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;; boot.stage1.asm
[bits 16]
[org 0x7c00]
global _start
_start:
;; Setup segment registers
xor ax, ax
mov ds, ax
mov es, ax
mov ss, ax
mov sp, STACK_ADDR ; Adjust stack
cld
mov [drive], dl ; Get boot drive number
;; Show boot message
mov si, boot_msg
call _print_string
;; Load Stage 2
mov ah, 0x42 ; Extended read
mov dl, [drive] ; Set drive number
xor ax, ax
mov ds, ax
mov si, DAP
int 0x13 ; Read disk
jc _disk_read_err
jmp 0x0000:STAGE2_ADDR
_disk_read_err:
mov si, disk_read_err_msg
call _print_string
.halt: hlt
jmp .halt
align 16
DAP:
db 0x10 ; Size of packet
db 0 ; Zero
dw READ_SECTORS_NUM ; Number of sectors to be read
dw STAGE2_ADDR ; Destination address
dw 0x0000 ; Segment
dq 1 ; Which sector to start at
drive: db 0
disk_read_err_msg: db "Disk error", 13, 10, 0
boot_msg: db "Booting", 13, 10, 0
%include "boot.stage1.print.asm"
%include "common.asm"
times 510-($-$$) db 0
dw 0xAA55
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