X-Git-Url: http://git.dujemihanovic.xyz/projects?a=blobdiff_plain;f=boot.s;h=a40b7508781e9dbc59b82587e003f2ccca6a21f8;hb=c9f2bccb44c5437f1cae0862b2c84d3af47eade8;hp=50730d0c39dd9566f3eef2e0b87582758af13444;hpb=4326df7844154f8c575a33b3898709944e08f74b;p=nameless-os.git

diff --git a/boot.s b/boot.s
index 50730d0..a40b750 100644
--- a/boot.s
+++ b/boot.s
@@ -1,22 +1,135 @@
-	bits 16 ; boot sectors run in real mode
-	org 7c00h ; boot sector is always loaded at 0x7c00
-
-	mov al, 1 ; update cursor after write
-	mov bh, 0 ; write to page 0
-	mov bl, 00000111b ; attribute: high nibble is foreground (light gray),
-					  ; low nibble is background (black)
-					  ; NOTE: in the binary, these will be inverted, so low nibble here will become high nibble in binary and vice versa!
-	mov cx, msg1end - msg1 ; size of message
-	mov dl, 0 ; column to write to
-	mov dh, 0 ; row to write to
-	push cs ; push code segment to stack
-	pop es ; pop pushed code segment to extra segment, this serves as the base to the string
-	mov bp, msg1 ; offset where the string is
-	mov ah, 13h ; write string subservice 
-	int 10h ; call BIOS interrupt 0x10
-	jmp msg1end ; jmp to endless loop
-	msg1 db "Gotta start somewhere"
-	msg1end: jmp msg1end
-
-	times 510-($-$$) db 0 ; fill with 0 until 0x1fc is reached
-	dw 0xaa55 ; BIOS MBR signature
+	bits 16
+	org 7C00h
+
+KERNEL_OFFSET equ 1000h
+
+	mov [BOOT_DRIVE], dl
+
+	mov bp, 9000h
+	mov sp, bp
+
+	mov di, 0
+
+	xor ax, ax
+	int 13h
+	jc reset_error
+
+	mov ah, 2
+	mov al, 10
+	xor ch, ch
+	mov cl, 2
+	xor dh, dh
+	xor bx, bx
+	mov es, bx
+	mov bx, KERNEL_OFFSET
+	int 13h
+	jc read_error
+	cmp al, 10
+	jl read_error
+	jmp switch_to_pm
+
+reset_error
+	mov bx, 0B800h
+	mov es, bx
+	mov byte [es:di], '1'
+	jmp halt
+
+read_error
+	mov bx, 0B800h
+	mov es, bx
+	mov byte [es:di], '2'
+	jmp halt
+
+	call switch_to_pm
+
+halt
+	jmp $
+
+switch_to_pm
+	mov bx, 0B800h
+	mov es, bx
+	mov byte [es:0], 'L'
+
+	cli
+	xor ax, ax
+	mov ds, ax
+	lgdt [gdt_desc]
+	
+	mov eax, cr0
+	or eax, 1
+	mov cr0, eax
+	jmp CODE_SEG:protected
+
+	bits 32
+protected
+	mov ax, DATA_SEG
+	mov ds, ax
+	mov ss, ax
+	mov es, ax
+	mov fs, ax
+	mov gs, ax
+	
+	mov ebp, 090000h
+	mov esp, ebp
+
+	mov ebx, pm_success
+	call pmprint
+
+	call KERNEL_OFFSET
+
+	jmp $
+
+pmprint
+	pusha
+	mov edx, video_memory
+
+.loop
+	mov al, [ebx]
+	mov ah, 0Fh
+
+	cmp al, 0
+	je .done
+
+	mov [edx], al
+	mov [edx+1], ah
+
+	inc ebx
+	add edx, 2
+
+	jmp .loop
+
+.done
+	popa
+	ret
+
+pm_success db "Now in protected mode", 0
+video_memory equ 0B8000h
+
+gdt_start
+null_seg
+	dq 0
+code_seg
+	dw 0FFFFh
+	dw 0
+	db 0
+	db 10011010b
+	db 11001111b
+	db 0
+data_seg
+	dw 0FFFFh
+	dw 0
+	db 0
+	db 10010010b
+	db 11001111b
+	db 0
+gdt_end
+gdt_desc
+	dw gdt_end - gdt_start - 1
+	dd gdt_start
+CODE_SEG equ code_seg - gdt_start
+DATA_SEG equ data_seg - gdt_start
+
+BOOT_DRIVE db 0
+
+	times 510-($-$$) db 0
+	dw 0AA55h