# TP3-comp

Recreating **Turbo Pascal 3.0** (shell, editor, compiler, interpreter) in
**GNU Modula-2** (`-fiso`). Faithful to the original: the screen layout, keys
and behaviours are reconstructed from the disassembled TP3.0 source
(`Resources/`) and the reference manual.

## Status

| Milestone | Tag | Status |
|---|---|---|
| Main-menu shell | `v0.1-shell` | done |
| WordStar-style editor | `v0.2-editor` | done |
| Shell/editor polish (Ctrl-K-D quit) | `v-TP3-SHELL-EDITOR-QUIT` | done |
| Compiler skeleton + two-phase build | `v-TP3-SHELL-COMPILES` | done |
| Parser `Skip` bug class (9 sites) | `v-TP3-PARSER-FIXES` | done |
| Standard procedures + `rel16` fix | `v-TP3-STDPROCS` | done |
| Runtime blob, linker, `CmdRun` interpreter | — | **not started** |

Current state: `tpshell` builds clean (120792 bytes); the compiler front end
parses and emits 8086 for 17 of 23 fixtures, verified by hex-dumping the
image. **No compiled program has been executed yet** — `CmdRun` is a stub and
the runtime blob does not exist. See `SUMMARY.md` for the verified detail.

## Build

Requires GNU Modula-2 (`gm2`, tested with 16.0.1) and a C compiler for the
`FOR "C"` bridge.

```sh
cd shell
make
./tpshell
```

The shell runs in raw mode: it needs a real ANSI terminal, no wrappers.

## Layout

- `shell/Term.def|mod` — raw termios keyboard + ANSI screen primitives
  (blocking `GetCh`, non-blocking `Avail`/`GetKey` via `poll`, `GotoXY`,
  highlight `Marked`/`Normal`, `Beep`).
- `shell/Posix.def|Posix.c` — `DEFINITION MODULE FOR "C"` bridge to libc:
  read/write/open/close/unlink/rename/getcwd/chdir/opendir/readdir/closedir/
  statvfs/poll and termios (`tcgetattr`/`tcsetattr`/`cfmakeraw`).
- `shell/TextBuf.def|mod` — the shared TP3-style text buffer: a 62903-char
  array, lines terminated by CR. Text is kept in memory so the editor and the
  shell's S (save) operate on the same buffer.
- `shell/Editor.def|mod` — WordStar-style full-screen editor.
- `shell/Shell.mod` — TP3.0 main-menu dispatcher (`kmenu`/`kcmdtab`),
  work-file load/save with `.BAK` rotation, directory listing, options menu.
- `shell/Makefile` — see notes below.
- `SUMMARY.md` — state summary and reflection notes per milestone.
- `RESUME-TP3.md` — book-derived reference for the 8086 code the TP3 compiler
  generates (source of the compiler phase).
- `Resources/` — OCR of "Au coeur de Turbo Pascal", TP3.0 manual and the
  disassembled TPSRC1-10.

## Shell (TP3.0 main menu)

Exact TP3.0 screen: `Logged drive`, `Active directory`, `Work file`,
`Main file`, `Edit Compile Run Save` / `Dir Quit compiler Options`,
`Text: n bytes`, `Free: n bytes`, `>` prompt. Command letters are drawn bold
(TP3 uses high-bit characters).

| Key | Action |
|---|---|
| `L` | new drive / directory |
| `A` | new active directory |
| `W` | set work file (auto-`.PAS`), `Loading`/`New File` |
| `M` | set main file |
| `E` | edit work file |
| `C` | compile (wired: TP3 error report + editor jumps to the error) |
| `R` | run — **stub**, prints "Interpreter pending" |
| `S` | save with `^Z` EOF; old version → `.BAK` |
| `D` | directory listing, DOS `*.*` mask, `k bytes free` |
| `O` | options submenu (compile target, Code/Data/Stack, params) |
| `Q` | quit (prompts to save when text changed) |

Any other key redraws the menu, like TP3.

## Editor

WordStar-style full-screen editing over `TextBuf`. Status line:
`Line n       Col n     Insert/Overwrite      Indent   X:FILENAME`.
Text rows are screen rows 2–24; row 1 carries status/prompt/messages.

Highlights:

- Movement — ^S/^D/^E/^X/^A/^F/^R/^C/^W/^Z and ^Q S/D/E/X/R/C/B/K/P,
  arrow keys / PgUp / PgDn / Home / End (ANSI escape sequences).
- Editing — insert/overwrite (^V), ^G delete char, backspace joins lines,
  ^T word, ^Y line, ^Q-Y to end of line, ^N / CR line break, TAB auto-indent
  to word start on the line above.
- Block — ^K B/K mark, ^K T word, ^K H show/hide, ^K C/V/Y copy/move/delete,
  ^K R/W read/write block to/from a file.
- Search — ^Q-F find, ^Q-A replace, ^L repeat last; options B/G/n/U/W, and
  N (no-confirm) for replace; ^A matches any char, CR LF searches a line break.
- ^P prefix inserts a literal control character; ^U / ESC abort prompts.
- ^K-D returns to the shell; the text stays in memory, `changed` is reported
  and S (or the quit prompt) writes it to disk.

Disk format matches TP3: CRLF line endings and a trailing `^Z`; load
normalizes CRLF/LF, save re-expands.

## Porting notes (gm2)

- Foreign modules (`DEFINITION MODULE FOR "C"`) must use `ADDRESS`, not
  Modula-2 record/pointer types — cast at the call site.
- gm2 ICEs on `FOR ... EXIT`; use `WHILE`+flag (or `LOOP`+`EXIT`).
- gm2 only emits `main` when the program module source is on the link line:
  `gm2 -fiso -o tpshell Shell.mod Term.o Posix.o TextBuf.o Editor.o`.
- termios is used in raw mode, so every newline is explicit `CR LF`.
- `EXIT` is only legal inside `LOOP` (ISO Modula-2), not `WHILE`.