!
! Display adapter & video mode setup, version 2.12 (25-May-98)
!
! Copyright (C) 1995 -- 1998 Martin Mares <mj@atrey.karlin.mff.cuni.cz>
! Based on the original setup.S code (C) Linus Torvalds and Mats Anderson
!
#include <linux/config.h> /* for CONFIG_VIDEO_* */
! Enable autodetection of SVGA adapters and modes. If you really need this
! feature, drop me a mail as I think of removing it some day...
#undef CONFIG_VIDEO_SVGA
! Enable autodetection of VESA modes
#define CONFIG_VIDEO_VESA
! Enable compacting of mode table
#define CONFIG_VIDEO_COMPACT
! Retain screen contents when switching modes
#define CONFIG_VIDEO_RETAIN
! Enable local mode list
#undef CONFIG_VIDEO_LOCAL
! Force 400 scan lines for standard modes (hack to fix bad behaviour
! of certain broken BIOS'es -- don't use unless needed)
#undef CONFIG_VIDEO_400_HACK
! A special hack allowing to force specific BIOS mode ID along with specific
! dimensions. Especially useful for certain X-Window graphics mode hacks
! (e.g., 800x600 modes on IBM ThinkPad).
#undef CONFIG_VIDEO_GFX_HACK
#define VIDEO_GFX_BIOS_AX 0x4f02 /* 800x600 on ThinkPad */
#define VIDEO_GFX_BIOS_BX 0x0102
#define VIDEO_GFX_DUMMY_RESOLUTION 0x6425 /* 100x37 */
! This code uses an extended set of video mode numbers. These include:
! Aliases for standard modes
! NORMAL_VGA (-1)
! EXTENDED_VGA (-2)
! ASK_VGA (-3)
! Video modes numbered by menu position -- NOT RECOMMENDED because of lack
! of compatibility when extending the table. These are between 0x00 and 0xff.
#define VIDEO_FIRST_MENU 0x0000
! Standard BIOS video modes (BIOS number + 0x0100)
#define VIDEO_FIRST_BIOS 0x0100
! VESA BIOS video modes (VESA number + 0x0200)
#define VIDEO_FIRST_VESA 0x0200
! Video7 special modes (BIOS number + 0x0900)
#define VIDEO_FIRST_V7 0x0900
! Special video modes
#define VIDEO_FIRST_SPECIAL 0x0f00
#define VIDEO_80x25 0x0f00
#define VIDEO_8POINT 0x0f01
#define VIDEO_80x43 0x0f02
#define VIDEO_80x28 0x0f03
#define VIDEO_CURRENT_MODE 0x0f04
#define VIDEO_80x30 0x0f05
#define VIDEO_80x34 0x0f06
#define VIDEO_80x60 0x0f07
#define VIDEO_GFX_HACK 0x0f08
#define VIDEO_LAST_SPECIAL 0x0f09
! Video modes given by resolution
#define VIDEO_FIRST_RESOLUTION 0x1000
! The "recalculate timings" flag
#define VIDEO_RECALC 0x8000
! Positions of various video parameters passed to the kernel
! (see also include/linux/tty.h)
#define PARAM_CURSOR_POS 0x00
#define PARAM_VIDEO_PAGE 0x04
#define PARAM_VIDEO_MODE 0x06
#define PARAM_VIDEO_COLS 0x07
#define PARAM_VIDEO_EGA_BX 0x0a
#define PARAM_VIDEO_LINES 0x0e
#define PARAM_HAVE_VGA 0x0f
#define PARAM_FONT_POINTS 0x10
#define PARAM_LFB_WIDTH 0x12
#define PARAM_LFB_HEIGHT 0x14
#define PARAM_LFB_DEPTH 0x16
#define PARAM_LFB_BASE 0x18
#define PARAM_LFB_SIZE 0x1c
#define PARAM_LFB_LINELENGTH 0x24
#define PARAM_LFB_COLORS 0x26
! Define DO_STORE according to CONFIG_VIDEO_RETAIN
#ifdef CONFIG_VIDEO_RETAIN
#define DO_STORE call store_screen
#else
#define DO_STORE
#endif /* CONFIG_VIDEO_RETAIN */
!
! This is the main entry point called by setup.S
!
! Input:
! DS pointing to the boot sector
video: push ds ! We use different segments
push ds ! FS contains original DS
pop fs
push cs ! DS is equal to CS
pop ds
push cs ! ES is equal to CS
pop es
xor ax,ax
mov gs,ax ! GS is zero
cld
call basic_detect ! Basic adapter type testing (EGA/VGA/MDA/CGA)
#ifdef CONFIG_VIDEO_SELECT
seg fs ! User-selected video mode
mov ax,[0x01fa]
cmp ax,#ASK_VGA ! Bring up the menu
jz vid2
call mode_set ! Set the mode
jc vid1
lea si,badmdt ! Invalid mode ID
call prtstr
vid2: call mode_menu
vid1:
#ifdef CONFIG_VIDEO_RETAIN
call restore_screen ! Restore screen contents
#endif /* CONFIG_VIDEO_RETAIN */
#endif /* CONFIG_VIDEO_SELECT */
call mode_params ! Store mode parameters
pop ds ! Restore original DS
ret
!
! Detect if we have CGA, MDA, EGA or VGA and pass it to the kernel.
!
basic_detect:
seg fs ! Default is no VGA
movb [PARAM_HAVE_VGA],#0
mov ah,#0x12 ! Check EGA/VGA
mov bl,#0x10
int 0x10
seg fs
mov [PARAM_VIDEO_EGA_BX],bx ! Used for identification of EGA in the kernel
cmp bl,#0x10 ! No, this is a CGA/MDA/HGA card.
je basret
incb [adapter]
mov ax,#0x1a00 ! Check for EGA/VGA discrimination
int 0x10
cmp al,#0x1a ! 1a means VGA, anything else EGA
jne basret
seg fs
incb [PARAM_HAVE_VGA] ! We've detected a VGA
incb [adapter]
basret: ret
!
! Store the video mode parameters for later usage by the kernel.
! This is done by asking the BIOS except for the rows/columns
! parameters in the default 80x25 mode -- these are set directly,
! because some very obscure BIOSes supply insane values.
!
mode_params:
#ifdef CONFIG_VIDEO_SELECT
cmpb [graphic_mode],#0
jnz mopar_gr
#endif
mov ah,#0x03 ! Read cursor position
xor bh,bh
int 0x10
seg fs
mov [PARAM_CURSOR_POS],dx
mov ah,#0x0f ! Read page/mode/width
int 0x10
seg fs
mov [PARAM_VIDEO_PAGE],bx
seg fs
mov [PARAM_VIDEO_MODE],ax ! Video mode and screen width
cmp al,#7 ! MDA/HGA => segment differs
jnz mopar0
mov [video_segment],#0xb000
mopar0: seg gs ! Font size
mov ax,[0x485]
seg fs
mov [PARAM_FONT_POINTS],ax ! (valid only on EGA/VGA)
mov ax,[force_size] ! Forced size?
or ax,ax
jz mopar1
seg fs
mov [PARAM_VIDEO_COLS],ah
seg fs
mov [PARAM_VIDEO_LINES],al
ret
mopar1: mov al,#25
cmpb [adapter],#0 ! If we are on CGA/MDA/HGA, the screen must
jz mopar2 ! have 25 lines.
seg gs ! On EGA/VGA, use the EGA+ BIOS variable
mov al,[0x484] ! containing maximal line number.
inc al
mopar2: seg fs
movb [PARAM_VIDEO_LINES],al
ret
#ifdef CONFIG_VIDEO_SELECT
!
! Fetching of VESA frame buffer parameters
!
mopar_gr:
lea di,modelist+1024
seg fs
movb [PARAM_HAVE_VGA],#0x23
mov ax,(di+16)
seg fs
mov [PARAM_LFB_LINELENGTH],ax
mov ax,(di+18)
seg fs
mov [PARAM_LFB_WIDTH],ax
mov ax,(di+20)
seg fs
mov [PARAM_LFB_HEIGHT],ax
mov al,(di+25)
mov ah,#0
seg fs
mov [PARAM_LFB_DEPTH],ax
mov eax,(di+40)
seg fs
mov [PARAM_LFB_BASE],eax
mov eax,(di+44)
seg fs
mov [PARAM_LFB_SIZE],eax
mov eax,(di+31)
seg fs
mov [PARAM_LFB_COLORS],eax
mov eax,(di+35)
seg fs
mov [PARAM_LFB_COLORS+4],eax
ret
!
! The video mode menu
!
mode_menu:
lea si,keymsg ! "Return/Space/Timeout" message
call prtstr
call flush
nokey: call getkt
cmp al,#0x0d ! ENTER ?
je listm ! yes - manual mode selection
cmp al,#0x20 ! SPACE ?
je defmd1 ! no - repeat
call beep
jmp nokey
defmd1: ret ! No mode selected => use the 80x25 default
listm: call mode_table ! We need a mode table to be listed
listm0: lea si,name_bann ! Print adapter name
call prtstr
mov si,[card_name]
or si,si
jnz an2
mov al,[adapter]
lea si,old_name
or al,al
jz an1
lea si,ega_name
dec al
jz an1
lea si,vga_name
jmp an1
an2: call prtstr
lea si,svga_name
an1: call prtstr
lea si,listhdr ! Table header
call prtstr
mov dl,#0x30 ! DL holds mode number
lea si,modelist
lm1: cmp (si),#ASK_VGA ! End?
jz lm2
mov al,dl ! Menu selection number
call prtchr
call prtsp2
lodsw
call prthw ! Mode ID
call prtsp2
mov al,(si+1)
call prtdec ! Rows
mov al,#0x78 ! 'x'
call prtchr
lodsw
call prtdec ! Columns
mov al,#0x0d ! New line
call prtchr
mov al,#0x0a
call prtchr
inc dl ! Next character
cmp dl,#0x3a
jnz lm1
mov dl,#0x61
jmp lm1
lm2: lea si,prompt ! Mode prompt
call prtstr
lea di,edit_buf ! Editor buffer
lm3: call getkey
cmp al,#0x0d ! Enter?
jz lment
cmp al,#0x08 ! Backspace?
jz lmbs
cmp al,#0x20 ! Printable?
jc lm3
cmp di,#edit_buf+4 ! Enough space?
jz lm3
stosb
call prtchr
jmp lm3
lmbs: cmp di,#edit_buf ! Backspace
jz lm3
dec di
mov al,#0x08
call prtchr
call prtspc
mov al,#0x08
call prtchr
jmp lm3
lment: movb (di),#0
lea si,crlft
call prtstr
lea si,edit_buf
cmpb (si),#0 ! Empty string => use default mode
jz lmdef
cmpb (si+1),#0 ! One character => menu selection
jz mnusel
cmp (si),#0x6373 ! "scan" => mode scanning
jnz lmhx
cmp (si+2),#0x6e61
jz lmscan
lmhx: xor bx,bx ! Else => mode ID in hex
lmhex: lodsb
or al,al
jz lmuse1
sub al,#0x30
jc lmbad
cmp al,#10
jc lmhx1
sub al,#7
and al,#0xdf
cmp al,#10
jc lmbad
cmp al,#16
jnc lmbad
lmhx1: shl bx,#4
or bl,al
jmp lmhex
lmuse1: mov ax,bx
jmp lmuse
mnusel: lodsb ! Menu selection
xor ah,ah
sub al,#0x30
jc lmbad
cmp al,#10
jc lmuse
cmp al,#0x61-0x30
jc lmbad
sub al,#0x61-0x30-10
cmp al,#36
jnc lmbad
lmuse: call mode_set
jc lmdef
lmbad: lea si,unknt
call prtstr
br lm2
lmscan: cmpb [adapter],#0 ! Scanning supported only on EGA/VGA
jz lmbad
mov [mt_end],#0 ! Scanning of modes: done as new autodetection
movb [scanning],#1
call mode_table
br listm0
lmdef: ret
!
! Additional parts of mode_set... (relative jumps, you know)
!
setv7: ! Video7 extended modes
DO_STORE
sub bh,#VIDEO_FIRST_V7>>8
mov ax,#0x6f05
int 0x10
stc
ret
_setrec: br setrec ! Ugly...
_set_80x25: br set_80x25
!
! Aliases for backward compatibility.
!
setalias:
mov ax,#VIDEO_80x25
inc bx
jz mode_set
mov al,#VIDEO_8POINT-VIDEO_FIRST_SPECIAL
inc bx
jnz setbad
! Fall-through!
!
! Setting of user mode (AX=mode ID) => CF=success
!
mode_set:
mov bx,ax
cmp ah,#0xff
jz setalias
test ah,#VIDEO_RECALC>>8
jnz _setrec
cmp ah,#VIDEO_FIRST_RESOLUTION>>8
jnc setres
cmp ah,#VIDEO_FIRST_SPECIAL>>8
jz setspc
cmp ah,#VIDEO_FIRST_V7>>8
jz setv7
cmp ah,#VIDEO_FIRST_VESA>>8
jnc check_vesa
or ah,ah
jz setmenu
dec ah
jz setbios
setbad: clc
movb [do_restore],#0 ! The screen needn't be restored
ret
setvesa:
DO_STORE
sub bh,#VIDEO_FIRST_VESA>>8
mov ax,#0x4f02 ! VESA BIOS mode set call
int 0x10
cmp ax,#0x004f ! AL=4f if implemented, AH=0 if OK
jnz setbad
stc
ret
setbios:
DO_STORE
int 0x10 ! Standard BIOS mode set call
push bx
mov ah,#0x0f ! Check if really set
int 0x10
pop bx
cmp al,bl
jnz setbad
stc
ret
setspc: xor bh,bh ! Set special mode
cmp bl,#VIDEO_LAST_SPECIAL-VIDEO_FIRST_SPECIAL
jnc setbad
add bx,bx
.word 0xa7ff, spec_inits ! JMP [BX+spec_inits]
setmenu:
or al,al ! 80x25 is an exception
jz _set_80x25
push bx ! Set mode chosen from menu
call mode_table ! Build the mode table
pop ax
shl ax,#2
add si,ax
cmp si,di
jnc setbad
mov ax,(si) ! Fetch mode ID
_m_s: jmp mode_set
setres:
push bx ! Set mode chosen by its resolution
call mode_table
pop bx
xchg bh,bl
setr1: lodsw
cmp ax,#ASK_VGA ! End of the list?
jz setbad
lodsw
cmp ax,bx
jnz setr1
mov ax,(si-4) ! Fetch mode ID
jmp _m_s
check_vesa:
lea di,modelist+1024
sub bh,#VIDEO_FIRST_VESA>>8
mov cx,bx ! Get mode information structure
mov ax,#0x4f01
int 0x10
add bh,#VIDEO_FIRST_VESA>>8
cmp ax,#0x004f
jnz setbad
mov al,(di) ! Check capabilities.
and al,#0x19
cmp al,#0x09
jz setvesa ! this is a text mode
mov al,(di) ! Check capabilities.
and al,#0x99
cmp al,#0x99
jnz _setbad ! to bad, no linear frame buffer
sub bh,#VIDEO_FIRST_VESA>>8
or bx,#0x4000 ! want use linear frame buffer
mov ax,#0x4f02 ! VESA BIOS mode set call
int 0x10
cmp ax,#0x004f ! AL=4f if implemented, AH=0 if OK
jnz _setbad
movb [graphic_mode],#1 ! flag graphic mode
movb [do_restore],#0 ! no screen restore
stc
ret
_setbad: br setbad ! Ugly...
!
! Recalculate vertical display end registers -- this fixes various
! inconsistencies of extended modes on many adapters. Called when
! the VIDEO_RECALC flag is set in the mode ID.
!
setrec: sub ah,#VIDEO_RECALC>>8 ! Set the base mode
call mode_set
jnc rct3
seg gs ! Font size in pixels
mov ax,[0x485]
seg gs ! Number of rows
mov bl,[0x484]
inc bl
mul bl ! Number of visible
dec ax ! scan lines - 1
mov dx,#0x3d4
mov bx,ax
mov al,#0x12 ! Lower 8 bits
mov ah,bl
out dx,ax
mov al,#0x07 ! Bits 8 and 9 in the overflow register
call inidx
xchg ah,al
and ah,#0xbd
shr bh,#1
jnc rct1
or ah,#0x02
rct1: shr bh,#1
jnc rct2
or ah,#0x40
rct2: mov al,#0x07
out dx,ax
stc
rct3: ret
!
! Table of routines for setting of the special modes.
!
spec_inits:
.word set_80x25
.word set_8pixel
.word set_80x43
.word set_80x28
.word set_current
.word set_80x30
.word set_80x34
.word set_80x60
.word set_gfx
!
! Set the 80x25 mode. If already set, do nothing.
!
set_80x25:
mov [force_size],#0x5019 ! Override possibly broken BIOS vars
use_80x25:
#ifdef CONFIG_VIDEO_400_HACK
mov ax,#0x1202 ! Force 400 scan lines
mov bl,#0x30
int 0x10
#else
mov ah,#0x0f ! Get current mode ID
int 0x10
cmp ax,#0x5007 ! Mode 7 (80x25 mono) is the only one available
jz st80 ! on CGA/MDA/HGA and is also available on EGAM
cmp ax,#0x5003 ! Unknown mode => force 80x25 color
jnz force3
st80: cmpb [adapter],#0 ! CGA/MDA/HGA => mode 3/7 is always 80x25
jz set80
seg gs ! This is EGA+ -- beware of 80x50 etc.
mov al,[0x0484]
or al,al ! Some buggy BIOSs set 0 rows
jz set80
cmp al,#24 ! Let's hope this is correct
jz set80
#endif /* CONFIG_VIDEO_400_HACK */
force3: DO_STORE
mov ax,#0x0003 ! Forced set
int 0x10
set80: stc
ret
!
! Set the 80x50/80x43 8-pixel mode. Simple BIOS calls.
!
set_8pixel:
DO_STORE
call use_80x25 ! The base is 80x25
set_8pt:
mov ax,#0x1112 ! Use 8x8 font
xor bl,bl
int 0x10
mov ax,#0x1200 ! Use alternate print screen
mov bl,#0x20
int 0x10
mov ax,#0x1201 ! Turn off cursor emulation
mov bl,#0x34
int 0x10
mov ah,#0x01 ! Define cursor (scan lines 6 to 7)
mov cx,#0x0607
int 0x10
set_current:
stc
ret
!
! Set the 80x28 mode. This mode works on all VGA's, because it's a standard
! 80x25 mode with 14-point fonts instead of 16-point.
!
set_80x28:
DO_STORE
call use_80x25 ! The base is 80x25
set14: mov ax,#0x1111 ! Use 9x14 font
xor bl,bl
int 0x10
mov ah,#0x01 ! Define cursor (scan lines 11 to 12)
mov cx,#0x0b0c
int 0x10
stc
ret
!
! Set the 80x43 mode. This mode is works on all VGA's.
! It's a 350-scanline mode with 8-pixel font.
!
set_80x43:
DO_STORE
mov ax,#0x1201 ! Set 350 scans
mov bl,#0x30
int 0x10
mov ax,#0x0003 ! Reset video mode
int 0x10
jmp set_8pt ! Use 8-pixel font
!
! Set the 80x30 mode (all VGA's). 480 scanlines, 16-pixel font.
!
set_80x30:
call use_80x25 ! Start with real 80x25
DO_STORE
mov dx,#0x3cc ! Get CRTC port
in al,dx
mov dl,#0xd4
ror al,#1 ! Mono or color?
jc set48a
mov dl,#0xb4
set48a: mov ax,#0x0c11 ! Vertical sync end (also unlocks CR0-7)
call outidx
mov ax,#0x0b06 ! Vertical total
call outidx
mov ax,#0x3e07 ! (Vertical) overflow
call outidx
mov ax,#0xea10 ! Vertical sync start
call outidx
mov ax,#0xdf12 ! Vertical display end
call outidx
mov ax,#0xe715 ! Vertical blank start
call outidx
mov ax,#0x0416 ! Vertical blank end
call outidx
push dx
mov dl,#0xcc ! Misc output register (read)
in al,dx
mov dl,#0xc2 ! (write)
and al,#0x0d ! Preserve clock select bits and color bit
or al,#0xe2 ! Set correct sync polarity
out dx,al
pop dx
mov [force_size],#0x501e
stc ! That's all.
ret
!
! Set the 80x34 mode (all VGA's). 480 scans, 14-pixel font.
!
set_80x34:
call set_80x30 ! Set 480 scans
call set14 ! And 14-pt font
mov ax,#0xdb12 ! VGA vertical display end
mov [force_size],#0x5022
setvde: call outidx
stc
ret
!
! Set the 80x60 mode (all VGA's). 480 scans, 8-pixel font.
!
set_80x60:
call set_80x30 ! Set 480 scans
call set_8pt ! And 8-pt font
mov ax,#0xdf12 ! VGA vertical display end
mov [force_size],#0x503c
jmp setvde
!
! Special hack for ThinkPad graphics
!
set_gfx:
#ifdef CONFIG_VIDEO_GFX_HACK
mov ax,# VIDEO_GFX_BIOS_AX
mov bx,# VIDEO_GFX_BIOS_BX
int 0x10
mov [force_size],# VIDEO_GFX_DUMMY_RESOLUTION
stc
#endif
ret
#ifdef CONFIG_VIDEO_RETAIN
!
! Store screen contents to temporary buffer.
!
store_screen:
cmpb [do_restore],#0 ! Already stored?
jnz stsr
testb [loadflags],#CAN_USE_HEAP ! Have we space for storing?
jz stsr
push ax
push bx
push [force_size] ! Don't force specific size
mov [force_size],#0
call mode_params ! Obtain params of current mode
pop [force_size]
seg fs
mov ah,[PARAM_VIDEO_LINES]
seg fs
mov al,[PARAM_VIDEO_COLS]
mov bx,ax ! BX=dimensions
mul ah
mov cx,ax ! CX=number of characters to store
add ax,ax ! Calculate image size
add ax,#modelist+1024+4
cmp ax,[heap_end_ptr]
jnc sts1 ! Unfortunately, out of memory
seg fs ! Store mode params
mov ax,[PARAM_CURSOR_POS]
lea di,modelist+1024
stosw
mov ax,bx
stosw
push ds ! Store the screen
mov ds,[video_segment]
xor si,si
rep
movsw
pop ds
incb [do_restore] ! Screen will be restored later
sts1: pop bx
pop ax
stsr: ret
!
! Restore screen contents from temporary buffer.
!
restore_screen:
cmpb [do_restore],#0 ! Has the screen been stored?
jz res1
call mode_params ! Get parameters of current mode
seg fs
mov cl,[PARAM_VIDEO_LINES]
seg fs
mov ch,[PARAM_VIDEO_COLS]
lea si,modelist+1024 ! Screen buffer
lodsw ! Set cursor position
mov dx,ax
cmp dh,cl
jc res2
mov dh,cl
dec dh
res2: cmp dl,ch
jc res3
mov dl,ch
dec dl
res3: mov ah,#0x02
mov bh,#0x00
int 0x10
lodsw ! Display size
mov dl,ah ! DL=number of lines
mov ah,#0 ! BX=physical length of orig. line
mov bx,ax
cmp dl,cl ! Too many?
jc res4
push ax
mov al,dl
sub al,cl
mul bl
add si,ax
add si,ax
pop ax
mov dl,cl
res4: cmp al,ch ! Too wide?
jc res5
mov al,ch ! AX=width of src. line
res5: mov cl,#0
xchg cl,ch
mov bp,cx ! BP=width of dest. line
push es
mov es,[video_segment]
xor di,di ! Move the data
add bx,bx ! Convert BX and BP to _bytes_
add bp,bp
res6: push si
push di
mov cx,ax
rep
movsw
pop di
pop si
add di,bp
add si,bx
dec dl
jnz res6
pop es ! Done
res1: ret
#endif /* CONFIG_VIDEO_RETAIN */
!
! Write to indexed VGA register (AL=index, AH=data, DX=index reg. port)
!
outidx: out dx,al
push ax
mov al,ah
inc dx
out dx,al
dec dx
pop ax
ret
!
! Build the table of video modes (stored after the setup.S code at the
! `modelist' label. Each video mode record looks like:
! .word MODE-ID (our special mode ID (see above))
! .byte rows (number of rows)
! .byte columns (number of columns)
! Returns address of the end of the table in DI, the end is marked
! with a ASK_VGA ID.
!
mode_table:
mov di,[mt_end] ! Already filled?
or di,di
jnz mtab1x
lea di,modelist ! Store standard modes:
mov eax,#VIDEO_80x25 + 0x50190000 ! The 80x25 mode (ALL)
stosd
mov al,[adapter] ! CGA/MDA/HGA -- no more modes
or al,al
jz mtabe
dec al
jnz mtabv
mov eax,#VIDEO_8POINT + 0x502b0000 ! The 80x43 EGA mode
stosd
jmp mtabe
mtab1x: jmp mtab1
mtabv: lea si,vga_modes ! All modes for std VGA
mov cx,#vga_modes_end-vga_modes
rep ! I'm unable to use movsw as I don't know how to store a half
movsb ! of the expression above to cx without using explicit shr.
cmpb [scanning],#0 ! Mode scan requested?
jz mscan1
call mode_scan
mscan1:
#ifdef CONFIG_VIDEO_LOCAL
call local_modes
#endif /* CONFIG_VIDEO_LOCAL */
#ifdef CONFIG_VIDEO_VESA
call vesa_modes ! Detect VESA VGA modes
#endif /* CONFIG_VIDEO_VESA */
#ifdef CONFIG_VIDEO_SVGA
cmpb [scanning],#0 ! Bypass when scanning
jnz mscan2
call svga_modes ! Detect SVGA cards & modes
mscan2:
#endif /* CONFIG_VIDEO_SVGA */
mtabe:
#ifdef CONFIG_VIDEO_COMPACT
lea si,modelist ! Compact video mode list if requested.
mov dx,di
mov di,si
cmt1: cmp si,dx ! Scan all modes
jz cmt2
lea bx,modelist ! Find in previous entries
mov cx,(si+2)
cmt3: cmp si,bx
jz cmt4
cmp cx,(bx+2) ! Found => don't copy this entry
jz cmt5
add bx,#4
jmp cmt3
cmt4: movsd ! Copy entry
jmp cmt1
cmt5: add si,#4 ! Skip entry
jmp cmt1
cmt2:
#endif /* CONFIG_VIDEO_COMPACT */
mov (di),#ASK_VGA ! End marker
mov [mt_end],di
mtab1: lea si,modelist ! Returning: SI=mode list, DI=list end
ret0: ret
! Modes usable on all standard VGAs
vga_modes:
.word VIDEO_8POINT
.word 0x5032 ! 80x50
.word VIDEO_80x43
.word 0x502b ! 80x43
.word VIDEO_80x28
.word 0x501c ! 80x28
.word VIDEO_80x30
.word 0x501e ! 80x30
.word VIDEO_80x34
.word 0x5022 ! 80x34
.word VIDEO_80x60
.word 0x503c ! 80x60
#ifdef CONFIG_VIDEO_GFX_HACK
.word VIDEO_GFX_HACK
.word VIDEO_GFX_DUMMY_RESOLUTION
#endif
vga_modes_end:
!
! Detect VESA modes.
!
#ifdef CONFIG_VIDEO_VESA
vesa_modes:
cmpb [adapter],#2 ! VGA only
jnz ret0
mov bp,di ! BP=original mode table end
add di,#0x200 ! Buffer space
mov ax,#0x4f00 ! VESA Get card info call
int #0x10
mov di,bp
cmp ax,#0x004f ! Successful?
jnz ret0
cmp (di+0x200),#0x4556
jnz ret0
cmp (di+0x202),#0x4153
jnz ret0
mov [card_name],#vesa_name ! Set name to "VESA VGA"
push gs
lgs si,(di+0x20e) ! GS:SI=mode list
mov cx,#128 ! Iteration limit
vesa1: seg gs ! Get next mode in the list
lodsw
cmp ax,#0xffff ! End of the table?
jz vesar
cmp ax,#0x0080 ! Check validity of mode ID
jc vesa2
or ah,ah ! Valid IDs are 0x0000-0x007f and 0x0100-0x07ff
jz vesan ! [Certain BIOSes erroneously report 0x80-0xff]
cmp ax,#0x0800
jnc vesae
vesa2: push cx
mov cx,ax ! Get mode information structure
mov ax,#0x4f01
int 0x10
mov bx,cx ! BX=mode number
add bh,#VIDEO_FIRST_VESA>>8
pop cx
cmp ax,#0x004f
jnz vesan ! Don't report errors (buggy BIOSES :-[ )
mov al,(di) ! Check capabilities. We require
and al,#0x19 ! a color text mode.
cmp al,#0x09
jnz vesan
cmp (di+8),#0xb800 ! Standard video memory address required
jnz vesan
testb (di),#2 ! Mode characteristics supplied?
mov (di),bx ! Store mode number
jz vesa3
xor dx,dx
mov bx,(di+0x12) ! Width
or bh,bh
jnz vesan
mov (di+3),bl
mov ax,(di+0x14) ! Height
or ah,ah
jnz vesan
mov (di+2),al
mul bl
cmp ax,#8193 ! Small enough for Linux console driver?
jnc vesan
jmp vesaok
vesa3: sub bx,#0x8108 ! This mode has no detailed info specified,
jc vesan ! so it must be a standard VESA mode.
cmp bx,#5
jnc vesan
mov ax,(bx+vesa_text_mode_table)
mov (di+2),ax
vesaok: add di,#4 ! The mode is valid. Store it.
vesan: loop vesa1 ! Next mode. Limit exceeded => error
vesae: lea si,vesaer
call prtstr
mov di,bp ! Discard already found modes.
vesar: pop gs
ret
!
! Dimensions of standard VESA text modes
!
vesa_text_mode_table:
db 60, 80 ! 0108
db 25, 132 ! 0109
db 43, 132 ! 010A
db 50, 132 ! 010B
db 60, 132 ! 010C
#endif /* CONFIG_VIDEO_VESA */
!
! Scan for video modes. A bit dirty, but should work.
!
mode_scan:
mov cx,#0x0100 ! Start with mode 0
scm1: mov ah,#0 ! Test the mode
mov al,cl
int 0x10
mov ah,#0x0f
int 0x10
cmp al,cl
jnz scm2 ! Mode not set
mov dx,#0x3c0 ! Test if it's a text mode
mov al,#0x10 ! Mode bits
call inidx
and al,#0x03
jnz scm2
mov dl,#0xce ! Another set of mode bits
mov al,#0x06
call inidx
shr al,#1
jc scm2
mov dl,#0xd4 ! Cursor location
mov al,#0x0f
call inidx
or al,al
jnz scm2
mov ax,cx ! OK, store the mode
stosw
seg gs ! Number of rows
mov al,[0x484]
inc al
stosb
seg gs ! Number of columns
mov ax,[0x44a]
stosb
scm2: inc cl
jns scm1
mov ax,#0x0003 ! Return back to mode 3
int 0x10
ret
tstidx: out dx,ax ! OUT DX,AX and inidx
inidx: out dx,al ! Read from indexed VGA register
inc dx ! AL=index, DX=index reg port -> AL=data
in al,dx
dec dx
ret
!
! Try to detect type of SVGA card and supply (usually approximate) video
! mode table for it.
!
#ifdef CONFIG_VIDEO_SVGA
svga_modes:
lea si,svga_table ! Test all known SVGA adapters
dosvga: lodsw
mov bp,ax ! Default mode table
or ax,ax
jz didsv1
lodsw ! Pointer to test routine
push si
push di
push es
mov bx,#0xc000
mov es,bx
call ax ! Call test routine
pop es
pop di
pop si
or bp,bp
jz dosvga
mov si,bp ! Found, copy the modes
mov ah,[svga_prefix]
cpsvga: lodsb
or al,al
jz didsv
stosw
movsw
jmp cpsvga
didsv: mov [card_name],si ! Store pointer to card name
didsv1: ret
!
! Table of all known SVGA cards. For each card, we store a pointer to
! a table of video modes supported by the card and a pointer to a routine
! used for testing of presence of the card. The video mode table is always
! followed by the name of the card or the chipset.
!
svga_table:
.word ati_md, ati_test
.word oak_md, oak_test
.word paradise_md, paradise_test
.word realtek_md, realtek_test
.word s3_md, s3_test
.word chips_md, chips_test
.word video7_md, video7_test
.word cirrus5_md, cirrus5_test
.word cirrus6_md, cirrus6_test
.word cirrus1_md, cirrus1_test
.word ahead_md, ahead_test
.word everex_md, everex_test
.word genoa_md, genoa_test
.word trident_md, trident_test
.word tseng_md, tseng_test
.word 0
!
! Test routines and mode tables:
!
! S3 - The test algorithm was taken from the SuperProbe package
! for XFree86 1.2.1. Report bugs to Christoph.Niemann@linux.org
s3_test:
mov cx,#0x0f35 ! we store some constants in cl/ch
mov dx,#0x03d4
movb al,#0x38
call inidx
mov bh,al ! store current value of CRT-register 0x38
mov ax,#0x0038
call outidx ! disable writing to special regs
movb al,cl ! check whether we can write special reg 0x35
call inidx
movb bl,al ! save the current value of CRT reg 0x35
andb al,#0xf0 ! clear bits 0-3
movb ah,al
movb al,cl ! and write it to CRT reg 0x35
call outidx
call inidx ! now read it back
andb al,ch ! clear the upper 4 bits
jz s3_2 ! the first test failed. But we have a
movb ah,bl ! second chance
mov al,cl
call outidx
jmp s3_1 ! do the other tests
s3_2: mov ax,cx ! load ah with 0xf and al with 0x35
orb ah,bl ! set the upper 4 bits of ah with the orig value
call outidx ! write ...
call inidx ! ... and reread
andb al,cl ! turn off the upper 4 bits
push ax
movb ah,bl ! restore old value in register 0x35
movb al,cl
call outidx
pop ax
cmp al,ch ! setting lower 4 bits was successful => bad
je no_s3 ! writing is allowed => this is not an S3
s3_1: mov ax,#0x4838 ! allow writing to special regs by putting
call outidx ! magic number into CRT-register 0x38
movb al,cl ! check whether we can write special reg 0x35
call inidx
movb bl,al
andb al,#0xf0
movb ah,al
movb al,cl
call outidx
call inidx
andb al,ch
jnz no_s3 ! no, we can't write => no S3
mov ax,cx
orb ah,bl
call outidx
call inidx
andb al,ch
push ax
movb ah,bl ! restore old value in register 0x35
movb al,cl
call outidx
pop ax
cmp al,ch
jne no_s31 ! writing not possible => no S3
movb al,#0x30
call inidx ! now get the S3 id ...
lea di,idS3
mov cx,#0x10
repne
scasb
je no_s31
movb ah,bh
movb al,#0x38
jmp s3rest
no_s3: movb al,#0x35 ! restore CRT register 0x35
movb ah,bl
call outidx
no_s31: xor bp,bp ! Detection failed
s3rest: movb ah,bh
movb al,#0x38 ! restore old value of CRT register 0x38
br outidx
idS3: .byte 0x81, 0x82, 0x90, 0x91, 0x92, 0x93, 0x94, 0x95
.byte 0xa0, 0xa1, 0xa2, 0xa3, 0xa4, 0xa5, 0xa8, 0xb0
s3_md: .byte 0x54, 0x2b, 0x84
.byte 0x55, 0x19, 0x84
.byte 0
.ascii "S3"
.byte 0
! ATI cards.
ati_test:
lea si,idati
mov di,#0x31
mov cx,#0x09
repe
cmpsb
je atiok
xor bp,bp
atiok: ret
idati: .ascii "761295520"
ati_md: .byte 0x23, 0x19, 0x84
.byte 0x33, 0x2c, 0x84
.byte 0x22, 0x1e, 0x64
.byte 0x21, 0x19, 0x64
.byte 0x58, 0x21, 0x50
.byte 0x5b, 0x1e, 0x50
.byte 0
.ascii "ATI"
.byte 0
! AHEAD
ahead_test:
mov ax,#0x200f
mov dx,#0x3ce
out dx,ax
inc dx
in al,dx
cmp al,#0x20
je isahed
cmp al,#0x21
je isahed
xor bp,bp
isahed: ret
ahead_md:
.byte 0x22, 0x2c, 0x84
.byte 0x23, 0x19, 0x84
.byte 0x24, 0x1c, 0x84
.byte 0x2f, 0x32, 0xa0
.byte 0x32, 0x22, 0x50
.byte 0x34, 0x42, 0x50
.byte 0
.ascii "Ahead"
.byte 0
! Chips & Tech.
chips_test:
mov dx,#0x3c3
in al,dx
or al,#0x10
out dx,al
mov dx,#0x104
in al,dx
mov bl,al
mov dx,#0x3c3
in al,dx
and al,#0xef
out dx,al
cmp bl,#0xa5
je cantok
xor bp,bp
cantok: ret
chips_md:
.byte 0x60, 0x19, 0x84
.byte 0x61, 0x32, 0x84
.byte 0
.ascii "Chips & Technologies"
.byte 0
! Cirrus Logic 5X0
cirrus1_test:
mov dx,#0x3d4
mov al,#0x0c
out dx,al
inc dx
in al,dx
mov bl,al
xor al,al
out dx,al
dec dx
mov al,#0x1f
out dx,al
inc dx
in al,dx
mov bh,al
xor ah,ah
shl al,#4
mov cx,ax
mov al,bh
shr al,#4
add cx,ax
shl cx,#8
add cx,#6
mov ax,cx
mov dx,#0x3c4
out dx,ax
inc dx
in al,dx
and al,al
jnz nocirr
mov al,bh
out dx,al
in al,dx
cmp al,#0x01
je iscirr
nocirr: xor bp,bp
iscirr: mov dx,#0x3d4
mov al,bl
xor ah,ah
shl ax,#8
add ax,#0x0c
out dx,ax
ret
cirrus1_md:
.byte 0x1f, 0x19, 0x84
.byte 0x20, 0x2c, 0x84
.byte 0x22, 0x1e, 0x84
.byte 0x31, 0x25, 0x64
.byte 0
.ascii "Cirrus Logic 5X0"
.byte 0
! Cirrus Logic 54XX
cirrus5_test:
mov dx,#0x3c4
mov al,#6
call inidx
mov bl,al ! BL=backup
mov ax,#6
call tstidx
cmp al,#0x0f
jne c5fail
mov ax,#0x1206
call tstidx
cmp al,#0x12
jne c5fail
mov al,#0x1e
call inidx
mov bh,al
mov ah,bh
and ah,#0xc0
mov al,#0x1e
call tstidx
and al,#0x3f
jne c5xx
mov al,#0x1e
mov ah,bh
or ah,#0x3f
call tstidx
xor al,#0x3f
and al,#0x3f
c5xx: pushf
mov al,#0x1e
mov ah,bh
out dx,ax
popf
je c5done
c5fail: xor bp,bp
c5done: mov al,#6
mov ah,bl
out dx,ax
ret
cirrus5_md:
.byte 0x14, 0x19, 0x84
.byte 0x54, 0x2b, 0x84
.byte 0
.ascii "Cirrus Logic 54XX"
.byte 0
! Cirrus Logic 64XX -- no known extra modes, but must be identified, because
! it's misidentified by the Ahead test.
cirrus6_test:
mov dx,#0x3ce
mov al,#0x0a
call inidx
mov bl,al ! BL=backup
mov ax,#0xce0a
call tstidx
or al,al
jne c2fail
mov ax,#0xec0a
call tstidx
cmp al,#0x01
jne c2fail
mov al,#0xaa
call inidx ! 4X, 5X, 7X and 8X are valid 64XX chip IDs
shr al,#4
sub al,#4
jz c6done
dec al
jz c6done
sub al,#2
jz c6done
dec al
jz c6done
c2fail: xor bp,bp
c6done: mov al,#0x0a
mov ah,bl
out dx,ax
ret
cirrus6_md:
.byte 0
.ascii "Cirrus Logic 64XX"
.byte 0
! Everex / Trident
everex_test:
mov ax,#0x7000
xor bx,bx
int 0x10
cmp al,#0x70
jne noevrx
shr dx,#4
cmp dx,#0x678
je evtrid
cmp dx,#0x236
jne evrxok
evtrid: lea bp,trident_md
evrxok: ret
noevrx: xor bp,bp
ret
everex_md:
.byte 0x03, 0x22, 0x50
.byte 0x04, 0x3c, 0x50
.byte 0x07, 0x2b, 0x64
.byte 0x08, 0x4b, 0x64
.byte 0x0a, 0x19, 0x84
.byte 0x0b, 0x2c, 0x84
.byte 0x16, 0x1e, 0x50
.byte 0x18, 0x1b, 0x64
.byte 0x21, 0x40, 0xa0
.byte 0x40, 0x1e, 0x84
.byte 0
.ascii "Everex/Trident"
.byte 0
! Genoa.
genoa_test:
lea si,idgenoa ! Check Genoa 'clues'
xor ax,ax
seg es
mov al,[0x37]
mov di,ax
mov cx,#0x04
dec si
dec di
l1: inc si
inc di
mov al,(si)
test al,al
jz l2
seg es
cmp al,(di)
l2: loope l1
or cx,cx
je isgen
xor bp,bp
isgen: ret
idgenoa: .byte 0x77, 0x00, 0x99, 0x66
genoa_md:
.byte 0x58, 0x20, 0x50
.byte 0x5a, 0x2a, 0x64
.byte 0x60, 0x19, 0x84
.byte 0x61, 0x1d, 0x84
.byte 0x62, 0x20, 0x84
.byte 0x63, 0x2c, 0x84
.byte 0x64, 0x3c, 0x84
.byte 0x6b, 0x4f, 0x64
.byte 0x72, 0x3c, 0x50
.byte 0x74, 0x42, 0x50
.byte 0x78, 0x4b, 0x64
.byte 0
.ascii "Genoa"
.byte 0
! OAK
oak_test:
lea si,idoakvga
mov di,#0x08
mov cx,#0x08
repe
cmpsb
je isoak
xor bp,bp
isoak: ret
idoakvga: .ascii "OAK VGA "
oak_md: .byte 0x4e, 0x3c, 0x50
.byte 0x4f, 0x3c, 0x84
.byte 0x50, 0x19, 0x84
.byte 0x51, 0x2b, 0x84
.byte 0
.ascii "OAK"
.byte 0
! WD Paradise.
paradise_test:
lea si,idparadise
mov di,#0x7d
mov cx,#0x04
repe
cmpsb
je ispara
xor bp,bp
ispara: ret
idparadise: .ascii "VGA="
paradise_md:
.byte 0x41, 0x22, 0x50
.byte 0x47, 0x1c, 0x84
.byte 0x55, 0x19, 0x84
.byte 0x54, 0x2c, 0x84
.byte 0
.ascii "Paradise"
.byte 0
! Trident.
trident_test:
mov dx,#0x3c4
mov al,#0x0e
out dx,al
inc dx
in al,dx
xchg ah,al
xor al,al
out dx,al
in al,dx
xchg al,ah
mov bl,al ! Strange thing ... in the book this wasn't
and bl,#0x02 ! necessary but it worked on my card which
jz setb2 ! is a trident. Without it the screen goes
and al,#0xfd ! blurred ...
jmp clrb2 !
setb2: or al,#0x02 !
clrb2: out dx,al
and ah,#0x0f
cmp ah,#0x02
je istrid
xor bp,bp
istrid: ret
trident_md:
.byte 0x50, 0x1e, 0x50
.byte 0x51, 0x2b, 0x50
.byte 0x52, 0x3c, 0x50
.byte 0x57, 0x19, 0x84
.byte 0x58, 0x1e, 0x84
.byte 0x59, 0x2b, 0x84
.byte 0x5a, 0x3c, 0x84
.byte 0
.ascii "Trident"
.byte 0
! Tseng.
tseng_test:
mov dx,#0x3cd
in al,dx ! Could things be this simple? :-)
mov bl,al
mov al,#0x55
out dx,al
in al,dx
mov ah,al
mov al,bl
out dx,al
cmp ah,#0x55
je istsen
isnot: xor bp,bp
istsen: ret
tseng_md:
.byte 0x26, 0x3c, 0x50
.byte 0x2a, 0x28, 0x64
.byte 0x23, 0x19, 0x84
.byte 0x24, 0x1c, 0x84
.byte 0x22, 0x2c, 0x84
.byte 0x21, 0x3c, 0x84
.byte 0
.ascii "Tseng"
.byte 0
! Video7.
video7_test:
mov dx,#0x3cc
in al,dx
mov dx,#0x3b4
and al,#0x01
jz even7
mov dx,#0x3d4
even7: mov al,#0x0c
out dx,al
inc dx
in al,dx
mov bl,al
mov al,#0x55
out dx,al
in al,dx
dec dx
mov al,#0x1f
out dx,al
inc dx
in al,dx
mov bh,al
dec dx
mov al,#0x0c
out dx,al
inc dx
mov al,bl
out dx,al
mov al,#0x55
xor al,#0xea
cmp al,bh
jne isnot
movb [svga_prefix],#VIDEO_FIRST_V7>>8 ! Use special mode switching
ret
video7_md:
.byte 0x40, 0x2b, 0x50
.byte 0x43, 0x3c, 0x50
.byte 0x44, 0x3c, 0x64
.byte 0x41, 0x19, 0x84
.byte 0x42, 0x2c, 0x84
.byte 0x45, 0x1c, 0x84
.byte 0
.ascii "Video 7"
.byte 0
! Realtek VGA
realtek_test:
lea si,idrtvga
mov di,#0x45
mov cx,#0x0b
repe
cmpsb
je isrt
xor bp,bp
isrt: ret
idrtvga: .ascii "REALTEK VGA"
realtek_md:
.byte 0x1a, 0x3c, 0x50
.byte 0x1b, 0x19, 0x84
.byte 0x1c, 0x1e, 0x84
.byte 0x1d, 0x2b, 0x84
.byte 0x1e, 0x3c, 0x84
.byte 0
.ascii "REALTEK"
.byte 0
#endif /* CONFIG_VIDEO_SVGA */
!
! User-defined local mode table (VGA only)
!
#ifdef CONFIG_VIDEO_LOCAL
local_modes:
lea si,local_mode_table
locm1: lodsw
or ax,ax
jz locm2
stosw
movsw
jmp locm1
locm2: ret
! This is the table of local video modes which can be supplied manually
! by the user. Each entry consists of mode ID (word) and dimensions
! (byte for column count and another byte for row count). These modes
! are placed before all SVGA and VESA modes and override them if table
! compacting is enabled. The table must end with a zero word followed
! by NUL-terminated video adapter name.
local_mode_table:
.word 0x0100 ! Example: 40x25
.byte 25,40
.word 0
.ascii "Local"
.byte 0
#endif /* CONFIG_VIDEO_LOCAL */
!
! Read a key and return the ASCII code in al, scan code in ah
!
getkey: xor ah,ah
int 0x16
ret
!
! Read a key with a timeout of 30 seconds. The hardware clock is used to get
! the time.
!
getkt: call gettime
add al,#30 ! Wait 30 seconds
cmp al,#60
jl lminute
sub al,#60
lminute:
mov cl,al
again: mov ah,#0x01
int 0x16
jnz getkey ! key pressed, so get it
call gettime
cmp al,cl
jne again
mov al,#0x20 ! timeout, return default char `space'
ret
!
! Flush the keyboard buffer
!
flush: mov ah,#0x01
int 0x16
jz empty
xor ah,ah
int 0x16
jmp flush
empty: ret
!
! Print hexadecimal number.
!
prthw: push ax
mov al,ah
call prthb
pop ax
prthb: push ax
shr al,#4
call prthn
pop ax
and al,#0x0f
prthn: cmp al,#0x0a
jc prth1
add al,#0x07
prth1: add al,#0x30
br prtchr
!
! Print decimal number (AL).
!
prtdec: push ax
push cx
xor ah,ah ! Clear ah
mov cl,#0x0a
idiv cl
cmp al,#0x09
jbe lt100
call prtdec
jmp skip10
lt100: add al,#0x30
call prtchr
skip10: mov al,ah
add al,#0x30
call prtchr
pop cx
pop ax
ret
!
! VIDEO_SELECT-only variables
!
mt_end: .word 0 ! End of video mode table if built
edit_buf: .space 6 ! Line editor buffer
card_name: .word 0 ! Pointer to adapter name
scanning: .byte 0 ! Performing mode scan
do_restore: .byte 0 ! Screen contents altered during mode change
svga_prefix: .byte VIDEO_FIRST_BIOS>>8 ! Default prefix for BIOS modes
graphic_mode: .byte 0 ! Graphic mode with a linear frame buffer
!
! Messages:
!
keymsg: .ascii "Press <RETURN> to see video modes available, "
.ascii "<SPACE> to continue or wait 30 secs"
db 0x0d, 0x0a, 0
listhdr: db 0x0d, 0x0a
.ascii "Mode: COLSxROWS:"
crlft: db 0x0d, 0x0a, 0
prompt: db 0x0d, 0x0a
.ascii "Enter mode number or `scan': "
db 0
unknt: .ascii "Unknown mode ID. Try again."
db 0
badmdt: .ascii "You passed an undefined mode number."
db 0x0d, 0x0a, 0
vesaer: .ascii "Error: Scanning of VESA modes failed. Please "
.ascii "report to <mj@k332.feld.cvut.cz>."
db 0x0d, 0x0a, 0
old_name: .ascii "CGA/MDA/HGA"
db 0
ega_name: .ascii "EGA"
db 0
svga_name: .ascii " "
vga_name: .ascii "VGA"
db 0
vesa_name: .ascii "VESA"
db 0
name_bann: .ascii "Video adapter: "
db 0
#endif /* CONFIG_VIDEO_SELECT */
!
! Other variables:
!
adapter: .byte 0 ! Video adapter: 0=CGA/MDA/HGA,1=EGA,2=VGA
video_segment: .word 0xb800 ! Video memory segment
force_size: .word 0 ! Use this size instead of the one in BIOS vars
