From 1f8a8ff81ac5383d61e0a07e5bb8aeb52874c2df Mon Sep 17 00:00:00 2001
From: Jakob Lechner <mail@jalr.de>
Date: Thu, 2 Jan 2025 14:56:10 +0100
Subject: [PATCH] Add constants for FAT12 partition

---
 src/main.rs | 31 ++++++++++++++++++++-----------
 1 file changed, 20 insertions(+), 11 deletions(-)

diff --git a/src/main.rs b/src/main.rs
index 9c7ac77..42a1cb9 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -134,6 +134,10 @@ fn main() -> ! {
         )
     };
 
+    const OEM: [u8; 8] = *b"mkfs.fat";
+    const FILESYSTEM_ID: [u8; 4] = [0xDE, 0xAD, 0xBE, 0xEF];
+    const FILESYSTEM_NAME: [u8; 11] = *b"RAM_USB\0\0\0\0";
+
     storage[0x1B8..0x1BC].copy_from_slice(&[0xEF, 0xBE, 0xAD, 0xDE]);
     storage[0x1BE..0x1C3].copy_from_slice(&[0x00, 0x00, 0x02, 0x00, 0x01]);
     storage[0x1C3] = last_head as u8;
@@ -145,20 +149,25 @@ fn main() -> ! {
     storage[0x1CC] = (LBA >> 16) as u8;
     storage[0x1CD] = (LBA >> 24) as u8;
     storage[0x1FE..0x200].copy_from_slice(&[0x55, 0xaa]); // boot signature
-    storage[0x200..0x23E].copy_from_slice(&[
-        /* 000 */ 0xEB, 0x3C, 0x90, b'm', b'k', b'f', b's', b'.', b'f', b'a', b't', 0x00, 0x02, 0x04, 0x01, 0x00,
-        /* 010 */ 0x02, 0x00, 0x02, (DISK_BLOCK_NUM & 0xff) as u8,
-                                          (DISK_BLOCK_NUM >> 8) as u8,
-                                                0xF8, 0x01, 0x00, 0x01, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00,
-        /* 020 */ 0x00, 0x00, 0x00, 0x00, 0x80, 0x00, 0x29, 0xDE, 0xAD, 0xBE, 0xEF, b'R', b'A', b'M', b'_', b'U',
-        /* 030 */ b'S', b'B', b' ', b' ', b' ', b' ', b'F', b'A', b'T', b'1', b'2', b' ', b' ', b' '
-    ]);
+
+    // FAT12 Partition
+    storage[0x200..0x203].copy_from_slice(&[0xEB, 0x3C, 0x90]);
+    storage[0x203..0x20B].copy_from_slice(&OEM);
+    storage[0x20B..0x227].copy_from_slice(&[0x00, 0x02, 0x04, 0x01, 0x00,
+        0x02, 0x00, 0x02, (DISK_BLOCK_NUM & 0xff) as u8,
+                                (DISK_BLOCK_NUM >> 8) as u8,
+                                      0xF8, 0x01, 0x00, 0x01, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00,
+        0x00, 0x00, 0x00, 0x00, 0x80, 0x00, 0x29]);
+    storage[0x227..0x22B].copy_from_slice(&FILESYSTEM_ID);
+    storage[0x22B..0x236].copy_from_slice(&FILESYSTEM_NAME);
+    storage[0x236..0x23E].copy_from_slice(b"FAT12   ");
     storage[0x3FE..0x400].copy_from_slice(&[0x55, 0xAA]);
+    
     storage[0x400..0x403].copy_from_slice(&[0xF8, 0xFF, 0xFF]);
     storage[0x600..0x603].copy_from_slice(&[0xF8, 0xFF, 0xFF]);
-    storage[0x800..0x81A].copy_from_slice(&[
-        /* 600 */ b'R', b'A', b'M', b'_', b'U', b'S', b'B', b' ', b' ', b' ', b' ', 0x08, 0x00, 0x00, 0xF9, 0x98,
-        /* 610 */ 0x3A, 0x58, 0x3A, 0x58, 0x00, 0x00, 0xF9, 0x98, 0x3A, 0x58
+    storage[0x800..0x80B].copy_from_slice(&FILESYSTEM_NAME);
+    storage[0x80B..0x81A].copy_from_slice(&[0x08, 0x00, 0x00, 0xF9, 0x98,
+        0x3A, 0x58, 0x3A, 0x58, 0x00, 0x00, 0xF9, 0x98, 0x3A, 0x58
     ]);
 
     let mut state: State = State {