Struct Fat12 

pub struct Fat12 { /* private fields */ }

FAT12 table implementation.

FAT12 uses 12-bit entries packed into 3 bytes for every 2 clusters.

Implementations

impl Fat12

pub fn new(start: usize, size: usize, count: usize, max_cluster: u16) -> Self

Creates a FAT12 table descriptor.

pub fn max_cluster(&self) -> u16

Get the maximum cluster number.

pub fn next_cluster<T: Read + Seek>( &self, reader: &mut T, cluster: usize, ) -> Result<Option<u32>>

Returns the next cluster in a chain, or None at end-of-chain.

pub fn write_clus<T: Read + Write + Seek>( &self, rw: &mut T, cluster: usize, value: u16, ) -> Result<()>

Write a cluster entry to all FAT table copies

pub fn allocate_cluster<T: Read + Write + Seek>( &self, rw: &mut T, hint: u16, ) -> Result<u16>

Allocate a single cluster, returns the allocated cluster number.

pub fn allocate_chain<T: Read + Write + Seek>( &self, rw: &mut T, count: usize, hint: u16, ) -> Result<u16>

Allocate a linked chain of count clusters, returning the first cluster.

Each cluster is allocated from a rolling hint (near the previous one) and linked to its successor; the last is marked end-of-chain. Mirrors Fat32::allocate_chain. On partial failure the already-allocated clusters are not rolled back (matching the FAT32 behavior).

pub fn extend_chain<T: Read + Write + Seek>( &self, rw: &mut T, last: u16, count: usize, hint: u16, ) -> Result<u16>

Extend the chain whose current last cluster is last by count clusters, returning the first newly allocated cluster. If count is 0, no clusters are allocated and last is returned unchanged. Mirrors Fat32::extend_chain.

pub fn free_chain<T: Read + Write + Seek>( &self, rw: &mut T, start: u16, ) -> Result<u32>

Free a cluster chain starting at start, returns count of freed clusters.

pub fn truncate_chain<T: Read + Write + Seek>( &self, rw: &mut T, cluster: u16, ) -> Result<u32>

Truncate a cluster chain after the specified cluster.

The specified cluster becomes the end of chain (marked with end-of-chain marker). All clusters following it are freed.

Returns the number of clusters freed.

pub fn mark_bad<T: Read + Write + Seek>( &self, rw: &mut T, cluster: u16, ) -> Result<()>

Mark a cluster as bad (0x0FF7) in all FAT copies.

impl Fat12

pub fn read_entry<T: Read + Seek>( &self, reader: &mut T, cluster: usize, ) -> Result<u16>

Read a raw FAT12 entry.