Action:
Retrieve information about a CWN row.
=0 if event was found)
The information is restored at the addresses specified by HBNAME
or HBNAMC (for CHARACTER data).
If the information is being retrieved by a program other than the
one that wrote the Ntuple then HBNAME
or HBNAMC must be called as appropriate (see below).
CALL HBNAME(ID,' ',0,'$CLEAR')
CALL HBNAME(ID,CHBLOK,VARIABLE,'$SET')
[HBNAME]
[HBNAMC]
These calls are required as HBOOK must obtain the location
at which the requested information is to be returned which is
obviously not valid between programs.
The first call clears all the addresses stored by HBOOK
for the specified Ntuple and the second one sets the
addresses for the variables in block CHBLOK starting at variable
VARIABLE. The second call should be repeated for every block of
which data has to be retrieved. The routine HUWFUN will generate
these calls automatically in the skeleton user function.
CALL HGNTB (ID,CHBLOK,IROW,IERR*)
Action:
Retrieve information about a named block in an Ntuple row.
=0 if row was found)
The information is restored at the addresses specified by HBNAME
or HBNAMC (for CHARACTER data).
CALL HGNTV (ID,CHVAR,NVAR,IROW,IERR*)
Action:
Retrieve information about the named variables in an Ntuple row.
CHVAR.
=0 if row was found)
The information is restored at the addresses specified by HBNAME
or HBNAMC (for CHARACTER data).
You should only call HBNAME for the blocks that
contain variables you want to read using HGNTV.
If you call HBNAME for all blocks you should
have a PAWC which is at least the same size as the one you used to
create the Ntuple.
If not you will run out of memory.
Also changing the buffer size will not help because the buffer used for reading will be the same size as the buffer used to write the Ntuple.
There is a special option in HBNAME with which you can tell HBNAME to only set the address for a single variable in a block (this option is used by PAW to reduce memory usage).
To set the address for a single variable call HBNAME (or HBNAMC) as follows:
CALL HBNAME(ID, BLOCK, IADDR, '$SET:NTVAR')This will tell HGNTV to restore the Ntuple variable
NTVAR in address IADDR.
Using this form of HBNAME will only reserve buffer space for
the variables you plan to read and not for all variables in the block.
However, you have to be careful that when you change the list
of variable for
HGNTV to also add or remove the correct HBNAME calls.
Action:
Retrieve information about all variables specified in a previous call to either HGNT, HGNTB or HGNTV, in an Ntuple row. This routine is much faster than either HGNT, HGNTB or HGNTV.
=0 if row was found)
The information is restored at the addresses specified by HBNAME
or HBNAMC (for CHARACTER data).
CALL HNTVDEF (ID1,IVAR,CHTAG,BLOCK,ITYPE)
Action:
Returns the definition as given in HBNAME for
the variable with index IVAR in Ntuple ID1.
The Ntuple must already be in memory.