Doubt Relating Use of "hufSize" in OMX DL

Hi. I am working on OMX DL for the implementation of OMXACMP3_HuffmanDecode module.
In this ,we have a input parameter hufSize, that is supposed to contain part3_Len as specified in ISO standard for MP3. My question is that how are we going to give the value of part3_Len to hufSize? OMXACMP3SideInfo only has the information part23Len, Since we are decoding part2_Len for Scale factors in UnpackScaleFactor. But Since SideInfo is an input parameter in ScaleFactor Decode Funtion, I cant manipulate part23_Len there to make it part3_Len. So what I am Supposed to do?