Struct System 

pub struct System {
    pub bus: Bus,
    pub cpu: Cpu,
    /* private fields */
}

Owns the run loop. Determinism contract: same seed + ROM + input => bit-identical AV.

Fields

bus: Bus

The Bus — owns everything mutable (PPU/APU/cart/WRAM/controllers/DMA + the master clock).

cpu: Cpu

The 65C816 main CPU. It borrows &mut bus for each Cpu::step.

Implementations

impl System

pub fn new(seed: u64) -> Self

Power on with a determinism seed.

pub fn reset(&mut self)

Reset the CPU from the cart’s emulation reset vector ($00FFFC). Safe to call with no cart (the CPU reads open bus and parks); the boot flag tracks readiness. Auto-detects NTSC vs PAL from the installed cart’s header (Bus::sync_region_from_cart) before resetting the CPU, so a PAL cart boots at the PAL line count/timing without the caller (frontend or test) having to know or guess the region up front.

pub fn run_frame(&mut self)

Run one full video frame: step the CPU until the PPU’s frame-count advances, firing the per-frame HDMA setup at the top of the frame and the per-line HDMA at each visible-line boundary.

pub fn sa1_cycles(&self) -> Option<u64>

Cumulative cycles the SA-1’s second CPU has executed since power-on, or None when no SA-1 cart is installed. A non-zero value is the SA-1 liveness signal: the second 65C816 actually fetched + executed out of the cart ROM (many SA-1 titles run their main logic on the SA-1).

pub fn sa1_regs(&self) -> Option<Regs>

The SA-1 second CPU’s architectural register file, or None when no SA-1 cart is installed. For the debugger overlay’s Cart panel (docs/frontend.md §Debugger overlay).

pub const fn seed(&self) -> u64

The determinism seed this System was constructed with (Self::new). A TAS movie’s power-on start point records this so a replay can verify the caller reconstructed the System with the exact same seed before calling crate::movie::Movie::seek_to_start — a different seed gives different power-on phase alignment, breaking bit-identical replay even against the same ROM and input log (docs/adr/0004).

pub fn step_instruction(&mut self)

Step a single CPU instruction (drives the whole machine in lockstep via the Bus).

pub fn tick_one_master(&mut self)

Advance by one CPU instruction (kept for API compatibility with the old skeleton). The real timebase advances through the CPU’s bus accesses, not a bare master tick.

pub fn save_state(&self) -> Vec<u8>

Serialize the entire emulated machine — the main CPU, the whole Bus (PPU, APU, DMA, WRAM, plus the cart’s coprocessor state and battery SRAM if a cart is loaded), the determinism seed, the boot/HDMA-line bookkeeping, and (if present) the SA-1 second CPU plus its master-clock catch-up accounting — into a versioned binary blob (docs/adr/0006-save-state-format.md). The blob leads with a 4-byte magic and a u16 format-version header that Self::load_state checks before trusting anything else. The cart’s ROM is never embedded (docs/adr/0003’s “never embed a ROM/firmware byte” posture, already applied to every coprocessor’s firmware) — restoring a cart-carrying save-state requires the caller to have already loaded the SAME ROM onto the target System first.

pub fn load_state(&mut self, bytes: &[u8]) -> Result<(), SaveStateError>

The inverse of Self::save_state.

Errors

SaveStateError::BadMagic if bytes doesn’t lead with the expected magic (not a RustySNES save-state at all); SaveStateError::UnsupportedVersion if the format version is newer than this build understands; SaveStateError on truncated/corrupt input or a section with unconsumed trailing bytes; or SaveStateError::Invalid if the save-state’s SA-1-second-CPU presence, or (via Bus::load_state) cart presence/SRAM size, doesn’t match this System’s own installed state — restoring onto the wrong ROM/board configuration is rejected rather than silently corrupting it.

Trait Implementations

impl Debug for System

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

Formats the value using the given formatter.