hh_to_c
if ( (c = hh_to_c( s )) != -1 ) {
( (c = hh_to_c( s + 1 )) != -1 ) ) {
if ( (c = hh_to_c( ++s )) != -1 ) {
static int hh_to_c( Byte *h );
static int hh_to_c();