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;; boot.stage1.asm
[bits 16]
[org 0x7c00]
global _start
jmp _start
%include "boot.stage1.print.asm"
%include "common.asm"
_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 si, DAP ; DAP is at cs:si
xor ax, ax
mov ah, 0x42 ; Extended read
mov dl, [drive] ; Set drive number
int 0x13 ; Read disk
jc _disk_read_err
mov dl, [drive]
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
db 0
dw READ_SECTORS_NUM
dw STAGE2_ADDR
dw 0x0000
dq 1
drive: db 0
disk_read_err_msg: db "Disk error", 13, 10, 0
boot_msg: db "Booting", 13, 10, 0
times 510-($-$$) db 0
dw 0xAA55
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