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[0.4.9][BLUE] Optimize ScrIoControl for speed (#5185)

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Optimize IOCTL_CONSOLE_FILL_OUTPUT_ATTRIBUTE and IOCTL_CONSOLE_FILL_OUTPUT_CHARACTER for speed by using cache.
a part of CORE-18838
It is faster because it minimizes the amount of pointer dereferences within the for-loops.

fix picked from 0.4.15-dev-5881-g 3526ffc094
---------
also partially pick unrelated cleanup from:
0.4.14-dev-439-g 75f188c200 (only the change in blue.c)
---------
and take back with me some whitespace-tweaks to bring the file closer to todays releases/0.4.14
This commit is contained in:
Joachim Henze 2023-06-06 23:43:40 +02:00
parent 63c4d66d6f
commit aecdd2eee7
1 changed files with 129 additions and 141 deletions
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270
drivers/setup/blue/blue.c
View file

@ -1,11 +1,8 @@
/*
* COPYRIGHT: See COPYING in the top level directory
* PROJECT: ReactOS kernel
* FILE: services/dd/blue/blue.c
* PURPOSE: Console (blue screen) device driver
* PROGRAMMER: Eric Kohl
* UPDATE HISTORY:
* ??? Created
* COPYRIGHT: See COPYING in the top level directory
* PROJECT: ReactOS kernel
* PURPOSE: Driver Management Functions.
* PROGRAMMER: Eric Kohl
*/
/* INCLUDES ******************************************************************/
@ -15,20 +12,11 @@
#define NDEBUG
#include <debug.h>
// ROS Internal. Please deprecate.
NTHALAPI
BOOLEAN
NTAPI
HalQueryDisplayOwnership(
VOID
);
/* NOTES ******************************************************************/
/*
* [[character][attribute]][[character][attribute]]....
*/
/* TYPEDEFS ***************************************************************/
typedef struct _DEVICE_EXTENSION
@ -38,9 +26,9 @@ typedef struct _DEVICE_EXTENSION
INT CursorVisible;
USHORT CharAttribute;
ULONG Mode;
UCHAR ScanLines; /* Height of a text line */
USHORT Rows; /* Number of rows */
USHORT Columns; /* Number of columns */
UCHAR ScanLines; /* Height of a text line */
USHORT Rows; /* Number of rows */
USHORT Columns; /* Number of columns */
} DEVICE_EXTENSION, *PDEVICE_EXTENSION;
typedef struct _VGA_REGISTERS
@ -104,7 +92,7 @@ ScrSetRegisters(const VGA_REGISTERS *Registers)
/* Write sequencer registers */
for (i = 1; i < sizeof(Registers->Sequencer); i++)
{
{
WRITE_PORT_UCHAR(SEQ, i);
WRITE_PORT_UCHAR(SEQDATA, Registers->Sequencer[i]);
}
@ -139,7 +127,7 @@ ScrSetRegisters(const VGA_REGISTERS *Registers)
WRITE_PORT_UCHAR(ATTRIB, Registers->Attribute[i]);
}
/* Set the PEL mask. */
/* Set the PEL mask */
WRITE_PORT_UCHAR(PELMASK, 0xff);
}
@ -152,7 +140,7 @@ ScrAcquireOwnership(PDEVICE_EXTENSION DeviceExtension)
ScrSetRegisters(&VidpMode3Regs);
/* Disable screen and enable palette access. */
/* Disable screen and enable palette access */
READ_PORT_UCHAR(STATUS);
WRITE_PORT_UCHAR(ATTRIB, 0x00);
@ -164,66 +152,65 @@ ScrAcquireOwnership(PDEVICE_EXTENSION DeviceExtension)
WRITE_PORT_UCHAR(PELDATA, DefaultPalette[Index * 3 + 2] >> 2);
}
/* Enable screen and disable palette access. */
/* Enable screen and disable palette access */
READ_PORT_UCHAR(STATUS);
WRITE_PORT_UCHAR(ATTRIB, 0x20);
/* get current output position */
WRITE_PORT_UCHAR (CRTC_COMMAND, CRTC_CURSORPOSLO);
offset = READ_PORT_UCHAR (CRTC_DATA);
WRITE_PORT_UCHAR (CRTC_COMMAND, CRTC_CURSORPOSHI);
offset += (READ_PORT_UCHAR (CRTC_DATA) << 8);
WRITE_PORT_UCHAR(CRTC_COMMAND, CRTC_CURSORPOSLO);
offset = READ_PORT_UCHAR(CRTC_DATA);
WRITE_PORT_UCHAR(CRTC_COMMAND, CRTC_CURSORPOSHI);
offset += (READ_PORT_UCHAR(CRTC_DATA) << 8);
/* switch blinking characters off */
READ_PORT_UCHAR (ATTRC_INPST1);
value = READ_PORT_UCHAR (ATTRC_WRITEREG);
WRITE_PORT_UCHAR (ATTRC_WRITEREG, 0x10);
data = READ_PORT_UCHAR (ATTRC_READREG);
READ_PORT_UCHAR(ATTRC_INPST1);
value = READ_PORT_UCHAR(ATTRC_WRITEREG);
WRITE_PORT_UCHAR(ATTRC_WRITEREG, 0x10);
data = READ_PORT_UCHAR(ATTRC_READREG);
data = data & ~0x08;
WRITE_PORT_UCHAR (ATTRC_WRITEREG, data);
WRITE_PORT_UCHAR (ATTRC_WRITEREG, value);
READ_PORT_UCHAR (ATTRC_INPST1);
WRITE_PORT_UCHAR(ATTRC_WRITEREG, data);
WRITE_PORT_UCHAR(ATTRC_WRITEREG, value);
READ_PORT_UCHAR(ATTRC_INPST1);
/* read screen information from crt controller */
WRITE_PORT_UCHAR (CRTC_COMMAND, CRTC_COLUMNS);
DeviceExtension->Columns = READ_PORT_UCHAR (CRTC_DATA) + 1;
WRITE_PORT_UCHAR (CRTC_COMMAND, CRTC_ROWS);
DeviceExtension->Rows = READ_PORT_UCHAR (CRTC_DATA);
WRITE_PORT_UCHAR (CRTC_COMMAND, CRTC_OVERFLOW);
data = READ_PORT_UCHAR (CRTC_DATA);
WRITE_PORT_UCHAR(CRTC_COMMAND, CRTC_COLUMNS);
DeviceExtension->Columns = READ_PORT_UCHAR(CRTC_DATA) + 1;
WRITE_PORT_UCHAR(CRTC_COMMAND, CRTC_ROWS);
DeviceExtension->Rows = READ_PORT_UCHAR(CRTC_DATA);
WRITE_PORT_UCHAR(CRTC_COMMAND, CRTC_OVERFLOW);
data = READ_PORT_UCHAR(CRTC_DATA);
DeviceExtension->Rows |= (((data & 0x02) << 7) | ((data & 0x40) << 3));
DeviceExtension->Rows++;
WRITE_PORT_UCHAR (CRTC_COMMAND, CRTC_SCANLINES);
DeviceExtension->ScanLines = (READ_PORT_UCHAR (CRTC_DATA) & 0x1F) + 1;
WRITE_PORT_UCHAR(CRTC_COMMAND, CRTC_SCANLINES);
DeviceExtension->ScanLines = (READ_PORT_UCHAR(CRTC_DATA) & 0x1F) + 1;
/* show blinking cursor */
WRITE_PORT_UCHAR (CRTC_COMMAND, CRTC_CURSORSTART);
WRITE_PORT_UCHAR (CRTC_DATA, (DeviceExtension->ScanLines - 1) & 0x1F);
WRITE_PORT_UCHAR (CRTC_COMMAND, CRTC_CURSOREND);
data = READ_PORT_UCHAR (CRTC_DATA) & 0xE0;
WRITE_PORT_UCHAR (CRTC_DATA,
data | ((DeviceExtension->ScanLines - 1) & 0x1F));
WRITE_PORT_UCHAR(CRTC_COMMAND, CRTC_CURSORSTART);
WRITE_PORT_UCHAR(CRTC_DATA, (DeviceExtension->ScanLines - 1) & 0x1F);
WRITE_PORT_UCHAR(CRTC_COMMAND, CRTC_CURSOREND);
data = READ_PORT_UCHAR(CRTC_DATA) & 0xE0;
WRITE_PORT_UCHAR(CRTC_DATA,
data | ((DeviceExtension->ScanLines - 1) & 0x1F));
/* calculate number of text rows */
DeviceExtension->Rows =
DeviceExtension->Rows / DeviceExtension->ScanLines;
DeviceExtension->Rows = DeviceExtension->Rows / DeviceExtension->ScanLines;
#ifdef BOCHS_30ROWS
DeviceExtension->Rows = 30;
#endif
DPRINT ("%d Columns %d Rows %d Scanlines\n",
DeviceExtension->Columns,
DeviceExtension->Rows,
DeviceExtension->ScanLines);
DPRINT("%d Columns %d Rows %d Scanlines\n",
DeviceExtension->Columns,
DeviceExtension->Rows,
DeviceExtension->ScanLines);
}
NTSTATUS NTAPI
DriverEntry (PDRIVER_OBJECT DriverObject, PUNICODE_STRING RegistryPath);
DriverEntry(PDRIVER_OBJECT DriverObject, PUNICODE_STRING RegistryPath);
static DRIVER_DISPATCH ScrCreate;
static NTSTATUS NTAPI
ScrCreate(PDEVICE_OBJECT DeviceObject,
PIRP Irp)
PIRP Irp)
{
PDEVICE_EXTENSION DeviceExtension;
PHYSICAL_ADDRESS BaseAddress;
@ -242,7 +229,7 @@ ScrCreate(PDEVICE_OBJECT DeviceObject,
}
else
{
/* store dummy values here */
/* Store dummy values */
DeviceExtension->Columns = 1;
DeviceExtension->Rows = 1;
DeviceExtension->ScanLines = 1;
@ -259,17 +246,17 @@ ScrCreate(PDEVICE_OBJECT DeviceObject,
Status = STATUS_SUCCESS;
Irp->IoStatus.Status = Status;
IoCompleteRequest (Irp, IO_NO_INCREMENT);
IoCompleteRequest(Irp, IO_NO_INCREMENT);
return (Status);
return Status;
}
static DRIVER_DISPATCH ScrWrite;
static NTSTATUS NTAPI
ScrWrite(PDEVICE_OBJECT DeviceObject,
PIRP Irp)
PIRP Irp)
{
PIO_STACK_LOCATION stk = IoGetCurrentIrpStackLocation (Irp);
PIO_STACK_LOCATION stk = IoGetCurrentIrpStackLocation(Irp);
PDEVICE_EXTENSION DeviceExtension = DeviceObject->DeviceExtension;
NTSTATUS Status;
char *pch = Irp->UserBuffer;
@ -286,7 +273,7 @@ ScrWrite(PDEVICE_OBJECT DeviceObject,
Status = STATUS_SUCCESS;
Irp->IoStatus.Status = Status;
IoCompleteRequest (Irp, IO_NO_INCREMENT);
IoCompleteRequest(Irp, IO_NO_INCREMENT);
return Status;
}
@ -296,37 +283,37 @@ ScrWrite(PDEVICE_OBJECT DeviceObject,
columns = DeviceExtension->Columns;
_disable();
WRITE_PORT_UCHAR (CRTC_COMMAND, CRTC_CURSORPOSHI);
offset = READ_PORT_UCHAR (CRTC_DATA)<<8;
WRITE_PORT_UCHAR (CRTC_COMMAND, CRTC_CURSORPOSLO);
offset += READ_PORT_UCHAR (CRTC_DATA);
WRITE_PORT_UCHAR(CRTC_COMMAND, CRTC_CURSORPOSHI);
offset = READ_PORT_UCHAR(CRTC_DATA)<<8;
WRITE_PORT_UCHAR(CRTC_COMMAND, CRTC_CURSORPOSLO);
offset += READ_PORT_UCHAR(CRTC_DATA);
_enable();
cursory = offset / columns;
cursorx = offset % columns;
if( processed == 0 )
{
if (!processed)
{
/* raw output mode */
memcpy( &vidmem[(cursorx * 2) + (cursory * columns * 2)], pch, stk->Parameters.Write.Length );
offset += (stk->Parameters.Write.Length / 2);
}
}
else {
for (i = 0; i < stk->Parameters.Write.Length; i++, pch++)
for (i = 0; i < stk->Parameters.Write.Length; i++, pch++)
{
switch (*pch)
switch (*pch)
{
case '\b':
if (cursorx > 0)
{
{
cursorx--;
}
}
else if (cursory > 0)
{
{
cursorx = columns - 1;
cursory--;
}
}
vidmem[(cursorx * 2) + (cursory * columns * 2)] = ' ';
vidmem[(cursorx * 2) + (cursory * columns * 2) + 1] = (char) DeviceExtension->CharAttribute;
vidmem[(cursorx * 2) + (cursory * columns * 2) + 1] = (char)DeviceExtension->CharAttribute;
break;
case '\n':
@ -341,49 +328,49 @@ ScrWrite(PDEVICE_OBJECT DeviceObject,
case '\t':
offset = TAB_WIDTH - (cursorx % TAB_WIDTH);
for (j = 0; j < offset; j++)
{
{
vidmem[(cursorx * 2) + (cursory * columns * 2)] = ' ';
cursorx++;
if (cursorx >= columns)
{
cursory++;
cursorx = 0;
}
}
{
cursory++;
cursorx = 0;
}
}
break;
default:
vidmem[(cursorx * 2) + (cursory * columns * 2)] = *pch;
vidmem[(cursorx * 2) + (cursory * columns * 2) + 1] = (char) DeviceExtension->CharAttribute;
vidmem[(cursorx * 2) + (cursory * columns * 2) + 1] = (char)DeviceExtension->CharAttribute;
cursorx++;
if (cursorx >= columns)
{
{
cursory++;
cursorx = 0;
}
}
break;
}
if (cursory >= rows)
if (cursory >= rows)
{
unsigned short *LinePtr;
memcpy (vidmem,
memcpy(vidmem,
&vidmem[columns * 2],
columns * (rows - 1) * 2);
LinePtr = (unsigned short *) &vidmem[columns * (rows - 1) * 2];
for (j = 0; j < columns; j++)
{
{
LinePtr[j] = DeviceExtension->CharAttribute << 8;
}
}
cursory = rows - 1;
for (j = 0; j < columns; j++)
{
{
vidmem[(j * 2) + (cursory * columns * 2)] = ' ';
vidmem[(j * 2) + (cursory * columns * 2) + 1] = (char)DeviceExtension->CharAttribute;
}
}
}
}
@ -391,27 +378,27 @@ ScrWrite(PDEVICE_OBJECT DeviceObject,
offset = (cursory * columns) + cursorx;
}
_disable();
WRITE_PORT_UCHAR (CRTC_COMMAND, CRTC_CURSORPOSLO);
WRITE_PORT_UCHAR (CRTC_DATA, offset);
WRITE_PORT_UCHAR (CRTC_COMMAND, CRTC_CURSORPOSHI);
WRITE_PORT_UCHAR(CRTC_COMMAND, CRTC_CURSORPOSLO);
WRITE_PORT_UCHAR(CRTC_DATA, offset);
WRITE_PORT_UCHAR(CRTC_COMMAND, CRTC_CURSORPOSHI);
offset >>= 8;
WRITE_PORT_UCHAR (CRTC_DATA, offset);
WRITE_PORT_UCHAR(CRTC_DATA, offset);
_enable();
Status = STATUS_SUCCESS;
Irp->IoStatus.Status = Status;
IoCompleteRequest (Irp, IO_NO_INCREMENT);
IoCompleteRequest(Irp, IO_NO_INCREMENT);
return (Status);
return Status;
}
static DRIVER_DISPATCH ScrIoControl;
static NTSTATUS NTAPI
ScrIoControl(PDEVICE_OBJECT DeviceObject,
PIRP Irp)
PIRP Irp)
{
PIO_STACK_LOCATION stk = IoGetCurrentIrpStackLocation (Irp);
PIO_STACK_LOCATION stk = IoGetCurrentIrpStackLocation(Irp);
PDEVICE_EXTENSION DeviceExtension;
NTSTATUS Status;
@ -429,10 +416,10 @@ ScrIoControl(PDEVICE_OBJECT DeviceObject,
{
/* read cursor position from crtc */
_disable();
WRITE_PORT_UCHAR (CRTC_COMMAND, CRTC_CURSORPOSLO);
offset = READ_PORT_UCHAR (CRTC_DATA);
WRITE_PORT_UCHAR (CRTC_COMMAND, CRTC_CURSORPOSHI);
offset += (READ_PORT_UCHAR (CRTC_DATA) << 8);
WRITE_PORT_UCHAR(CRTC_COMMAND, CRTC_CURSORPOSLO);
offset = READ_PORT_UCHAR(CRTC_DATA);
WRITE_PORT_UCHAR(CRTC_COMMAND, CRTC_CURSORPOSHI);
offset += (READ_PORT_UCHAR(CRTC_DATA) << 8);
_enable();
}
else
@ -456,7 +443,7 @@ ScrIoControl(PDEVICE_OBJECT DeviceObject,
pcsbi->dwMaximumWindowSize.X = columns;
pcsbi->dwMaximumWindowSize.Y = rows;
Irp->IoStatus.Information = sizeof (CONSOLE_SCREEN_BUFFER_INFO);
Irp->IoStatus.Information = sizeof(CONSOLE_SCREEN_BUFFER_INFO);
Status = STATUS_SUCCESS;
}
break;
@ -473,10 +460,10 @@ ScrIoControl(PDEVICE_OBJECT DeviceObject,
if (!InbvCheckDisplayOwnership())
{
_disable();
WRITE_PORT_UCHAR (CRTC_COMMAND, CRTC_CURSORPOSLO);
WRITE_PORT_UCHAR (CRTC_DATA, offset);
WRITE_PORT_UCHAR (CRTC_COMMAND, CRTC_CURSORPOSHI);
WRITE_PORT_UCHAR (CRTC_DATA, offset>>8);
WRITE_PORT_UCHAR(CRTC_COMMAND, CRTC_CURSORPOSLO);
WRITE_PORT_UCHAR(CRTC_DATA, offset);
WRITE_PORT_UCHAR(CRTC_COMMAND, CRTC_CURSORPOSHI);
WRITE_PORT_UCHAR(CRTC_DATA, offset>>8);
_enable();
}
@ -492,7 +479,7 @@ ScrIoControl(PDEVICE_OBJECT DeviceObject,
pcci->dwSize = DeviceExtension->CursorSize;
pcci->bVisible = DeviceExtension->CursorVisible;
Irp->IoStatus.Information = sizeof (CONSOLE_CURSOR_INFO);
Irp->IoStatus.Information = sizeof(CONSOLE_CURSOR_INFO);
Status = STATUS_SUCCESS;
}
break;
@ -520,11 +507,11 @@ ScrIoControl(PDEVICE_OBJECT DeviceObject,
data |= (UCHAR)(height - size);
_disable();
WRITE_PORT_UCHAR (CRTC_COMMAND, CRTC_CURSORSTART);
WRITE_PORT_UCHAR (CRTC_DATA, data);
WRITE_PORT_UCHAR (CRTC_COMMAND, CRTC_CURSOREND);
value = READ_PORT_UCHAR (CRTC_DATA) & 0xE0;
WRITE_PORT_UCHAR (CRTC_DATA, value | (height - 1));
WRITE_PORT_UCHAR(CRTC_COMMAND, CRTC_CURSORSTART);
WRITE_PORT_UCHAR(CRTC_DATA, data);
WRITE_PORT_UCHAR(CRTC_COMMAND, CRTC_CURSOREND);
value = READ_PORT_UCHAR(CRTC_DATA) & 0xE0;
WRITE_PORT_UCHAR(CRTC_DATA, value | (height - 1));
_enable();
}
@ -565,13 +552,15 @@ ScrIoControl(PDEVICE_OBJECT DeviceObject,
if (!InbvCheckDisplayOwnership())
{
UCHAR attr = Buf->wAttribute;
vidmem = DeviceExtension->VideoMemory;
offset = (Buf->dwCoord.Y * DeviceExtension->Columns * 2) +
(Buf->dwCoord.X * 2) + 1;
(Buf->dwCoord.X * 2) + 1;
for (dwCount = 0; dwCount < Buf->nLength; dwCount++)
{
vidmem[offset + (dwCount * 2)] = (char) Buf->wAttribute;
vidmem[offset + (dwCount * 2)] = attr;
}
}
@ -598,7 +587,7 @@ ScrIoControl(PDEVICE_OBJECT DeviceObject,
for (dwCount = 0; dwCount < stk->Parameters.DeviceIoControl.OutputBufferLength; dwCount++, pAttr++)
{
*((char *) pAttr) = vidmem[offset + (dwCount * 2)];
*((char *)pAttr) = vidmem[offset + (dwCount * 2)];
}
Buf->dwTransfered = dwCount;
@ -653,6 +642,8 @@ ScrIoControl(PDEVICE_OBJECT DeviceObject,
if (!InbvCheckDisplayOwnership())
{
UCHAR ch = Buf->cCharacter;
vidmem = DeviceExtension->VideoMemory;
offset = (Buf->dwCoord.Y * DeviceExtension->Columns * 2) +
(Buf->dwCoord.X * 2);
@ -660,7 +651,7 @@ ScrIoControl(PDEVICE_OBJECT DeviceObject,
for (dwCount = 0; dwCount < Buf->nLength; dwCount++)
{
vidmem[offset + (dwCount * 2)] = (char) Buf->cCharacter;
vidmem[offset + (dwCount * 2)] = ch;
}
}
@ -755,10 +746,10 @@ ScrIoControl(PDEVICE_OBJECT DeviceObject,
ConsoleDraw->CursorX;
_disable();
WRITE_PORT_UCHAR (CRTC_COMMAND, CRTC_CURSORPOSLO);
WRITE_PORT_UCHAR (CRTC_DATA, Offset);
WRITE_PORT_UCHAR (CRTC_COMMAND, CRTC_CURSORPOSHI);
WRITE_PORT_UCHAR (CRTC_DATA, Offset >> 8);
WRITE_PORT_UCHAR(CRTC_COMMAND, CRTC_CURSORPOSLO);
WRITE_PORT_UCHAR(CRTC_DATA, Offset);
WRITE_PORT_UCHAR(CRTC_COMMAND, CRTC_CURSORPOSHI);
WRITE_PORT_UCHAR(CRTC_DATA, Offset >> 8);
_enable();
}
@ -787,7 +778,7 @@ ScrIoControl(PDEVICE_OBJECT DeviceObject,
}
Irp->IoStatus.Status = Status;
IoCompleteRequest (Irp, IO_NO_INCREMENT);
IoCompleteRequest(Irp, IO_NO_INCREMENT);
return Status;
}
@ -795,7 +786,7 @@ ScrIoControl(PDEVICE_OBJECT DeviceObject,
static DRIVER_DISPATCH ScrDispatch;
static NTSTATUS NTAPI
ScrDispatch(PDEVICE_OBJECT DeviceObject,
PIRP Irp)
PIRP Irp)
{
PIO_STACK_LOCATION stk = IoGetCurrentIrpStackLocation(Irp);
NTSTATUS Status;
@ -811,51 +802,48 @@ ScrDispatch(PDEVICE_OBJECT DeviceObject,
break;
}
Irp->IoStatus.Status = Status;
IoCompleteRequest (Irp, IO_NO_INCREMENT);
IoCompleteRequest(Irp, IO_NO_INCREMENT);
return (Status);
return Status;
}
/*
* Module entry point
*/
NTSTATUS NTAPI
DriverEntry (PDRIVER_OBJECT DriverObject, PUNICODE_STRING RegistryPath)
DriverEntry(PDRIVER_OBJECT DriverObject, PUNICODE_STRING RegistryPath)
{
PDEVICE_OBJECT DeviceObject;
NTSTATUS Status;
UNICODE_STRING DeviceName = RTL_CONSTANT_STRING(L"\\Device\\BlueScreen");
UNICODE_STRING SymlinkName = RTL_CONSTANT_STRING(L"\\??\\BlueScreen");
DPRINT ("Screen Driver 0.0.6\n");
DPRINT("Screen Driver 0.0.6\n");
DriverObject->MajorFunction[IRP_MJ_CREATE] = ScrCreate;
DriverObject->MajorFunction[IRP_MJ_CLOSE] = ScrDispatch;
DriverObject->MajorFunction[IRP_MJ_READ] = ScrDispatch;
DriverObject->MajorFunction[IRP_MJ_WRITE] = ScrWrite;
DriverObject->MajorFunction[IRP_MJ_DEVICE_CONTROL ] = ScrIoControl;
Status = IoCreateDevice (DriverObject,
sizeof(DEVICE_EXTENSION),
&DeviceName,
FILE_DEVICE_SCREEN,
FILE_DEVICE_SECURE_OPEN,
TRUE,
&DeviceObject);
DriverObject->MajorFunction[IRP_MJ_DEVICE_CONTROL] = ScrIoControl;
Status = IoCreateDevice(DriverObject,
sizeof(DEVICE_EXTENSION),
&DeviceName,
FILE_DEVICE_SCREEN,
FILE_DEVICE_SECURE_OPEN,
TRUE,
&DeviceObject);
if (!NT_SUCCESS(Status))
{
return Status;
}
Status = IoCreateSymbolicLink (&SymlinkName, &DeviceName);
Status = IoCreateSymbolicLink(&SymlinkName, &DeviceName);
if (NT_SUCCESS(Status))
DeviceObject->Flags &= ~DO_DEVICE_INITIALIZING;
else
IoDeleteDevice (DeviceObject);
IoDeleteDevice(DeviceObject);
return Status;
}