diff --git a/CMakeLists.txt b/CMakeLists.txt
index 8afd931..7afbb66 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -12,6 +12,16 @@
 cmake_minimum_required( VERSION 3.1 )
 
 
+##### project settings ##########################
+
+project( arts )
+
+set( ARTS_MAJOR_VERSION 1 )
+set( ARTS_MINOR_VERSION 5 )
+set( ARTS_MICRO_VERSION 10 )
+set( ARTS_VERSION "${ARTS_MAJOR_VERSION}.${ARTS_MINOR_VERSION}.${ARTS_MICRO_VERSION}" )
+
+
 ##### include essential cmake modules ###########
 
 include( CheckCXXSourceCompiles )
@@ -28,19 +38,18 @@ include( FindPkgConfig )
 include( TDEMacros )
 
 
-##### project settings ##########################
-
-project( arts )
+##### set version number ########################
 
-set( ARTS_MAJOR_VERSION 1 )
-set( ARTS_MINOR_VERSION 5 )
-set( ARTS_MICRO_VERSION 10 )
-set( ARTS_VERSION "${ARTS_MAJOR_VERSION}.${ARTS_MINOR_VERSION}.${ARTS_MICRO_VERSION}" )
+tde_set_project_version( )
 
 
-##### set version number ########################
+##### paths setup ###############################
 
-tde_set_project_version( )
+tde_setup_install_path( EXEC_INSTALL_PREFIX   "${CMAKE_INSTALL_PREFIX}" )
+tde_setup_install_path( BIN_INSTALL_DIR       "${EXEC_INSTALL_PREFIX}/bin"  )
+tde_setup_install_path( LIB_INSTALL_DIR       "${EXEC_INSTALL_PREFIX}/lib${LIB_SUFFIX}" )
+tde_setup_install_path( INCLUDE_INSTALL_DIR   "${CMAKE_INSTALL_PREFIX}/include/${CMAKE_PROJECT_NAME}" )
+tde_setup_install_path( PKGCONFIG_INSTALL_DIR "${LIB_INSTALL_DIR}/pkgconfig" )
 
 
 ##### user requested options ####################
@@ -56,190 +65,30 @@ option( WITH_SNDIO "Enable SNDIO support" OFF )
 option( WITH_GCC_VISIBILITY "Enable fvisibility and fvisibility-inlines-hidden" ${WITH_ALL_OPTIONS} )
 
 
-##### paths setup ###############################
-
-tde_setup_install_path( EXEC_INSTALL_PREFIX   "${CMAKE_INSTALL_PREFIX}" )
-tde_setup_install_path( BIN_INSTALL_DIR       "${EXEC_INSTALL_PREFIX}/bin"  )
-tde_setup_install_path( LIB_INSTALL_DIR       "${EXEC_INSTALL_PREFIX}/lib${LIB_SUFFIX}" )
-tde_setup_install_path( INCLUDE_INSTALL_DIR   "${CMAKE_INSTALL_PREFIX}/include/${CMAKE_PROJECT_NAME}" )
-tde_setup_install_path( PKGCONFIG_INSTALL_DIR "${LIB_INSTALL_DIR}/pkgconfig" )
-
-
-##### setup architecture flags ##################
-
-tde_setup_architecture_flags( )
-
-include(TestBigEndian)
-test_big_endian(WORDS_BIGENDIAN)
-
-tde_setup_largefiles( )
-
-
-##### check for include files ###################
-
-check_include_file( "sys/time.h" HAVE_SYS_TIME_H )
-check_include_file( "time.h" TIME_WITH_SYS_TIME )
-check_include_file( "stdio.h" HAVE_STDIO_H )
-check_include_file( "stdlib.h" HAVE_STDLIB_H )
-check_include_file( "string.h" HAVE_STRING_H )
-check_include_file( "strings.h" HAVE_STRINGS_H )
-check_include_file( "ctype.h" HAVE_CTYPE_H )
-check_include_file( "malloc.h" HAVE_MALLOC_H )
-check_include_file( "memory.h" HAVE_MEMORY_H )
-check_include_file( "dlfcn.h" HAVE_DLFCN_H )
-check_include_file( "sys/soundcard.h" HAVE_SYS_SOUNDCARD_H )
-check_include_file( "pthread.h" HAVE_LIBPTHREAD )
-
-
-##### check for system libraries ################
-
-set( DL_LIBRARIES dl )
-check_library_exists( ${DL_LIBRARIES} dlopen /lib HAVE_LIBDL )
-if( NOT HAVE_LIBDL )
-  unset( DL_LIBRARIES )
-  check_function_exists( dlopen HAVE_DLOPEN )
-  if( HAVE_DLOPEN )
-    set( HAVE_LIBDL 1 )
-  endif( HAVE_DLOPEN )
-endif( NOT HAVE_LIBDL )
-
-find_package( Threads )
-
-
-##### check for functions #######################
-
-set( bak_CMAKE_REQUIRED_LIBRARIES ${CMAKE_REQUIRED_LIBRARIES} )
-set( CMAKE_REQUIRED_LIBRARIES ${DL_LIBRARIES} )
-check_function_exists( dlerror HAVE_DLERROR )
-check_function_exists( strcmp HAVE_STRCMP )
-check_function_exists( strchr HAVE_STRCHR )
-check_function_exists( index HAVE_INDEX )
-check_function_exists( strrchr HAVE_STRRCHR )
-check_function_exists( rindex HAVE_RINDEX )
-check_function_exists( memcpy HAVE_MEMCPY )
-check_function_exists( bcopy HAVE_BCOPY )
-set( CMAKE_REQUIRED_LIBRARIES ${bak_CMAKE_REQUIRED_LIBRARIES} )
-unset( bak_CMAKE_REQUIRED_LIBRARIES )
-check_prototype_definition( ioctl "int ioctl(int d, int request, ...)" "-1" "unistd.h;sys/ioctl.h" HAVE_IOCTL_INT_INT_DOTS )
-check_prototype_definition( ioctl "int ioctl(int d, unsigned long request, ...)" "-1" "unistd.h;sys/ioctl.h" HAVE_IOCTL_INT_ULONG_DOTS )
-
-
-##### check for audiofile #######################
-
-set( HAVE_LIBAUDIOFILE 0 )
-if( WITH_AUDIOFILE )
-
-  pkg_search_module( AUDIOFILE audiofile )
-  if( AUDIOFILE_FOUND )
-    set( HAVE_LIBAUDIOFILE 1 )
-  else( AUDIOFILE_FOUND )
-    message(FATAL_ERROR "\naudiofile (wav) support are requested, but `libaudiofile` not found" )
-  endif( AUDIOFILE_FOUND )
-
-endif( WITH_AUDIOFILE )
-
-
-##### check for alsa ############################
-
-set( HAVE_LIBASOUND2 0 )
-if( WITH_ALSA )
+##### configure checks
 
-  pkg_search_module( ALSA alsa )
+set( PC_LIB_REQUIRE "" CACHE INTERNAL "List of required packages" FORCE )
+include( ConfigureChecks.cmake )
 
-  if( ALSA_FOUND )
-
-    # there is support only for ALSA 1.x
-
-    set( HAVE_LIBASOUND2 1 )
-    set( ALSA_PCM_OLD_SW_PARAMS_API 1 )
-    set( ALSA_PCM_OLD_HW_PARAMS_API 1 )
-
-    check_include_file( "alsa/asoundlib.h" HAVE_ALSA_ASOUNDLIB_H )
-    if( NOT HAVE_ALSA_ASOUNDLIB_H )
-      check_include_file( "sys/asoundlib.h" HAVE_SYS_ASOUNDLIB_H )
-    endif( NOT HAVE_ALSA_ASOUNDLIB_H )
-
-    set( bak_CMAKE_REQUIRED_LIBRARIES ${CMAKE_REQUIRED_LIBRARIES} )
-    set( CMAKE_REQUIRED_LIBRARIES ${ALSA_LIBRARIES} )
-    check_function_exists( snd_pcm_resume HAVE_SND_PCM_RESUME )
-    set( CMAKE_REQUIRED_LIBRARIES ${bak_CMAKE_REQUIRED_LIBRARIES} )
-    unset( bak_CMAKE_REQUIRED_LIBRARIES )
-
-  else( ALSA_FOUND )
-
-    message(FATAL_ERROR "\nALSA support are requested, but not found on your system" )
-
-  endif( ALSA_FOUND )
-
-endif( WITH_ALSA )
-
-
-##### check for esound #######################
-
-set( HAVE_LIBESD 0 )
-if( WITH_ESOUND )
-
-  pkg_search_module( ESOUND esound )
-  if( ESOUND_FOUND )
-    set( HAVE_LIBESD 1 )
-  else( ESOUND_FOUND )
-    message(FATAL_ERROR "\nESOUND support is requested, but `libesd` not found" )
-  endif( ESOUND_FOUND )
-
-endif( WITH_ESOUND )
-
-
-##### check for JACK ############################
-
-set( HAVE_LIBJACK 0 )
-if( WITH_JACK )
-  pkg_search_module( LIBJACK jack )
-  if( LIBJACK_FOUND )
-    set( HAVE_LIBJACK 1 )
-  else( LIBJACK_FOUND )
-    message(FATAL_ERROR "\nJACK support is requested, but `jack.pc` was not found" )
-  endif( LIBJACK_FOUND )
-endif( WITH_JACK )
-
-
-##### check for SNDIO ###########################
-
-set( HAVE_LIBSNDIO 0 )
-if( WITH_SNDIO )
-  check_include_file( "sndio.h" HAVE_SNDIO_H )
-  if( HAVE_SNDIO_H )
-    set( HAVE_LIBSNDIO 1 )
-    set( LIBSNDIO_LIBRARIES "sndio" )
-  else( HAVE_SNDIO_H )
-    tde_message_fatal( "SNDIO support is requested, but `sndio.h` was not found" )
-  endif( HAVE_SNDIO_H )
-endif( WITH_SNDIO )
-
-
-##### check for glib/gthread modules ############
-
-pkg_search_module( GLIB2 glib-2.0 )
-
-if( GLIB2_FOUND )
-  pkg_search_module( GTHREAD2 gthread-2.0 )
-  if( NOT GTHREAD2_FOUND )
-    message(FATAL_ERROR "\ngthread-2.0 are required, but not found on your system" )
-  endif( NOT GTHREAD2_FOUND )
-else( GLIB2_FOUND )
-  message(FATAL_ERROR "\nglib-2.0 are required, but not found on your system" )
-endif( GLIB2_FOUND )
 
+##### global compiler settings ##################
 
-##### check for TQt #############################
+add_definitions( -DHAVE_CONFIG_H )
 
-find_package( TQt )
+set( CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} -Wl,--no-undefined" )
 
 
-##### check for gcc visibility support #########
+##### project subdirectories ####################
 
-if( WITH_GCC_VISIBILITY )
-  tde_setup_gcc_visibility( )
-endif( )
+add_subdirectory( libltdl )
+add_subdirectory( mcop )
+add_subdirectory( mcopidl )
+add_subdirectory( flow )
+add_subdirectory( mcop_mt )
+add_subdirectory( soundserver )
+add_subdirectory( artsc )
+add_subdirectory( gmcop )
+add_subdirectory( qtmcop )
 
 
 ##### write config.h file #######################
@@ -249,29 +98,10 @@ configure_file( config.h.cmake config.h @ONLY )
 
 ##### write pkgconfig file ######################
 
-set( PC_LIB_REQUIRE "" )
-if( WITH_ALSA )
-  list( APPEND PC_LIB_REQUIRE "alsa" )
-endif( WITH_ALSA )
-if( WITH_AUDIOFILE )
-  list( APPEND PC_LIB_REQUIRE "audiofile" )
-endif( WITH_AUDIOFILE )
-if( WITH_VORBIS )
-  list( APPEND PC_LIB_REQUIRE "vorbis" )
-  list( APPEND PC_LIB_REQUIRE "vorbisfile" )
-endif( WITH_VORBIS )
-if( WITH_MAD )
-  list( APPEND PC_LIB_REQUIRE "mad" )
-endif( WITH_MAD )
-if( WITH_ESOUND )
-  list( APPEND PC_LIB_REQUIRE "esound" )
-endif( WITH_ESOUND )
-if( WITH_JACK )
-  list( APPEND PC_LIB_REQUIRE "jack" )
-endif( WITH_JACK )
-
 list( LENGTH PC_LIB_REQUIRE PC_LIB_REQUIRES_FOUND )
 if( PC_LIB_REQUIRES_FOUND GREATER 0 )
+  list( SORT PC_LIB_REQUIRE )
+  list( REMOVE_DUPLICATES PC_LIB_REQUIRE )
   string( REPLACE ";" " " PC_LIB_REQUIRES "Requires: ${PC_LIB_REQUIRE}" )
 else( )
   set( PC_LIB_REQUIRES "" )
@@ -282,25 +112,3 @@ string( REGEX REPLACE "^${CMAKE_INSTALL_PREFIX}" "\${prefix}" PC_INCLUDE_DIR ${I
 string( REGEX REPLACE "^${CMAKE_INSTALL_PREFIX}" "\${prefix}" PC_LIB_DIR ${LIB_INSTALL_DIR} )
 configure_file( arts.pc.cmake arts.pc @ONLY )
 install( FILES ${CMAKE_CURRENT_BINARY_DIR}/arts.pc DESTINATION ${PKGCONFIG_INSTALL_DIR} )
-
-
-##### global compiler settings ##################
-
-add_definitions(
-  -DHAVE_CONFIG_H
-)
-
-set( CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} -Wl,--no-undefined" )
-
-
-##### project subdirectories ####################
-
-add_subdirectory( libltdl )
-add_subdirectory( mcop )
-add_subdirectory( mcopidl )
-add_subdirectory( flow )
-add_subdirectory( mcop_mt )
-add_subdirectory( soundserver )
-add_subdirectory( artsc )
-add_subdirectory( gmcop )
-add_subdirectory( qtmcop )
diff --git a/ConfigureChecks.cmake b/ConfigureChecks.cmake
new file mode 100644
index 0000000..5e3fb98
--- /dev/null
+++ b/ConfigureChecks.cmake
@@ -0,0 +1,194 @@
+#################################################
+#
+#  (C) 2010 Serghei Amelian
+#  serghei (DOT) amelian (AT) gmail.com
+#
+#  Improvements and feedback are welcome
+#
+#  This file is released under GPL >= 2
+#
+#################################################
+
+
+# required stuff
+
+tde_setup_architecture_flags( )
+
+include(TestBigEndian)
+test_big_endian(WORDS_BIGENDIAN)
+
+tde_setup_largefiles( )
+
+
+##### check for TQt #############################
+
+find_package( TQt )
+
+
+##### check for gcc visibility support #########
+
+if( WITH_GCC_VISIBILITY )
+  tde_setup_gcc_visibility( )
+endif( )
+
+
+##### check for include files ###################
+
+check_include_file( "sys/time.h" HAVE_SYS_TIME_H )
+check_include_file( "time.h" TIME_WITH_SYS_TIME )
+check_include_file( "stdio.h" HAVE_STDIO_H )
+check_include_file( "stdlib.h" HAVE_STDLIB_H )
+check_include_file( "string.h" HAVE_STRING_H )
+check_include_file( "strings.h" HAVE_STRINGS_H )
+check_include_file( "ctype.h" HAVE_CTYPE_H )
+check_include_file( "malloc.h" HAVE_MALLOC_H )
+check_include_file( "memory.h" HAVE_MEMORY_H )
+check_include_file( "dlfcn.h" HAVE_DLFCN_H )
+check_include_file( "sys/soundcard.h" HAVE_SYS_SOUNDCARD_H )
+check_include_file( "pthread.h" HAVE_LIBPTHREAD )
+
+
+##### check for system libraries ################
+
+set( DL_LIBRARIES dl )
+check_library_exists( ${DL_LIBRARIES} dlopen /lib HAVE_LIBDL )
+if( NOT HAVE_LIBDL )
+  unset( DL_LIBRARIES )
+  check_function_exists( dlopen HAVE_DLOPEN )
+  if( HAVE_DLOPEN )
+    set( HAVE_LIBDL 1 )
+  endif( HAVE_DLOPEN )
+endif( NOT HAVE_LIBDL )
+
+find_package( Threads )
+
+
+##### check for functions #######################
+
+tde_save_and_set( CMAKE_REQUIRED_LIBRARIES ${DL_LIBRARIES} )
+check_function_exists( dlerror HAVE_DLERROR )
+check_function_exists( strcmp HAVE_STRCMP )
+check_function_exists( strchr HAVE_STRCHR )
+check_function_exists( index HAVE_INDEX )
+check_function_exists( strrchr HAVE_STRRCHR )
+check_function_exists( rindex HAVE_RINDEX )
+check_function_exists( memcpy HAVE_MEMCPY )
+check_function_exists( bcopy HAVE_BCOPY )
+tde_restore( CMAKE_REQUIRED_LIBRARIES )
+
+check_prototype_definition( ioctl "int ioctl(int d, int request, ...)" "-1" "unistd.h;sys/ioctl.h" HAVE_IOCTL_INT_INT_DOTS )
+check_prototype_definition( ioctl "int ioctl(int d, unsigned long request, ...)" "-1" "unistd.h;sys/ioctl.h" HAVE_IOCTL_INT_ULONG_DOTS )
+
+
+##### check for audiofile #######################
+
+set( HAVE_LIBAUDIOFILE 0 )
+if( WITH_AUDIOFILE )
+
+  pkg_search_module( AUDIOFILE audiofile )
+  if( AUDIOFILE_FOUND )
+    set( HAVE_LIBAUDIOFILE 1 )
+    list( APPEND PC_LIB_REQUIRE "audiofile" )
+  else( AUDIOFILE_FOUND )
+    tde_message_fatal( "audiofile (wav) support is requested, but `libaudiofile` not found" )
+  endif( AUDIOFILE_FOUND )
+
+endif( WITH_AUDIOFILE )
+
+
+##### check for alsa ############################
+
+set( HAVE_LIBASOUND2 0 )
+if( WITH_ALSA )
+
+  pkg_search_module( ALSA alsa )
+
+  if( ALSA_FOUND )
+
+    # there is support only for ALSA 1.x
+
+    set( HAVE_LIBASOUND2 1 )
+    set( ALSA_PCM_OLD_SW_PARAMS_API 1 )
+    set( ALSA_PCM_OLD_HW_PARAMS_API 1 )
+
+    check_include_file( "alsa/asoundlib.h" HAVE_ALSA_ASOUNDLIB_H )
+    if( NOT HAVE_ALSA_ASOUNDLIB_H )
+      check_include_file( "sys/asoundlib.h" HAVE_SYS_ASOUNDLIB_H )
+    endif( NOT HAVE_ALSA_ASOUNDLIB_H )
+
+    tde_save_and_set( CMAKE_REQUIRED_LIBRARIES ${ALSA_LIBRARIES} )
+    check_function_exists( snd_pcm_resume HAVE_SND_PCM_RESUME )
+    tde_restore( CMAKE_REQUIRED_LIBRARIES )
+
+    list( APPEND PC_LIB_REQUIRE "alsa" )
+
+  else( ALSA_FOUND )
+
+    tde_message_fatal( "ALSA support is requested, but not found on your system" )
+
+  endif( ALSA_FOUND )
+
+endif( WITH_ALSA )
+
+
+##### check for esound #######################
+
+set( HAVE_LIBESD 0 )
+if( WITH_ESOUND )
+
+  pkg_search_module( ESOUND esound )
+  if( ESOUND_FOUND )
+    set( HAVE_LIBESD 1 )
+    list( APPEND PC_LIB_REQUIRE "esound" )
+  else( ESOUND_FOUND )
+    tde_message_fatal( "ESOUND support is requested, but `libesd` not found" )
+  endif( ESOUND_FOUND )
+
+endif( WITH_ESOUND )
+
+
+##### check for JACK ############################
+
+set( HAVE_LIBJACK 0 )
+if( WITH_JACK )
+  pkg_search_module( LIBJACK jack )
+  if( LIBJACK_FOUND )
+    set( HAVE_LIBJACK 1 )
+    list( APPEND PC_LIB_REQUIRE "jack" )
+  else( LIBJACK_FOUND )
+    tde_message_fatal( "JACK support is requested, but `jack.pc` was not found" )
+  endif( LIBJACK_FOUND )
+endif( WITH_JACK )
+
+
+##### check for SNDIO ###########################
+
+set( HAVE_LIBSNDIO 0 )
+if( WITH_SNDIO )
+  check_include_file( "sndio.h" HAVE_SNDIO_H )
+  if( HAVE_SNDIO_H )
+    set( HAVE_LIBSNDIO 1 )
+    set( LIBSNDIO_LIBRARIES "sndio" )
+  else( HAVE_SNDIO_H )
+    tde_message_fatal( "SNDIO support is requested, but `sndio.h` was not found" )
+  endif( HAVE_SNDIO_H )
+endif( WITH_SNDIO )
+
+
+##### check for glib/gthread modules ############
+
+pkg_search_module( GLIB2 glib-2.0 )
+
+if( GLIB2_FOUND )
+  pkg_search_module( GTHREAD2 gthread-2.0 )
+  if( NOT GTHREAD2_FOUND )
+    tde_message_message( "gthread-2.0 is required, but not found on your system" )
+  endif( NOT GTHREAD2_FOUND )
+else( GLIB2_FOUND )
+  tde_message_fatal( "glib-2.0 is required, but not found on your system" )
+endif( GLIB2_FOUND )
+
+
+##### save cached value of required packages ####
+
+set( PC_LIB_REQUIRE "${PC_LIB_REQUIRE}" CACHE INTERNAL "List of required packages" FORCE )
diff --git a/flow/gsl/CMakeLists.txt b/flow/gsl/CMakeLists.txt
index e8e9576..b3370fd 100644
--- a/flow/gsl/CMakeLists.txt
+++ b/flow/gsl/CMakeLists.txt
@@ -9,97 +9,9 @@
 #
 #################################################
 
-include( CheckCSourceCompiles )
+##### configure checks
 
-
-##### check for ogg/vorbis ######################
-
-set( GSL_HAVE_OGGVORBIS 0 )
-if( WITH_VORBIS )
-
-  pkg_search_module( VORBIS vorbis )
-
-  if( VORBIS_FOUND )
-
-    pkg_search_module( VORBISFILE vorbisfile )
-
-    if( VORBISFILE_FOUND )
-
-      set( GSL_HAVE_OGGVORBIS 1 )
-
-      set( bak_CMAKE_REQUIRED_LIBRARIES ${CMAKE_REQUIRED_LIBRARIES} )
-      set( CMAKE_REQUIRED_LIBRARIES ${VORBISFILE_LIBRARIES} )
-      check_c_source_compiles(
-        "#include <vorbis/vorbisfile.h>
-        int main() { ov_read_float(0,0,0); return 0; } "
-        GSL_HAVE_OGGVORBIS_RC3 )
-      if( NOT GSL_HAVE_OGGVORBIS_RC3 )
-        set( GSL_HAVE_OGGVORBIS_RC3 0 )
-      endif( NOT GSL_HAVE_OGGVORBIS_RC3 )
-      set( CMAKE_REQUIRED_LIBRARIES ${bak_CMAKE_REQUIRED_LIBRARIES} )
-
-    else( VORBISFILE_FOUND )
-
-      message(FATAL_ERROR "\nOgg/Vorbis support are requested, but `libvorbisfile` not found" )
-
-    endif( VORBISFILE_FOUND )
-
-  else( VORBIS_FOUND )
-
-    message(FATAL_ERROR "\nOgg/Vorbis support are requested, but `libvorbis` but found" )
-
-  endif( VORBIS_FOUND )
-
-endif( WITH_VORBIS )
-
-
-##### check for libmad MPEG decoder #############
-
-set( GSL_HAVE_LIBMAD 0 )
-if( WITH_MAD )
-
-  pkg_search_module( MAD mad )
-
-  if( MAD_FOUND )
-    set( GSL_HAVE_LIBMAD 1 )
-  else( MAD_FOUND )
-    find_library( MAD_LIBRARIES NAMES mad )
-    find_path( MAD_INCLUDE_DIRS mad.h )
-    if( NOT MAD_LIBRARIES )
-        message(FATAL_ERROR "\nMAD support is requested, but `libmad` not found" )
-    endif( NOT MAD_LIBRARIES )
-  endif( MAD_FOUND )
-
-endif( WITH_MAD )
-
-
-##### check for some type sizes #################
-
-include( CheckTypeSize )
-
-check_type_size( pthread_mutex_t GSL_SIZEOF_PTH_MUTEX_T )
-check_type_size( pthread_cond_t GSL_SIZEOF_PTH_COND_T )
-check_type_size( intmax_t GSL_SIZEOF_STD_INTMAX_T )
-
-set( bak_CMAKE_REQUIRED_LIBRARIES ${CMAKE_REQUIRED_LIBRARIES} )
-set( CMAKE_REQUIRED_LIBRARIES ${CMAKE_THREAD_LIBS_INIT} )
-check_c_source_compiles(
-  "#define _XOPEN_SOURCE 500
-  #include <pthread.h>
-  int main()
-  {
-      int (*attr_settype) (pthread_mutexattr_t *__attr, int __kind) = pthread_mutexattr_settype;
-      int val = PTHREAD_MUTEX_RECURSIVE; attr_settype = 0; val = 0;
-      return 0;
-  }"
-  GSL_HAVE_MUTEXATTR_SETTYPE )
-  if( NOT GSL_HAVE_MUTEXATTR_SETTYPE )
-    set( GSL_HAVE_MUTEXATTR_SETTYPE 0 )
-  endif( NOT GSL_HAVE_MUTEXATTR_SETTYPE )
-set( CMAKE_REQUIRED_LIBRARIES ${bak_CMAKE_REQUIRED_LIBRARIES} )
-
-set( GSL_USE_GSL_GLIB 1 )
-set( GSL_USE_ARTS_THREADS 1 )
+include( ConfigureChecks.cmake )
 
 
 ##### write configuration #######################
@@ -152,4 +64,3 @@ tde_add_library( ${target} STATIC_PIC
   LINK ${GLIB2_LIBRARIES} ${GTHREAD2_LIBRARIES} ${VORBISFILE_LIBRARIES} ${VORBIS_LIBRARIES} ${MAD_LIBRARIES}
   DESTINATION ${LIB_INSTALL_DIR}
 )
-
diff --git a/flow/gsl/ConfigureChecks.cmake b/flow/gsl/ConfigureChecks.cmake
new file mode 100644
index 0000000..f0a9dee
--- /dev/null
+++ b/flow/gsl/ConfigureChecks.cmake
@@ -0,0 +1,112 @@
+#################################################
+#
+#  (C) 2010 Serghei Amelian
+#  serghei (DOT) amelian (AT) gmail.com
+#
+#  Improvements and feedback are welcome
+#
+#  This file is released under GPL >= 2
+#
+#################################################
+
+include( CheckCSourceCompiles )
+include( CheckTypeSize )
+
+
+##### check for ogg/vorbis ######################
+
+set( GSL_HAVE_OGGVORBIS 0 )
+if( WITH_VORBIS )
+
+  pkg_search_module( VORBIS vorbis )
+
+  if( VORBIS_FOUND )
+
+    pkg_search_module( VORBISFILE vorbisfile )
+
+    if( VORBISFILE_FOUND )
+
+      set( GSL_HAVE_OGGVORBIS 1 )
+
+      tde_save_and_set( CMAKE_REQUIRED_LIBRARIES ${VORBISFILE_LIBRARIES} )
+      check_c_source_compiles(
+        "#include <vorbis/vorbisfile.h>
+        int main() { ov_read_float(0,0,0); return 0; } "
+        GSL_HAVE_OGGVORBIS_RC3 )
+      if( NOT GSL_HAVE_OGGVORBIS_RC3 )
+        set( GSL_HAVE_OGGVORBIS_RC3 0 )
+      endif( NOT GSL_HAVE_OGGVORBIS_RC3 )
+      tde_restore( CMAKE_REQUIRED_LIBRARIES )
+
+      list( APPEND PC_LIB_REQUIRE "vorbis" "vorbisfile" )
+
+    else( VORBISFILE_FOUND )
+
+      tde_message_fatal( "Ogg/Vorbis support are requested, but `libvorbisfile` not found" )
+
+    endif( VORBISFILE_FOUND )
+
+  else( VORBIS_FOUND )
+
+    tde_message_fafal( "Ogg/Vorbis support are requested, but `libvorbis` but found" )
+
+  endif( VORBIS_FOUND )
+
+endif( WITH_VORBIS )
+
+
+##### check for libmad MPEG decoder #############
+
+set( GSL_HAVE_LIBMAD 0 )
+if( WITH_MAD )
+
+  pkg_search_module( MAD libmad )
+  set( MAD_MODULE_NAME "libmad" )
+  if( NOT MAD_FOUND )
+    pkg_search_module( MAD mad )
+    set( MAD_MODULE_NAME "mad" )
+  endif()
+
+  if( MAD_FOUND )
+    set( GSL_HAVE_LIBMAD 1 )
+    list( APPEND PC_LIB_REQUIRE ${MAD_MODULE_NAME} )
+  else( MAD_FOUND )
+    find_library( MAD_LIBRARIES NAMES mad )
+    find_path( MAD_INCLUDE_DIRS mad.h )
+    if( NOT MAD_LIBRARIES )
+        tde_message_fatal( "MAD support is requested, but `libmad` not found" )
+    endif( NOT MAD_LIBRARIES )
+  endif( MAD_FOUND )
+
+endif( WITH_MAD )
+
+
+##### check for some type sizes #################
+
+check_type_size( pthread_mutex_t GSL_SIZEOF_PTH_MUTEX_T )
+check_type_size( pthread_cond_t GSL_SIZEOF_PTH_COND_T )
+check_type_size( intmax_t GSL_SIZEOF_STD_INTMAX_T )
+
+tde_save_and_set( CMAKE_REQUIRED_LIBRARIES ${CMAKE_THREAD_LIBS_INIT} )
+check_c_source_compiles(
+  "#define _XOPEN_SOURCE 500
+  #include <pthread.h>
+  int main()
+  {
+      int (*attr_settype) (pthread_mutexattr_t *__attr, int __kind) = pthread_mutexattr_settype;
+      int val = PTHREAD_MUTEX_RECURSIVE; attr_settype = 0; val = 0;
+      return 0;
+  }"
+  GSL_HAVE_MUTEXATTR_SETTYPE )
+  if( NOT GSL_HAVE_MUTEXATTR_SETTYPE )
+    set( GSL_HAVE_MUTEXATTR_SETTYPE 0 )
+  endif( NOT GSL_HAVE_MUTEXATTR_SETTYPE )
+tde_restore( CMAKE_REQUIRED_LIBRARIES )
+
+set( GSL_USE_GSL_GLIB 1 )
+set( GSL_USE_ARTS_THREADS 1 )
+
+
+##### save cached value of required packages ####
+
+set( PC_LIB_REQUIRE "${PC_LIB_REQUIRE}" CACHE INTERNAL "List of required packages" FORCE )