CsmVideo

Function Table

Address	Name	Description
	_ModuleEntryPoint
	CsmVideoDriverEntry
	CsmVideoChildInit
	CsmVideoModeSet
	CsmVideoInstanceCreate
	CsmVideoDetectDevice
	CsmVideoChildAddProtocol
	CsmVideoFreeBuffers
	EdidParseAndMerge
	VesaGetControllerCapabilities
	VesaEnumerateModes
	GraphicsOutputQueryMode
	AllocateVideoBuffers
	GraphicsOutputSetMode
	GraphicsOutputSetModeWrapper
	VgaTextSetCursorPosition
	EdidOverrideUninstall
	VgaClassConstructor
	VgaClassDestructor
	VgaTextInit
	VgaTextStringOutput
	VgaTextTestStringValid
	VgaTextClearScreen
	VgaTextEnableCursor
	VgaTextQueryModeInfo
	VgaTextSetMode
	VgaCursorSetPosition
	VgaWriteCrtRegister
	VgaOemCharTranslate
	IsVgaEnableCheck
	LegacyBiosPlatformSetVideoController
	IsPciRootBridgeVgaCompatible
	CmosReadVideoType
Forward	declarations from CsmVideo.h / library code
EFI_BOOT_SERVICES	*gBS;
_ModuleEntryPoint	@ 0x390
CsmVideoDriverEntry	@ 0x44C
Install	protocols on ImageHandle:
Status	= gBS->InstallMultipleProtocolInterfaces (
Install	EDID_ACTIVE protocol on a child handle
ChildHandle	= NULL;
Connect	the LegacyBiosPlatform protocol
Status	= gBS->ConnectController (
sub_7A0	-- CsmVideoChildInit: initialize a VGA/display child
Get	PCI Root Bridge IO protocol on the child
Status	= gBS->HandleProtocol (
Locate	Legacy BIOS Platform protocol
Status	= gBS->LocateProtocol (
Open	PCI IO protocol with VGA attribute
Attributes	*= (UINT64* )((UINT8 )Instance + 40); // Instance->Attributes*
Get	current mode / attributes
Status	= PciIo->GetAttributes (PciIo, NULL, &Supported, NULL, NULL);
Enable	VGA decode, IO, and memory access
Status	= PciIo->SetAttributes (
Check	if this is a VGA-compatible device via LegacyBIOS platform
Status	= LegacyBiosPlatform->GetVgaCompatible (
Allocate	resources descriptor for VGA legacy IO range
if	(CsmVideo != NULL) {
Check	if already VGA enabled - skip if so
if	(IsVgaEnableCheck (ChildHandle)) {
Create	the CsmVideo instance
Status	= CsmVideoInstanceCreate (
sub_9EC	-- CsmVideoModeSet: set display mode
If	no modes requested, try EDID_OVERRIDE first, then EDID_ACTIVE
if	(ModeCount == 0) {
Try	to open EDID_OVERRIDE protocol
Status	= gBS->OpenProtocol (
Otherwise	open EDID_ACTIVE and configure display
Detect	VGA child info
For	each requested mode, try to add it
for	(Index = 0; Index < ModeCount; Index++) {
Restore	previous VGA mode if needed
if	(!IsVgaEnableCheck (ChildHandle) && IsVesaModeEnabled) {
Detect	the video device
Status	= CsmVideoDetectDevice (Instance, ModeArray[0], &CsmVideo);
Add	each requested mode
Restore	VGA mode if necessary
sub_CE0	-- CsmVideoInstanceCreate: create and initialize video instance
Allocate	264-byte instance
Status	= gBS->AllocatePool (EfiBootServicesData, sizeof (CSM_VIDEO_INSTANCE), (VOID )&CsmVideo);**
Query	the VGA PCI config space for class code
Status	= PciIo->Pci.Read (
Detect	device type: VGA compatible (class 3) or not
if	**(!(Class[2] == 3		(Class[2] == 0 && Class[1] == 3 && !Class[0]))) {**
Not	VGA-compatible; check for other video class
Not	VGA, not a display controller
Is	VGA compatible - check for VESA mode
Not	already in VGA mode, but VGA compatible
Initialize	instance fields
Default	to legacy VGA
Assume	VESA-capable
If	no Legacy BIOS platform, go straight to legacy VGA
if	(!gLegacyBiosPlatformAvailable) {
Create	end of device path for VGA IO range claim
if	(LegacyBiosHandle == NULL) {
Create	ACPI device path for VGA IO range
Apppend	device path for the VGA rom
Install	protocol interfaces for the VESA/child
Enumerate	VESA modes
Status	= VesaEnumerateModes (CsmVideo);
VESA	succeeded
Fall	back to legacy VGA
Legacy	BIOS platform path	install EDID protocol only
Install	full set of protocols for VESA/child
Install	GOP protocol
Legacy	VGA mode: populate VGA text mode parameters
Legacy	VGA CRTC parameters
CRTC	index
CRTC	data
Mono	CRTC index
Mono	CRTC data
Attribute	Controller
Sequencer	CsmVideo->InputRanges = 0xFF;
sub_1080	-- CsmVideoDetectDevice: detect video controller and return instance
Returns	ptr to EdidActive field
Adjust	from field offset back to instance start
EdidActive	is at offset 32 in CsmVideoInstance
Fall	back to EDID_OVERRIDE protocol
EdidOverride	is at offset 0x60 (96) in the instance
sub_1178	-- CsmVideoChildAddProtocol: install protocols on video child
Status	= CsmVideoDetectDevice (Instance, ParentHandle, &CsmVideo);
Close	any existing EDID_ACTIVE protocol on the target handle
Install	the full protocol set on this child (VESA mode)
Install	EDID_OVERRIDE (legacy VGA mode)
If	install failed, re-open EDID_ACTIVE to restore state
Initialize	cursor to 80x25 text mode
80x25	color text mode
VGA	INT10 AH=00h: set video mode 3 (80x25 color text)
VGA	INT10 AH=01h: set cursor shape (no cursor)
Function	01h, CH=11h, CL=14h
Initialize	VESA controller
VesaGetControllerCapabilities	(CsmVideo);
Mark	the global child handle
sub_1300	-- CsmVideoFreeBuffers: free all resources
Free	frame buffer 3
Free	frame buffer 2
Free	frame buffer
Free	scan line buffer
Free	text buffer + its memory descriptor
Free	EDID override buffer
Free	the instance itself
sub_145C	-- EdidParseAndMerge: parse EDID block, extract timings
Validate	EDID checksum
Parse	established timings from EDID byte 0x23
EstablishedTimings	**= Edid->EstablishedTimings[0]	**
Map	known established timing resolutions
Established	timings from EDID spec
720x400	@ 70Hz
Check	each flag bit
for	(TimingIndex = 0; TimingIndex < 17; TimingIndex++) {
Parse	detailed timing descriptors (EDID bytes 0x36-0x6F, 18 bytes each)
for	(DetailedTimingIndex = 0; DetailedTimingIndex < 4; DetailedTimingIndex++) {
Check	if this is a timing descriptor (byte 0 = tag, byte 1 != 1 = pixel clock)
if	(TimingDescriptor[0] != 0x01 && TimingDescriptor[1] != 0x01) {
Extract	Horizontal pixels from bytes 0x02-0x04 (packed)
HorizontalPixels	= (UINT16)(TimingDescriptor[2] + ((TimingDescriptor[4] & 0xF0) << 4));
Aspect	ratio / Vertical lines extraction
AspectRatio	= TimingDescriptor[3] >> 6;
Ratio	16:10
Ratio	4:3
Ratio	5:4
Ratio	16:9
sub_16A0	-- VesaGetControllerCapabilities: query VESA VBE BIOS
48	bytes
Issue	VBE controller capabilities call
0x4F15	VbeControllerInfo[1] = 0x10; // Function = Get Capabilities
Number	of graphics ports
Default	to 1
Enumerate	each graphics port to find a connected display
for	(PortIndex = 0; PortIndex < GraphicsPortCount; PortIndex++) {
Function	= Get Port
Found	a connected port
sub_17D8	-- VesaEnumerateModes: enumerate all VESA VBE modes
256	byte VBE mode info block
256	byte VBE controller info
Get	VBE controller info
Status	= VesaGetControllerCapabilities (CsmVideo);
Get	EDID override data if present
EdidOverrideProtocolSize	= 0;
Allocate	space for mode list (up to ~256 VBE modes)
ModeBuffer	*= AllocateZeroPool (256 sizeof (UINT16));**
Loop	through VESA/VBE modes
for	(Index = 0; ; Index++) {
Get	VBE mode info for this mode number
VBE	function 0x4F01: Get Mode Info
VBE	function
Mode	number
No	more modes or error
Validate	mode number
if	(VbeModeNumber < 0x100) {
Check	mode attributes bit 7 (linear FB supported) and bit 0 (mode supported)
if	**(!(VbeModeInfo[0] & 0x80)		!(VbeModeInfo[0] & 0x01)) {**
Check	mode type (must be invalid type to be graphical)
if	((VbeModeInfo & 0x08) == 0) {
Check	for linear frame buffer
if	(!(VbeModeInfo[0] & VESA_MODE_LINEAR_FB_BIT)) {
Check	bits per pixel: must be 24-32, and modulo 8 == 0
Check	PhysBasePtr is non-zero
Check	resolution against EDID table
HorizontalRes	*= (UINT32* )&VbeModeInfo[0x12]; // XResolution**
YResolution	EdidMatchFound = FALSE;
Check	for duplicate
for	(Index = 0; Index < UsableModes; Index++) {
Mode	is usable	add to our mode table
Update	mode count
Allocate	video buffers for this instance
Status	= AllocateVideoBuffers (CsmVideo);
sub_21AC	-- GraphicsOutputQueryMode: GOP QueryMode
Get	instance from CR (This is at offset 32 from instance)
CsmVideo	*= (CSM_VIDEO_INSTANCE )((UINT8* )This - 32);**
Check	if initialized
if	(CsmVideo->bEdidOverrideActive) {
Validate	parameters
if	**(ModeNumber >= CsmVideo->MaxMode		SizeOfInfo == NULL	Info == NULL) {**
Allocate	output buffer (36 bytes as observed)
Populate	mode info from VESA mode table (72 bytes per entry)
ModeInfoEntry	= &CsmVideo->VesaModeInfo[ModeNumber];
Calculate	pixel information
PixelsPerScanLine	*= 8 BytesPerScanLine / BitsPerPixel**
sub_22D4	-- AllocateVideoBuffers: allocate scan line, text, and frame buffers
Compute	worst-case dimensions from all modes
Scan	all modes to find the largest
Status	= gBS->AllocatePool (
Allocate	*text buffer (153600 bytes = 8025224**	VGA text mode save area)
sub_24AC	-- GraphicsOutputSetMode: GOP SetMode
48	bytes buffer for INT10
Find	instance via CR (This at offset 32)
if	(ModeNumber >= CsmVideo->MaxMode) {
Prepare	VBE call buffer
If	mode number < 0x100, use standard VGA mode set
if	(ModeInfo->VbeModeNumber < 0x100) {
VGA	mode set via INT10 AH=00h, AL=mode
VBE	Set Mode
Update	current mode info
Calculate	frame buffer size
Clear	the frame buffer (fill with zeros)
Copy	current frame buffer from VESA linear FB to our shadow buffer
sub_26DC	-- GraphicsOutputSetModeWrapper: 10-param wrapper for GOP SetMode
Get	current EDID override info from instance
CsmVideo	= CR_FROM_EDID_ACTIVE (CsmVideo);
If	currently in EDID override mode, handle state transition
if	(EdidOverrideActive) {
Close	EDID_ACTIVE protocol (open from child controller)
Status	= gBS->CloseProtocol (
Set	the VGA mode
Status	= GraphicsOutputSetMode (&CsmVideo->GraphicsOutput, ModeNumber);
Open	EDID_ACTIVE with BY_CHILD_CONTROLLER after mode set
sub_2D84	-- VgaTextSetCursorPosition: set cursor via INT10 AH=02h
Validate	cursor mode
if	(CursorMode > Instance->ModeTableSize) {
Perform	INT10 call
DX	= 0 (row=0, col=0)
Set	cursor to end of screen for mode 1
Call	INT10 to set cursor position
sub_2E58	-- EdidOverrideUninstall: remove EDID override protocols
Open	EDID_OVERRIDE protocol on child
Close	and uninstall EDID_ACTIVE protocol
sub_2ED0	-- VgaClassConstructor: create VGA text class
Get	PCI Root Bridge IO protocol
Open	PCI IO protocol
Open	EDID_OVERRIDE protocol
Allocate	VGA Class Instance (144 bytes)
Status	= gBS->AllocatePool (EfiBootServicesData, sizeof (VGA_CLASS_INSTANCE), (VOID )&VgaClass);**
Set	signature
Fill	vtable
Initialize	the VGA class instance:
init	-> set mode (15) -> set cursor -> enable cursor
Status	= VgaClass->SetMode (&VgaClass->ModeTableSize, 15);
Install	Legacy BIOS protocol on the child
sub_3138	-- VgaClassDestructor: destroy VGA class instance
Open	Legacy BIOS protocol
Adjust	from LegacyBios protocol interface back to instance
VgaClass	*= (VGA_CLASS_INSTANCE )((UINT8* )VgaClass - 16);**
Status	= gBS->ReinstallProtocolInterface (
Uninstall	EDID_ACTIVE protocol
Free	the instance
sub_322C	-- VgaTextInit: initialize VGA text mode
Set	palette registers (INT10 AH=0Bh/BH=01h)
Set	cursor type (start, end)
return	This->SetCursor (This, 0);
sub_3280	-- VgaTextStringOutput: output string to VGA text screen
Validate	This signature
if	(This->Signature != VGA_CLASS_INSTANCE_SIGNATURE) {
Get	current mode dimensions
Status	= This->QueryMode (This, &ScreenWidth, &ScreenHeight);
Get	text cursor position from attribute fields
CursorX	= This->CursorX;
Get	current attribute
Attribute	= This->Attribute;
Get	frame buffer stride (bytes per scan line)
Stride	= This->FrameBufferStride;
Process	each character in the string
for	*(; String != 0; String++) {**
Backspace	if (CursorX > 0) {
Line	feed
Scroll	the screen up by one line
if	(CursorY == (ScreenHeight - 1)) {
Scroll	**CursorData[0] = ((Attribute << 8)	0x20);**
Carriage	return
Convert	OEM characters to VGA glyphs
if	(VgaOemCharTranslate (CurrentChar, &GlyphData)) {
Write	character to frame buffer at current cursor position
FrameBufferOffset	*= CursorY Stride + CursorX* 2;**
Write	character + attribute to VGA text buffer (B8000 or shadow)
Advance	to next line
Update	cursor position
sub_34BC	-- VgaTextTestStringValid: validate Unicode string for VGA
ASCII	printable range (0x20-0x7F)
if	((CurrentChar - 0x20) > 0x5F) {
Check	for control characters (0x00-0x0D with supported set)
if	**(CurrentChar > 0x0D		**
Check	for OEM character range
if	(((CurrentChar & 0xFF00) - 0x2100) & 0xFBFF) {
Look	up in OEM-to-VGA translation table
if	(!VgaOemCharTranslate (CurrentChar, NULL)) {
sub_3550	-- VgaTextClearScreen: fill VGA text screen with spaces
Validate	//
Get	dimensions
Clear	the entire screen buffer
Stride	*= ScreenWidth 2; // Two bytes per character (char + attr)**
Space	with current attribute
Fill	the VGA text region
for	(CursorY = 0; CursorY < ScreenHeight; CursorY++) {
Set	cursor to home (0,0)
sub_362C	-- VgaTextSetCursorPosition: set text cursor with bounds check
Status	= This->QueryMode (This, &MaxCol, &MaxRow);
Bounds	check
if	**(Column >= MaxCol		Row >= MaxRow) {**
Set	cursor position via CRT controller registers
VgaCursorSetPosition	(This, Column, Row, MaxCol);
Update	internal state
sub_36D0	-- VgaTextEnableCursor: enable/disable cursor
Enable	cursor via INT10: AH=01h, CH=cursor start, CL=cursor end
if	(Enable) {
Disable	cursor by moving it off screen
VgaWriteCrtRegister	(This, CRTC_CURSOR_START, 0x20);
sub_3770	-- VgaTextQueryModeInfo: return cols/rows for VGA text mode
Validate	mode index
if	(ModeIndex >= This->ModeTableSize) {
Mode	0 = 80x25, Mode 1 = 80x50
if	(ModeIndex == 0) {
sub_3810	-- VgaTextSetMode: select VGA text mode
Clear	the current screen
Store	current mode index
Program	the frame buffer mode
return	This->FrameBufferModeSet (This->FrameBufferAccess, ModeIndex);
sub_388C	-- VgaCursorSetPosition: program cursor via CRT registers
Calculate	linear cursor offset
CursorOffset	*= X + ScreenWidth Y;**
Write	cursor location high byte to CRTC register 0x0E
VgaWriteCrtRegister	(This, CRTC_CURSOR_LOC_HIGH, (CursorOffset >> 8));
Write	cursor location low byte to CRTC register 0x0F
VgaWriteCrtRegister	(This, CRTC_CURSOR_LOC_LOW, (CursorOffset & 0xFF));
sub_38F4	-- VgaWriteCrtRegister: write CRTC register
__outbyte	(CRTC_INDEX_PORT, RegisterIndex);
sub_396C	-- VgaOemCharTranslate: convert OEM/Unicode to VGA glyph
OEM	character range: Unicode code page 437 / OEM
if	(((UnicodeChar & 0xFF00) - 0x2100) & 0xFBFF) {
Look	up the character in the translation table (a global static list)
The	table maps pairs of (Unicode, VGA_Index)
sub_568	-- IsVgaEnableCheck: check if any child has VGA enable
Open	protocol info for EDID_ACTIVE on this handle
Status	= gBS->OpenProtocolInformation (
Check	each open protocol entry for BIT3 (VGA enable flag)
for	(Index = 0; Index < OpenInfoCount; Index++) {
sub_5E0	-- LegacyBiosPlatformSetVideoController: set/clear video owner
If	no platform handle or already in the desired state, skip
if	(BiosPlatformHandle == NULL) {
Check	if the current state matches the request (byte_5770 optimization)
if	(gIsLegacyVgaMode == SetAsActive && !Force) {
Set	or clear VGA controller ownership on the legacy BIOS platform
if	(SetAsActive) {
sub_6B0	-- IsPciRootBridgeVgaCompatible: check PCI class code
Get	PCI IO protocol on the child handle
Read	PCI class code
Check	if VGA compatible (class 3, subclass 0, prog IF 0)
or	VGA-compatible (class 3, any subclass, prog IF 0)
if	(Class[2] == 3 && Class[1] == 0 && Class[0] == 0) {
Is	VGA compatible
Close	protocol
sub_2E0	-- CopyMemInternal: low-level memcpy
Handle	overlapping case: if Source < Dest and overlap detected
copy	backwards from end
if	(Source < Destination &&
Copy	backwards
return	CopyMemBackwards (Destination, Source, Length);
Copy	forwards with 8-byte chunks then remaining bytes
return	CopyMemForward (Destination, Source, Length);
sub_4310	-- CmosReadVideoType: get video type from CMOS
Read	CMOS register 0x4B (video type)
NmiBits	= __inbyte (0x70) & 0x80;
Invalid	or non-standard video
EFI_VGA_DEVICE	}
sub_46AE	-- SetMem: memset with alignment optimization
Build	64-bit word: 8 copies of Value
QuadValue	= Value;
Align	to 4-byte boundary
if	(Length >= 4 && ((UINTN)Buf & 3)) {
Write	aligned 32-bit words
for	(AlignedCount = Length >> 2; AlignedCount > 0; AlignedCount--) {
Write	remaining bytes
if	(Length > 0) {
sub_4700	-- CopyMemOverlapped: memcpy with direction detection
Determine	direction: backward if src < dst && overlap
if	(Src < Dst && (Src + Length) > Dst) {
Fast	aligned copy: 8 bytes at a time when both aligned
if	(Length >= 8 && ((UINTN)Src & 7) == ((UINTN)Dst & 7)) {
Handle	leading misaligned bytes
UINTN	Align = (UINTN)Src & 7;
Copy	alignment bytes
Copy	aligned 8-byte chunks
UINTN	Count = Length >> 3;
qmemcpy	with 8-byte alignment
qmemcpy	remaining

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