use bytemuck::*;
use core::{num::Wrapping, ops::Neg};
pub const DEFAULT_LOGO: [u8; 156] = [
0x24, 0xFF, 0xAE, 0x51, 0x69, 0x9A, 0xA2, 0x21, 0x3D, 0x84, 0x82, 0x0A, 0x84,
0xE4, 0x09, 0xAD, 0x11, 0x24, 0x8B, 0x98, 0xC0, 0x81, 0x7F, 0x21, 0xA3, 0x52,
0xBE, 0x19, 0x93, 0x09, 0xCE, 0x20, 0x10, 0x46, 0x4A, 0x4A, 0xF8, 0x27, 0x31,
0xEC, 0x58, 0xC7, 0xE8, 0x33, 0x82, 0xE3, 0xCE, 0xBF, 0x85, 0xF4, 0xDF, 0x94,
0xCE, 0x4B, 0x09, 0xC1, 0x94, 0x56, 0x8A, 0xC0, 0x13, 0x72, 0xA7, 0xFC, 0x9F,
0x84, 0x4D, 0x73, 0xA3, 0xCA, 0x9A, 0x61, 0x58, 0x97, 0xA3, 0x27, 0xFC, 0x03,
0x98, 0x76, 0x23, 0x1D, 0xC7, 0x61, 0x03, 0x04, 0xAE, 0x56, 0xBF, 0x38, 0x84,
0x00, 0x40, 0xA7, 0x0E, 0xFD, 0xFF, 0x52, 0xFE, 0x03, 0x6F, 0x95, 0x30, 0xF1,
0x97, 0xFB, 0xC0, 0x85, 0x60, 0xD6, 0x80, 0x25, 0xA9, 0x63, 0xBE, 0x03, 0x01,
0x4E, 0x38, 0xE2, 0xF9, 0xA2, 0x34, 0xFF, 0xBB, 0x3E, 0x03, 0x44, 0x78, 0x00,
0x90, 0xCB, 0x88, 0x11, 0x3A, 0x94, 0x65, 0xC0, 0x7C, 0x63, 0x87, 0xF0, 0x3C,
0xAF, 0xD6, 0x25, 0xE4, 0x8B, 0x38, 0x0A, 0xAC, 0x72, 0x21, 0xD4, 0xF8, 0x07,
];
#[derive(Clone, Copy)]
#[repr(C)]
pub struct GBAHeader {
pub start_code: [u8; 4],
pub logo: [u8; 156],
pub title: [u8; 12],
pub game_code: [u8; 4],
pub maker_code: [u8; 2],
pub ninety_six: u8,
pub main_unit: u8,
pub device_type: u8,
pub reserved_zeroed: [u8; 7],
pub version: u8,
pub checksum: u8,
pub reserved_zeroed2: [u8; 2],
}
#[test]
fn test_align() {
assert_eq!(core::mem::align_of::<GBAHeader>(), 1);
}
unsafe impl Zeroable for GBAHeader {}
unsafe impl Pod for GBAHeader {}
impl Default for GBAHeader {
fn default() -> Self {
let mut header = Self::zeroed();
header.start_code = [0xEA, 0x00, 0x00, 0x2E];
header.logo = DEFAULT_LOGO;
header.ninety_six = 0x96;
header
}
}
impl GBAHeader {
pub fn update_checksum(&mut self) {
self.checksum = self.calculate_checksum()
}
pub fn calculate_checksum(&self) -> u8 {
let self_bytes: &[Wrapping<u8>] = cast_slice(bytes_of(self));
self_bytes[0xA0..0xBD]
.iter()
.chain(Some(&Wrapping(0x19_u8)))
.sum::<Wrapping<u8>>()
.neg()
.0
}
pub fn set_debugging(&mut self, debug: bool) {
if debug {
self.logo = DEFAULT_LOGO;
self.logo[0x9C - 0x04] = 0xA5;
self.device_type = 0b1000_0000;
} else {
self.logo = DEFAULT_LOGO;
self.device_type = 0;
}
}
}