StupidOS/boot/boot0.asm
d0p1 🏳️‍⚧️ 9aaad60e6e
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fix: multiboot in stpdboot.sys
2024-03-20 10:48:47 +01:00

121 lines
2.3 KiB
NASM

INCLUDE 'const.inc'
ORG STAGE0_BASE
USE16
jmp short _start
nop
; Boot Record
OEM_identifier db 'STUPID '
bytes_per_sector dw 512
sectors_per_cluster db 1
reserved_sectors dw 1
FAT_count db 2
root_dir_entries dw 224
total_sectors dw 2880
media_desc_type db 0xF0
sectors_per_FAT dw 9
sectors_per_track dw 18
heads_per_cylinder dw 2
hidden_sectors dd 0
large_sector_count dd 0
; Extended Boot Record
drive_number db 0x0
reserved db 0x0
signature db 0x29 ; 0x28 or 0x29
volume_id dd 0xB00B135 ; hope mine will grow :'(
volume_label db 'Stupid Boot'
system_id db 'FAT12 '
_start:
cli
cld
jmp 0x0:.canonicalize_cs
.canonicalize_cs:
xor ax, ax
mov ds, ax
mov ss, ax
mov es, ax
mov sp, 0x7c00
mov [drive_number], dl
; reset floppy disk
@@:
mov dl, [drive_number]
xor ah, ah
int 0x13
jc @b
call fat_load_root
; search in root directory
mov si, kernel_file
call fat_search_root
jc .error_not_found
mov [kernel_start], ax
mov si, stage1_file
call fat_search_root
jc .error_not_found
mov [stage1_start], ax
; load fat
xor ax, ax
mov al, [FAT_count]
mul word [sectors_per_FAT]
mov cx, ax
mov ax, [reserved_sectors]
xor bx, bx
call disk_read_sectors
; preload kernel
mov ax, KERNEL_PRELOAD/0x10
mov es, ax
mov ax, [kernel_start]
xor bx, bx
call fat_load_binary
; load stage 2
mov ax, STAGE1_BASE/0x10
mov es, ax
mov ax, [stage1_start]
xor bx, bx
call fat_load_binary
jmp 0x0:STAGE1_BASE
.error_not_found:
push si
mov si, msg_error
call bios_print
pop si
call bios_print
mov si, msg_not_found
call bios_print
hlt
jmp $
INCLUDE "utils.inc"
INCLUDE "fat12.inc"
msg_error db "ERROR: ", 0
msg_not_found db " not found", CR, LF, 0
kernel_file db "VMSTUPIDSYS", 0
stage1_file db "STPDBOOTSYS", 0
kernel_start dw 0x0
stage1_start dw 0x0
rb 0x7C00+512-2-$
db 0x55, 0xAA