Files
tdkpin/tdkpin-rs/PARITY_AUDIT.md
T
ddidderr 17a7b3c328 fix(divergence): keep claw releases on the table during multiball
Bug: with several balls in play the claw could still drop its ball into
the shooter lane (terminal frame 18), sending it back to the launcher.

Cause: the restriction to table releases (frames 1, 6, 7) is latched
when the ball enters the claw's capture zone, from the ball count at
that moment. Balls added afterwards (crazy mode, a release-ball spawn)
did not affect a capture that had already chosen frame 18.

Fix: while the claw holds a ball and is heading for frame 18,
update_claw checks the live ball count every timer callback. With more
than one ball (the held one included) it re-targets the claw to a
random table frame using the same restricted draw as a multiball
capture. The claw animates one frame per callback, so it simply turns
around towards the new target.

Single-ball captures, and multiball captures that were already
restricted at entry, behave exactly as before; the extra random draw only
happens in the situation that used to misbehave.

Test Plan:
- cargo test claw_never_drops_into_the_shooter_lane_with_several_balls:
  a frame-18 capture gains a second ball mid-ride and must release at
  frame 1, 6, or 7, onto the table.
- A release-mode stress run (40 two-player crazy-mode games) counted 254
  claw releases and none into the shooter lane with several balls.
2026-10-10 11:46:00 +02:00

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8.3 KiB
Markdown

# 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.
- The release-ball effect (effect seven) frees a parked special-hole ball
whenever one is parked, not only when exactly one ball is in play. The
released ball owns the hole's contact under its own slot number.
- The claw re-targets a shooter-lane release (terminal frame 18) to a table
release whenever more than one ball is in play during its ride, not only
when the capture began in multiball.
- 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
```sh
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.