# DVX Loader

Bootstrap loader for the DVX desktop environment.  Builds as
`dvx.exe` -- the only native executable in the system.  Everything
else is a dynamically loaded DXE module.


## What It Does

1. Changes to the executable's directory so relative paths resolve
2. Calls `platformRegisterDxeExports()` to register platform functions
   and C runtime symbols (libc, libm, libgcc, DJGPP internals) with
   the DXE3 loader via `dlregsym()`
3. Recursively scans `LIBS/` for `*.lib` modules and `WIDGETS/` for
   `*.wgt` modules
4. Reads `.dep` files to build a dependency graph
5. Topologically sorts all modules and loads them in order with
   `RTLD_GLOBAL` (each module's exports become available to
   subsequent modules)
6. Calls `wgtRegister()` on any module that exports it (widget
   registration)
7. Finds `shellMain()` across all loaded modules and calls it
8. On return, closes all modules in reverse order


## Files

| File | Purpose |
|------|---------|
| `loaderMain.c` | Entry point, directory scanning, dependency resolution, module loading |
| `Makefile` | Cross-compilation rules; links `dvxPlatformDos.c` directly |

The DXE export table lives in `core/platform/dvxPlatformDos.c`, not
in the loader.  The loader is platform-agnostic -- all DJGPP/DXE3
knowledge is in the platform layer.


## Dependency Resolution

Each module may have a `.dep` file alongside it (same base name,
`.dep` extension).  The file lists base names of modules that must
be loaded first, one per line.  Lines starting with `#` are comments.

Example -- `dvxshell.dep`:
```
libtasks
libdvx
box
button
label
listview
```

A dependency is satisfied when either:
- A module with that base name has been loaded, or
- No module with that base name exists in the scan (external, assumed OK)

The loader iterates until all modules are loaded or no further
progress can be made (circular dependency).  Unloadable modules are
reported to stderr.


## Building

```
make        # builds ../bin/dvx.exe
make clean
```

The Makefile compiles `loaderMain.c` and links it with
`dvxPlatformDos.o` (compiled from `../core/platform/dvxPlatformDos.c`)
and `-lm`.  The result goes through `exe2coff` + `CWSDSTUB` to
produce a DOS executable.