A question about msdosfs code

[dave jones]

Hello,

I have a question about the MSDOSFSROOT_OFS definition in denode.h:

/*
 * Internal pseudo-offset for (nonexistent) directory entry for the root
 * dir in the root dir
 */
#define MSDOSFSROOT_OFS 0x1fffffff

I'm wondering why setting the root directory offset is 0x1fffffff?
Is there any formula to calculate root dir offset instead? Thank you.

Regards,
Dave.