# R1-P0 — pseudocode pins and ambiguity resolutions

The verbatim extraction lives in `r1-csequence-decomp.md` (1,756 lines, per-
function raw pseudo-C + cleaned translation, line anchors into
`docs/research/named-retail/acclient_2013_pseudo_c.txt`). This note records
the corrections and pins the R1 port codes against, per the gap map
(`r1-gap-map.md`).

## Corrections to the extraction (verified against raw decomp + ACE)

1. **§21 `update_internal` cleaned flow is garbled in two places.** The
   authoritative skeleton is ACE `Sequence.cs:351-443` (verified verbatim,
   matches the raw decomp branch layout at 0x005255d0-0x005259ca):
   overshoot check → clamp `frame_number` to `get_high_frame()` (fwd) /
   `get_low_frame()` (rev) + compute `frameTimeElapsed` leftover +
   `animDone = true` → per-frame crossing loop → `if (!animDone) return` →
   AnimDone gate (`anim_list.head != first_cyclic`) →
   `advance_to_next_animation` → carry leftover → loop.
2. **Hook direction constants**: forward crossings pass +1
   (0x0052578c, counter `++` after), reverse pass −1 (0x0052590c, counter
   `--` after). Retail encoding == ACE/DatReaderWriter `AnimationHookDir`
   (Backward=−1 / Both=0 / Forward=1) — no remap.

## PINNED ambiguity — leftover-time carry after node advance

Raw decomp at 0x0052598a-0x0052598d APPEARS to zero the elapsed argument
after `advance_to_next_animation` before looping; ACE carries the leftover
(`timeElapsed = frameTimeElapsed`, Sequence.cs:436-442).

**PIN: the ACE reading (carry the leftover).** Rationale: (a) Binary Ninja
routinely loses x87 stack-slot reassignments (the same artifact class as the
garbled setcc returns in `is_newer`); (b) zeroing would make a lag spike
unable to fast-forward through multiple queued nodes in one tick, visibly
freezing links under hitches — behavior nobody has ever reported on retail;
(c) the loop structure (`while(true)` with the leftover recomputed per
node) only makes sense with a carry.

**Confirmation pending (not blocking):** cdb breakpoints on
`acclient!CSequence::update` + `acclient!CSequence::advance_to_next_animation`
with hit counters (pattern `tools/cdb/l2g-observer.cdb`) under an induced
stall — an advance/update ratio > 1 in a single update proves the carry.
Fold into the next live retail session; if it DISPROVES the carry, the fix
is one line in `update_internal` + rerun of the P4 conformance suite.

## P0 addenda for later stages

- The same cdb session should also capture `append_animation` /
  `remove_cyclic_anims` argument logs (P2/P5 goldens) — one session serves
  all of R1.
- `frame_number` is x87 `long double` (acclient.h:30747); C# `double` is the
  closest available → divergence-register row lands with the P2 commit
  (G15).
- ACE's `PhysicsGlobals.EPSILON` subtraction in
  `get_starting/get_ending_frame` is an ACE fabrication (compensating for
  ACE's `float FrameNumber`) — retail returns bare ints. Do NOT copy (G1).