check_match
check_match(s, s->strstart, s->match_start, (int)s->match_length);
check_match(s, s->strstart - 1, s->prev_match, (int)s->prev_length);
check_match(s, s->strstart, s->strstart - 1, (int)s->match_length);
check_match(s, s->strstart, s->match_start, (int)s->match_length);
check_match(s, s->strstart - 1, s->prev_match, (int)s->prev_length);
check_match(s, s->strstart, s->strstart - 1, (int)s->match_length);