Added bootloader and basic ext2 parsing

2 files changed, 87 insertions, 11 deletions

diff --git a/run b/run
index bc583ab..3ed1240 100755
--- a/run
+++ b/run
@@ -101,15 +101,15 @@ make_build() {
 	make_genext2fs
 	/usr/local/bin/genext2fs -B 4096 -d disk/ -U -N 4096 -b 65536 build/disk.img
 
-	nasm ./src/entry.asm -f bin -o disk/boot/boot.bin
+	nasm src/entry.asm -f bin -o disk/boot/boot.bin
 	cp build/melvix.bin disk/boot/
-	dd if=disk/boot/boot.bin bs=512 of=build/disk.img
+	dd if=disk/boot/boot.bin of=build/disk.img conv=notrunc
 
 	printf "Build finshed successfully!\n\n"
 }
 
 make_test() {
-	qemu_with_flags -hda ./build/disk.img
+	qemu_with_flags -hdb build/disk.img
 }
 
 make_disasm() {
@@ -134,7 +134,7 @@ make_tidy() {
 }
 
 make_clean() {
-	rm -rf ./disk/bin/ ./build/
+	rm -rf ./disk/bin/ ./disk/boot/ ./build/
 }
 
 if [ "${mode}" = "cross" ]; then
@@ -147,6 +147,7 @@ elif [ "${mode}" = "clean" ]; then
 	make_clean
 elif [ "${mode}" = "test" ]; then
 	make_cross
+	make_clean
 	make_build
 	make_sync &
 	make_test
diff --git a/src/entry.asm b/src/entry.asm
index 7404ccc..0567f61 100644
--- a/src/entry.asm
+++ b/src/entry.asm
@@ -1,8 +1,36 @@
 bits 16
-
 org 0x7c00
 
-jmp start
+global _start
+_start:
+	; Clear screen
+	mov ax, 0x003
+	int 0x10
+
+	; Welcome user!
+	mov si, hello_msg
+	call print
+
+	; Check LBA support
+	mov ah, 0x41
+	mov bx, 0x55AA
+	int 0x13
+	jc lba_error
+	cmp bx, 0xAA55
+	jnz lba_error
+
+	; Check disk and move dl
+	and dl, 0x80
+	jz disk_error
+	mov [drive], dl
+
+	; Load stage two
+	mov bx, stage_two
+	mov [dest], bx
+	call disk_read
+
+	; JUMP
+	jmp stage_two
 
 print:
 	mov ah, 0x0E
@@ -16,15 +44,62 @@ print:
 	print_end:
 	ret
 
-start:
-	mov ax, 0x003
-	int 0x10
+disk_read:
+	mov si, packet ; Address of dap
+	mov ah, 0x42 ; Extended read
+	mov dl, [drive] ; Drive number
+	int 0x13
+	jc disk_error
+	ret
 
-	mov si, hello
+; Errors
+disk_error:
+	mov si, disk_error_msg
 	call print
 	jmp $
+lba_error:
+	mov si, lba_error_msg
+	call print
+	jmp $
+
+; Variables
+hello_msg db "Welcome! Loading Melvix...", 0x0A, 0x0D, 0x00
+disk_error_msg db "Disk error!", 0x0a, 0x0d, 0x00
+lba_error_msg db "LBA error!", 0x0a, 0x0d, 0x00
+stage_two_msg db "Stage2 loaded", 0x0a, 0x0d, 0x00
+disk_success_msg db "Disk is valid", 0x0a, 0x0d, 0x00
+drive db 0
 
-hello db "Loading Melvix...", 0x0A, 0x0D, 0x00
+; Data
+packet:
+	db 0x10 ; Packet size
+	db 0 ; Always 0
+count:
+	dw 4 ; Number of sectors to transfer
+dest:
+	dw 0 ; Destination offset
+	dw 0 ; Destination segment
+lba:
+	dd 1 ; LBA number
+	dd 0 ; More storage bytes
 
+; End of boot sector
 times 510 - ($ - $$) db 0
 dw 0xAA55
+
+stage_two:
+	mov si, stage_two_msg
+	call print
+
+	mov ax, [superblock +56]
+	cmp ax, 0xEF53
+	jne disk_error
+
+	mov si, disk_success_msg
+	call print
+
+	jmp $
+
+
+times 1024 - ($ - $$) db 0
+superblock: