# Roadmap

## Completed

### Ahead-of-Time Compiler (v0.16.0)

`gwbasic-compile` translates tokenized .bas programs to C source, then
invokes GCC to produce native executables linked against `libgwrt.a`.

Pipeline: `.bas` → `gw_crunch()` → analysis pass → C codegen → `gcc` → native binary.

**Phase 1**: PRINT, LET, IF/THEN/ELSE, GOTO, GOSUB/RETURN,
FOR/NEXT, END/STOP/SYSTEM, REM, DATA/READ/RESTORE, CLS, arithmetic,
string functions, core math functions.

**Phase 2** (current): WHILE/WEND, ON GOTO/GOSUB, ON ERROR GOTO,
MOD/IDIV/POW operators (buffered left operand for proper casting),
SWAP, POKE, DEF SEG, RANDOMIZE, LOCATE, COLOR, SCREEN, WIDTH, KEY,
WRITE, OPTION BASE, DEF type statements, extended statement dispatch.
DIM/array subscript access (gwrt_array_elem runtime), number formatting
via gw_print_value() with expression type tracking, combined relational
operators (<=, >=, <>), PRINT USING (token embedding with variable sync),
STRING$/INSTR single-byte token support, PRINT USING (token embedding
with variable sync), RESUME, ERROR, ON TIMER/KEY skip, MID$ assign skip,
FOR scope fix (static limit/step), SWAP with array elements, ENVIRON$/
DATE$/TIME$/ENVIRON$ expression support, RESUME/ERROR statements,
DEF FN (token embedding + variable sync), DEFINT/DEFSNG/DEFDBL/DEFSTR
(pre-scan in analysis), gw_cint() rounding for integer assignment,
STRING$(n,"c") string arg handling, READ into arrays, array assignment
self-reference fix, PRINT USING colon-in-string. **Zero compile errors**
— all 72 programs compile. **46 produce correct output (64%).** String
concatenation (A$+B$), READ into arrays, self-referencing array assignment
fix, float division semantics, PRINT USING null-byte token fix,
string comparison (strcmp), ON ERROR GOTO (setjmp), graphics/sound
delegation to runtime via token embedding, CVI/MKI$/CVS/MKS$/CVD/MKD$,
MID$ assignment delegation, ON ERROR GOTO with setjmp/gw_run_jmp,
RESUME/RESUME NEXT, ERR/ERL, file I/O delegation (OPEN/CLOSE/PRINT#/
INPUT#/WRITE#/LINE INPUT via emit_delegate_stmt), PMAP/POINT/PSET
graphics, BSAVE/BLOAD/SAVE/LOAD, MKDIR/CHDIR/RMDIR/KILL file ops.
**67 of 72 tests produce correct output (93%).** CHAIN/COMMON/RUN "file"
delegated to runtime interpreter. Only 2 failures remain (RNG-dependent).

### Hardware I/O Simulator (v0.15.0)

Implemented in `portio.c` / `portio.h` following the `virmem.c` dispatch
pattern.  Emulates 8253 PIT channel 2 (speaker frequency), PPI port B
(speaker on/off with continuous tone via PulseAudio), CGA mode/color
registers, game port (joystick stub), and COM1 serial (transmitter-ready
stub).  Default: reads return 0xFF (floating bus), writes discarded.

Statements: `OUT`, `WAIT`, `MOTOR`.  Functions: `INP()`, `STICK()`, `STRIG()`.

Also in v0.15.0: filled remaining statement/function gaps — `RESET`,
`ENVIRON`/`ENVIRON$`, `ERDEV`/`ERDEV$`, `IOCTL`/`IOCTL$`, `LCOPY`,
`DATE$`/`TIME$` assignment, `CALL`/`CALLS`, `COM`.  All 144 defined
tokens are now handled (100% token coverage).

String space pool with compacting garbage collector (`strpool.c`),
replacing individual `malloc`/`free`.  32KB default pool, bump-pointer
allocation, compaction at statement boundaries.  `FRE()` returns actual
free space; `CLEAR n` resizes the pool.

### Jupyter Kernel (v0.15.0)

`gwbasickernel/` — Jupyter notebook kernel using the persistent subprocess
model.  GW-BASIC reads BASIC from stdin in piped mode (no banner, no prompts,
unbuffered stdout).  Sentinel protocol (`PRINT "<<<GWDONE>>>"`) delimits
output per cell.  State persists across cells.

- **Inline Sixel graphics** — `SCREEN 1`/`SCREEN 2` drawing commands render
  as inline PNG images in the notebook.  Pure-Python Sixel decoder (no PIL
  or Ghostscript dependency).
- **INPUT statement support** — when a program executes `INPUT`, the kernel
  requests input from the notebook front-end via the Jupyter stdin protocol.
- **Pygments syntax highlighting** — GW-BASIC lexer registered as a Pygments
  entry point for code cell highlighting.
- **Tab completion** for all GW-BASIC keywords.
- **Magic commands**: `%reset`, `%timeout`, `%new`.

Install: `pip install -e . && gwbasickernel-install --user`

## Next Up

### IDE Integration
- **JetBrains plugin (IntelliJ/CLion)** — full-featured language plugin with
  syntax highlighting, code completion, line number navigation, run
  configurations, debugger integration (breakpoints via `STOP`, variable
  inspection), structure view (line number outline), and error annotations.
- **VS Code extension** — language extension providing syntax highlighting
  (TextMate grammar), snippets, run/debug tasks, integrated terminal runner,
  and Language Server Protocol support for diagnostics and hover info.

## Known Limitations

- Maximum 256 variables, 64 arrays, 16 FOR nesting, 24 GOSUB nesting,
  16 WHILE nesting
- `CALL`/`CALLS` (machine code execution) raises Illegal function call
- `DATE$`/`TIME$` assignment accepted but does not modify the system clock
- Device stubs (`ERDEV`, `IOCTL`, `COM`, `LCOPY`) return defaults — no real
  device emulation