On UNIX machines, and if Zebra has been installed with the
FZLIBC option, one can select user I/O for a particular
file by giving the K
option to FZFILE.
As with the L
option this causes the I/O requests to be
channelled to the routines CFPUT,
CFGET, etc.
To code user I/O one has to take the source of these routines and add a new branch, or two, into each one to do what one wants to do.
One finds the source of these routines on the Pam file
KERNFOR in P=CCGENCF; there is also the Fortran dummy
routine P=TCGEN, D=CFWEOF to write system file-marks.
Careful, it is possible that there is a machine-specific
implementation of these routines; for example if one
wanted to do this on the Sun one should check that
KERNSUN does not contain versions of these routines
(it does not right now).
The second parameter for each routine is MEDIUM,
and on entry its value selects the wanted branch.
MEDIUM is 0,1,2,3 for L,TL,K,TK selected
with FZFILE for the that file.
Be careful not to destroy the existing path.