+# do we have long longs?
+AC_CHECK_TYPES([long long])
+
+# check for specific header (.h) files that we are interested in
+AC_CHECK_HEADERS([ctype.h fcntl.h signal.h sys/resource.h termios.h time.h])
+
+# Enable large file support. Do this before testing the types ino_t, off_t, and
+# rlim_t, because it will affect the result of that test.
+AC_SYS_LARGEFILE
+
+dnl ** check for wide-char classifications
+dnl FreeBSD has an emtpy wctype.h, so test one of the affected
+dnl functions if it's really there.
+AC_CHECK_HEADERS([wctype.h], [AC_CHECK_FUNCS(iswspace)])
+
+AC_CHECK_FUNCS([ftime gmtime_r localtime_r lstat readdir_r])
+
+AC_CHECK_FUNCS([_chsize ftruncate])
+
+# map standard C types and ISO types to Haskell types
+FPTOOLS_CHECK_HTYPE(char)
+FPTOOLS_CHECK_HTYPE(signed char)
+FPTOOLS_CHECK_HTYPE(unsigned char)
+FPTOOLS_CHECK_HTYPE(short)
+FPTOOLS_CHECK_HTYPE(unsigned short)
+FPTOOLS_CHECK_HTYPE(int)
+FPTOOLS_CHECK_HTYPE(unsigned int)
+FPTOOLS_CHECK_HTYPE(long)
+FPTOOLS_CHECK_HTYPE(unsigned long)
+if test "$ac_cv_type_long_long" = yes; then
+FPTOOLS_CHECK_HTYPE(long long)
+FPTOOLS_CHECK_HTYPE(unsigned long long)
+fi
+FPTOOLS_CHECK_HTYPE(float)
+FPTOOLS_CHECK_HTYPE(double)
+FPTOOLS_CHECK_HTYPE(ptrdiff_t)
+FPTOOLS_CHECK_HTYPE(size_t)
+FPTOOLS_CHECK_HTYPE(wchar_t)
+# Int32 is a HACK for non-ISO C compilers
+FPTOOLS_CHECK_HTYPE(sig_atomic_t, Int32)
+FPTOOLS_CHECK_HTYPE(clock_t)
+FPTOOLS_CHECK_HTYPE(time_t)
+FPTOOLS_CHECK_HTYPE(dev_t, Word32)
+FPTOOLS_CHECK_HTYPE(ino_t)
+FPTOOLS_CHECK_HTYPE(mode_t)
+FPTOOLS_CHECK_HTYPE(off_t)
+FPTOOLS_CHECK_HTYPE(pid_t)
+FPTOOLS_CHECK_HTYPE(gid_t)
+FPTOOLS_CHECK_HTYPE(uid_t)
+FPTOOLS_CHECK_HTYPE(cc_t)
+FPTOOLS_CHECK_HTYPE(speed_t)
+FPTOOLS_CHECK_HTYPE(tcflag_t)
+FPTOOLS_CHECK_HTYPE(nlink_t)
+FPTOOLS_CHECK_HTYPE(ssize_t)
+FPTOOLS_CHECK_HTYPE(rlim_t)
+FPTOOLS_CHECK_HTYPE(wint_t)
+
+# test errno values