gba/examples/hello.rs

108 lines
2.7 KiB
Rust

#![no_std]
#![no_main]
use core::fmt::Write;
use gba::{
mgba::{MgbaBufferedLogger, MgbaMessageLevel},
prelude::*,
};
#[panic_handler]
fn panic_handler(info: &core::panic::PanicInfo) -> ! {
if let Ok(mut logger) = MgbaBufferedLogger::try_new(MgbaMessageLevel::Fatal) {
write!(logger, "{info}").ok();
}
loop {}
}
#[link_section = ".ewram"]
static FRAME_KEYS: GbaCell<KeyInput> = GbaCell::new(KeyInput::new());
#[link_section = ".iwram"]
extern "C" fn irq_handler(_: IrqBits) {
// We'll read the keys during vblank and store it for later.
FRAME_KEYS.write(KEYINPUT.read());
}
const TILE_LAYOUT: [u32; 512] = {
// Rust's const eval is limited at the moment, but with a bit of careful math
// we can set up `u32` values that store the right data. Tile maps are 32x32
// `u16` values, so when packing it as `u32` instead we have to throw in some
// `/2` stuff in a few places. Seperately, the tiles that we're using come
// from an image that was drawn as a 16 by 16 tile sheet, so most of the
// layout's area will be left as zero. Thankfully, tile index 0 is a blank
// tile in this tileset, so it all works out.
let mut data = [0; 512];
let mut r = 0;
while r < 16 {
let mut c = 0;
while c < 16 {
let index = r * (32 / 2) + (c / 2);
let a = r * 16 + c;
let b = r * 16 + c + 1;
data[index] = (a as u32) | ((b as u32) << 16);
//
c += 2;
}
//
r += 1;
}
data
};
#[no_mangle]
extern "C" fn main() -> ! {
RUST_IRQ_HANDLER.write(Some(irq_handler));
DISPSTAT.write(DisplayStatus::new().with_irq_vblank(true));
IE.write(IrqBits::VBLANK);
IME.write(true);
if let Ok(mut logger) = MgbaBufferedLogger::try_new(MgbaMessageLevel::Debug) {
writeln!(logger, "hello!").ok();
}
{
// get our tile data into memory.
Cga8x8Thick.bitunpack_to_4bpp(CHARBLOCK0_4BPP, 0);
}
{
// get the the tilemap copied into place
let tsb = TextScreenblock::new(31);
tsb.write_words(&TILE_LAYOUT);
}
{
// Set BG0 to use the tilemap we just made, and set it to be shown.
BG0CNT.write(BackgroundControl::new().with_screenblock(31));
DISPCNT.write(DisplayControl::new().with_show_bg0(true));
}
let mut x_off = 0_u32;
let mut y_off = 0_u32;
let mut backdrop_color = Color(0);
loop {
VBlankIntrWait();
// show current frame
BACKDROP_COLOR.write(backdrop_color);
BG0HOFS.write(x_off as u16);
BG0VOFS.write(y_off as u16);
// prep next frame
let k = FRAME_KEYS.read();
backdrop_color = Color(k.to_u16());
if k.up() {
y_off = y_off.wrapping_add(1);
}
if k.down() {
y_off = y_off.wrapping_sub(1);
}
if k.left() {
x_off = x_off.wrapping_add(1);
}
if k.right() {
x_off = x_off.wrapping_sub(1);
}
}
}