1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
|
bits 16
jmp kmain
%include "constants.asm"
%include "string.asm"
%include "disk.asm"
%include "console.asm"
%include "stdio.asm"
kmain:
cli ; disable interrupts
mov ax, cs ; get code segment (i.e. far jump address in bootloader)
mov ds, ax ; set data segment
mov es, ax ; set extra segment
mov ax, 06000h
mov ss, ax ; set stack segment
mov sp, 0ffffh ; set stack pointer (~64k)
sti ; enable interrupts
mov [drive0], dx ; store bootloader's drive number
; reset general purpose registers
xor ax, ax
xor bx, bx
xor cx, cx
xor dx, dx
xor di, di
xor si, si
xor bp, bp
push banner
call puts
.mainloop:
call kbd_read
call putc
jmp .mainloop
cli
jmp $
panic:
; Hang system with supplied error message
push bp
mov bp, sp
push error_msg_panic ; i.e. 'PANIC:'
call puts
add sp, 2
push word [bp + 4] ; address of error string buffer
call puts ; print error
add sp, 2
cli ; disable interrupts
jmp $ ; hang (no return)
; stack is dead
; data
kernel_address: dd 0 ; format DS:ADDR
banner: db "+========================+", CR, LF
db "| Welcome to MINOS 0.0.1 |", CR, LF
db "+========================+", CR, LF
db CR, LF, 0
; Error messages
error_msg_panic: db "PANIC: ", 0
times 512 * 16 db 0
dw 0xefbe
|
