Dear sir:

I am reading the kernel routine about ufs file system.
In fs.h, cbtorpos(fs,bno) computers the rotational position of 
a cyl block addr. 

#define cbtorpos(fs, bno)
    (((bno) * NSPF(fs) % (fs)->fs_spc / (fs)->fs_nsect * (fs)->fs_trackskew +
     (bno) * NSPF(fs) % (fs)->fs_spc % (fs)->fs_nsect * (fs)->fs_interleave) %
     (fs)->fs_nsect * (fs)->fs_nrpos / (fs)->fs_npsect)

I have the problem to understand the principles behind this conversion.
Can any one please give me some detail explanation.

Your help will be greatly appreciated.



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