cmake: detection of the targer architecture bit size

CMakeLists.txt

@@ -34,6 +34,8 @@ option(BUILD_WITH_LIBSTL  "Build the libSTL module" ON)
 file(GLOB  ALL_SRC_FILES  src/gmio_core/*  src/gmio_core/internal/*)
 set(ALL_SRC_FILES  ${ALL_SRC_FILES})
 
+math(EXPR GMIO_TARGET_ARCH_BIT_SIZE "8 * ${CMAKE_SIZEOF_VOID_P}")
+
 if(NOT BUILD_STRICT_C90)
     # Have <stdint.h> ?
     check_include_files(stdint.h GMIO_HAVE_STDINT_H)

src/gmio_core/config.h.cmake

@@ -29,4 +29,16 @@
 
 #cmakedefine GMIO_HAVE_MSVC_BUILTIN_BSWAP_FUNC
 
+#if defined(__APPLE__)
+#  if defined(__i386__) || defined(__ppc__)
+#    define GMIO_TARGET_ARCH_BIT_SIZE  32
+#  elif defined(__x86_64__) || defined(__ppc64__)
+#    define GMIO_TARGET_ARCH_BIT_SIZE  64
+#  else
+#    error "Unknown architecture!"
+#  endif
+#else
+#  define GMIO_TARGET_ARCH_BIT_SIZE  @GMIO_TARGET_ARCH_BIT_SIZE@
+#endif
+
 #endif /* GMIO_CONFIG_H_CMAKE */