Struct Slot 

pub struct Slot {
    pub idx: usize,
    pub chksum: Chksum,
    pub len: u32,
    pub prev: Chksum,
}

A savegame slot containing metadata about stored data

Each slot represents a savegame header stored in flash memory. Slots form a chain where each new savegame references the previous one via checksums, enabling the scanner to find the most recent valid savegame even after power failures.

Fields

• idx: The slot index in flash memory
• chksum: Checksum of the savegame data
• len: Length of the savegame data in bytes
• prev: Checksum of the previous savegame (for chain verification)

Fields

idx: usize

chksum: Chksum

len: u32

prev: Chksum

Implementations

impl Slot

pub const HEADER_SIZE: usize = 12usize

Size of the slot header in bytes: two checksums and one length field. The first byte of the checksum is also used to indicate if the slot is in use.

pub const fn create(idx: usize, prev: Chksum, data: &[u8]) -> Self

Create a new slot for the given data

Calculates the checksum for the data and creates a slot that references the previous savegame’s checksum.

Arguments

• idx - The slot index where this will be stored
• prev - The checksum of the previous savegame (or zero for first savegame)
• data - The savegame data to store

pub const fn is_valid(&self) -> bool

Check if this slot has valid checksums

A slot is valid if both its checksum and previous checksum have the correct format (most significant bit is zero).

pub fn is_update_to(&self, other: &Self) -> bool

Check if this slot is an update to another slot

Returns true if this slot’s prev checksum matches the other slot’s checksum, indicating this is a newer version of the savegame.

pub fn used_bytes<const SLOT_SIZE: usize>(&self) -> usize

Calculate the total number of bytes used by this savegame

Accounts for the header in the first slot and continuation bytes in subsequent slots if the savegame spans multiple slots.

Type Parameters

• SLOT_SIZE - The size of each slot in bytes

pub fn next_slot<const SLOT_SIZE: usize, const SLOT_COUNT: usize>( &self, ) -> usize

Calculate the index of the next free slot after this savegame

Takes into account how many slots this savegame occupies and wraps around using modulo arithmetic.

Type Parameters

• SLOT_SIZE - The size of each slot in bytes
• SLOT_COUNT - The total number of slots available

pub fn to_bytes(&self) -> [u8; 12]

Serialize the slot header to bytes for writing to flash

The format is: checksum (4 bytes) + length (4 bytes) + prev checksum (4 bytes)

pub fn from_bytes(idx: usize, bytes: [u8; 12]) -> Self

Deserialize a slot header from bytes

Arguments

• idx - The slot index where this header was read from
• bytes - The header bytes in the format: checksum + length + prev checksum

Trait Implementations

impl Debug for Slot

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl PartialEq for Slot

fn eq(&self, other: &Slot) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl StructuralPartialEq for Slot