MiOS/boot.asm at main · Mirik9724/MiOS · GitHub

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[BITS 16]
[ORG 0x7C00]

BootDrive db 0

start:
	cli
	xor ax, ax
    mov ds, ax
    mov es, ax
    mov ss, ax
    mov sp, 0x7C00

	mov [BootDrive], dl

	mov ax, 0
	mov ds, ax
	mov es, ax
	cld

	call wc2boot
	call load_kernel
	call oscore
	jmp $

print:
	lodsb
	cmp al, 0
	je done

	mov ah, 0x0E
	mov bl, 0x7
	int 0x10
	jmp print

nl:
	mov si, nltxt
	call print
	ret

done:
	ret

KERNEL_SECTORS equ 16

load_kernel:
    mov ax, 0x0000
    mov es, ax
    mov bx, 0x1000

    mov ah, 0x02
    mov al, KERNEL_SECTORS
    mov ch, 0x00
    mov cl, 0x02
    mov dh, 0x00
    mov dl, [BootDrive]

    int 0x13
    jc disk_error

    ret

disk_error:
    mov si, errtxt
    call print
    jmp $

errtxt db 'Disk read error',0

disable_cursor:
    mov dx, 0x3D4
    mov al, 0x0A
    out dx, al
    inc dx
    mov al, 0x20
    out dx, al
    ret

wc2boot:
	mov si, long1
	call print
	mov si, long1
	call print
	call nl

	mov si, body1
	call print
	call nl

	mov si, wctxt
	call print
	call nl

	mov si, wctxt2a
	call print
	call nl
	mov si, wctxt2b
	call print
	call nl
	mov si, wctxt2c
	call print
	call nl

	mov si, body1
	call print
	call nl

	mov si, long1
	call print
	mov si, long1
	call print
	call nl
	ret

align 8
gdt32b:
	dq 0x0000000000000000
	dq 0x00CF9A000000FFFF
	dq 0x00CF92000000FFFF
gdt32bEnd:
gdt32bLoc:
	dw gdt32bEnd - gdt32b - 1
	dd gdt32b

oscore:
	mov si, lchkrl
	call print
	call nl
	call disable_cursor
	cli

	in al, 0x92
	or al, 00000010b
	out 0x92, al

	lgdt [gdt32bLoc]

	mov eax, cr0
	or eax, 1
	mov cr0, eax

	jmp 0x08:safeMode

wctxt db '#     MiBoot16Bit      #', 0
wctxt2a db '#   If you want to     #', 0
wctxt2b db '#   use this os whow   #', 0
wctxt2c	db '# main, you are idiot  #', 0

lchkrl db 'Loading core', 0
long1 db '############',0
body1 db '#                      #',0

nltxt db 0x0D, 0x0A, 0

[BITS 32]
safeMode:
	mov ax, 0x10
	mov ds, ax
	mov es, ax
	mov fs, ax
	mov gs, ax
	mov ss, ax
	mov esp, 0x90000

	jmp 0x08:0x1000


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