# Mechanics reconstruction progress

This ledger scopes the current reverse-engineering pass to the claw and
flippers. The preserved executable is the authority; `TDKPIN_GHIDRA_RAW.c`
remains immutable raw evidence, while `TDKPIN_MECHANICS_RESTORED.c` carries
reviewed names and control flow.

Target: `TDKPIN.EXE` SHA-256
`a9022f1894e3e6e21fc42e8f6c932f7c549ca77f63aaa0c488bb9d55d9d0174c`.

## Function inventory

| Address | Raw name | Restored role | Status |
| --- | --- | --- | --- |
| `1000:638e` | `FUN_1000_638e` | key-release flag updates | reviewed |
| `1000:6bf8` | `FUN_1000_6bf8` | key-press flag updates | reviewed |
| `1000:7ed9` | `FUN_1000_7ed9` | flipper collision movement and sound | reviewed; inner fixed-point geometry still raw |
| `1000:8b0d` | `FUN_1000_8b0d` | flipper bitmap/collider movement | reviewed; inner fixed-point geometry still raw |
| `1000:99f0` | `FUN_1000_99f0` | binary flipper transition state machine | restored |
| `1000:c79c` | `FUN_1000_c79c` | collision dispatch, including claw object `0x59` | claw branch restored |
| `1000:eab1` | exported ordinal 10 | timer tick, claw release and return | claw branch restored |
| `1008:0002` | `FUN_1008_0002` | sound-enabled dispatch | restored |
| `1008:0e08` | `FUN_1008_0e08` | claw background restore and sprite slicing | restored |

Inventory coverage is 9/9 functions inspected for this mechanism pass. This is
not a claim that all instructions in the two large physics functions have been
renamed.

## Proven behavior now available to the Rust port

- Left Control (scan `0x1d`) and keypad Enter (scan `0x1c`) set input flags;
  the timer changes each flipper position only between 0 and 1.
- Every flipper movement edge, including return, invokes sound number 21,
  Win16 WAVE resource 2021.
- Claw collision object `0x59` suspends the ball, zeros its live motion,
  disables collision records 12 through 20, and selects terminal frame 1, 6,
  7, or 18.
- The claw advances exactly one frame per timer tick to its terminal, releases
  the ball, then advances one frame per tick back to frame 10 before clearing
  the overlay and restoring collision records 12 through 20.
- Resource 900 is sliced into 100x74 frames, nine columns by four rows. The
  destination is `(238,47)`; closing rows begin at source y=0 and opening rows
  at source y=148.
- Claw capture/contact uses sound 2015; release uses sound 2016.
- The release-coordinate projection is `(raw + 500) / 1000` for rendering;
  decoded physics centers are `(258,78)`, `(270,94)`, `(275,97)`, and
  `(325,92)` for the four selectable terminal frames.
- The speed scalar is 3800 millipixels per tick. Its Borland Real48 direction
  constants are decoded for all release cases in the readable C companion.

## Explicit pending evidence

- Differentially verify the recovered 10/20/30/40/50 ms timer choices against
  live original captures; the Rust port intentionally uses the default 30 ms
  claw cadence independently of render rate.
- Transcribe the full fixed-point flipper impulse calculation, then compare it
  with the Rust floating-point collision response.
- Force a chosen claw terminal in the live original and compare its complete
  frame/trajectory sequence with the deterministic Rust trace.

Those items are intentionally not counted as semantic parity. The readable
C file preserves their raw constants and labels the unresolved conversion so a
later implementation cannot silently turn an estimate into claimed evidence.

## Runtime comparison on 2026-08-22

Wine 11.15 (staging) ran the preserved 16-bit NE executable from this tree.
Keypad `+` was sent to the real window and produced the one-player started
state. Down was then held for 1.1 seconds and released; captures confirmed that
the original plunger advances while held and launches only on release.

The Rust validation mode captured the corresponding started and half-charge
states plus closing and release frames for claw terminal 6. The original claw
was not forced into a chosen terminal during the live session, so its claw
parity evidence remains the decoded `1000:c79c`/`1000:eab1` control flow,
millipixel/Real48 constants, sprite sheet, and deterministic Rust traces rather
than a claimed live trajectory comparison.

## Live fixed-point tracing

Wine's remote debugger changes the Win16 exception path and is not suitable for
continuous gameplay traces. On Linux, `tools/run_traceable_original.sh` starts
the unmodified executable with a same-user ptrace opt-in. While it is waiting at
the launcher, `tools/trace_original_state.py` locates the live DGROUP and game
object by recovered binary/state signatures and records their fixed-point state:

```sh
original/tools/run_traceable_original.sh
original/tools/trace_original_state.py --duration 5 --output /tmp/launch.csv
```

The sampler records original millipixel positions, predicted positions,
velocities, flipper inputs and states, and claw animation state whenever any of
them changes. It neither patches `TDKPIN.EXE` nor pauses Wine. The tracing helper
is Linux-only development infrastructure; it is not part of the Rust replica.