vgaddi.h File Reference

#include <stdarg.h>
#include <windef.h>
#include <wingdi.h>
#include <winddi.h>
#include <winioctl.h>
#include <ntddvdeo.h>
#include <ioaccess.h>
#include "vgavideo/vgavideo.h"

Include dependency graph for vgaddi.h:

This graph shows which files directly or indirectly include this file:

Go to the source code of this file.

Classes
struct	_RECT_ENUM
struct	_XYPAIR
struct	_SAVED_SCREEN_BITS
struct	_PDEV
struct	BANK_INFO
struct	_DEVSURF

Macros
#define	_WINBASE_
#define	_WINDOWS_H
#define	DPRINT   DbgPrint
#define	DPRINT1   DbgPrint
#define	DDKFASTAPI   __fastcall
#define	FASTCALL   __fastcall
#define	DS_SOLIDBRUSH   0x00000001
#define	DS_GREYBRUSH   0x00000002
#define	DS_BRUSH   0x00000004
#define	DS_DIB   0x00000008
#define	POW2(stride)   (!((stride) & ((stride)-1)))
#define	BROKEN_RASTERS(stride, cy)   ((!(POW2(stride))) && ((stride*cy) > 0x10000))
#define	ENUM_RECT_LIMIT   50
#define	CURSOR_COLOR   0x00000004
#define	CURSOR_HW   0x00000010
#define	CURSOR_HW_ACTIVE   0x00000020
#define	CURSOR_ANIMATE   0x00000040
#define	BMF_PHYSDEVICE   0xFF
#define	BMF_DFB   0xFE
#define	PDEV_IDENT   ('V' + ('P' << 8) + ('D' << 16) + ('V' << 24))
#define	DEVSURF_IDENT   ('V' + ('S' << 8) + ('R' << 16) + ('F' << 24))
#define	DRIVER_EXTRA_SIZE   0
#define	ALLOC_TAG   'agvD'
#define	DLL_NAME   L"vga"
#define	MAX_SCAN_WIDTH   2048
#define	DRIVER_OFFSCREEN_REFRESHED   0x04L
#define	PLANAR_PELS_PER_CPU_ADDRESS   8
#define	PACKED_PELS_PER_CPU_ADDRESS   2

Typedefs
typedef struct _RECT_ENUM	RECT_ENUM
typedef struct _XYPAIR	XYPAIR
typedef struct _SAVED_SCREEN_BITS	SAVED_SCREEN_BITS
typedef struct _SAVED_SCREEN_BITS *	PSAVED_SCREEN_BITS
typedef struct _PDEV	PDEV
typedef struct _PDEV *	PPDEV
typedef struct BANK_INFO *	PBANK_INFO
typedef VOID(*	PFN_BankControl) (PVOID, ULONG, BANK_JUST)
typedef struct _DEVSURF	DEVSURF
typedef struct _DEVSURF *	PDEVSURF
typedef VOID(*	PFN_ScreenToScreenBlt) (PDEVSURF, PRECTL, PPOINTL, INT)

Enumerations
enum	BANK_JUST { JustifyTop = 0 , JustifyBottom }

Functions
ULONG	DbgPrint (PCCH Format,...)
static __inline BOOLEAN	RemoveEntryList (IN PLIST_ENTRY Entry)
static __inline VOID	InsertHeadList (IN PLIST_ENTRY ListHead, IN PLIST_ENTRY Entry)
static __inline VOID	InitializeListHead (IN PLIST_ENTRY ListHead)
BOOL	InitVGA (PPDEV ppdev, BOOL bFirst)
BOOL	DeinitVGA (PPDEV ppdev)
BOOL	VGAtoGDI (SURFOBJ *Dest, SURFOBJ *Source, SURFOBJ *Mask, XLATEOBJ *ColorTranslation, RECTL *DestRect, POINTL *SourcePoint)
VOID	VGADDI_BltFromSavedScreenBits (ULONG DestX, ULONG DestY, PSAVED_SCREEN_BITS Src, ULONG SizeX, ULONG SizeY)
VOID	VGADDI_BltToSavedScreenBits (PSAVED_SCREEN_BITS Dest, ULONG SourceX, ULONG SourceY, ULONG SizeX, ULONG SizeY)
VOID	VGADDI_FreeSavedScreenBits (PSAVED_SCREEN_BITS SavedBits)
PSAVED_SCREEN_BITS	VGADDI_AllocSavedScreenBits (ULONG Size)
VOID	VGADDI_InitializeOffScreenMem (ULONG Start, ULONG Length)
BOOL	InitPointer (PPDEV ppdev)
DWORD	getAvailableModes (HANDLE Driver, PVIDEO_MODE_INFORMATION *modeInformation, DWORD *ModeSize)
VOID FASTCALL	vgaReadScan (int x, int y, int w, void *b)
VOID FASTCALL	vgaWriteScan (int x, int y, int w, void *b)

Macro Definition Documentation

_WINBASE_

#define _WINBASE_

Definition at line 4 of file vgaddi.h.

_WINDOWS_H

#define _WINDOWS_H

Definition at line 5 of file vgaddi.h.

ALLOC_TAG

#define ALLOC_TAG   'agvD'

Definition at line 246 of file vgaddi.h.

BMF_DFB

#define BMF_DFB   0xFE

Definition at line 235 of file vgaddi.h.

BMF_PHYSDEVICE

#define BMF_PHYSDEVICE   0xFF

Definition at line 234 of file vgaddi.h.

BROKEN_RASTERS

#define BROKEN_RASTERS	(		stride,
			cy
	)		((!(POW2(stride))) && ((stride*cy) > 0x10000))

Definition at line 72 of file vgaddi.h.

CURSOR_ANIMATE

#define CURSOR_ANIMATE   0x00000040

Definition at line 101 of file vgaddi.h.

CURSOR_COLOR

#define CURSOR_COLOR   0x00000004

Definition at line 98 of file vgaddi.h.

CURSOR_HW

#define CURSOR_HW   0x00000010

Definition at line 99 of file vgaddi.h.

CURSOR_HW_ACTIVE

#define CURSOR_HW_ACTIVE   0x00000020

Definition at line 100 of file vgaddi.h.

DDKFASTAPI

#define DDKFASTAPI   __fastcall

Definition at line 25 of file vgaddi.h.

DEVSURF_IDENT

#define DEVSURF_IDENT   ('V' + ('S' << 8) + ('R' << 16) + ('F' << 24))

Definition at line 240 of file vgaddi.h.

DLL_NAME

#define DLL_NAME   L"vga"

Definition at line 247 of file vgaddi.h.

DPRINT

#define DPRINT   DbgPrint

Definition at line 17 of file vgaddi.h.

DPRINT1

#define DPRINT1   DbgPrint

Definition at line 21 of file vgaddi.h.

DRIVER_EXTRA_SIZE

#define DRIVER_EXTRA_SIZE   0

Definition at line 245 of file vgaddi.h.

DRIVER_OFFSCREEN_REFRESHED

#define DRIVER_OFFSCREEN_REFRESHED   0x04L

Definition at line 250 of file vgaddi.h.

DS_BRUSH

#define DS_BRUSH   0x00000004

Definition at line 68 of file vgaddi.h.

DS_DIB

#define DS_DIB   0x00000008

Definition at line 69 of file vgaddi.h.

DS_GREYBRUSH

#define DS_GREYBRUSH   0x00000002

Definition at line 67 of file vgaddi.h.

DS_SOLIDBRUSH

#define DS_SOLIDBRUSH   0x00000001

Definition at line 66 of file vgaddi.h.

ENUM_RECT_LIMIT

#define ENUM_RECT_LIMIT   50

Definition at line 74 of file vgaddi.h.

FASTCALL

#define FASTCALL   __fastcall

Definition at line 26 of file vgaddi.h.

MAX_SCAN_WIDTH

#define MAX_SCAN_WIDTH   2048

Definition at line 249 of file vgaddi.h.

PACKED_PELS_PER_CPU_ADDRESS

#define PACKED_PELS_PER_CPU_ADDRESS   2

Definition at line 252 of file vgaddi.h.

PDEV_IDENT

#define PDEV_IDENT   ('V' + ('P' << 8) + ('D' << 16) + ('V' << 24))

Definition at line 239 of file vgaddi.h.

PLANAR_PELS_PER_CPU_ADDRESS

#define PLANAR_PELS_PER_CPU_ADDRESS   8

Definition at line 251 of file vgaddi.h.

POW2

#define POW2

(

stride

)

(!((stride) & ((stride)-1)))

Definition at line 71 of file vgaddi.h.

Typedef Documentation

DEVSURF

typedef struct _DEVSURF DEVSURF

PBANK_INFO

typedef struct BANK_INFO * PBANK_INFO

PDEV

typedef struct _PDEV PDEV

PDEVSURF

typedef struct _DEVSURF * PDEVSURF

PFN_BankControl

typedef VOID(* PFN_BankControl) (PVOID, ULONG, BANK_JUST)

Definition at line 158 of file vgaddi.h.

PFN_ScreenToScreenBlt

typedef VOID(* PFN_ScreenToScreenBlt) (PDEVSURF, PRECTL, PPOINTL, INT)

Definition at line 230 of file vgaddi.h.

PPDEV

typedef struct _PDEV * PPDEV

PSAVED_SCREEN_BITS

typedef struct _SAVED_SCREEN_BITS * PSAVED_SCREEN_BITS

RECT_ENUM

typedef struct _RECT_ENUM RECT_ENUM

SAVED_SCREEN_BITS

typedef struct _SAVED_SCREEN_BITS SAVED_SCREEN_BITS

XYPAIR

typedef struct _XYPAIR XYPAIR

Enumeration Type Documentation

BANK_JUST

enum BANK_JUST

Enumerator
JustifyTop
JustifyBottom

Definition at line 151 of file vgaddi.h.

             {
  JustifyTop = 0,
  JustifyBottom,
} BANK_JUST;

Function Documentation

DbgPrint()

ULONG DbgPrint	(	PCCH	Format,
			...
	)

Definition at line 432 of file debug.c.

{
    return 0;
}

DeinitVGA()

BOOL DeinitVGA

(

PPDEV

ppdev

)

Definition at line 112 of file screen.c.

{
    VIDEO_MEMORY VideoMemory;
    ULONG ReturnedDataLength;
 
    VideoMemory.RequestedVirtualAddress = (PVOID)ppdev->fbScreen;
 
    if (EngDeviceIoControl(ppdev->KMDriver,
                           IOCTL_VIDEO_UNMAP_VIDEO_MEMORY,
                           (PVOID)&VideoMemory,
                           sizeof(VIDEO_MEMORY),
                           NULL,
                           0,
                           &ReturnedDataLength))
    {
        DPRINT1("Failed to unmap video memory.\n");
        EngDebugBreak();
        return FALSE;
    }
    return TRUE;
}

Referenced by DrvDisableSurface().

getAvailableModes()

DWORD getAvailableModes	(	HANDLE	Driver,
		PVIDEO_MODE_INFORMATION *	modeInformation,
		DWORD *	ModeSize
	)

Definition at line 507 of file screen.c.

{
    ULONG ulTemp;
    VIDEO_NUM_MODES modes;
    PVIDEO_MODE_INFORMATION pVideoTemp;
 
    //
    // Get the number of modes supported by the mini-port
    //
 
    if (EngDeviceIoControl(hDriver,
                           IOCTL_VIDEO_QUERY_NUM_AVAIL_MODES,
                           NULL,
                           0,
                           &modes,
                           sizeof(VIDEO_NUM_MODES),
                           &ulTemp))
    {
        DISPDBG((0, "getAvailableModes failed VIDEO_QUERY_NUM_AVAIL_MODES\n"));
        return 0;
    }
 
    *cbModeSize = modes.ModeInformationLength;
 
    //
    // Allocate the buffer for the mini-port to write the modes in.
    //
 
    *modeInformation = (PVIDEO_MODE_INFORMATION)
                        EngAllocMem(0, modes.NumModes *
                                    modes.ModeInformationLength, ALLOC_TAG);
 
    if (*modeInformation == NULL)
    {
        DISPDBG((0, "getAvailableModes failed EngAllocMem\n"));
 
        return 0;
    }
 
    //
    // Ask the mini-port to fill in the available modes.
    //
 
    if (EngDeviceIoControl(hDriver,
                           IOCTL_VIDEO_QUERY_AVAIL_MODES,
                           NULL,
                           0,
                           *modeInformation,
                           modes.NumModes * modes.ModeInformationLength,
                           &ulTemp))
    {
 
        DISPDBG((0, "getAvailableModes failed VIDEO_QUERY_AVAIL_MODES\n"));
 
        EngFreeMem(*modeInformation);
        *modeInformation = NULL;
 
        return 0;
    }
 
    //
    // Now see which of these modes are supported by the display driver.
    // As an internal mechanism, set the length to 0 for the modes we
    // DO NOT support.
    //
 
    ulTemp = modes.NumModes;
    pVideoTemp = *modeInformation;
 
    //
    // Mode is rejected if it is not one plane, or not graphics, or is not
    // one of 8, 16 or 32 bits per pel.
    //
 
    while (ulTemp--)
    {
        if ((pVideoTemp->NumberOfPlanes != 1 ) ||
            !(pVideoTemp->AttributeFlags & VIDEO_MODE_GRAPHICS) ||
// eVb: 2.6 [DDK CHANGE] - Do not process banked video modes
             (pVideoTemp->AttributeFlags & VIDEO_MODE_BANKED) ||
// eVb: 2.6 [END]
            ((pVideoTemp->BitsPerPlane != 8) &&
             (pVideoTemp->BitsPerPlane != 16) &&
             (pVideoTemp->BitsPerPlane != 24) &&
             (pVideoTemp->BitsPerPlane != 32)))
        {
            pVideoTemp->Length = 0;
        }
 
        pVideoTemp = (PVIDEO_MODE_INFORMATION)
            (((PUCHAR)pVideoTemp) + modes.ModeInformationLength);
    }
 
    return modes.NumModes;
 
}

InitializeListHead()

static __inline VOID InitializeListHead ( IN PLIST_ENTRY  ListHead )

static

Definition at line 58 of file vgaddi.h.

{
  ListHead->Flink = ListHead->Blink = ListHead;
}

InitPointer()

BOOL InitPointer

(

PPDEV

ppdev

)

Definition at line 143 of file pointer.c.

{
    ULONG CursorWidth = 32, CursorHeight = 32;
    ULONG PointerAttributesSize;
    ULONG SavedMemSize;
 
    ppdev->xyHotSpot.x = 0;
    ppdev->xyHotSpot.y = 0;
 
    /* Determine the size of the pointer attributes */
    PointerAttributesSize = sizeof(VIDEO_POINTER_ATTRIBUTES) +
      ((CursorWidth * CursorHeight * 2) >> 3);
 
    /* Allocate memory for pointer attributes */
    ppdev->pPointerAttributes = EngAllocMem(0, PointerAttributesSize, ALLOC_TAG);
 
    ppdev->pPointerAttributes->Flags = 0; /* FIXME: Do this right */
    ppdev->pPointerAttributes->Width = CursorWidth;
    ppdev->pPointerAttributes->Height = CursorHeight;
    ppdev->pPointerAttributes->WidthInBytes = CursorWidth >> 3;
    ppdev->pPointerAttributes->Enable = 0;
    ppdev->pPointerAttributes->Column = 0;
    ppdev->pPointerAttributes->Row = 0;
 
    /* Allocate memory for the pixels behind the cursor */
    SavedMemSize = ((((CursorWidth + 7) & ~0x7) + 16) * CursorHeight) >> 3;
    ppdev->ImageBehindCursor = VGADDI_AllocSavedScreenBits(SavedMemSize);
 
    return TRUE;
}

Referenced by DrvAssertMode(), and DrvEnableSurface().

InitVGA()

BOOL InitVGA	(	PPDEV	ppdev,
		BOOL	bFirst
	)

Definition at line 134 of file screen.c.

{
    ULONG ReturnedDataLength;
    VIDEO_MEMORY VideoMemory;
    VIDEO_MEMORY_INFORMATION VideoMemoryInfo;
 
    ppdev->sizeSurf.cx = 640;
    ppdev->sizeSurf.cy = 480;
    ppdev->ModeNum = 2;
 
    /* Set the mode that was requested */
    if (EngDeviceIoControl(ppdev->KMDriver,
                           IOCTL_VIDEO_SET_CURRENT_MODE,
                           &ppdev->ModeNum,
                           sizeof(VIDEO_MODE),
                           NULL,
                           0,
                           &ReturnedDataLength))
    {
        return FALSE;
    }
 
    /* set up internal palette */
    if (EngDeviceIoControl(ppdev->KMDriver,
                           IOCTL_VIDEO_SET_PALETTE_REGISTERS,
                           (PVOID) PaletteBuffer,
                           sizeof (PaletteBuffer),
                           NULL,
                           0,
                           &ReturnedDataLength))
    {
       return FALSE;
    }
 
    /* set up the DAC */
    if (EngDeviceIoControl(ppdev->KMDriver,
                           IOCTL_VIDEO_SET_COLOR_REGISTERS,
                           (PVOID) ColorBuffer,
                           sizeof (ColorBuffer),
                           NULL,
                           0,
                           &ReturnedDataLength))
    {
        return FALSE;
    }
 
    if (bFirst)
    {
        /* map video memory into virtual memory */
        VideoMemory.RequestedVirtualAddress = NULL;
 
        if (EngDeviceIoControl(ppdev->KMDriver,
                               IOCTL_VIDEO_MAP_VIDEO_MEMORY,
                               (PVOID) &VideoMemory,
                               sizeof (VIDEO_MEMORY),
                               (PVOID) &VideoMemoryInfo,
                               sizeof (VideoMemoryInfo),
                               &ReturnedDataLength))
        {
            /* Failed to map to virtual memory */
            return FALSE;
        }
 
        ppdev->fbScreen = VideoMemoryInfo.FrameBufferBase;
        vidmem = (PUCHAR)ppdev->fbScreen;
    }
 
    return TRUE;
}

Referenced by DrvAssertMode(), and DrvEnableSurface().

InsertHeadList()

static __inline VOID InsertHeadList ( IN PLIST_ENTRY  ListHead, IN PLIST_ENTRY  Entry  )

static

Definition at line 45 of file vgaddi.h.

{
  PLIST_ENTRY OldFlink;
  OldFlink = ListHead->Flink;
  Entry->Flink = OldFlink;
  Entry->Blink = ListHead;
  OldFlink->Blink = Entry;
  ListHead->Flink = Entry;
}

RemoveEntryList()

static __inline BOOLEAN RemoveEntryList ( IN PLIST_ENTRY  Entry )

static

Definition at line 31 of file vgaddi.h.

{
  PLIST_ENTRY OldFlink;
  PLIST_ENTRY OldBlink;
 
  OldFlink = Entry->Flink;
  OldBlink = Entry->Blink;
  OldFlink->Blink = OldBlink;
  OldBlink->Flink = OldFlink;
  return (OldFlink == OldBlink);
}

VGADDI_AllocSavedScreenBits()

PSAVED_SCREEN_BITS VGADDI_AllocSavedScreenBits

(

ULONG

Size

)

Definition at line 121 of file offscreen.c.

{
    PSAVED_SCREEN_BITS Current;
    PLIST_ENTRY CurrentEntry;
    PSAVED_SCREEN_BITS Best;
    PSAVED_SCREEN_BITS New;
 
    Best = NULL;
    CurrentEntry = SavedBitsList.Flink;
    while (CurrentEntry != &SavedBitsList)
    {
        Current = CONTAINING_RECORD(CurrentEntry, SAVED_SCREEN_BITS, ListEntry);
 
        if (Current->Free && Current->Size >= Size &&
            (Best == NULL || (Current->Size - Size) < (Best->Size - Size)))
        {
            Best = Current;
        }
 
        CurrentEntry = CurrentEntry->Flink;
    }
 
    if (!Best)
      return NULL;
 
    if (Best->Size == Size)
    {
        Best->Free = FALSE;
        return Best;
    }
    else
    {
        New = EngAllocMem(0, sizeof(SAVED_SCREEN_BITS), ALLOC_TAG);
        New->Free = FALSE;
        New->Offset = Best->Offset + Size;
        New->Size = Size;
        Best->Size -= Size;
        InsertHeadList(&Best->ListEntry, &New->ListEntry);
        return New;
    }
}

Referenced by DrvSetPointerShape(), and InitPointer().

VGADDI_BltFromSavedScreenBits()

VOID VGADDI_BltFromSavedScreenBits	(	ULONG	DestX,
		ULONG	DestY,
		PSAVED_SCREEN_BITS	Src,
		ULONG	SizeX,
		ULONG	SizeY
	)

VGADDI_BltToSavedScreenBits()

VOID VGADDI_BltToSavedScreenBits	(	PSAVED_SCREEN_BITS	Dest,
		ULONG	SourceX,
		ULONG	SourceY,
		ULONG	SizeX,
		ULONG	SizeY
	)

VGADDI_FreeSavedScreenBits()

VOID VGADDI_FreeSavedScreenBits

(

PSAVED_SCREEN_BITS

SavedBits

)

Definition at line 87 of file offscreen.c.

{
    SavedBits->Free = TRUE;
 
    if (SavedBits->ListEntry.Blink != &SavedBitsList)
    {
        PSAVED_SCREEN_BITS Previous;
 
        Previous = CONTAINING_RECORD(SavedBits->ListEntry.Blink,
                                     SAVED_SCREEN_BITS, ListEntry);
        if (Previous->Free)
        {
            Previous->Size += SavedBits->Size;
            RemoveEntryList(&SavedBits->ListEntry);
            EngFreeMem(SavedBits);
            SavedBits = Previous;
        }
    }
    if (SavedBits->ListEntry.Flink != &SavedBitsList)
    {
        PSAVED_SCREEN_BITS Next;
 
        Next = CONTAINING_RECORD(SavedBits->ListEntry.Flink, SAVED_SCREEN_BITS,
                                 ListEntry);
        if (Next->Free)
        {
            SavedBits->Size += Next->Size;
            RemoveEntryList(&SavedBits->ListEntry);
            EngFreeMem(SavedBits);
        }
    }
}

Referenced by DrvSetPointerShape().

VGADDI_InitializeOffScreenMem()

VOID VGADDI_InitializeOffScreenMem	(	ULONG	Start,
		ULONG	Length
	)

vgaReadScan()

VOID FASTCALL vgaReadScan	(	int	x,
		int	y,
		int	w,
		void *	b
	)

Definition at line 579 of file vgavideo.c.

{
    unsigned char *vp, *vpP;
    unsigned char data, mask, maskP;
    unsigned char *bp;
    unsigned char plane_mask;
    int plane, i;
 
    ASSIGNVP4(x, y, vpP)
    ASSIGNMK4(x, y, maskP)
    get_masks(x, w);
    WRITE_PORT_USHORT((PUSHORT)GRA_I, 0x0005);  // read mode 0
    WRITE_PORT_UCHAR((PUCHAR)GRA_I, 0x04);  // read map select
 
    memset ( b, 0, w );
 
    for ( plane=0, plane_mask=1; plane < 4; plane++, plane_mask<<=1 )
    {
        WRITE_PORT_UCHAR((PUCHAR)GRA_D, plane);  // read map select
 
        vp = vpP;
        bp = b;
        if ( leftMask )
        {
            mask = maskP;
            data = *vp++;
            do
            {
                if (data & mask)
                    *bp |= plane_mask;
                bp++;
                mask >>= 1;
            } while (mask & leftMask);
        }
        if (byteCounter)
        {
            for (i=byteCounter; i>0; i--)
            {
                data = *vp++;
                if (data & 0x80) *bp |= plane_mask;
                bp++;
 
                if (data & 0x40) *bp |= plane_mask;
                bp++;
                if (data & 0x20) *bp |= plane_mask;
                bp++;
                if (data & 0x10) *bp |= plane_mask;
                bp++;
                if (data & 0x08) *bp |= plane_mask;
                bp++;
                if (data & 0x04) *bp |= plane_mask;
                bp++;
                if (data & 0x02) *bp |= plane_mask;
                bp++;
                if (data & 0x01) *bp |= plane_mask;
                bp++;
            }
        }
        if (rightMask)
        {
            mask = 0x80;
            data = *vp;
            do
            {
                if (data & mask)
                *bp |= plane_mask;
                bp++;
                mask >>= 1;
            } while (mask & rightMask);
        }
    }
}

Referenced by VGAtoVGA().

VGAtoGDI()

BOOL VGAtoGDI	(	SURFOBJ *	Dest,
		SURFOBJ *	Source,
		SURFOBJ *	Mask,
		XLATEOBJ *	ColorTranslation,
		RECTL *	DestRect,
		POINTL *	SourcePoint
	)

vgaWriteScan()

VOID FASTCALL vgaWriteScan	(	int	x,
		int	y,
		int	w,
		void *	b
	)

Definition at line 655 of file vgavideo.c.

{
    unsigned char *bp;
    unsigned char *vp;
    //unsigned char init_mask;
    volatile unsigned char dummy;
    //int byte_per_line;
    int i, j, off, init_off = x&7;
 
    bp = b;
    ASSIGNVP4(x, y, vp)
    //ASSIGNMK4(x, y, init_mask)
    //byte_per_line = SCREEN_X >> 3;
 
    WRITE_PORT_UCHAR((PUCHAR)GRA_I, 0x05);      // write mode 2
    WRITE_PORT_UCHAR((PUCHAR)GRA_D, 0x02);
    WRITE_PORT_UCHAR((PUCHAR)GRA_I, 0x03);      // replace
    WRITE_PORT_UCHAR((PUCHAR)GRA_D, 0x00);
    WRITE_PORT_UCHAR((PUCHAR)GRA_I, 0x08);      // bit mask
 
    for ( j = 0; j < 8; j++)
    {
        unsigned int mask = 0x80 >> j;
        WRITE_PORT_UCHAR ( (PUCHAR)GRA_D, (unsigned char)mask );
        i = j - init_off;
        off = 0;
        if (j < init_off)
            i += 8, off++;
        while (i < w)
        {
            /*
             * In write mode 2, the incoming data is 4-bit and represents the
             * value of entire bytes on each of the 4 memory planes. First, VGA
             * performs a logical operation on these bytes and the value of the
             * latch register, but in this case there is none. Then, only the
             * bits that are set in the bit mask are used from the resulting
             * bytes, and the other bits are taken from the latch register.
             *
             * The latch register always contains the value previously read from
             * VGA memory, and therefore, we must first read from vp[off] to
             * load the latch register, and then write bp[i] to vp[off], which
             * will be converted to 4 bytes of VGA memory as described.
             */
            dummy = vp[off];
            dummy = bp[i];
            vp[off] = dummy;
            i += 8;
            off++;
        }
    }
}

Referenced by VGAtoVGA().