Clean up boot sector code

Author: phil-opp

bios/boot_sector/src/boot unreal.s

@@ -1,6 +1,7 @@
-use core::arch::{asm, global_asm};
+use core::arch::asm;
 
 #[repr(packed)]
+#[allow(dead_code)] // the structure format is defined by the hardware
 pub struct DiskAddressPacket {
     /// Size of the DAP structure
     packet_size: u8,
@@ -17,17 +18,6 @@ pub struct DiskAddressPacket {
 }
 
 impl DiskAddressPacket {
-    pub fn new(memory_buffer_start: u16, file_offset: u64, bytes: u32) -> Self {
-        Self {
-            packet_size: 0x10,
-            zero: 0,
-            number_of_sectors: (bytes / 512) as u16,
-            offset: memory_buffer_start,
-            segment: 0,
-            start_lba: file_offset / 512,
-        }
-    }
-
     pub fn from_lba(memory_buffer_start: u16, start_lba: u64, number_of_sectors: u16) -> Self {
         Self {
             packet_size: 0x10,
@@ -41,18 +31,20 @@ impl DiskAddressPacket {
 
     pub unsafe fn perform_load(&self, disk_number: u16) {
         let self_addr = self as *const Self as u16;
-        asm!(
-            "push 0x7a", // error code `z`, passed to `fail` on error
-            "mov {1:x}, si",
-            "mov si, {0:x}",
-            "int 0x13",
-            "jc fail",
-            "pop si", // remove error code again
-            "mov si, {1:x}",
-            in(reg) self_addr,
-            out(reg) _,
-            in("ax") 0x4200u16,
-            in("dx") disk_number,
-        );
+        unsafe {
+            asm!(
+                "push 0x7a", // error code `z`, passed to `fail` on error
+                "mov {1:x}, si",
+                "mov si, {0:x}",
+                "int 0x13",
+                "jc fail",
+                "pop si", // remove error code again
+                "mov si, {1:x}",
+                in(reg) self_addr,
+                out(reg) _,
+                in("ax") 0x4200u16,
+                in("dx") disk_number,
+            );
+        }
     }
 }