cordle/DOS_BUILD.md

# Building Cordle for DOS

Cordle is fully compatible with DOS systems using either DJGPP or Borland C compilers. The code is strictly C90 compliant and includes platform-specific conditional compilation.

## Platform Support

### Tested Environments
- **MS-DOS 6.22**
- **FreeDOS 1.3**
- **DOSBox** (with DJGPP)
- **DOSBox-X**

### Compiler Options

#### Option 1: DJGPP (Recommended)
DJGPP is a complete 32-bit C/C++ development system for DOS, based on GCC.

**Requirements:**
- DJGPP 2.05 or later
- PDCurses library (DOS port)
- GNU Make
- Minimum 2MB RAM

**Installation:**
1. Download DJGPP from http://www.delorie.com/djgpp/
2. Required packages:
   - `djdev205.zip` (DJGPP development kit)
   - `gcc930b.zip` (GNU C Compiler)
   - `bnu234b.zip` (GNU Binutils)
   - `mak43b.zip` (GNU Make)

3. Extract all to `C:\DJGPP`

4. Set environment variables in `AUTOEXEC.BAT`:
   ```
   SET DJGPP=C:\DJGPP\DJGPP.ENV
   SET PATH=C:\DJGPP\BIN;%PATH%
   ```

**Building PDCurses:**
1. Download PDCurses from https://pdcurses.org/
2. Extract and build:
   ```
   cd pdcurses\dos
   make -f Makefile.dj
   ```
3. Install:
   ```
   copy pdcurses.a C:\DJGPP\LIB\libpdcurses.a
   copy curses.h C:\DJGPP\INCLUDE\
   copy panel.h C:\DJGPP\INCLUDE\
   ```

**Building Cordle:**
```
cd \CORDLE
make
```

This creates `CORDLE.EXE` in the `build` directory.

#### Option 2: Borland C/C++ 3.1 or Turbo C++

**Requirements:**
- Borland C/C++ 3.1 or later
- PDCurses for DOS
- Minimum 640KB RAM

**Manual Build:**
```
bcc -mc -IC:\BC\INCLUDE -LC:\BC\LIB -std=c90 src\main.c src\game.c src\ui.c src\words.c -lpdcurses -ocordle.exe
```

Note: Borland uses slightly different command-line syntax. Adjust paths as needed.

## File Paths in DOS Build

The DOS version automatically detects the platform and uses DOS-appropriate paths:

**DOS Search Order:**
1. `wordlists\` (relative to executable - for development)
2. `C:\CORDLE\wordlists\` (system installation)
3. Custom path via `--wordlist` argument

**Unix Search Order:**
1. `wordlists/` (relative to executable)
2. `/usr/local/share/cordle/wordlists/`
3. `$HOME/.local/share/cordle/wordlists/`
4. Custom path via `--wordlist` argument

## Installation on DOS

### Directory Structure
```
C:\CORDLE\
  ├── CORDLE.EXE
  └── wordlists\
      ├── CORDLE_WORDS_EASY.TXT
      ├── CORDLE_WORDS_MEDIUM.TXT
      ├── CORDLE_WORDS_HARD.TXT
      └── ...
```

### Quick Install
1. Create directory: `mkdir C:\CORDLE`
2. Copy `CORDLE.EXE` to `C:\CORDLE`
3. Copy `wordlists` directory to `C:\CORDLE`
4. Add to PATH in `AUTOEXEC.BAT`:
   ```
   SET PATH=C:\CORDLE;%PATH%
   ```

## Running on DOS

```
C:\> cordle
C:\> cordle --easy
C:\> cordle --medium
C:\> cordle --hard
C:\> cordle --help
```

## Memory Requirements

- **Minimum:** 2MB RAM (DJGPP), 640KB (Borland)
- **Recommended:** 4MB RAM
- **Display:** VGA compatible (for colors)
- **DOS Version:** 5.0 or higher

## Troubleshooting

### "Out of memory" Error
- Increase DOS memory limit
- Use CWSDPMI.EXE memory extender (included with DJGPP)
- Free up conventional memory by unloading TSRs

### "libpdcurses.a not found"
- Verify PDCurses installation
- Check library path: `C:\DJGPP\LIB\`

### "curses.h not found"
- Copy `curses.h` to `C:\DJGPP\INCLUDE\`

### Colors Not Working
- Ensure VGA-compatible display
- Try running in DOSBox with `machine=svga_s3`

### Arrow Keys Crash (Fixed in v1.1)
- Arrow keys are now properly handled and ignored
- Update to latest version if experiencing issues

## Testing in DOSBox

A DOSBox configuration is included in the `dosbox/` directory:

```
dosbox -conf dosbox/dosbox_config_cordle.ini
```

## Platform Detection

The code automatically detects DOS vs Unix at compile time:

```c
#if defined(__MSDOS__) || defined(_MSDOS) || defined(__DOS__) || defined(MSDOS)
    /* DOS-specific code */
#else
    /* Unix-specific code */
#endif
```

## Differences from Unix Version

1. **Curses Library:** PDCurses instead of ncurses
2. **Path Separators:** Backslash (`\`) instead of forward slash (`/`)
3. **File Paths:** DOS-style paths (`C:\CORDLE\wordlists\`)
4. **Executable:** `.exe` extension
5. **No HOME Environment:** Uses fixed system path instead

## Source Code Portability

The code is 100% C90 compliant with:
- No C99/C11 features
- No GNU extensions
- Conditional compilation for platform differences
- Standard library only (stdio, stdlib, string, time, ctype)
- Platform-specific curses handling

## For Modern Development

For testing DOS builds on modern systems:
1. Use DOSBox-X (more accurate DOS emulation)
2. Install DJGPP within DOSBox
3. Use cross-compilation from Linux/macOS (advanced)

## License Note

Ensure PDCurses license compatibility with your distribution. PDCurses is public domain.

---

For Unix/Linux/macOS build instructions, see the main README.md.