update fbs

flatbuffers/README.md

@@ -31,5 +31,11 @@ https://cmake.org/install/
 ```
 
 
+----
+
+FlatBuffers Binary Format
+
+* https://qiita.com/termoshtt/items/c337cd67e678bac2c795#flatbuffers-binary-format
+* https://github.com/dvidelabs/flatcc/blob/master/doc/binary-format.md
 
 

flatbuffers/src/main.rs

@@ -27,4 +27,20 @@ fn main() {
     let monster_2 = flatbuffers::get_root::<Monster>(&buff);
     println!("Monster hp: {}", monster_2.hp());
     println!("Monster name: {:?}", monster_2.name());
+
+    let offset_to_body = i32::from_le_bytes(get_4bytes(&buff));
+    println!("Offset to body  : {:>4}, hex: {}", offset_to_body, hex::encode(&get_4bytes(&buff)));
+    let xx = &buff[4..offset_to_body as usize];
+    println!("{}", hex::encode(xx));
+    let offset_to_vtable = i32::from_le_bytes(get_4bytes(&buff[offset_to_body as usize..]));
+    println!("Offset to vtable: {:>4}, hex: {}", offset_to_vtable, hex::encode(get_4bytes(&buff[offset_to_body as usize..])));
+}
+
+fn get_4bytes(buff: &[u8]) -> [u8; 4] {
+    let mut ret = [0_u8; 4];
+    ret[0] = buff[0];
+    ret[1] = buff[1];
+    ret[2] = buff[2];
+    ret[3] = buff[3];
+    ret
 }