WaffleBears/ZigBoy

ZigBoy

A Game Boy, Game Boy Color, and Game Boy Advance emulator for Windows, written in Zig.

Features

Game Boy (GB), Game Boy Color (GBC), and Game Boy Advance (GBA) support
Auto-detects ROM type by extension or header magic
10 save state slots per ROM
Battery save support (.sav written next to the ROM)
5 selectable DMG palette presets (Classic Green, Grayscale, Autumn, Ocean Blue, Pocket)
Volume control with smooth fade transitions
Drag-and-drop ROM loading
Fullscreen toggle, screenshot capture (PNG)
Aspect-ratio-preserving and integer-only scaling modes
Smooth and pixel-perfect texture filtering
Pause, reset, mute, turbo (4×, hold Tab)
Configurable settings panel (in-app, no config file required)

Controls

Key	Action
Arrow keys	D-pad
Z / X	A / B
A / S	L / R (GBA)
Enter	Start
Right Shift / Backspace	Select
Tab (hold)	Turbo (4×)
F1 or F5	Save state
F3 or F7	Load state
`[` / `]`	Previous / next state slot
- / =	Volume down / up
P	Pause
R	Reset
M	Mute
F11	Toggle fullscreen
F12	Take screenshot
Ctrl+O	Open ROM
Esc	Close menu

Usage

Run the executable and pick a ROM from the file dialog, drag a .gb, .gbc, or .gba file onto the window, or pass the ROM path on the command line:

ZigBoy.exe path\to\game.gba

Battery saves: <rom>.sav written next to the ROM on exit and on ROM switch.
Save state slot 0: <rom>.state. Slots 1-9: <rom>.state1 … <rom>.state9.
Screenshots: <rom>_NNNN.png next to the working directory, auto-numbered.

Building

Requires Zig 0.16.0 or newer.

zig build                       # ReleaseFast (default)
zig build -Doptimize=Debug      # debug build with console
zig build run -- path\to\game.gba

raylib is fetched automatically via build.zig.zon. The build targets Windows by default and links against user32, gdi32, winmm, comdlg32, shell32, ole32, kernel32, dwmapi, and opengl32.

Project Layout

src/
  main.zig          Entry point, main loop, mouse/click dispatch
  app.zig           App struct, types, ROM/state/input handlers
  draw.zig          UI rendering (toolbar, status bar, modals, placeholder)
  audio.zig         Audio stream pump with smooth gain transitions
  platform.zig      Windows file I/O and Open ROM dialog
  system.zig        GB/GBA backend dispatcher
  gb/               Game Boy / Color emulator core
    cpu.zig         SM83 CPU
    mmu.zig         Memory map and bus
    ppu.zig         Pixel processor (DMG and CGB)
    apu.zig         Audio processor
    cart.zig        Cartridge and MBC1/2/3/5 + RTC
    timer.zig       DIV/TIMA timer
    joypad.zig      Input
    savestate.zig   State serialization
    gb.zig          Top-level glue and frame stepping
  gba/              Game Boy Advance emulator core
    arm.zig         ARM7TDMI CPU (ARM and THUMB)
    bus.zig         Memory map, mirrors, wait states
    ppu.zig         PPU (modes 0-5, BG, OBJ, blending, mosaic, windows)
    apu.zig         APU (DMG channels + DirectSound A/B)
    cart.zig        ROM, EEPROM/Flash/SRAM, RTC
    bios.zig        BIOS HLE (SWI handlers, decompression)
    dma.zig         4-channel DMA
    timer.zig       4 timers with cascade
    irq.zig         Interrupt definitions
    gba.zig         Top-level glue and frame stepping

README