Schematically:
FuncNgbOp2dExtra2Dispatch --> _Row(P1,Cnum) --> _Pix_P1Cnum | | +-> _Row(P1,Loop) --> _Pix_P1Loop | / +-> _Row(P2,Loop) --> _Pix_P2Loop | +-> _Row(PN,Loop) --> _Pix_P1Loop