Crate gb

Expand description

gb: Game Boy hardware abstractions.

§Feature flags

bank — Enable ROM banking: the gb::bank module and the #[gb::bank] attribute.

A banked build needs a cartridge controller, but the code compiles without one, so a crate can carry banked code that a 32 KiB program still links.
pak — Enable the Game Pak’s own hardware: gb::pak.

Which peripherals a cartridge actually has comes from header.toml.
cgb — Enable Game Boy Color hardware features.
cgb-double-speed — Run in CGB double speed mode.

The processor and the timer run twice as fast, while the screen and sound carry on as they were. A cartridge built with this is a Color-only one.
critical-section-impl — Register an implementation of the critical-section crate.

IME is write-only, so the implementation tracks every interrupt state change in a mirror variable, which costs a store in each gb::interrupt call and at the entry and exit of every handler. Turn it on only to link a driver that requires it; in your own code use free or the token a handler is already handed.

apu: The four sound channels and the mixer.
bankbank: Compile-time-safe ROM bank switching for the Game Boy.
hram: Typed handles to the Game Boy’s High RAM (HRAM, 0xFF80..=0xFFFE).
interrupt: Interrupt control: the IME master switch and the IE / IF masks.
ircgb: The Game Boy Color’s infrared port.
joypad: The eight buttons.
mmio: Typed, volatile handles to the Game Boy’s hardware registers and memory.
pakpak: The Game Pak’s own hardware.
ppu: The pixel-processing unit, which draws the screen.
ram_fn: Functions whose machine code can be copied into RAM (or HRAM) and run there.
rt: Core Game Boy (SM83) runtime.
serial: Byte exchange over the link cable.
timer: The timer and the free-running divider.

hram: Declare static HRAM cells and areas, each at a linker-assigned High RAM address.

is_cgb: Whether the machine has the Game Boy Color’s hardware.
is_gba: Whether the machine is a Game Boy Advance running a Game Boy Color cartridge.