BaseKernel/bootstrap.asm at main · ankushhKapoor/BaseKernel · GitHub

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start:
	mov ax, 07C0h
	mov ds, ax

	mov si, title_string
	call print_string

	mov si, message_string
	call print_string

	call load_kernel_from_disk
	jmp 0900h:0000


load_kernel_from_disk:
	mov ax, [curr_sector_to_load]
	sub ax, 2
	mov bx, 512d
	mul bx
	mov bx, ax	; as multiple sectors are to be loaded, this part loads all sectors at correct address

	mov ax, 0900h
	mov es, ax

	mov ah, 02h
	mov al, 01h
	mov ch, 0h
	mov cl, [curr_sector_to_load]
	mov dh, 0h
	mov dl, 80h
	; mov bx, 0h
	int 13h

	jc kernel_load_error

	sub byte [number_of_sectors_to_load], 1
	add byte [curr_sector_to_load], 1
	cmp byte [number_of_sectors_to_load], 0

	jne load_kernel_from_disk

	ret

kernel_load_error:
	mov si, load_error_string
	call print_string

	jmp $

print_string:
	mov ah, 0Eh

print_char:
	lodsb

	cmp al, 0
	je printing_finished

	int 10h

	jmp print_char

printing_finished:
	mov al, 10d ; Print new line
	int 10h

	; Reading current cursor position
	mov ah, 03h
	mov bh, 0
	int 10h

	; Move the cursor to the beginning
	mov ah, 02h
	mov dl, 0
	int 10h

	ret

title_string			db 'The Bootloader of 539Kernel.', 0
message_string			db 'The kernel is loading.', 0
load_error_string		db 'The kernel cannot be loaded.', 0
number_of_sectors_to_load	db 15d
curr_sector_to_load		db 2d

times 510-($-$$) db 0
dw 0xAA55