-static const char *pfSelectFileModeCreate( int fam );
-static const char *pfSelectFileModeOpen( int fam );
+/* Truncate the unsigned double cell integer LO/HI to an uint64_t. */
+static uint64_t UdToUint64( ucell_t Lo, ucell_t Hi )
+{
+ return (( 2 * sizeof(ucell_t) == sizeof(uint64_t) )
+ ? (((uint64_t)Lo) | (((uint64_t)Hi) >> (sizeof(ucell_t) * 8)))
+ : Lo);
+}
+
+/* Return TRUE if the unsigned double cell integer LO/HI is not greater
+ * then the greatest uint64_t.
+ */
+static int UdIsUint64( ucell_t Lo, ucell_t Hi )
+{
+ return (( 2 * sizeof(ucell_t) == sizeof(uint64_t) )
+ ? TRUE
+ : Hi == 0);
+}
+
+static const char *pfSelectFileModeCreate( cell_t fam );
+static const char *pfSelectFileModeOpen( cell_t fam );