evv/gw-basic-2026

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T

Eremey Valetov 0d9f29aa7a Fix DRAW M/S/A bugs, add TA rotation, =variable; substitution, X substring execution

Rewrites gfx_draw() as a recursive draw_engine() to support all DRAW
mini-language features:

Bug fixes:
- M command parsing: skip generic arg parser so M100,50 correctly
  parses both coordinates instead of consuming x as a generic arg
- S (scale) semantics: distance is now (arg ?: 1) * scale / 4, matching
  original GW-BASIC where S4 means 1 pixel per unit, not 4
- A (rotation): implements 90-degree rotation state with direction
  vector transform for all 8 direction commands

New features:
- TA n: arbitrary rotation angle (-360 to 360 degrees) via cos/sin
- =variable;: numeric variable substitution in DRAW strings
- X stringvar;: execute substring from string variable (recursive)
- Scale factor applied to relative M coordinates

2026-03-21 02:48:17 -04:00

2.7 KiB

Raw Blame History

Roadmap

The Big One

GW-BASIC 2026 Compiler — ahead-of-time compilation of BASIC programs to native executables. Because nothing says "premature optimization" like compiling a language designed for an interpreter running on a 4.77 MHz 8088. But we've come this far, so why not? Likely approach: translate the token stream to C and lean on GCC/Clang for the heavy lifting.

Next Up

Hardware I/O Simulator

An optional emulation layer for OUT, INP, WAIT, MOTOR, and friends, following the established virmem.c dispatch-by-address pattern.

New module: portio.c / portio.h with portio_inp(port) / portio_out(port, value) dispatch.

Priority ports:

Port	Device	Emulation
0x42–0x43	8253 PIT channel 2	Speaker frequency divisor (1193180 / divisor Hz)
0x61	PPI Port B	Speaker on/off (bits 0–1), routes to `snd_start_continuous()` / `snd_stop_continuous()`
0x3D8	CGA mode control	Mode register storage, feeds `gfx_init()`
0x3D9	CGA color select	Palette/background bits, feeds `gfx_palette_set()`
0x201	Game port	Joystick stub (returns 0xF0 = no buttons)
0x3F8–0x3FE	COM1 serial	Minimal stub (LSR reports transmitter ready to prevent spin loops)
Default	—	Reads return 0xFF (floating bus), writes silently discarded

Statement/function changes:

OUT port, value → portio_out(port, value)
WAIT port, mask [, xor_mask] → busy loop with portio_inp(), break check, timeout
MOTOR → accept and silently ignore
INP(port) → portio_inp(port) (currently returns 0)
STICK(n) / STRIG(n) → joystick state from port 0x201

IDE and Notebook Integration

Jupyter kernel for GW-BASIC — a Jupyter Notebook kernel that runs GW-BASIC programs cell-by-cell, with rich output for PRINT, inline graphics rendering for drawing commands, and interactive INPUT via notebook widgets. Similar in spirit to foxkernel.
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

String garbage collection not implemented (uses malloc/free instead)
Maximum 256 variables, 64 arrays, 16 FOR nesting, 24 GOSUB nesting, 16 WHILE nesting

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