Build: Add very limited experimental CMake support.

This does *NOT* replace the Autotools-based build system in
the foreseeable future. See the comment in the beginning
of CMakeLists.txt.

So far this has been tested only on GNU/Linux but I commit
it anyway to make it easier for others to test. Since I
haven't played much with CMake before, it's likely that
there are things that have been done in a silly or wrong
way and need to be fixed.

1 files changed, 173 insertions, 0 deletions

diff --git a/cmake/tuklib_cpucores.cmake b/cmake/tuklib_cpucores.cmake
new file mode 100644
index 00000000..34546b0d
--- /dev/null
+++ b/cmake/tuklib_cpucores.cmake
@@ -0,0 +1,173 @@
+#
+# tuklib_cpucores.cmake - see tuklib_cpucores.m4 for description and comments
+#
+# Author: Lasse Collin
+#
+# This file has been put into the public domain.
+# You can do whatever you want with this file.
+#
+
+include(${CMAKE_CURRENT_LIST_DIR}/tuklib_common.cmake)
+include(CheckCSourceCompiles)
+include(CheckIncludeFile)
+
+function(tuklib_cpucores_internal_check)
+    if(CACHE{TUKLIB_CPUCORES_DEFINITIONS})
+        return()
+    endif()
+
+    if(WIN32 OR CYGWIN)
+        # Nothing to do, the tuklib_cpucores.c handles it.
+        set(TUKLIB_CPUCORES_DEFINITIONS "" CACHE INTERNAL "")
+        return()
+    endif()
+
+    # glibc-based systems (GNU/Linux and GNU/kFreeBSD) have
+    # sched_getaffinity(). The CPU_COUNT() macro was added in glibc 2.9.
+    # glibc 2.9 is old enough that if someone uses the code on older glibc,
+    # the fallback to sysconf() should be good enough.
+    #
+    # NOTE: This required that _GNU_SOURCE is defined. We assume that whatever
+    #       feature test macros the caller wants to use are already set in
+    #       CMAKE_REQUIRED_DEFINES and in the target defines.
+    check_c_source_compiles("
+            #include <sched.h>
+            int main(void)
+            {
+                cpu_set_t cpu_mask;
+                sched_getaffinity(0, sizeof(cpu_mask), &cpu_mask);
+                return CPU_COUNT(&cpu_mask);
+            }
+        "
+        TUKLIB_CPUCORES_SCHED_GETAFFINITY)
+    if(TUKLIB_CPUCORES_SCHED_GETAFFINITY)
+        set(TUKLIB_CPUCORES_DEFINITIONS
+            "TUKLIB_CPUCORES_SCHED_GETAFFINITY"
+            CACHE INTERNAL "")
+        return()
+    endif()
+
+    # FreeBSD has both cpuset and sysctl. Look for cpuset first because
+    # it's a better approach.
+    #
+    # This test would match on GNU/kFreeBSD too but it would require
+    # -lfreebsd-glue when linking and thus in the current form this would
+    # fail on GNU/kFreeBSD. The above test for sched_getaffinity() matches
+    # on GNU/kFreeBSD so the test below should never run on that OS.
+    check_c_source_compiles("
+            #include <sys/param.h>
+            #include <sys/cpuset.h>
+            int main(void)
+            {
+                cpuset_t set;
+                cpuset_getaffinity(CPU_LEVEL_WHICH, CPU_WHICH_PID, -1,
+                                   sizeof(set), &set);
+                return 0;
+            }
+        "
+        TUKLIB_CPUCORES_CPUSET)
+    if(TUKLIB_CPUCORES_CPUSET)
+        set(TUKLIB_CPUCORES_DEFINITIONS "HAVE_PARAM_H;TUKLIB_CPUCORES_CPUSET"
+            CACHE INTERNAL "")
+        return()
+    endif()
+
+    # On OS/2, both sysconf() and sysctl() pass the tests in this file,
+    # but only sysctl() works. On QNX it's the opposite: only sysconf() works
+    # (although it assumes that _POSIX_SOURCE, _XOPEN_SOURCE, and
+    # _POSIX_C_SOURCE are undefined or alternatively _QNX_SOURCE is defined).
+    #
+    # We test sysctl() first and intentionally break the sysctl() test on QNX
+    # so that sysctl() is never used on QNX.
+    check_include_file(sys/param.h HAVE_SYS_PARAM_H)
+    if(HAVE_SYS_PARAM_H)
+        list(APPEND CMAKE_REQUIRED_DEFINITIONS -DHAVE_SYS_PARAM_H)
+    endif()
+    check_c_source_compiles("
+            #ifdef __QNX__
+            compile error
+            #endif
+            #ifdef HAVE_SYS_PARAM_H
+            #   include <sys/param.h>
+            #endif
+            #include <sys/sysctl.h>
+            int main(void)
+            {
+                int name[2] = { CTL_HW, HW_NCPU };
+                int cpus;
+                size_t cpus_size = sizeof(cpus);
+                sysctl(name, 2, &cpus, &cpus_size, NULL, 0);
+                return 0;
+            }
+        "
+        TUKLIB_CPUCORES_SYSCTL)
+    if(TUKLIB_CPUCORES_SYSCTL)
+        if(HAVE_SYS_PARAM_H)
+            set(TUKLIB_CPUCORES_DEFINITIONS
+                "HAVE_PARAM_H;TUKLIB_CPUCORES_SYSCTL"
+                CACHE INTERNAL "")
+        else()
+            set(TUKLIB_CPUCORES_DEFINITIONS
+                "TUKLIB_CPUCORES_SYSCTL"
+                CACHE INTERNAL "")
+        endif()
+        return()
+    endif()
+
+    # Many platforms support sysconf().
+    check_c_source_compiles("
+            #include <unistd.h>
+            int main(void)
+            {
+                long i;
+            #ifdef _SC_NPROCESSORS_ONLN
+                /* Many systems using sysconf() */
+                i = sysconf(_SC_NPROCESSORS_ONLN);
+            #else
+                /* IRIX */
+                i = sysconf(_SC_NPROC_ONLN);
+            #endif
+                return 0;
+            }
+        "
+        TUKLIB_CPUCORES_SYSCONF)
+    if(TUKLIB_CPUCORES_SYSCONF)
+        set(TUKLIB_CPUCORES_DEFINITIONS "TUKLIB_CPUCORES_SYSCONF"
+            CACHE INTERNAL "")
+        return()
+    endif()
+
+    # HP-UX
+    check_c_source_compiles("
+            #include <sys/param.h>
+            #include <sys/pstat.h>
+            int main(void)
+            {
+                struct pst_dynamic pst;
+                pstat_getdynamic(&pst, sizeof(pst), 1, 0);
+                (void)pst.psd_proc_cnt;
+                return 0;
+            }
+        "
+        TUKLIB_CPUCORES_PSTAT_GETDYNAMIC)
+    if(TUKLIB_CPUCORES_PSTAT_GETDYNAMIC)
+        set(TUKLIB_CPUCORES_DEFINITIONS "TUKLIB_CPUCORES_PSTAT_GETDYNAMIC"
+            CACHE INTERNAL "")
+        return()
+    endif()
+endfunction()
+
+function(tuklib_cpucores TARGET_OR_ALL)
+    message(STATUS "Checking how to detect the number of available CPU cores")
+
+    tuklib_cpucores_internal_check()
+
+    if(NOT DEFINED CACHE{TUKLIB_CPUCORES_DEFINITIONS})
+        set(TUKLIB_CPUCORES_FOUND 0 PARENT_SCOPE)
+        message(WARNING
+                "No method to detect the number of CPU cores was found")
+    else()
+        set(TUKLIB_CPUCORES_FOUND 1 PARENT_SCOPE)
+        tuklib_add_definitions(${TARGET_OR_ALL} ${TUKLIB_CPUCORES_DEFINITIONS})
+    endif()
+endfunction()