+ [with_readline="$withval"], [with_readline=yes])
+
+# enable debug build
+AC_ARG_ENABLE(debug,
+ [AS_HELP_STRING([--enable-debug], [enable debug mode [default=no]])],
+ [enable_debug=yes], [enable_debug=no])
+
+# enable/disable documentation generation
+AC_ARG_ENABLE(doc,
+ [AS_HELP_STRING([--enable-doc], [enable documentation generation [default=no]])],
+ [enable_doc=yes], [enable_doc=no])
+
+# enable/disable build of NgSpy
+AC_ARG_ENABLE(spy,
+ [AS_HELP_STRING([--enable-spy], [enable NgSpy [default=no]])],
+ [enable_spy=yes], [enable_spy=no])
+AM_CONDITIONAL(ENABLE_SPY, test x$enable_spy = xyes)
+
+# enable/disable build of NgEmu
+AC_ARG_ENABLE(emu,
+ [AS_HELP_STRING([--enable-emu], [enable NgEmu [default=no]])],
+ [enable_emu=yes], [enable_emu=no])
+AM_CONDITIONAL(ENABLE_EMU, test x$enable_emu = xyes)
+