boot/boot.68k

@@ -3,16 +3,25 @@ _start:
 move.b #0x4, d0
 bsr.w find_first_card
 | Load the header sector for the kernel binary
-move.l #0x200, a1 | Set the destination address to 0x200
-move.l #0x1, d0 | Set the starting sector number to 1
-move.l #0x1, d1 | Set the sector count to 1
-bsr.w read_sectors
+move.l #0x1, (a0) | Set the sector number to 1
+| Transfer 0x100 (256) bytes from the storage card's data register to 0x100
+move.w #0x100, a1 | Load a1, the destination address register, with 0x100
+move.w #0xFF, d0 | Load d0 with the sector size - 1.
+hdr_sector_loop:
+move.b (4, a0), (a1)+ | Transfer a byte of sector data to the destination
+dbra d0, hdr_sector_loop | Loop back if there is more to transfer
+move.w (0x102), d0 | Load d0 with the number of sectors for the kernel - 1
+subq.w #0x1, d0
 | load the ELF kernel binary off the disk
-move.l #0xA000, a1 | Set the destination address to 0xA000
-move.l #0x2, d0 | Set the starting sector number to 2
-clr.l d1
-move.w (0x202), d1 | Set the sector count
-bsr.b read_sectors
+move.l #0x2, (a0) | Set the sector number to 2
+| Transfer 0x100 (256) * d0 bytes from the storage card's data register to 0xA000
+move.l #0xA000, a1 | Load a1, the destination address register, with 0xA000
+sectors_loop:
+move.w #0xFF, d1 | Load d0 with the sector size - 1.
+sector_loop:
+move.b (4, a0), (a1)+ | Transfer a byte of sector data to the destination
+dbra d1, sector_loop | Loop back if there is more to transfer
+dbra d0, sectors_loop | Loop back if there are more sectors to transfer
 move.l (0xA01C), d0 | Load the offset of the program headers in the file 
 move.l #0xA000, a0 | Put the address of the program headers in a0
 adda.w d0, a0
@@ -63,32 +72,8 @@ ffc_done:
   rts
 
 
-| Reads sectors from a storage card
-| Card base in a0
-| Destination in a1
-| Start sector in d0.l
-| Sector count in d1.l
-| Clobbers a1, d1
-read_sectors:
-move.l d0, (a0) | Set the sector number
-move.l d1, (4, a0) | Set the sector count
-move.w #0x0, (8, a0) | Issue a read command
-| Transfer 0x200 (512) * sector_count bytes from the storage card's data register to (a1)
-lsl.l #8, d1 | d0 = d0 * 256 to compute the number of words to transfer
-subq.l #0x1, d1 | Subtract 1 from the word count to account for the extra loop done by dbra
-bra.b rs_loop
-rs_loop_swap:
-swap.w d1
-rs_loop:
-move.w (0xA, a0), (a1)+ | Transfer a word of sector data to the destination
-dbra.w d1, rs_loop 
-swap.w d1
-dbra.w d1, rs_loop_swap
-rts
-
-.if . != 512
-.org 511
+.if . != 256
+.org 255
 .byte 0
 .endif
 
-

initrd_maker.rs

@@ -5,8 +5,7 @@ use std::{
     path::Path,
 };
 
-const BLOCK_SIZE: u16 = 512;
-const MAX_NAME_LEN: u16 = BLOCK_SIZE - 8;
+const BLOCK_SIZE: u16 = 256;
 
 fn main() {
     let mut archive = File::create("initrd").expect("Could not open initrd");
@@ -14,38 +13,34 @@ fn main() {
         let file_path = Path::new(&file_path);
         let file_name = file_path.file_name().unwrap();
         let file_name_len =
-            u16::try_from(file_name.len()).expect("File name length greater than 256 bytes");
-        assert!(
-            file_name_len <= MAX_NAME_LEN,
-            "File {:?} has name longer than {} bytes",
-            file_name,
-            MAX_NAME_LEN
-        );
+            u8::try_from(file_name.len()).expect("File name length greater than 256 bytes");
+        if file_name_len > 252 {
+            panic!("File {:?} has name longer than 252 bytes", file_name);
+        }
         let mut file = File::open(file_path).expect("File did not exist");
         let length = u16::try_from(file.metadata().expect("Could not get file metadata").len())
             .expect("File size greater than 64 KiB");
-        let file_num_blocks = (length / BLOCK_SIZE) + if length % BLOCK_SIZE == 0 { 0 } else { 1 };
+        let file_num_blocks = (length / BLOCK_SIZE) + if length % BLOCK_SIZE != 0 { 1 } else { 0 };
         let mut header_block = Vec::new();
         header_block.extend_from_slice(&length.to_be_bytes());
         header_block.extend_from_slice(&file_num_blocks.to_be_bytes());
-        header_block.extend_from_slice(&file_name_len.to_be_bytes());
+        header_block.push(file_name_len);
         header_block.extend_from_slice(file_name.to_str().unwrap().as_bytes());
         header_block.push(0);
         header_block.resize(BLOCK_SIZE as usize, 0);
         archive
             .write_all(&header_block)
             .expect("Could not write to initrd");
-        #[allow(clippy::cast_possible_truncation)]
-        let bytes_written = io::copy(&mut file, &mut archive)
-            .expect("Could not read from file/write to initrd") as u16;
-        if (bytes_written % BLOCK_SIZE) != 0 {
-            let bytes_padding = (BLOCK_SIZE) - (bytes_written % BLOCK_SIZE);
+        let bytes_written =
+            io::copy(&mut file, &mut archive).expect("Could not read from file/write to initrd");
+        if (bytes_written as u16 % BLOCK_SIZE) != 0 {
+            let bytes_padding = (BLOCK_SIZE) - (bytes_written as u16 % BLOCK_SIZE);
             for _ in 0..bytes_padding {
                 archive.write_all(&[0]).expect("Could not write to initrd");
             }
         }
     }
     archive
-        .write_all(&[0; BLOCK_SIZE as usize])
+        .write_all(&[0; 256])
         .expect("Could not write to initrd");
 }

kernel/main.68k

@@ -1,6 +1,3 @@
 .global _start
 _start:
-  move.b #'H', 0xFF0200
-  move.b #'i', 0xFF0200
-  move.b #0xA, 0xFF0200
   stop #0x2700