How the game talks to Windows

The decompiled code calls the Win32 API directly, in a small number of places. This chapter lists them; they are also exactly what miniwin has to implement for the port.

The window (platform.cpp)

• One window. createMainWindow registers a window class named after the program's own file name (that is also how a second instance finds the first with FindWindow) and creates a borderless popup covering the whole screen, shown maximised. The game's 640×480 area is centred on larger screens (placeGamePort, alignRect; gameRect/shownGameRect).
• mainWindowProc (0x45605e) handles: WM_CHAR/WM_KEYDOWN and WM_L/R/MBUTTONDOWN (turned into game events), WM_SETCURSOR, WM_ACTIVATEAPP/WM_NCACTIVATE/WM_SETFOCUS/WM_KILLFOCUS (activateApp), WM_SYSCOMMAND (screen savers and minimising are blocked or handled), WM_PALETTECHANGED/WM_QUERYNEWPALETTE (realizeFullScreenPalette), WM_PAINT (through paintHook), and WM_CLOSE/WM_DESTROY/WM_QUIT/WM_ENDSESSION (a fatal "error" that quits). While a movie is showing, QuickTime's component manager sees each message first. Messages are also logged to a ring of 1,024 (logMessage) and dumped to msgNNN.txt on request (dumpMessages).
• The message pump is the game's own: PeekMessage/GetMessage in pumpMessage, handleNextMessage, waitWhilePaused, called from the main loop and from every blocking wait. There is no GetMessage loop in WinMain.
• Activation. Deactivating (Alt-Tab) shuts down the screen port and the sound driver, and in some setups minimises the window; reactivating rebuilds them (activateApp, gameActivated), asking to retry while the sound device is missing.
• Display modes. checkDisplayMode asks for 640×480 at 256 colours (falling back to 512×384, or another depth) and setDisplayMode switches. The game requires a palettised mode. canUseDisplayMode/getDisplayMode in the engine use Windows 95's 0x94-byte DEVMODE.

Graphics (GDI)

All drawing goes through the engine's ports (see Graphics), which wrap GDI:

The game draws every scene off screen into workPort and copies changed regions to screenPort; e2MapSave saves screen areas for restoring. Palettes: the game builds its own 256-colour logical palette so that realising it is the identity, animates PC_RESERVED entries in place for fades and colour cycling (fadeInViews, cycleColors), and brightens colours made for the Mac's lighter gamma (brightenPalette: c + 31 - c/8). A 20-colour static-colours question (does the system keep them?) decides whether 236 or 255 colours are realised.

Sound and music (WINMM, DirectSound)

• Wave sounds go through WaveMix-style objects: either straight to waveOut (wmxWaveOut) or mixed in software (wmxMixer) into one output buffer per device, written through waveOut (wavebufWO, a polling thread) or a looping one-second DirectSound buffer (wavebufDS, when [WaveMix] fEnableDirectSound is on and DSOUND.DLL loads). Long sounds stream from their file in 4 KB buffers.
• Music is MIDI. The engine sequences it itself (midisound.cpp: tempo, loop and Setup end markers, program changes) and sends channel messages to midiOut as they fall due, through a MIDI map (MIDIMAP.DAT, controller resets for all 16 channels) that adapts to the device. The device list comes from the registry's Sound Mapper (Software\Microsoft\Multimedia\Sound Mapper) or MOHAWK.INI's [Audio] section.
• Timers are multimedia timers (timeSetEvent at the finest resolution, timeBeginPeriod); their callbacks only post to a DeferLock, so procedures run on a thread that holds or releases it. timeGetTime is the clock.

Files and the CD

fileSpec/files model Mac FSSpecs over Win32. Reads that could block (the CD) go through an asyncAPI family with a worker thread above normal priority; the port runs that on its cooperative scheduler. The game finds its data through Zoombi32.CFG and asks for the CD if Data\Zoombini.mhk is missing. Drive::setLocked locks and unlocks removable media through VWIN32's DOS IOCTL 440Dh/0848h, whose 2-byte parameter block has to be a 2-byte local (a 1-byte one overwrote the saved frame pointer). MOHAWK.W32 (installed beside the program; mohawk.w32 in assets/zoombi32/installed/) is the INI that configures the engine.

Memory

The engine's Mac-style memory manager sits on GlobalAlloc/GlobalLock (moveable blocks whose first word Win32 makes point at the memory, which the engine relies on). Startup checks virtual memory and, on anything newer than Windows 3.11, total physical memory (6 MB, via GlobalMemoryStatus). The game installs a grow-zone procedure that notes an out-of-memory condition.

Threads and fibers

The Mohawk OS layer runs its own cooperative threads on the one Win32 thread, each on a Win32 fiber it finds in KERNEL32 at run time (Borland C++ 4.5's headers predate them; Windows 98 and NT 4 have them, Windows 95 doesn't). Its scheduler runs on calls into the layer and every 20 ms, picks the highest-priority runnable thread, and pumps messages while idle. Real threads exist only where Windows forces them: waveOut callbacks, multimedia timers, the preload thread. See OS layer.

Run-time loaded libraries

The movie's video codec qb32.qtc is loaded by QuickTime, not by the game.

Global atom

The atom Zoombini is the single-instance lock: added at startup, deleted once graphics are up and at exit.