From-scratch reimplementation of the Sword of the Stars (2006) engine. Clean-room; engine code only — bring your own game copy. Planning/RE evidence live in sots-re.
Find a file
alex 5bae56a397 G: wire schema channel + widen the save codec to 97% typed coverage
The serializer recovery reaches this repo as a generated wire schema
(include/generated/sots_stream_schema.h, 386 classes / 2042 items): for each
class, the ordered sequence of items its Write puts on the stream. Facts only —
no field offsets, no sizeof, no strides. This engine reads and writes the on-disk
format; it does not inherit the original's memory layout.

The table is a specification, not a program: the recovery is a linear pass over
Write, so it cannot see Write's branches (StarShip's BQ2 is gated on hbq but
listed unconditionally) and it flattens container loops. A codec driven off it
would desynchronise. The hand-written io() shapes stay the codec; SchemaProbe
(probe.h) walks them with every branch taken and test_wire_schema LCS-aligns
that against the table — 56 shapes bound, 657 items matched, 0 mismatches.

Four defects the check found, all invisible to a round-trip test:
  - SystemParams field 1 is a string, not an int. It is the empty string in
    every save, and an empty string is four zero bytes — byte-identical to the
    int 0, so it round-tripped by luck. A named planet would have desynced.
  - ObservedTech/ObservedWeapon odet is a bool, not an int. Byte-safe only
    because a 4-char tag makes a bool item and an int item both 12 bytes.
  - SpeciesRatios nv and ShipRecords srbd are counts, not fields.

CoverageArchive separates items a field names from items a Node merely carries,
because a byte-identical round trip is not a coverage claim. Typed coverage of a
real save goes 37.9% -> 97.1% (97.2/97.2/97.6 on the others) with the round trip
still byte-identical, by typing TechTree (both NumTechs sections), Events,
ShipRecs, sprjs, civr, comms, spy2, spymgr, aid, Ojvs, AIEnf, FNG, trdmgr and
the Des section/gun-bank tree. Ratchet at 95%.

trdmgr resolves a recorded trap: ServerTradeManager's Read/Write really are the
inherited no-op, but the call is virtual and ServerTradeManagerImpl has the real
serializer. Same shape resolves IServerSpyManager -> ServerSpyManager.

ctest 34/34, clean_room_check OK, test_save skips cleanly with SOTS_SAVES_DIR unset.
2026-09-08 06:30:35 -04:00
cmake m0: binkw32 proxy shim, minhook, trace hook on Application::Initialize; build/deploy tooling 2026-09-07 17:22:15 -04:00
docs G: wire schema channel + widen the save codec to 97% typed coverage 2026-09-08 06:30:35 -04:00
include/generated G: wire schema channel + widen the save codec to 97% typed coverage 2026-09-08 06:30:35 -04:00
src G: wire schema channel + widen the save codec to 97% typed coverage 2026-09-08 06:30:35 -04:00
tests G: wire schema channel + widen the save codec to 97% typed coverage 2026-09-08 06:30:35 -04:00
third_party mars/vfs: gob ZIP reader + native override, miniz 3.1.2; oracle-verified 8352+2035 entries 2026-09-07 17:40:51 -04:00
tools b4: colony + movement hooks; 22 formula corrections (growth curve has no capacity term, range margin +0.05f, ties-to-even rounding); 3 verified signatures 2026-09-08 00:57:55 -04:00
.gitignore init commit 2026-09-07 17:07:54 -04:00
CMakeLists.txt merge lane F: x87 control-word sensitivity - 53-bit and 64-bit identical; 24-bit and round-up each move 2 named leaves 2026-09-08 05:10:21 -04:00
CMakePresets.json m0: binkw32 proxy shim, minhook, trace hook on Application::Initialize; build/deploy tooling 2026-09-07 17:22:15 -04:00
CONTRIBUTING.md CONTRIBUTING: cmake >=3.25 requirement and the uv workaround 2026-09-08 05:13:31 -04:00
LICENSE init commit 2026-09-07 17:07:54 -04:00
README.md b3: research hook + RNG-snapshot compare design; fix draw mapping to y/(2^32-1), NextInt inclusive, float32 odds, spend floor, decay constants 2026-09-07 23:14:08 -04:00

sots-engine

A from-scratch, functional reimplementation of the engine behind Sword of the Stars (2006). Not a byte-for-byte decompilation: behavior-equivalent code, built up one verified piece at a time (OpenRCT2-style) until the tree can build the whole application on its own.

Bring your own game. This repository contains engine code only. Game data, assets, saves, and the original binaries are never included; tests and tools read an owner-supplied copy via $SOTS_DATA_DIR. See CONTRIBUTING.md for the clean-room rules.

Status

Phase 2. M0 done — the shim frontend (src/shim/, a proxy binkw32.dll the original game loads) builds, deploys, hooks, and logs from a real game launch. Engine code accrues under src/mars/ and src/game/; each module is oracle-verified against the owner's game data before merge:

  • mars/parse — brace-block + .effect readers (1,531/1,531 files agree with the reference)
  • mars/text — flat key/value tables, id manifests, CSV (64/64 files agree)
  • game/sim — strategic formulas (economy, research, colonies, movement) as pure functions; 356 hand-computed checks
  • mars/vfs — .gob (ZIP) archive reader + loose-file override; entry counts and bytes verified against unzip
  • mars/stream — the game's self-describing save/serialization format (reader, writer, typed shapes) + gzip; three real saves round-trip byte-identical
  • mars/rng — MT19937 with save-state load/store; layout confirmed against real saves, draw mappings read off the binary (docs/mars-rng.md)
  • game/data — typed catalogs (weapons, ship sections, turrets, id registries, tech tree, strings) with cross-reference checks; 229k values agree with the reference
  • game/design — ship-design assembly/fit/tech-gating rules and derived stats; validates all 127 stock designs from real saves

Build: cmake --preset host && cmake --build --preset host && ctest --preset host (Linux); tools/sync-build.sh cross-builds the shim on the lab box and stages it for deployment.

Layout (grows with the work)

  • src/shim/ — binkw32 proxy + hooks + old-vs-new compare harness (frontend #1)
  • src/mars/, src/game/ — the engine and game reimplementation (accruing)
  • include/generated/sots_addresses.h — binary facts (RVAs/prototypes), generated from the RE repo
  • tests/ — host tests; real-data tests skip unless $SOTS_DATA_DIR is set
  • tools/ — build (MinGW i686 cross) and deploy scripts

Planning, findings, and verification evidence are tracked in the private RE repo (sots-re).