diff options
| -rw-r--r-- | bootloader.asm | 143 |
1 files changed, 139 insertions, 4 deletions
diff --git a/bootloader.asm b/bootloader.asm index 181c1dc..2993726 100644 --- a/bootloader.asm +++ b/bootloader.asm @@ -1,12 +1,147 @@ +[BITS 16] +[ORG 7c00h] - mov cx, 0x10 - mov ah, 0x0A - mov al, 0x74 - int 0x10 +init: + mov cx, 0xB800 + mov gs, cx +start: + call clr_vga + mov si, HELLO + call write_str + call disk_read + mov si, VERIFY + call write_str + mov ax, 0x61 + call cursor_next_line + call write_char_default_attr + mov ax, 0x62 + call cursor_next_line + call write_char_default_attr + mov ax, 0x63 + call cursor_next_line + call write_char_default_attr + call write_char_default_attr + call write_char_default_attr + call cursor_back_one + call cursor_backspace + jmp hang + +read_err: + mov si, READ_ERR + call write_str hang: jmp hang +write_str: + push ax + push si + xor ax, ax +write_str_each_char: + mov al, byte [si] + cmp al, 0 + je write_str_done + inc si + call write_char_default_attr + jmp write_str_each_char +write_str_done: + pop si + pop ax + ret + +write_char_default_attr: + push bx + mov bl, 0x07 + jmp write_char_inner +write_char: + push bx +write_char_inner: + push di + mov di, [CURSOR_LOC] + mov byte [gs:di], al + inc di + mov byte [gs:di], bl + inc di + mov [CURSOR_LOC], di + pop di + pop bx + ret + +clr_vga: + mov di, 4000 +clr_vga_loop: + dec di + mov byte [gs:di], 0x00 + cmp di, 0 + jne clr_vga_loop + mov word [CURSOR_LOC], 0 + ret + +disk_read: + ; ax = disk number to read from + ; reference: http://www.delorie.com/djgpp/doc/rbinter/id/14/7.html + mov dx, 0x80 + or ax, dx + mov si, LBA_DISK_READ_PACKET + mov ah, 0x42 + int 0x13 + jc read_err + mov si, READ_SUCC + call write_str + ret + +READ_ERR: + db 'Read failed: ', 0 +READ_SUCC: + db 'Read didnt fail: ', 0 +HELLO: + db 'Bootloader init: ', 0 +CURSOR_LOC: + dw 0 + + ; reference: http://www.delorie.com/djgpp/doc/rbinter/it/72/2.html +LBA_DISK_READ_PACKET: + db 0x10 + db 0 + dw 1 ; number of blocks to read, reset to # actually read when done + dw 0x7e00 ; read destination address + dw 0 + dd 1 ; lba to read from + dd 0 ; for extended lba adresses (not really used here) + times 510-($-$$) db 0 db 0x55 db 0xAA + +cursor_next_line: + mov di, [CURSOR_LOC] + add di, 160 + mov [CURSOR_LOC], di + ret + +cursor_prev_line: + mov di, [CURSOR_LOC] + sub di, 160 + mov [CURSOR_LOC], di + ret + +cursor_backspace: + push ax + call cursor_back_one + mov ax, 0x00 + call write_char_default_attr + call cursor_back_one + pop ax + ret + +cursor_back_one: + mov di, [CURSOR_LOC] + dec di + dec di + mov [CURSOR_LOC], di + ret + +VERIFY: + db '[x] read next block: ', 0 + + times 1024-($-$$) db 0 |