LBFGS_INSTALL_STATIC_LIBS - Whether to install static library files.
+#                                Shared libraries are always installed.
+#                                When a library is installed, its public header
+#                                files are installed as well. The default is
+#                                to not install static libraries when this
+#                                project is a subproject of another project.
+#    LBFGS_INSTALL_HEADERS     - Can be used to omit installation of public header files.
+#    LBFGS_INSTALL_CONFIG      - Whether to install CMake configuration files.
+#                                By default, the CMake configuration files are
+#                                installed when the library itself is installed.
+#    LBFGS_INSTALL_RUNTIME_DIR - Installation directory for runtime files. (default: bin)
+#    LBFGS_INSTALL_INCLUDE_DIR - Installation directory for public header files. (default: include)
+#    LBFGS_INSTALL_LIBRARY_DIR - Installation directory for library files. (default: lib)
+#    LBFGS_INSTALL_CONFIG_DIR  - Installation directory for CMake configuration. (default: lib/cmake/liblbfgs)
+
+# ==============================================================================
+# libLBFGS: C library of limited-memory BFGS (L-BFGS)
+#
+# Copyright (c) 1990, Jorge Nocedal
+# Copyright (c) 2007-2010, Naoaki Okazaki
+#
+# libLBFGS is distributed under the term of the MIT license.
+# Please refer to COPYING file in the distribution.
+# ==============================================================================
+
+# ----------------------------------------------------------------------------
+# CMake version and policies
+cmake_minimum_required(VERSION 2.8.12 FATAL_ERROR)
+
+if (POLICY CMP0042)
+  cmake_policy(SET CMP0042 NEW)
+endif ()
+
+# ----------------------------------------------------------------------------
+# includes
+include("${CMAKE_CURRENT_SOURCE_DIR}/cmake/Subproject.cmake")
+
+# ----------------------------------------------------------------------------
+# package info
+subproject(LBFGS VERSION 1.10.0 LANGUAGES C)
+
+set(PACKAGE_NAME      "libLBFGS")
+set(PACKAGE_STRING    "${PACKAGE_NAME} ${PROJECT_VERSION}")
+set(PACKAGE_TARNAME   "liblbfgs-${PROJECT_VERSION}")
+set(PACKAGE_BUGREPORT "https://github.com/chokkan/liblbfgs/issues")
+
+# ----------------------------------------------------------------------------
+# options
+subproject_define(BOOL BUILD_SHARED_LIBS "Enable build of shared libraries"                OFF)
+subproject_define(BOOL BUILD_EXAMPLES    "Enable build of sample programs"                 OFF)
+subproject_define(BOOL USE_DOUBLE        "Use double precision floating point arithmetics" ON)
+subproject_define(BOOL USE_SSE           "Use SSE/SSE2 instructions for optimization"      OFF)
+subproject_define(BOOL USE_IEEE754       "Activate optimization routines for IEEE754 floating point values" ON)
+
+subproject_set_property(USE_IEEE754 ADVANCED TRUE)
+
+# ----------------------------------------------------------------------------
+# checks for SSE/SSE2 instructions header files
+if (USE_SSE)
+  include(CheckIncludeFile)
+  if (USE_DOUBLE)
+    check_include_file(emmintrin.h HAVE_EMMINTRIN_H)
+    if (NOT HAVE_EMMINTRIN_H)
+      message(WARNING "SSE2 instructions header file emmintrin.h not found. Disabled SSE optimizations.")
+      subproject_set_property(USE_SSE VALUE OFF)
+    endif ()
+  else ()
+    check_include_file(xmmintrin.h HAVE_XMMINTRIN_H)
+    if (NOT HAVE_XMMINTRIN_H)
+      message(WARNING "SSE instructions header file xmmintrin.h not found. Disabled SSE optimizations.")
+      subproject_set_property(USE_SSE VALUE OFF)
+    endif ()
+  endif ()
+endif ()
+
+# ----------------------------------------------------------------------------
+# library
+set(HEADERS
+  "include/lbfgs.h"
+)
+
+set(SOURCES
+  "lib/lbfgs.c"
+  "lib/arithmetic_ansi.h"
+  "lib/arithmetic_sse_float.h"
+  "lib/arithmetic_sse_double.h"
+)
+
+subproject_add_library(_lib "lib" ${HEADERS} ${SOURCES})
+
+set_target_properties(${_lib} PROPERTIES
+  OUTPUT_NAME   lbfgs
+  VERSION       ${PROJECT_VERSION}
+  SOVERSION     ${PROJECT_SOVERSION}
+  DEBUG_POSTFIX d
+  POSITION_INDEPENDENT_CODE TRUE
+)
+
+target_include_directories(${_lib}
+  PUBLIC  "$<BUILD_INTERFACE:${PROJECT_SOURCE_DIR}/include>"
+  PRIVATE "${PROJECT_SOURCE_DIR}/lib"
+)
+
+if (NOT USE_DOUBLE)
+  target_compile_definitions(${_lib} INTERFACE LBFGS_FLOAT=32)
+endif ()
+if (NOT USE_IEEE754)
+  target_compile_definitions(${_lib} INTERFACE LBFGS_IEEE_FLOAT=0)
+endif ()
+if (USE_SSE)
+  if (USE_DOUBLE)
+    target_compile_definitions(${_lib} PRIVATE HAVE_EMMINTRIN_H=${HAVE_EMMINTRIN_H})
+    if (MSVC)
+      target_compile_definitions(${_lib} PRIVATE __SSE2__)
+    endif ()
+  else ()
+    target_compile_definitions(${_lib} PRIVATE HAVE_XMMINTRIN_H=${HAVE_XMMINTRIN_H})
+    if (MSVC)
+      target_compile_definitions(${_lib} PRIVATE __SSE__)
+    endif ()
+  endif ()
+endif ()
+
+if (CMAKE_COMPILER_IS_GNUC)
+  target_compile_options(${_lib} PRIVATE "$<$<CONFIG:Release>:-ffast-math>")
+  if (USE_SSE)
+    if (USE_DOUBLE)
+      target_compile_options(${_lib} PRIVATE "-msse2")
+    else ()
+      target_compile_options(${_lib} PRIVATE "-msse")
+    endif ()
+  endif ()
+endif ()
+
+subproject_install_library(${_lib}
+  RUNTIME_DESTINATION "bin"
+  LIBRARY_DESTINATION "lib"
+  INCLUDE_DESTINATION "include"
+  PUBLIC_HEADER_FILES "${HEADERS}"
+)
+
+# ----------------------------------------------------------------------------
+# examples
+if (BUILD_EXAMPLES)
+  subproject_add_executable(_sample "sample" sample/sample.c)
+  target_link_libraries(${_sample} ${_lib})
+endif ()
+
+# ----------------------------------------------------------------------------
+# configuration
+include(CMakePackageConfigHelpers)
+
+subproject_get_install_config_dir(PROJECT_INSTALL_CONFIG_DIR)
+
+configure_package_config_file(
+  "${PROJECT_SOURCE_DIR}/cmake/Config.cmake.in"
+  "${PROJECT_BINARY_DIR}/${PROJECT_NAME}Config.cmake"
+  INSTALL_DESTINATION "${PROJECT_INSTALL_CONFIG_DIR}"
+  NO_SET_AND_CHECK_MACRO
+  NO_CHECK_REQUIRED_COMPONENTS_MACRO
+)
+
+write_basic_package_version_file(
+  "${PROJECT_BINARY_DIR}/${PROJECT_NAME}ConfigVersion.cmake"
+  VERSION       ${PROJECT_VERSION}
+  COMPATIBILITY AnyNewerVersion
+)
+
+subproject_install_config_files(
+  FILES
+    "${PROJECT_BINARY_DIR}/${PROJECT_NAME}Config.cmake"
+    "${PROJECT_BINARY_DIR}/${PROJECT_NAME}ConfigVersion.cmake"
+  DESTINATION
+    "${PROJECT_INSTALL_CONFIG_DIR}"
+)
+
+subproject_export(TARGETS ${_lib})
+subproject_install_exports(DESTINATION "${PROJECT_INSTALL_CONFIG_DIR}")
diff --git a/cmake/Config.cmake.in b/cmake/Config.cmake.in
new file mode 100644
index 0000000..2c55a88
--- /dev/null
+++ b/cmake/Config.cmake.in
@@ -0,0 +1,15 @@
+## @PROJECT_NAME@ CMake configuration file
+
+# library version information
+set(@PROJECT_NAME@_VERSION_STRING "@PROJECT_VERSION@")
+set(@PROJECT_NAME@_VERSION_MAJOR  @PROJECT_VERSION_MAJOR@)
+set(@PROJECT_NAME@_VERSION_MINOR  @PROJECT_VERSION_MINOR@)
+set(@PROJECT_NAME@_VERSION_PATCH  @PROJECT_VERSION_PATCH@)
+
+# import exported targets
+if (NOT TARGET @PROJECT_NAME@::lib)
+  include("${CMAKE_CURRENT_LIST_DIR}/@PROJECT_NAME@Targets.cmake")
+endif ()
+
+# project libraries
+set(@PROJECT_NAME@_LIBRARIES @PROJECT_NAME@::lib)
diff --git a/cmake/Subproject.cmake b/cmake/Subproject.cmake
new file mode 100644
index 0000000..f982795
--- /dev/null
+++ b/cmake/Subproject.cmake
@@ -0,0 +1,360 @@
+# ==============================================================================
+# Utility CMake functions for standalone or subproject build configuration.
+#
+# This CMake source file is released into the public domain.
+#
+# Author: Andreas Schuh (andreas.schuh.84@gmail.com)
+# ==============================================================================
+
+include(CMakeParseArguments)
+
+# ----------------------------------------------------------------------------
+## Start (sub-)project
+#
+# This macro is for CMake versions 2.8.12 which did not have the VERSION
+# argument yet. It additionally sets the PROJECT_SOVERSION to either the
+# project major version number or ${PROJECT_NAME}_SOVERSION if set.
+# When ${PROJECT_NAME}_IS_SUBPROJECT is not defined, PROJECT_IS_SUBPROJECT
+# is set to TRUE when the source directory of this project is not the
+# top-level source directory, and FALSE otherwise.
+#
+# Besides the PROJECT_NAME variable, this macro also sets PROJECT_NAME_LOWER
+# and PROJECT_NAME_UPPER to the respective all lower- or uppercase strings.
+macro (subproject name)
+  cmake_parse_arguments("" "" "VERSION;SOVERSION" "LANGUAGES" ${ARGN})
+  if (_UNPARSED_ARGUMENTS)
+    message(FATAL_ERROR "Unrecognized arguments: ${_UNPARSED_ARGUMENTS}")
+  endif ()
+  if (NOT _VERSION)
+    set(_VERSION 0.0.0) # invalid version number
+  endif ()
+  unset(PROJECT_VERSION)
+  unset(PROJECT_VERSION_MAJOR)
+  unset(PROJECT_VERSION_MINOR)
+  unset(PROJECT_VERSION_PATCH)
+  unset(${name}_VERSION)
+  unset(${name}_VERSION_MAJOR)
+  unset(${name}_VERSION_MINOR)
+  unset(${name}_VERSION_PATCH)
+  project(${name} ${_LANGUAGES})
+  set(PROJECT_VERSION "${_VERSION}")
+  _subproject_split_version_numbers(${PROJECT_VERSION}
+    PROJECT_VERSION_MAJOR
+    PROJECT_VERSION_MINOR
+    PROJECT_VERSION_PATCH
+  )
+  set(${name}_VERSION       ${PROJECT_VERSION})
+  set(${name}_VERSION_MAJOR ${PROJECT_VERSION_MAJOR})
+  set(${name}_VERSION_MINOR ${PROJECT_VERSION_MINOR})
+  set(${name}_VERSION_PATCH ${PROJECT_VERSION_PATCH})
+  if (NOT _SOVERSION)
+    set(_SOVERSION ${PROJECT_VERSION_MAJOR})
+  endif ()
+  _subproject_set_abi_version(PROJECT_SOVERSION ${_SOVERSION})
+  set(${name}_SOVERSION ${PROJECT_SOVERSION})
+  _subproject_check_if_subproject()
+  string(TOLOWER ${PROJECT_NAME} PROJECT_NAME_LOWER)
+  string(TOUPPER ${PROJECT_NAME} PROJECT_NAME_UPPER)
+  unset(_VERSION)
+  unset(_SOVERSION)
+  unset(_LANGUAGES)
+  unset(_UNPARSED_ARGUMENTS)
+  if (${PROJECT_NAME}_EXPORT_NAME)
+    set(PROJECT_EXPORT_NAME ${${PROJECT_NAME}_EXPORT_NAME})
+  else ()
+    set(PROJECT_EXPORT_NAME ${PROJECT_NAME})
+  endif ()
+  set_property(GLOBAL PROPERTY ${PROJECT_NAME}_HAVE_EXPORT FALSE)
+endmacro ()
+
+# ----------------------------------------------------------------------------
+## Add configuration variable
+#
+# The default value of the (cached) configuration value can be overridden
+# either on the CMake command-line or the super-project by setting the
+# ${PROJECT_NAME}_${varname} variable. When this project is a subproject
+# of another project, i.e., PROJECT_IS_SUBPROJECT is TRUE, the variable
+# is not added to the CMake cache and set to the value of
+# ${PROJECT_NAME}_${varname} regardless if the parent project defines
+# a (cached) variable of the same name. Otherwise, when this project is
+# a standalone project, the variable is cached.
+macro (subproject_define type varname docstring default)
+  if (ARGC GREATER 5)
+    message (FATAL_ERROR "Too many macro arguments")
+  endif ()
+  if (NOT DEFINED ${PROJECT_NAME}_${varname})
+    if (PROJECT_IS_SUBPROJECT AND ARGC EQUAL 5)
+      set(${PROJECT_NAME}_${varname} "${ARGV4}")
+    else ()
+      set(${PROJECT_NAME}_${varname} "${default}")
+    endif ()
+  endif ()
+  if (PROJECT_IS_SUBPROJECT)
+    set(${varname} "${${PROJECT_NAME}_${varname}}")
+  else ()
+    set(${varname} "${${PROJECT_NAME}_${varname}}" CACHE ${type} "${docstring}")
+  endif ()
+endmacro ()
+
+# ----------------------------------------------------------------------------
+## Set property of (cached) configuration variable
+#
+# This command does nothing when the previously defined variable was not added
+# to the CMake cache because this project is build as subproject unless
+# the property to be set is the VALUE of the configuration variable.
+#
+# @see subproject_define
+macro (subproject_set_property varname property value)
+  _subproject_check_if_cached(_is_cached ${varname})
+  if (_is_cached)
+    if (property STREQUAL ADVANCED)
+      if (${value})
+        mark_as_advanced(FORCE ${varname})
+      else ()
+        mark_as_advanced(CLEAR ${varname})
+      endif ()
+    else ()
+      set_property(CACHE ${varname} PROPERTY "${property}" "${value}")
+    endif ()
+  elseif (property STREQUAL VALUE)
+    set(${varname} "${value}")
+  endif ()
+  unset(_is_cached)
+endmacro ()
+
+# ----------------------------------------------------------------------------
+## Get unique target name
+macro (subproject_target_name uid target)
+  if (${PROJECT_NAME}_${target}_TARGET_NAME)
+    set(${uid} ${${PROJECT_NAME}_${target}_TARGET_NAME})
+  elseif (PROJECT_IS_SUBPROJECT)
+    set(${uid} "${PROJECT_NAME_LOWER}_${target}")
+  else ()
+    set(${uid} "${target}")
+  endif ()
+endmacro ()
+
+# ----------------------------------------------------------------------------
+## Add executable target
+function (subproject_add_executable uid target)
+  subproject_target_name(_uid ${target})
+  add_executable(${_uid} ${ARGN})
+  if (NOT ${PROJECT_NAME}_NO_ALIASES)
+    add_executable(${PROJECT_NAME}::${target} ALIAS ${_uid})
+  endif ()
+  set(${uid} "${_uid}" PARENT_SCOPE)
+endfunction ()
+
+# ----------------------------------------------------------------------------
+## Add library target
+function (subproject_add_library uid target)
+  subproject_target_name(_uid ${target})
+  add_library(${_uid} ${ARGN})
+  if (NOT ${PROJECT_NAME}_NO_ALIASES)
+    add_library(${PROJECT_NAME}::${target} ALIAS ${_uid})
+  endif ()
+  set(${uid} "${_uid}" PARENT_SCOPE)
+endfunction ()
+
+# ----------------------------------------------------------------------------
+## Install files of library target
+function (subproject_install_library target)
+  # parse arguments
+  if (NOT TARGET ${target})
+    message(FATAL_ERROR "Unknown target: ${target}")
+  endif ()
+  get_target_property(type ${target} TYPE)
+  if (NOT PROJECT_IS_SUBPROJECT OR NOT "^${type}$" STREQUAL "^STATIC_LIBRARY$" OR ${PROJECT_NAME}_INSTALL_STATIC_LIBS)
+    cmake_parse_arguments(""
+      ""
+      "INCLUDE_DESTINATION;LIBRARY_DESTINATION;RUNTIME_DESTINATION"
+      "PUBLIC_HEADER_FILES"
+      ${ARGN}
+    )
+    if (_UNPARSED_ARGUMENTS)
+      message(FATAL_ERROR "Too many or unrecognized arguments: ${_UNPARSED_ARGUMENTS}")
+    endif ()
+    # override (default) arguments
+    if (${PROJECT_NAME}_INSTALL_RUNTIME_DIR)
+      set(_RUNTIME_DESTINATION "${${PROJECT_NAME}_INSTALL_RUNTIME_DIR}")
+    elseif (NOT _RUNTIME_DESTINATION)
+      set(_RUNTIME_DESTINATION bin)
+    endif ()
+    if (${PROJECT_NAME}_INSTALL_INCLUDE_DIR)
+      set(_INCLUDE_DESTINATION "${${PROJECT_NAME}_INSTALL_INCLUDE_DIR}")
+    elseif (NOT _INCLUDE_DESTINATION)
+      set(_INCLUDE_DESTINATION include)
+    endif ()
+    if (${PROJECT_NAME}_INSTALL_LIBRARY_DIR)
+      set(_LIBRARY_DESTINATION "${${PROJECT_NAME}_INSTALL_LIBRARY_DIR}")
+    elseif (NOT _LIBRARY_DESTINATION)
+      set(_LIBRARY_DESTINATION lib)
+    endif ()
+    # skip installation of static subproject library
+    if (_PUBLIC_HEADER_FILES AND (NOT DEFINED ${PROJECT_NAME}_INSTALL_HEADERS OR ${PROJECT_NAME}_INSTALL_HEADERS))
+      install(FILES ${_PUBLIC_HEADER_FILES} DESTINATION ${_INCLUDE_DESTINATION} COMPONENT Development)
+      target_include_directories(${target} INTERFACE "$<INSTALL_INTERFACE:${_INCLUDE_DESTINATION}>")
+    endif ()
+    install(TARGETS ${target} EXPORT ${PROJECT_EXPORT_NAME}
+      RUNTIME DESTINATION ${_RUNTIME_DESTINATION} COMPONENT RuntimeLibraries
+      LIBRARY DESTINATION ${_LIBRARY_DESTINATION} COMPONENT RuntimeLibraries
+      ARCHIVE DESTINATION ${_LIBRARY_DESTINATION} COMPONENT Development
+    )
+    set_property(GLOBAL PROPERTY ${PROJECT_NAME}_HAVE_EXPORT TRUE)
+  endif ()
+endfunction ()
+
+# ----------------------------------------------------------------------------
+## Whether to install package configuration files of (sub-)project
+macro (subproject_get_install_config_option var)
+  if (PROJECT_IS_SUBPROJECT AND ${PROJECT_NAME}_INSTALL_CONFIG)
+    set (${var} 1)
+  elseif (NOT PROJECT_IS_SUBPROJECT AND (NOT DEFINED ${PROJECT_NAME}_INSTALL_CONFIG OR ${PROJECT_NAME}_INSTALL_CONFIG))
+    set (${var} 1)
+  else ()
+    set (${var} 0)
+  endif ()
+endmacro ()
+
+# ----------------------------------------------------------------------------
+## Get relative path of package configuration installation directory
+macro (subproject_get_install_config_dir config_dir)
+  if (${PROJECT_NAME}_INSTALL_CONFIG_DIR)
+    set(${config_dir} "${${PROJECT_NAME}_INSTALL_CONFIG_DIR}")
+  elseif (WIN32 AND NOT MINGW AND NOT CYGWIN)
+    set(${config_dir} "cmake")
+  else ()
+    set(${config_dir} "lib/cmake/${PROJECT_NAME_LOWER}")
+  endif ()
+endmacro ()
+
+# ----------------------------------------------------------------------------
+## Install package configuration files
+function (subproject_install_config_files)
+  subproject_get_install_config_option (_install_config)
+  if (_install_config)
+    # parse arguments
+    cmake_parse_arguments("" "" "DESTINATION" "FILES" ${ARGN})
+    if (_UNPARSED_ARGUMENTS)
+      message(FATAL_ERROR "Unrecognized arguments: ${_UNPARSED_ARGUMENTS}")
+    endif ()
+    if (${PROJECT_NAME}_INSTALL_CONFIG_DIR OR NOT _DESTINATION)
+      subproject_get_install_config_dir(_DESTINATION)
+    endif ()
+    # install package configuration files if not overriden
+    install(FILES ${_FILES} DESTINATION ${_DESTINATION} COMPONENT Development)
+  endif ()
+endfunction ()
+
+# ----------------------------------------------------------------------------
+## Generate build tree targets configuration file
+function (subproject_export)
+  cmake_parse_arguments("" "" "" "TARGETS" ${ARGN})
+  export(TARGETS ${_TARGETS} ${_UNPARSED_ARGUMENTS}
+    FILE      "${PROJECT_BINARY_DIR}/${PROJECT_NAME}Targets.cmake"
+    NAMESPACE "${PROJECT_NAME}::"
+  )
+endfunction ()
+
+# ----------------------------------------------------------------------------
+## Install exported targets configuration files
+function (subproject_install_exports)
+  subproject_get_install_config_option (_install_config)
+  if (_install_config)
+    # parse arguments
+    cmake_parse_arguments("" "" "DESTINATION" "" ${ARGN})
+    if (_UNPARSED_ARGUMENTS)
+      message(FATAL_ERROR "Unrecognized arguments: ${_UNPARSED_ARGUMENTS}")
+    endif ()
+    if (${PROJECT_NAME}_INSTALL_CONFIG_DIR OR NOT _DESTINATION)
+      subproject_get_install_config_dir(_DESTINATION)
+    endif ()
+    # install export sets
+    get_property(have_export GLOBAL PROPERTY ${PROJECT_NAME}_HAVE_EXPORT)
+    if (have_export)
+      install(EXPORT ${PROJECT_EXPORT_NAME}
+        FILE        "${PROJECT_NAME}Targets.cmake"
+        NAMESPACE   "${PROJECT_NAME}::"
+        DESTINATION "${_DESTINATION}"
+        COMPONENT   Development
+      )
+    endif ()
+  endif ()
+endfunction ()
+
+# ==============================================================================
+# Private auxiliary functions
+# ==============================================================================
+
+# ----------------------------------------------------------------------------
+# Extract version numbers from version string
+function (_subproject_split_version_numbers version major minor patch)
+  if (version MATCHES "([0-9]+)(\\.[0-9]+)?(\\.[0-9]+)?(rc[1-9][0-9]*|[a-z]+)?")
+    if (CMAKE_MATCH_1)
+      set(_major ${CMAKE_MATCH_1})
+    else ()
+      set(_major 0)
+    endif ()
+    if (CMAKE_MATCH_2)
+      set(_minor ${CMAKE_MATCH_2})
+      string (REGEX REPLACE "^\\." "" _minor "${_minor}")
+    else ()
+      set(_minor 0)
+    endif ()
+    if (CMAKE_MATCH_3)
+      set(_patch ${CMAKE_MATCH_3})
+      string(REGEX REPLACE "^\\." "" _patch "${_patch}")
+    else ()
+      set(_patch 0)
+    endif ()
+  else ()
+    set(_major 0)
+    set(_minor 0)
+    set(_patch 0)
+  endif ()
+  set("${major}" "${_major}" PARENT_SCOPE)
+  set("${minor}" "${_minor}" PARENT_SCOPE)
+  set("${patch}" "${_patch}" PARENT_SCOPE)
+endfunction ()
+
+# ----------------------------------------------------------------------------
+# Set ABI version number
+#
+# When the variable ${PROJECT_NAME}_SOVERSION is set, it overrides the ABI
+# version number argument.
+macro (_subproject_set_abi_version varname number)
+  if (${PROJECT_NAME}_SOVERSION)
+    set(${varname} "${${PROJECT_NAME}_SOVERSION}")
+  else ()
+    set(${varname} "${number}")
+  endif ()
+endmacro ()
+
+# ----------------------------------------------------------------------------
+# Determine if project is build as subproject
+#
+# When included as subproject (e.g., as Git submodule/subtree) in the source
+# tree of a project that uses it, no variables should be added to the CMake cache;
+# users may set the (non-cached) variable ${PROJECT_NAME}_IS_SUBPROJECT before
+# the add_subdirectory command that adds this subdirectory to the build.
+#
+# @returns Sets PROJECT_IS_SUBPROJECT to either TRUE or FALSE.
+macro (_subproject_check_if_subproject)
+  if (DEFINED ${PROJECT_NAME}_IS_SUBPROJECT)
+    set(PROJECT_IS_SUBPROJECT ${PROJECT_NAME}_IS_SUBPROJECT)
+  elseif ("^${CMAKE_SOURCE_DIR}$" STREQUAL "^${PROJECT_SOURCE_DIR}$")
+    set(PROJECT_IS_SUBPROJECT FALSE)
+  else ()
+    set(PROJECT_IS_SUBPROJECT TRUE)
+  endif ()
+endmacro ()
+
+# ----------------------------------------------------------------------------
+# Determine if cache entry exists
+macro (_subproject_check_if_cached retvar varname)
+  if (DEFINED ${varname})
+    get_property(${retvar} CACHE ${varname} PROPERTY TYPE SET)
+  else ()
+    set(${retvar} FALSE)
+  endif ()
+endmacro ()