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Sword of the Stars (2006) reverse-engineering worklog. Infra docs live in trikilli services/re-lab.md.
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alex 849c5069fc lane F: x87 precision sensitivity measured; STATE_CHECKSUM 3.5 closed 
Seven End Turns from ref-turn2.sav on VM140, six control words, whole-state
checksum on every post-turn autosave.

53-bit and 64-bit x87 give byte-identical state across all 35,394 leaves, so
an x64/SSE port computing in IEEE double has NO double-rounding budget to
preserve and floats=bits is free. Two settings do move state, each reproduced
on a repeat run:

  0x007f (24-bit)   Sys[112 "Gamma Cephei"]/Pop2/PopG/PopC 540000000 -> 540000002
  0x1a7f (round-up) Flt[34 "Beta Fleet"]/Pos/.[0] and /Pos/.[2], 1 ULP each

So the port must hold intermediates at 53 bits and use round-to-nearest --
both SSE defaults, now measured rather than assumed, each with a named
regression witness.

The briefed triple was under-powered: 0x027f is 53-bit (it differs from 0x127f
only in bit 12, infinity control, ignored since the 387) and 0x137f is 64-bit,
not a rounding change. Run as written all three come back identical, and that
would have "proved" something false on both axes that matter.

Evidence the forced word actually held: read-back at each force site plus 38
independent in-pipeline hook samples per run spanning turn phases 4, 6 and 8,
all reading the forced value. Mars::Application::Run calls
_controlfp(0x50000,0x3070300) at 0x0089f606 every frame, which is 0x127f, so
forcing at StrategyClient::EndTurn is wiped before the turn runs;
StrategyServer::BeginProcessTurn is the point that works.

Also re-confirms the End-Turn determinism oracle on engine cef889e:
bb4fd9ac... / 978041ac... unchanged.

New tools: verify/fpu-cw/cw_census.py, verify/fpu-cw/trace_bitdiff.py (the
latter exists because under a forced 24-bit word the CRT's own %g rendering
degrades, so trace text is not a valid comparison surface).
2026-09-08 05:07:53 -04:00
campaign board: lane X scanner verified; ObservedTech pinned; std::string size contradiction; audit row 11 corrected 2026-09-08 04:46:54 -04:00
findings lane F: x87 precision sensitivity measured; STATE_CHECKSUM 3.5 closed 2026-09-08 05:07:53 -04:00
ghidra lane X: x86 displacement xref scanner; pin sizeof(ObservedTech) and its append site 2026-09-08 04:44:18 -04:00
guides guides: RE how-to for 2000s MSVC/DX9 games (98 sources); queue replay-checksum, class recovery, apitrace/TTD 2026-09-07 18:05:58 -04:00
notes init commit 2026-09-07 12:31:56 -04:00
scripts campaign: forgejo issues sync script; issues are the published board 2026-09-07 15:04:57 -04:00
tools lane X: x86 displacement xref scanner; pin sizeof(ObservedTech) and its append site 2026-09-08 04:44:18 -04:00
verify lane F: x87 precision sensitivity measured; STATE_CHECKSUM 3.5 closed 2026-09-08 05:07:53 -04:00
.gitignore ignore pycache 2026-09-07 15:55:37 -04:00
README.md guides: RE how-to for 2000s MSVC/DX9 games (98 sources); queue replay-checksum, class recovery, apitrace/TTD 2026-09-07 18:05:58 -04:00

README.md

sots-re

Reverse-engineering worklog for Sword of the Stars (2006, SOTS1) — the 32-bit DX9 original + expansions. The nitty-gritty: static/dynamic analysis notes, Ghidra & ReVa scripts, function/struct maps, D3D9 call traces, decomp progress, findings.

Where this runs

Analysis lab on spicy (PVE, 192.168.3.201):

  • CT111 sots-re — Linux workspace: Ghidra + headless ReVa server, radare2/rizin/cutter, binwalk. Hosts the Samba share and this repo's working tree at /srv/re-lab/notes.
  • VM140 sots-re-win10 — Win10 runtime + dynamic analysis (x64dbg, Cheat Engine, RenderDoc/apitrace, DXVK→CPU-Vulkan for GPU-less rendering).

Infra (guests, storage, network, share, ReVa endpoint) is documented from the system-maintainer POV in trikilli → services/re-lab.md. This repo is everything else.

Layout

  • findings/ — the running findings log (append-only), one file per subsystem.
  • ghidra/ — exported scripts, data-type archives, struct definitions.
  • traces/ — D3D9 / Win32 API call captures + analysis.
  • scripts/ — helper tooling (loaders, extractors, parsers).
  • notes/ — session notes, scratch, hypotheses.

Ownership / legality

Game binaries come from the owner's own GOG/Steam copy. RE is for personal interoperability, bug-fixing, and preservation. Binaries themselves are not committed here (see .gitignore) — they live on the lab's Samba share /srv/re-lab/samples.

Campaign (how this repo is run)

A 4-agent crew (defined in ~/.claude/agents/re-*.md) runs the exploration: re-quartermaster (backlog + board) → re-analyst (maps via ReVa) → re-verifier (proves vs real data; old-vs-new differential once reimpl starts) → re-scribe (files the note, links it, commits).

  • campaign/board.md — live status board (start here).
  • Live tracking = Forgejo issues on alex/sots-re (labels status/* are the kanban columns; type/*, conf/*). campaign/board.md is the editable mirror — publish with scripts/forgejo_campaign.py bootstrap (needs FORGEJO_TOKEN).
  • campaign/backlog.md — prioritized target queue.
  • campaign/open-questions.md — unresolved threads.
  • findings/_template.md — the record format every finding follows.
  • findings/{objects,control-flow,subsystems}/ — the growing engine map.
  • verify/{parsers,traces,harness,results}/ — validation: struct parsers now, golden-trace replay + shim compare-mode for reimplementation.
  • ghidra/ — exported scripts + datatype archives.

Approach & north star: findings/00-strategy.md. Binary facts: findings/01-fingerprint.md.

Sibling repo

alex/sots-engine — the from-scratch engine source (clean-room, public-capable). This repo keeps the evidence + planning for both; binary facts cross over only via ghidra/addresses.json → tools/gen_addresses.py.

  • guides/re-windows-2000s-howto.md — annotated bibliography + how-to for RE of mid-2000s MSVC/DX9 Windows games, with our-experience call-outs.