FixedKeyNode getFixedKeyNode(int bufferId) throws IOException {
		FixedKeyNode node = (FixedKeyNode) nodeTable.get(bufferId);
		if (node != null) {
			return node;
		}

		DataBuffer buf = bufferMgr.getBuffer(bufferId);
		int nodeType = getNodeType(buf);
		switch (nodeType) {
			case FIXEDKEY_VAR_REC_NODE:
				node = new FixedKeyVarRecNode(this, buf);
				leafRecordCnt += node.keyCount;
				break;
			case FIXEDKEY_FIXED_REC_NODE:
				node = new FixedKeyFixedRecNode(this, buf);
				leafRecordCnt += node.keyCount;
				break;
			case FIXEDKEY_INTERIOR_NODE:
				node = new FixedKeyInteriorNode(this, buf);
				break;
			default:
				bufferMgr.releaseBuffer(buf);
				throw new IOException(
					"Unexpected Node Type (" + nodeType + ") found, expecting FixedKeyNode");
		}
		return node;
	}
Get a FixedKeyNode object for a specified buffer
@param bufferId buffer ID
@return LongKeyNode instance
@throws ClassCastException if node type is incorrect.
@throws IOException if IO error occurs on database
Ghidra/Framework/DB/src/main/java/db/NodeMgr.java