Files
tdkpin/tdkpin-rs/PARITY_AUDIT.md
T
ddidderr a8cc0fc5fc feat(divergence): make every ball identical and bind crazy mode to 0
Crazy mode first shipped as a side list of "crazy balls" with reduced
physics (walls, bumpers, flippers only) next to the original primary and
secondary slots. That is not what was wanted: a ball in the machine is a
ball, with no main/second/extra distinction. This replaces the two-slot
engine with one ordered list and moves the shortcut to a single key.

Ball model (src/game.rs)
- Game::balls: Vec<Ball> replaces `ball`, `secondary_ball`, and
  `crazy_balls`. The list is never empty while the game runs; a waiting
  ball is simply a ball with in_launcher set.
- advance_ball_slots runs one timer callback: every ball, in slot order,
  integrates up to `substeps` steps through the single integrator
  step_ball (record scan, ball-to-ball contact, rule dispatch, drain) and
  stops after its first collision, exactly like the original slot pass.
- BallPass carries the ball's current index plus the slot number and
  ball count from the start of the callback. The original keeps slot two
  numbered 2 for the rest of a callback even after slot one drained, and
  type-three contact records publish that number as their owner; keeping
  it per pass preserves that.
- Effect seven's ball goes to `spawned_balls` and joins after all slot
  passes, as the original publishes slot two only after slot one's pass.
- lose_ball removes a drained ball while others remain (Drain event,
  normal scoring once one ball is left) and only the last ball takes the
  special respawn or ends the player's ball. remove_ball keeps the claw's
  captured/entry indices and the claw and lock-hole contact owners
  pointing at the same physical ball when an earlier slot leaves.
- The claw stores a ball index instead of a Primary/Secondary enum.
- Nudge, flipper kicks, multiball scoring, and the "no third ball from
  effect seven" guard are expressed over the list. With one or two balls
  the original order, random draws, and ownership rules are unchanged;
  all existing parity and multiball tests pass after a mechanical port
  (test-only shims fixed_update, advance_secondary_ball, drain,
  secondary/set_secondary/take_secondary keep them readable).
- Crazy mode adds ten ordinary balls (capped at MAX_BALLS = 64 because
  contact records reserve 99 as a sentinel) and marks the player.

Deliberate differences from the original (also in PARITY_AUDIT.md),
mostly because there is no longer a special slot one:
- A ball resting on the shooter stop returns to an empty launcher from
  any slot; the original deleted a slot-two ball there. If the launcher
  is occupied the ball leaves the table without costing a ball.
- Flipper kicks, record countdowns, and target rotation keep running for
  balls in play while another ball waits in the launcher.
- Ball-to-ball contact skips only the claw-held ball; every ball's hit
  is published as last_collision_id.
- Stress runs with 10-64 balls showed balls trapped forever: two balls
  settle into one lock hole, one fills it (contact 99), and the rim then
  reflects the other from the inside. A filled hole's rim now only
  repels balls moving towards its center. Lock-hole owners of a removed
  ball are cleared/renumbered like the claw owner.

Input (src/app.rs)
- Crazy mode is the bare main-row 0 key. It overlaps no original or
  modern binding and has no browser default action, so the WASM build
  receives it. The Ctrl+Shift+0 combo and its Shift-release nudge
  suppression are gone.
- Rendering draws every ball not held by the claw.

Simulator: snapshots report `balls: [...]` instead of `ball` and
`secondary_ball`; autoplay flips for any ball near a flipper.

Test Plan:
- cargo test (160 tests), including new ones:
  a_ball_moves_the_same_in_any_slot (same ball in slot one vs. behind a
  waiting ball follows the identical trajectory),
  crazy_mode_adds_ten_ordinary_balls_and_marks_the_player,
  the_turn_ends_only_when_the_last_ball_drains,
  shooter_stop_rearms_a_returning_ball_from_any_slot,
  crazy_mode_is_capped_and_rejected_after_the_game.
- A temporary release-mode stress test (not committed) ran 12 seeded
  two-player games with crazy mode, autoplay flippers, and nudges to
  completion, and 4 seeds at the 64-ball cap for 30k frames, asserting
  finite state, a non-empty ball list, and valid claw indices.
- Manual: during a game press 0 (also in the browser build); ten balls
  appear, each can be captured by the claw, lock holes, and targets, and
  the turn ends only after the last ball drains.
2026-10-10 11:15:11 +02:00

7.9 KiB

Rust player-experience parity audit

Audit date: 2026-08-23

Decision

The Rust rewrite passes the reconstructed-binary requirements for the same game and player experience at the 640x460 logical gameplay boundary. No known raw, placeholder, guessed, partial, or unverified gameplay unit remains in the Rust path. This is a semantic and presentation result, not a claim that a native Rust executable is a byte-identical Win16 implementation.

The authoritative source is the preserved executable with SHA-256 a9022f1894e3e6e21fc42e8f6c932f7c549ca77f63aaa0c488bb9d55d9d0174c, the complete readable C under ../original/reconstructed/, and the zero-gap C ledger in ../original/C_RECONSTRUCTION_FINAL_AUDIT.md.

Requirement matrix

Requirement Binary/C basis Rust evidence Result
Original presentation All 63 resources round-trip; DAT/bitmap bounds and GDI call sites are reconstructed Original images/samples are embedded; loading, attract, game, panel, target, effect-seven, high-score, and name-entry scenarios export 640x460 frames Verified
Collision inventory All 175 initialized records are typed in OBJECTS.tsv; raw scan order is address-linked 109 type-2 lines, 40 type-1 circles, all type-3/4 mechanisms, layer masks, response fields, and initial activity are represented; relative chains 54-59 and 69-74 have record-exact tests Verified
Fixed-point/Real48 physics 1000:c79c and Borland runtime arithmetic are reconstructed; the DOS reference probe is bit-exact 10 ms millipixel steps, both speed clamps, four board bounds, first-record selection, signed dot-product tangent response, spin, auxiliary kick, and dynamic-ball transfer use exact-width arithmetic Verified
Live collision behavior Stopped Wine probes expose position, velocity, and six-byte spin Rails, circles, bumper, record 2, record 57, and record 72 have exact expected transitions in Rust and C tests Verified
Timer ordering 1000:eab1 fixes 5/4/3/2/1 substeps, ball-slot order, countdowns, mechanisms, flippers, and Tilt decay Timer-batch, collision-break, per-slot, target-rotation, panel, claw, countdown, and Tilt tests cover the recovered callback order Verified
Attract mode Raw 1000:01b7-063b distinguishes quotient and remainder outputs; marquee GDI lifetime is reconstructed %32/2, %32/4, %40/4, %16/4, %144/8, magnetic %32, and six-callback marquee cycles are tested and rendered Verified
Inputs 1000:638e/6bf8 define low-byte scans, Key-Up actions, auxiliary-window gate, launcher impulses, nudges, Tilt, and flipper latches Both Ctrl/Enter aliases, both plus positions, release-time add/nudge/F12, held launcher, flipper rearm, and auxiliary-window blocking follow those paths Verified
Rules and scoring 1000:b476, 1000:c4e1, 1000:bc36, 1000:ae6e, and 1000:9e85 define awards and state transitions Bank progression, ninth-diamond order, ball-scoped double, marker comparison, lock transfer, special hole, all seven effects, Type-3 Tilt finish, and score/sound ordering have focused tests Verified
Multiball Records 148, 174, and 175 plus timer collapse/spawn paths define ownership and lifetime Deferred spawn, per-slot capture age, survivor promotion, no-third-ball guard, nudge, fifth-lock deferral/reset, special respawn, and contact clearing are tested Verified
Player turns 1000:ae6e saves all record activity/contact mirrors and advances live players Four-player bounds, add-before-launch, per-player rule state, final-ball high-score ordering, flipper key lifetime, and normal/special drain behavior are tested Verified
Audio Sixteen WAV resources and every in-image play/stop call are inventoried Samples are unchanged; monophonic async replacement, full volume, Tilt suppression, threshold precedence, panel stops, and no-WAV-2022 behavior are represented Verified
High scores/configuration The 276-byte IWIK table, dialog 32514, HighScore child, and INI reads are reconstructed Signed-high comparisons, all ten entries, 21-byte name semantics, OK/Cancel flow, localized help, original settings names/defaults, and screenshots are tested Verified
Randomness The Borland LCG, high-product Random(n), Real48 result, and program-global seed are reconstructed All gameplay draws use one exact stream; seeded traces are repeatable and the final seed continues across games Verified
Stability/build Native replacement must preserve finite state and compile on supported hosts Production Linux build, 125 Rust tests, strict Clippy, two-minute finite autoplay, and Windows/macOS cross-target checks pass; native CI covers all three hosts Verified

Differential evidence

  • Record 2 special response: (157000,453000)/(0,3000) publishes the special ball at (17000,23000)/(0,3040) and continues to (16698,21191)/(-302,-1809).
  • Record 57 left relative slingshot: (75530,354765)/(3000,15) becomes (77369,356597)/(1839,1832), Real48 spin -5.28 (83 5d 8f c2 f5 a8).
  • Record 72 right relative slingshot: (235348,356825)/(-3000,15) becomes (233253,358494)/(-2095,1669), Real48 spin +5.46 (83 86 eb 51 b8 2e).
  • Ordinary circle 155, the outer/inner shooter rails, bumper response, all four claw terminals, moving flippers, Type-3/4 records, scoring, and multiball also have focused C/Rust or Wine-backed tests documented in RECONSTRUCTION.md.

Deliberate host substitutions

  • The native fixed window replaces ObjectWindows/Win16 ownership, but retains the title, logical client size, original pixels, controls, modal gameplay blocking, and visible flows.
  • Portable JSON replaces writes to HISCORES.DAT and TDKPIN.INI; the original files are imported, while table ordering, names, settings, and UI semantics remain unchanged. F9/F10 expose additional viewers/settings without replacing any original gameplay key.
  • Windows and macOS were cross-checked in this Linux checkout; native execution on those hosts is delegated to the repository's three-OS CI matrix. The semantic core is platform-independent and has no target-specific branches.

Modern additions and their divergences

Crazy mode (main-row 0) adds up to 64 live balls. To make every ball behave identically, the two original timer slots became one ordered ball list. One- and two-ball play keeps the recovered slot order, slot-numbered contact ownership, deferred effect-seven spawn, survivor identity, nudge draws, and multiball scoring, and all multiball tests above still pass. These deliberate differences follow from treating every ball alike:

  • A ball resting on the shooter stop returns to the launcher from any slot (the original deleted a slot-two ball there) unless another ball already waits.
  • Flipper kicks, record countdowns, and target rotation continue for balls in play while another ball waits in the launcher.
  • Ball-to-ball contact ignores only the claw-held ball, and every ball's collision is published as the last collision record.
  • When a ball leaves, claw and lock-hole contact owners move with their ball, and a lock hole the leaving ball was settling into is freed.
  • The rim of a filled lock hole only repels balls from the outside, so a ball that was settling into it when another ball filled it rolls back out.
  • High-score entries carry a crazy flag that both local storage and the shared service persist; older entries default to normal scores.

Reproducible final gates

cargo build --profile production
cargo test --workspace --all-targets --all-features
cargo clippy --workspace --all-targets --all-features -- -D warnings
cargo check --target x86_64-pc-windows-gnu
cargo check --target x86_64-apple-darwin
bash original/tools/test_reconstructed_c.sh
python3 original/tools/audit_reconstruction.py --require-complete

The C ledger gate reports zero raw, partial, restored, unknown, blocked, or unclassified required units. The only files intentionally outside commits are user diagnostic media in the repository root.