code: public final int rightAdjustCharHeadWithPrev(byte[]bytes, int p, int s, int end, IntHolder prev) {
          int p_ = leftAdjustCharHead(bytes, p, s, end);
          if (p_ < s) {
              if (prev != null) prev.value = p_;
              p_ += length(bytes, p_, end);
          } else {
              if (prev != null) prev.value = -1; /* Sorry */
          }
          return p_;
      }
docs: /* onigenc_get_right_adjust_char_head_with_prev