docs: public int getPrevOpcode(int offset) {
          if (offset < 0) {
              throw new IllegalArgumentException("offset (" + offset + ") must be nonnegative");
          }
          if (offset >= prevOpcode.length || offset > sizePrevOpcodeBuffer) {
              return Const.NOP;
          }
          int pos = currentPosInPrevOpcodeBuffer - offset;
          if (pos < 0) {
              pos += prevOpcode.length;
          }
          return prevOpcode[pos];
      }