Struct RewindRing 

pub struct RewindRing { /* private fields */ }

Rewind ring buffer.

Configure once via Self::new (or Self::default); call Self::push after each emulated frame; call Self::pop_back to step backwards in time during rewind playback.

Implementations

impl RewindRing

pub fn new(max_bytes: usize, keyframe_period: u32) -> Self

New ring with max_bytes of in-memory budget and a keyframe every keyframe_period captures.

keyframe_period of 0 is treated as 1 (every entry is a keyframe).

pub fn len(&self) -> usize

Number of buffered entries (each one is a frame).

pub fn is_empty(&self) -> bool

true if no frames are buffered.

pub const fn bytes_used(&self) -> usize

Approximate memory footprint in bytes.

pub fn clear(&mut self)

Drop every entry.

pub fn push(&mut self, frame: u64, snapshot: &[u8])

Capture one frame’s worth of state.

frame is informational; pass the emulator’s frame counter so debug output can label entries.

pub fn pop_back(&mut self) -> Option<Result<Vec<u8>, RewindError>>

Pop the most recent entry and return its decoded snapshot bytes.

Returns None when the ring is empty. Walking back across a keyframe boundary is allowed; once the keyframe itself is consumed, the next pop reads its predecessor (which must itself be a keyframe — by construction, since deltas refer forward to a keyframe).

Errors

Returns RewindError when an entry can’t be reconstructed (corrupt LZ4 payload, etc.).

pub fn back_frame(&self) -> Option<u64>

Borrow the most recent entry’s frame number, if any.

Trait Implementations

impl Debug for RewindRing

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

Formats the value using the given formatter.

impl Default for RewindRing

fn default() -> Self

Returns the “default value” for a type.