# BTL4.CPP — reconstruction notes

**Status: RECONSTRUCTED (normal launch path); review/camera branch staged with Fail().**

The 4.10 main TU. No original survives anywhere in the archive (OPT.MAK links
`btl4.obj` as a bare object next to the libs — it was never a lib member).

## Evidence base

1. **Ghidra decomp of the 4.11 binary** — `C:\VWE\BT411\reference\decomp\all\part_000.c`,
   `FUN_0040109c` (the 524-byte function the Borland startup calls = `main`).
   The 4.10 and 4.11 binaries share the same string pool layout for this TU.
2. **String pool of the original 4.10 `BTL4OPT.EXE`** (ALPHA_1/REL410/BT), file
   offset ~917884: `"btl4" "HEAPSIZE" "BattleTech v4.10" "btl4.res" "SPOOLSIZE"
   "Spool size = "` — banner text and resource name byte-exact.
3. **Surviving 1995 launcher-style TU** `CODE/RP/RP_L4/RPL4TOOL.CPP` — house
   style for `main(int, char*[])` and the `ProgName` global pattern.
4. **BT411's win32 launcher** `game/btl4main.cpp` (adapted from RP's RPL4.CPP)
   independently reconstructs the same skeleton and pins `version[3] = {1,0,6}`
   against the RESOURCE.cpp version check.

## Decoded decomp → source mapping

| decomp | source |
|---|---|
| `FUN_004dbb24(&cout, "BattleTech v4.10", 0); FUN_004d9c38(&cout)` | `DEBUG_STREAM << "BattleTech v4.10" << endl` |
| `FUN_0047b2ec(argc, argv, &LAB_0047af8c)` | `L4Application::ParseCommandLine(argc, argv, L4Application::ParseToken)` |
| `FUN_00407218(stack84, "btl4.res", &DAT_004e0070, 3)` | `StreamableResourceFile resources("btl4.res", version)` (match_level=3 is the declared default) |
| `DAT_004e0070` = 3 bytes | `version[3]` = `{MAJOR_DATA_VERSION, RELEASE_VERSION, MINOR_DATA_VERSION}` = {1,0,6} from BTL4VER.HPP |
| `DAT_004fd550 < 1` | `L4Application::GetMissionReviewMode() < 1` (inline static accessor) |
| `new(0x28) FUN_0044f29c(this, DAT_0052140c)` | `new ApplicationManager(GetTicksPerSecond())` (inline friend accessor, TIME.HPP:49) — DAT_0052140c is set to 28.0f by `SystemClock::SystemClock()` (L4TIME.CPP:93) when `L4TIMER=FAST` |
| `new(0xd4) FUN_004d34c4(this, &resources, 0x3EB, &DAT_0051e8d8)` | `new BTL4Application(&resources)` — 0x3EB/`DefaultData` are the declared default args (BTL4APP.HPP:34) |
| `FUN_0044f318(mgr, app)` | `application_manager->StartApplication(application)` |
| `FUN_0044f344(mgr)` | `application_manager->RunMissions()` |
| vcall slot 0 (mgr, 3) | `delete application_manager` |
| `return DAT_004efc98` | `return Exit_Code` (APP.HPP:542) |

## Review/camera branch (NOT yet reconstructed — staged Fail)

Decomp structure for `missionReviewMode >= 1` (mode 1 = camera, 2 = review per
emulator/CAMERA-REVIEW-NOTES.md):

```
spool_size = getenv("SPOOLSIZE") ? atoi(...) : 0x800000;   // "Spool size = " printed
mgr  = new(0x38) MissionReviewApplicationManager(ticksPerSecond,
                    (mode != 2) ? 2 : 1, spool_size);
spool_file = <mgr getter, FUN_0044fa14>;
if (spool_file)
    mgr->StartApplication(new(0xd8) BTL4PlaybackApplication(&resources, spool_file));
if (mode == 1)
    mgr->StartApplication(new(0xd8) <camera app, FUN_0047c3fc>(&resources, 1));
```

Class declarations survive: `BTL4PlaybackApplication` (CODE/BT/BT_L4/BTL4PB.HPP),
spooler bricks in CODE/RP/MUNGA_L4/L4SPLR.HPP (`MissionReviewApplicationManager`
referenced there). Their .CPP bodies are not staged, so the branch Fails loudly
instead of linking half a subsystem.

## Deliberate differences from the binary

- `HEAPSIZE` string sits in the pool between ProgName and the banner but is not
  referenced from the decompiled main — it likely belongs to the runtime heap
  init, not this TU. Not reproduced.
- `Register_Object`/`Start_Registering` debug bookkeeping is absent from the
  optimized binary (DEBUG_LEVEL=0 compiles it out), so it is not written here.