NOFAT(iR) access data from file (FAT/FAT32, NTFS whatever) without FAT parsing

[Antti....@googlemail.com]

Hi

I am late publishing my ideas (and registered ideas ;), NOFAT has been
used for some time already
but I have not published the information yet. So here is the brief
description:


A utility is used (nofat.exe) that creates a file that has 2 areas:
header and payload
Header areas should be large, good values are 1 to 2 MByte
Withing Header each sector has signature, and offset to the payload
Payload area should be created just large enough to hold maximum data
needed for the application

Next: the removable media is formatted, the data.nofat is copied to
the media first

Access to the nofat payload is accomplished by 1 sector read at
absolut sector number equal to the number in the nofat reader. This
will fetch one sector from the header, it doesnt matter which one, as
all we need is the offset.
After verifying the signature, we take the offset, and calculate the
payload sector.

This works with just any type of file system where single file is laid
out as sequence of sector on the physical media.

Nofat.exe has additional feature, it can update the payload without
changing the location of the sectors/clusters. Nofat in update mode
reads the nofat file, finds payload, updates it, places write pointer
to the end of file and closes it.

Actually i dont recall, maybe my current nofat.exe uses direct read of
sectors, need look sources :) either way it works great and as been
used in commercial products for small bootloaders.

NOFAT enabled self-updating bootloader for AVR that reads from SD card
in SD-1 bit mode occupies about 70% from 1K bootsector, so the boot
area could include some extra code too.

Antti Lukats