feat: add ffi c_layout

__ffi/c_layout/src/main_1.rs

@@ -0,0 +1,41 @@
+use std::io::Read;
+use std::mem;
+use std::slice;
+
+#[repr(C, packed)]
+#[derive(Debug, Copy, Clone)]
+struct Configuration {
+    item1: u8,
+    item2: u16,
+    item3: i32,
+    item4: [char; 8],
+}
+
+const CONFIG_DATA: &[u8] = &[
+    0xfd, // u8
+    0xb4, 0x50, // u16
+    0x45, 0xcd, 0x3c, 0x15, // i32
+    0x71, 0x3c, 0x87, 0xff, // char
+    0xe8, 0x5d, 0x20, 0xe7, // char
+    0x5f, 0x38, 0x05, 0x4a, // char
+    0xc4, 0x58, 0x8f, 0xdc, // char
+    0x67, 0x1d, 0xb4, 0x64, // char
+    0xf2, 0xc5, 0x2c, 0x15, // char
+    0xd8, 0x9a, 0xae, 0x23, // char
+    0x7d, 0xce, 0x4b, 0xeb, // char
+];
+
+pub fn run_main() {
+    let mut buffer = CONFIG_DATA;
+
+    let mut config: Configuration = unsafe { mem::zeroed() };
+
+    let config_size = mem::size_of::<Configuration>();
+    unsafe {
+        let config_slice = slice::from_raw_parts_mut(&mut config as *mut _ as *mut u8, config_size);
+        // `read_exact()` comes from `Read` impl for `&[u8]`
+        buffer.read_exact(config_slice).unwrap();
+    }
+
+    println!("Read structure: {:#?}", config);
+}