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|
VIDEO_MEMORY equ 0xb8000
VIDEO_COLS equ 80
VIDEO_ROWS equ 25
CURSOR_X:
dw 0
CURSOR_Y:
dw 0
pm_print_newline:
push eax
mov [CURSOR_X], word 0
mov ax, [CURSOR_Y]
inc ax
mov [CURSOR_Y], ax
pop eax
call update_vga_cursor
ret
; IN si
pm_print_string:
push eax
_loop_pm_print_string:
lodsb
cmp al, 0
je pm_print_string_fini
call pm_print_char
jmp _loop_pm_print_string
pm_print_string_fini:
pop eax
ret
; IN al: character to print
pm_print_char:
push edx
push ecx
push ebx
push eax
mov ax, [CURSOR_Y]
mov cl, VIDEO_COLS
mul cl
mov bx, [CURSOR_X]
add ax, bx
shl ax, 1
mov edx, VIDEO_MEMORY
add dx, ax
pop eax
mov ah, 0x07
mov [edx], ax
pop ebx
pop ecx
pop edx
call inc_cursor
ret
; IN dx: hex value to print
pm_print_hex:
push bx
push si
mov si, HEX_TEMPLATE
mov bx, dx
shr bx, 12
mov bx, [HEXABET+bx]
mov [HEX_TEMPLATE+2], bl
mov bx, dx
and bx, 0x0FFF
shr bx, 8
mov bx, [HEXABET+bx]
mov [HEX_TEMPLATE+3], bl
mov bx, dx
and bx, 0x00FF
shr bx, 4
mov bx, [HEXABET+bx]
mov [HEX_TEMPLATE+4], bl
mov bx, dx
and bx, 0x000F
mov bx, [HEXABET+bx]
mov [HEX_TEMPLATE+5], bl
call pm_print_string
pop si
pop bx
ret
inc_cursor:
push eax
mov ax, [CURSOR_X]
inc ax
mov [CURSOR_X], ax
cmp ax, VIDEO_COLS
jl inc_cursor_fini
mov [CURSOR_X], word 1
mov ax, [CURSOR_Y]
inc ax
mov [CURSOR_Y], ax
cmp ax, VIDEO_ROWS
jl inc_cursor_fini
; TODO: scoll one line, for now restart on top
mov [CURSOR_Y], word 0
inc_cursor_fini:
call update_vga_cursor
pop eax
ret
; update the VGA cursor on screen
update_vga_cursor:
push eax
push ebx
push ecx
push edx
mov al, [CURSOR_Y]
mov cl, VIDEO_COLS
mul cl
mov bx, ax
movzx ax, [CURSOR_X]
add bx, ax
mov cx, bx
;cursor LOW port to vga INDEX register
mov al, 0fh ;Cursor Location Low Register --
mov dx, 3d4h ;VGA port 3D4h
out dx, al
mov ax, cx ;restore 'postion' back to AX
mov dx, 3d5h ;VGA port 3D5h
out dx, al ;send to VGA hardware
;cursor HIGH port to vga INDEX register
mov al, 0eh
mov dx, 3d4h ;VGA port 3D4h
out dx, al
mov ax, cx ;restore 'position' back to AX
shr ax, 8 ;get high byte in 'position'
mov dx, 3d5h ;VGA port 3D5h
out dx, al ;send to VGA hardware
pop edx
pop ecx
pop ebx
pop eax
ret
; read cursor from hardware
read_hardware_vga_cursor:
push eax
push ebx
push ecx
push edx
xor eax, eax
xor ebx, ebx
mov al, 0eh
mov dx, 3d4h
out dx, al
mov dx, 3d5h
in al, dx
mov bh, al
mov al, 0fh
mov dx, 3d4h
out dx, al
mov dx, 3d5h
in al, dx
mov bl, al
mov ax, bx
mov edx, 0
mov cx, VIDEO_COLS
div cx
mov [CURSOR_X], dx
mov [CURSOR_Y], ax
pop edx
pop ecx
pop ebx
pop eax
ret
; check whether the end of the loaded image contains in fact the magic
; string (avoid truncation of image)
check_magic:
push ebx
push ecx
push edx
push esi
push edi
mov eax, NOF_LOAD_SECTORS ; number of 512-byte sectors
shl eax, 9 ; 512 bytes per sector
mov edx, 0x7e00 ; offset of stage 2
add edx, eax
sub edx, MAGICLEN ; subtract the length of the magic string
mov esi, edx ; now use edx as first string address to compare to
mov edi, COMPARE_MAGIC ; position of second string
mov ecx, MAGICLEN ; length of the magic string
repe cmpsb
jne MAGIC_MISMATCH
jmp MAGIC_OK
MAGIC_MISMATCH:
mov si, MAGIC_OK_MSG
call pm_print_string
call pm_print_newline
xor eax, eax
jmp MAGIC_END
MAGIC_OK:
mov si, MAGIC_NOT_OK_MSG
call pm_print_string
call pm_print_newline
xor eax, eax
mov eax, 1
MAGIC_END:
pop edi
pop esi
pop edx
pop ecx
pop ebx
ret
COMPARE_MAGIC:
db "ABAOSMAGIC", 0
MAGICLEN equ $ - COMPARE_MAGIC
MAGIC_NOT_OK_MSG:
db "Magic signature found", 0
MAGIC_OK_MSG:
db "Magic signature not found!", 0
|
