Ghidra decompilation environment stood up on Linux (headless, no sudo): JDK 21 +
Ghidra 12.1.2 in ~/tools, reusing the existing analyzed project at
tools/ghidra_project/ from the prior Windows session instead of starting fresh.
FPS-coupling investigation: traced the main game loop's per-frame path and found
the real root cause - compute_frame_delta_ticks_60hz_min1_clamp (0x4092D0) computes
correct delta-time from timeGetTime(), but clamps the minimum return value to 1 tick
even when zero ticks truly elapsed, causing simulation speed to scale with framerate
above 60fps. First patch attempt (NOP the clamp) crashed on level load because the
shared delta value has 203 read sites across 40+ functions and only 2 were checked
for zero-safety; reverted and archived as a documented lesson. The corrected fix
(busy-wait instead of lying) is designed but not yet built.
Pause-loop hang fixed: the pause command handler blocks the Windows message queue
in a tight GetAsyncKeyState polling loop (found while locating the cheat code
handler), which trips modern Windows' "Not Responding" hang detection if left
paused too long, permanently disconnecting input. Patched (HAVOC_NOCD_PAUSEFIX_v1.EXE)
to pump one message per loop iteration via the game's own existing message-drain
function; confirmed fixed by play-testing, including the related "alt-tab while
paused resets to menu" symptom. A separate "alt-tab while not paused" reset symptom
remains open.
New tracking docs: docs/FUNCTIONS.md (function-by-function RE progress),
docs/PATCH_VERSIONS.md (binary patch version log), docs/LEVEL_NOTES.md (level/AI
design quirks for the Remaster variant). Extended docs/PATCHES.md and
docs/METHODOLOGY.md with full discovery narratives including dead ends.
Diagnosed and fixed the crash that killed HAVOC_NOCD.EXE ~1s after launch
(dgVoodoo window appears black, then the process exits). It was not a clean
exit: an ACCESS_VIOLATION (null-pointer read at VA 0x444E6A) during init.
Root cause is a copy-protection check in the WORLDS\ data-file loader
(0x42a480). It opens each file (GRAFIX/LAND/MAP/STUF) from both a local
"WORLDS\<name>" path and a CD-drive path (HAVOC.INI [SETUP] DRIVE=D:\), and
returns a valid stream only when the local open fails and the CD-drive open
succeeds. With files present locally and no D: drive it returned NULL, and the
GRAFIX loader (0x444db0) dereferenced that NULL without checking.
Fix: 14-byte patch at FO 0x29a2b rewrites the return decision to hand back the
successfully-opened local object. The game now boots to the title screen
("HAVOC(tm) by Reality Bytes"), responsive, main loop running.
- docs/PATCHES.md: full patch table (28 patches) + crash write-up
- tools/: RE + patching scripts (r2pipe disasm, minidump parser, ctypes
debugger, PE/IAT/import analysis)
- run_probe.bat / run_and_log.bat: reliable native launch for repro
- .gitignore: exclude CD images, Ghidra install/project, dgVoodoo, *.ini
Diagnosed via WER minidumps (%LOCALAPPDATA%\CrashDumps) parsed in pure Python
(no cdb/windbg available).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01TN4Ytn3gdWRonNmHpisWQv
