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global vbe_set_mode
global vbe_find_mode
vbe_set_mode:
mov [width], ax
mov [height], bx
mov [bpp], cl
sti
; Get VBE BIOS info
push es
mov ax, 0x4F00
mov di, [vbe_info]
int 0x10
pop es
; Check if BIOS has VBE support
cmp ax, 0x4F
jne error
mov ax, word[vbe_info.video_modes]
mov [offset], ax
mov ax, word[vbe_info.video_modes+2]
mov [mode_segment], ax
mov ax, [mode_segment]
mov fs, ax
mov si, [offset]
vbe_find_mode:
mov dx, [fs:si]
add si, 2
mov [offset], si
mov [mode], dx
mov ax, 0
mov fs, ax
cmp [mode], word 0xFFFF
je error
; Get VBE mode info
push es
mov ax, 0x4F01
mov cx, [mode]
mov di, [vbe_mode_info]
int 0x10
pop es
cmp ax, 0x4F
jne error
mov ax, [width]
cmp ax, [vbe_mode_info.width]
jne next_mode
mov ax, [height]
cmp ax, [vbe_mode_info.height]
jne next_mode
mov al, [bpp]
cmp al, [vbe_mode_info.bpp]
jne next_mode
; Found best mode!
mov ax, [width]
mov word[vbe_best.width], ax
mov ax, [height]
mov word[vbe_best.height], ax
mov eax, [vbe_mode_info.framebuffer]
mov dword[vbe_best.framebuffer], eax
mov ax, [vbe_mode_info.pitch]
mov word[vbe_best.bytes_per_line], ax
mov eax, 0
mov al, [bpp]
mov byte[vbe_best.bpp], al
shr eax, 3
mov dword[vbe_best.bytes_per_pixel], eax
mov ax, [width]
shr ax, 3
dec ax
mov word[vbe_best.x_cur_max], ax
mov ax, [height]
shr ax, 4
dec ax
mov word[vbe_best.y_cur_max], ax
; Set the mode
push es
mov ax, 0x4F02
mov bx, [mode]
or bx, 0x4000
mov di, 0
int 0x10
pop es
cmp ax, 0x4F
jne error
clc
ret
next_mode:
mov ax, [mode_segment]
mov fs, ax
mov si, [offset]
jmp vbe_find_mode
error:
stc
ret
width dw 0
height dw 0
bpp db 0
mode_segment dw 0
offset dw 0
mode dw 0
vbe_info:
.signature db "VESA"
.version dw 0
.oem dd 0
.capabilities dd 0
.video_modes dd 0
.video_memory dw 0
.software_rev dw 0
.vendor dd 0
.product_name dd 0
.product_rev dd 0
.reserved times 222 db 0
.oem_data times 256 db 0
vbe_mode_info:
.attributes dw 0
.window_a db 0
.window_b db 0
.granularity dw 0
.window_size dw 0
.segment_a dw 0
.segment_b dw 0
.win_func_ptr dd 0
.pitch dw 0
.width dw 0
.height dw 0
.w_char db 0
.y_char db 0
.planes db 0
.bpp db 0
.banks db 0
.memory_model db 0
.bank_size db 0
.image_pages db 0
.reserved0 db 0
.red_mask db 0
.red_position db 0
.green_mask db 0
.green_position db 0
.blue_mask db 0
.blue_position db 0
.reserved_mask db 0
.reserved_position db 0
.direct_color_attributes db 0
.framebuffer dd 0
.off_screen_mem_off dd 0
.off_screen_mem_size dw 0
.reserved1 times 206 db 0
vbe_best:
.bpp db 0
.height dw 0
.width dw 0
.mode dw 0
.framebuffer dd 0
.bytes_per_line dw 0
.bytes_per_pixel dd 0
.x_cur_max dw 0
.y_cur_max dw 0
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