gba/examples/light_cycle.rs

162 lines
4.1 KiB
Rust

#![feature(start)]
#![no_std]
#[cfg(not(test))]
#[panic_handler]
fn panic(_info: &core::panic::PanicInfo) -> ! {
loop {}
}
#[start]
fn main(_argc: isize, _argv: *const *const u8) -> isize {
unsafe {
DISPCNT.write_volatile(MODE3 | BG2);
}
let mut px = SCREEN_WIDTH / 2;
let mut py = SCREEN_HEIGHT / 2;
let mut color = rgb16(31, 0, 0);
loop {
// read the input for this frame
let this_frame_keys = read_key_input();
// adjust game state and wait for vblank
px += 2 * this_frame_keys.column_direction() as isize;
py += 2 * this_frame_keys.row_direction() as isize;
wait_until_vblank();
// draw the new game and wait until the next frame starts.
unsafe {
if px < 0 || py < 0 || px == SCREEN_WIDTH || py == SCREEN_HEIGHT {
// out of bounds, reset the screen and position.
mode3_clear_screen(0);
color = color.rotate_left(5);
px = SCREEN_WIDTH / 2;
py = SCREEN_HEIGHT / 2;
} else {
let color_here = mode3_read_pixel(px, py);
if color_here != 0 {
// crashed into our own line, reset the screen
mode3_clear_screen(0);
color = color.rotate_left(5);
} else {
// draw the new part of the line
mode3_draw_pixel(px, py, color);
mode3_draw_pixel(px, py + 1, color);
mode3_draw_pixel(px + 1, py, color);
mode3_draw_pixel(px + 1, py + 1, color);
}
}
}
wait_until_vdraw();
}
}
pub const DISPCNT: *mut u16 = 0x04000000 as *mut u16;
pub const MODE3: u16 = 3;
pub const BG2: u16 = 0b100_0000_0000;
pub const VRAM: usize = 0x06000000;
pub const SCREEN_WIDTH: isize = 240;
pub const SCREEN_HEIGHT: isize = 160;
pub const fn rgb16(red: u16, green: u16, blue: u16) -> u16 {
blue << 10 | green << 5 | red
}
pub unsafe fn mode3_clear_screen(color: u16) {
let color = color as u32;
let bulk_color = color << 16 | color;
let mut ptr = VRAM as *mut u32;
for _ in 0..SCREEN_HEIGHT {
for _ in 0..(SCREEN_WIDTH / 2) {
ptr.write_volatile(bulk_color);
ptr = ptr.offset(1);
}
}
}
pub unsafe fn mode3_draw_pixel(col: isize, row: isize, color: u16) {
(VRAM as *mut u16).offset(col + row * SCREEN_WIDTH).write_volatile(color);
}
pub unsafe fn mode3_read_pixel(col: isize, row: isize) -> u16 {
(VRAM as *mut u16).offset(col + row * SCREEN_WIDTH).read_volatile()
}
pub const KEYINPUT: *mut u16 = 0x400_0130 as *mut u16;
/// A newtype over the key input state of the GBA.
#[derive(Debug, Clone, Copy, Default, PartialEq, Eq)]
#[repr(transparent)]
pub struct KeyInputSetting(u16);
/// A "tribool" value helps us interpret the arrow pad.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
#[repr(i32)]
pub enum TriBool {
Minus = -1,
Neutral = 0,
Plus = 1,
}
pub fn read_key_input() -> KeyInputSetting {
unsafe { KeyInputSetting(KEYINPUT.read_volatile() ^ 0b1111_1111_1111_1111) }
}
pub const KEY_A: u16 = 1 << 0;
pub const KEY_B: u16 = 1 << 1;
pub const KEY_SELECT: u16 = 1 << 2;
pub const KEY_START: u16 = 1 << 3;
pub const KEY_RIGHT: u16 = 1 << 4;
pub const KEY_LEFT: u16 = 1 << 5;
pub const KEY_UP: u16 = 1 << 6;
pub const KEY_DOWN: u16 = 1 << 7;
pub const KEY_R: u16 = 1 << 8;
pub const KEY_L: u16 = 1 << 9;
impl KeyInputSetting {
pub fn contains(&self, key: u16) -> bool {
(self.0 & key) != 0
}
pub fn difference(&self, other: KeyInputSetting) -> KeyInputSetting {
KeyInputSetting(self.0 ^ other.0)
}
pub fn column_direction(&self) -> TriBool {
if self.contains(KEY_RIGHT) {
TriBool::Plus
} else if self.contains(KEY_LEFT) {
TriBool::Minus
} else {
TriBool::Neutral
}
}
pub fn row_direction(&self) -> TriBool {
if self.contains(KEY_DOWN) {
TriBool::Plus
} else if self.contains(KEY_UP) {
TriBool::Minus
} else {
TriBool::Neutral
}
}
}
pub const VCOUNT: *mut u16 = 0x0400_0006 as *mut u16;
pub fn read_vcount() -> u16 {
unsafe { VCOUNT.read_volatile() }
}
pub fn wait_until_vblank() {
while read_vcount() < SCREEN_HEIGHT as u16 {}
}
pub fn wait_until_vdraw() {
while read_vcount() >= SCREEN_HEIGHT as u16 {}
}