Looping through disk data files like a mileometer

[user#606]

I have three data files on disk to read through, a bit like a mileometer on a car, so the contents of each file combination can be processed.
The lines of data in each file is TAB delimited and contain different numbers of fields. There has to be the 3 files.
File 1 - 3 tabed fields File 2 - 2 tabbed fields File 3 - 4 tabbed fields
File 1 cycles through its contents and increments File 2 by 1
This repeats until File 2 has cycled through all its contents and increments File 3 by 1
This whole process continues until File 3 has cycled through all its contents and the process stops.
At the end of all File Cycles the data must not be empty (as can happen after the last line has been read).

Has anyone a neat solution for this?

[BvG]

Try to put several loops into each other, that'd do the trick