Add support for pkg-config (#60)

3 files changed, 110 insertions, 1 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index e2d7d53..a492b10 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,7 +1,11 @@
 CMAKE_MINIMUM_REQUIRED(VERSION 3.5 FATAL_ERROR)
 
 # ---[ Project and semantic versioning.
-PROJECT(cpuinfo C CXX)
+PROJECT(
+    cpuinfo
+    LANGUAGES C CXX
+    HOMEPAGE_URL https://github.com/pytorch/cpuinfo
+    VERSION 0.1.0)
 
 # ---[ Options.
 SET(CPUINFO_LIBRARY_TYPE "default" CACHE STRING "Type of cpuinfo library (shared, static, or default) to build")
@@ -14,6 +18,7 @@ OPTION(CPUINFO_BUILD_TOOLS "Build command-line tools" ON)
 OPTION(CPUINFO_BUILD_UNIT_TESTS "Build cpuinfo unit tests" ON)
 OPTION(CPUINFO_BUILD_MOCK_TESTS "Build cpuinfo mock tests" ON)
 OPTION(CPUINFO_BUILD_BENCHMARKS "Build cpuinfo micro-benchmarks" ON)
+OPTION(CPUINFO_BUILD_PKG_CONFIG "Build pkg-config manifest" ON)
 
 # ---[ CMake options
 INCLUDE(GNUInstallDirs)
@@ -821,3 +826,32 @@ IF(CPUINFO_SUPPORTED_PLATFORM AND CPUINFO_BUILD_TOOLS)
     INSTALL(TARGETS cpuid-dump RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR})
   ENDIF()
 ENDIF()
+
+# ---[ pkg-config manifest. This is mostly from JsonCpp...
+if(CPUINFO_BUILD_PKG_CONFIG AND (CPUINFO_LIBRARY_TYPE STREQUAL "default" OR CPUINFO_LIBRARY_TYPE STREQUAL "shared"))
+
+    function(join_paths joined_path first_path_segment)
+        set(temp_path "${first_path_segment}")
+        foreach(current_segment IN LISTS ARGN)
+            if(NOT ("${current_segment}" STREQUAL ""))
+                if(IS_ABSOLUTE "${current_segment}")
+                    set(temp_path "${current_segment}")
+                else()
+                    set(temp_path "${temp_path}/${current_segment}")
+                endif()
+            endif()
+        endforeach()
+        set(${joined_path} "${temp_path}" PARENT_SCOPE)
+    endfunction()
+
+    join_paths(libdir_for_pc_file "\${exec_prefix}" "${CMAKE_INSTALL_LIBDIR}")
+    join_paths(includedir_for_pc_file "\${prefix}" "${CMAKE_INSTALL_INCLUDEDIR}")
+
+    configure_file(
+        "libcpuinfo.pc.in"
+        "libcpuinfo.pc"
+        @ONLY)
+    install(FILES "${CMAKE_CURRENT_BINARY_DIR}/libcpuinfo.pc"
+        DESTINATION "${CMAKE_INSTALL_LIBDIR}/pkgconfig")
+endif()
+
diff --git a/README.md b/README.md
index 97e65cd..3712640 100644
--- a/README.md
+++ b/README.md
@@ -100,6 +100,68 @@ for (uint32_t i = 0; i < current_l2->processor_count; i++) {
 pthread_setaffinity_np(pthread_self(), sizeof(cpu_set_t), &cpu_set);
 ```
 
+## Use via pkg-config
+
+If you would like to automatically have your project's build environment use the appropriate compiler and linker build flags, [pkg-config](https://www.freedesktop.org/wiki/Software/pkg-config/) can greatly simplify things. It is the portable international _de facto_ standard for determining build flags. Here is an example:
+
+### GNU Autotools
+
+To [use](https://autotools.io/pkgconfig/pkg_check_modules.html) with the GNU Autotools, as an example, include the following snippet in your project's `configure.ac`:
+
+```makefile
+# CPU INFOrmation library...
+PKG_CHECK_MODULES(
+    [libcpuinfo], [libcpuinfo >= 0.1], [],
+    [AC_MSG_ERROR([libcpuinfo >= 0.1 missing...])])
+YOURPROJECT_CXXFLAGS="$YOURPROJECT_CXXFLAGS $libcpuinfo_CFLAGS"
+YOURPROJECT_LIBS="$YOURPROJECT_LIBS $libcpuinfo_LIBS"
+```
+
+### Meson
+
+To use with Meson, you just need to add `dependency('libcpuinfo')` as a dependency for your executable.
+
+```meson
+project(
+    'MyCpuInfoProject',
+    'cpp',
+    meson_version: '>=0.55.0'
+)
+
+executable(
+    'MyCpuInfoExecutable',
+    sources: 'main.cpp',
+    dependencies: dependency('libcpuinfo')
+)
+```
+
+### CMake
+
+To use with a CMake build environment, use the [FindPkgConfig](https://cmake.org/cmake/help/latest/module/FindPkgConfig.html) module. Here is an example:
+
+```cmake
+cmake_minimum_required(VERSION 3.6)
+project("MyCpuInfoProject")
+
+find_package(PkgConfig)
+pkg_check_modules(CpuInfo REQUIRED IMPORTED_TARGET libcpuinfo)
+
+add_executable(${PROJECT_NAME} main.cpp)
+target_link_libraries(${PROJECT_NAME} PkgConfig::CpuInfo)
+```
+
+### Makefile
+
+To use within a vanilla makefile, you can call `pkg-config` directly to supply compiler and linker flags using shell substitution.
+
+```makefile
+CFLAGS=-g3 -Wall -Wextra -Werror ...
+LDFLAGS=-lfoo ...
+...
+CFLAGS+= $(pkg-config --cflags libcpuinfo)
+LDFLAGS+= $(pkg-config --libs libcpuinfo)
+```
+
 ## Exposed information
 - [x] Processor (SoC) name
 - [x] Microarchitecture
@@ -202,3 +264,4 @@ pthread_setaffinity_np(pthread_self(), sizeof(cpu_set_t), &cpu_set);
   - [x] Using `GetLogicalProcessorInformationEx` (Windows)
   - [x] Using sysfs (Linux)
   - [x] Using chipset name (ARM/Linux)
+
diff --git a/libcpuinfo.pc.in b/libcpuinfo.pc.in
new file mode 100644
index 0000000..a8fe607
--- /dev/null
+++ b/libcpuinfo.pc.in
@@ -0,0 +1,12 @@
+prefix=@CMAKE_INSTALL_PREFIX@
+exec_prefix=@CMAKE_INSTALL_PREFIX@
+libdir=@libdir_for_pc_file@
+includedir=@includedir_for_pc_file@
+
+Name: libcpuinfo
+Description: Library to detect essential performance optimization information about host CPU.
+Version: @PROJECT_VERSION_MAJOR@.@PROJECT_VERSION_MINOR@.@PROJECT_VERSION_PATCH@
+URL: @PROJECT_HOMEPAGE_URL@
+Libs: -L${libdir} -lcpuinfo
+Cflags: -I${includedir}
+