FAT 16 berekenen

Voor FAT16 te berekenen kan je kijken op https://github.com/ISW-Leuven/fat16 met dank aan ISW

Hieronder staat de repo gekopiëerd:

FAT16

This repo contains a few things to help you find / calculate FAT16 properties, ...

Disclaimer

The info in this repo may contain errors. Please do not rely on this and always check it for yourself!

GPT Header

GPT Partition Entry

Boot Sector

Disk Layout

• Boot Sector Address [HEX] = First LBA (GPT Entry, DEC) * 512
• Size of cluster [BYTES] = Bytes per sector * Sectors per cluster
• First FAT Address [HEX] = Boot Sector Address + Size of cluster [IN DEC]
• Root Directory Address = First FAT Address + (Small number of sectors * Sectors per cluster) [HEX]
• Root Directory Size [BYTES] = Number of possible root entries * Directory Entry size (often 32 bytes)
• Data Region Address = Root Directory Address + Root Directory Size [IN HEX]
• Total FAT16 Volume in Bytes = Small number of sectors * Bytes per sector

Files

• To find the next cluster index = First FAT Address + Previous Cluster * 2
• File contents of the cluster = Start of data region + cluster_size * (cluster_index - 2)

Time

1. First 5 bits for hours
2. Next 6 bits for minutes
3. Last 5 bits for seconds (you have seconds multiply by 2 to get the value, eg.: 00011 => 3, 3 * 2 => 6 seconds)

Date

1. First 7 bytes years since 1980 (eg.: if value in dec is 28, 1980 + 28 = 2008)
2. Next 4 bits for the month
3. Last 5 bits for the day

Sources

• UCLL
• Pieter Philippaerts