support swapped roms

src/main.rs

@@ -4,10 +4,38 @@ use std::fs;
 mod device;
 mod ui;
 
+fn swap_rom(contents: Vec<u8>) -> Vec<u8> {
+    let test = u32::from_be_bytes(contents[0..4].try_into().unwrap());
+    if test == 0x80371240 {
+        // z64
+        return contents;
+    } else if test == 0x37804012 {
+        // v64
+        let mut data: Vec<u8> = vec![0; contents.len()];
+        for i in (0..contents.len()).step_by(2) {
+            let temp = u16::from_ne_bytes(contents[i..i + 2].try_into().unwrap());
+            data[i..i + 2].copy_from_slice(&temp.to_be_bytes());
+        }
+        return data;
+    } else if test == 0x40123780 {
+        // n64
+        let mut data: Vec<u8> = vec![0; contents.len()];
+        for i in (0..contents.len()).step_by(4) {
+            let temp = u32::from_ne_bytes(contents[i..i + 4].try_into().unwrap());
+            data[i..i + 4].copy_from_slice(&temp.to_be_bytes());
+        }
+        return data;
+    } else {
+        panic!("unknown rom format")
+    }
+}
+
 fn main() {
     let args: Vec<String> = env::args().collect();
     let file_path = &args[1];
-    let contents = fs::read(file_path).expect("Should have been able to read the file");
+    let mut contents = fs::read(file_path).expect("Should have been able to read the file");
+
+    contents = swap_rom(contents);
 
     let mut device = device::Device::new();