pcvideo.c

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/*
 *  FreeLoader
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License along
 *  with this program; if not, write to the Free Software Foundation, Inc.,
 *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */
 
#include <freeldr.h>
#include <suppress.h>
 
#include <debug.h>
DBG_DEFAULT_CHANNEL(UI);
 
#define VIDEOPORT_PALETTE_READ      0x03C7
#define VIDEOPORT_PALETTE_WRITE     0x03C8
#define VIDEOPORT_PALETTE_DATA      0x03C9
#define VIDEOPORT_VERTICAL_RETRACE  0x03DA
 
#define VIDEOVGA_MEM_ADDRESS  0xA0000
#define VIDEOTEXT_MEM_ADDRESS 0xB8000
#define VIDEOTEXT_MEM_SIZE    0x8000
 
#define VIDEOCARD_CGA_OR_OTHER 0
#define VIDEOCARD_EGA          1
#define VIDEOCARD_VGA          2
 
#define VIDEOMODE_NORMAL_TEXT   0
#define VIDEOMODE_EXTENDED_TEXT 1
#define    VIDEOMODE_80X28         0x501C
#define    VIDEOMODE_80X30         0x501E
#define    VIDEOMODE_80X34         0x5022
#define    VIDEOMODE_80X43         0x502B
#define    VIDEOMODE_80X60         0x503C
#define    VIDEOMODE_132X25        0x8419
#define    VIDEOMODE_132X43        0x842B
#define    VIDEOMODE_132X50        0x8432
#define    VIDEOMODE_132X60        0x843C
 
#define VERTRES_200_SCANLINES        0x00
#define VERTRES_350_SCANLINES        0x01
#define VERTRES_400_SCANLINES        0x02
 
#include <pshpack2.h>
typedef struct
{
    USHORT ModeAttributes;             /* Mode attributes (see #00080) */
    UCHAR  WindowAttributesA;          /* Window attributes, window A (see #00081) */
    UCHAR  WindowsAttributesB;         /* Window attributes, window B (see #00081) */
    USHORT WindowGranularity;          /* Window granularity in KB */
    USHORT WindowSize;                 /* Window size in KB */
    USHORT WindowAStartSegment;        /* Start segment of window A (0000h if not supported) */
    USHORT WindowBStartSegment;        /* Start segment of window B (0000h if not supported) */
    ULONG  WindowPositioningFunction;  /* -> FAR window positioning function (equivalent to AX=4F05h) */
    USHORT BytesPerScanLine;           /* Bytes per scan line */
    /* ---remainder is optional for VESA modes in v1.0/1.1, needed for OEM modes--- */
    USHORT WidthInPixels;              /* Width in pixels (graphics) or characters (text) */
    USHORT HeightInPixels;             /* Height in pixels (graphics) or characters (text) */
    UCHAR  CharacterWidthInPixels;     /* Width of character cell in pixels */
    UCHAR  CharacterHeightInPixels;    /* Height of character cell in pixels */
    UCHAR  NumberOfMemoryPlanes;       /* Number of memory planes */
    UCHAR  BitsPerPixel;               /* Number of bits per pixel */
    UCHAR  NumberOfBanks;              /* Number of banks */
    UCHAR  MemoryModel;                /* Memory model type (see #00082) */
    UCHAR  BankSize;                   /* Size of bank in KB */
    UCHAR  NumberOfImagePanes;         /* Number of image pages (less one) that will fit in video RAM */
    UCHAR  Reserved1;                  /* Reserved (00h for VBE 1.0-2.0, 01h for VBE 3.0) */
    /* ---VBE v1.2+ --- */
    UCHAR  RedMaskSize;                /* Red mask size */
    UCHAR  RedMaskPosition;            /* Red field position */
    UCHAR  GreenMaskSize;              /* Green mask size */
    UCHAR  GreenMaskPosition;          /* Green field size */
    UCHAR  BlueMaskSize;               /* Blue mask size */
    UCHAR  BlueMaskPosition;           /* Blue field size */
    UCHAR  ReservedMaskSize;           /* Reserved mask size */
    UCHAR  ReservedMaskPosition;       /* Reserved mask position */
    UCHAR  DirectColorModeInfo;        /* Direct color mode info
                                        * bit 0:Color ramp is programmable
                                        * bit 1:Bytes in reserved field may be used by application */
    /* ---VBE v2.0+ --- */
    ULONG  LinearVideoBufferAddress;   /* Physical address of linear video buffer */
    ULONG  OffscreenMemoryPointer;     /* Pointer to start of offscreen memory */
    USHORT OffscreenMemorySize;        /* KB of offscreen memory */
    /* ---VBE v3.0 --- */
    USHORT LinearBytesPerScanLine;     /* Bytes per scan line in linear modes */
    UCHAR  BankedNumberOfImages;       /* Number of images (less one) for banked video modes */
    UCHAR  LinearNumberOfImages;       /* Number of images (less one) for linear video modes */
    UCHAR  LinearRedMaskSize;          /* Linear modes:Size of direct color red mask (in bits) */
    UCHAR  LinearRedMaskPosition;      /* Linear modes:Bit position of red mask LSB (e.g. shift count) */
    UCHAR  LinearGreenMaskSize;        /* Linear modes:Size of direct color green mask (in bits) */
    UCHAR  LinearGreenMaskPosition;    /* Linear modes:Bit position of green mask LSB (e.g. shift count) */
    UCHAR  LinearBlueMaskSize;         /* Linear modes:Size of direct color blue mask (in bits) */
    UCHAR  LinearBlueMaskPosition;     /* Linear modes:Bit position of blue mask LSB (e.g. shift count) */
    UCHAR  LinearReservedMaskSize;     /* Linear modes:Size of direct color reserved mask (in bits) */
    UCHAR  LinearReservedMaskPosition; /* Linear modes:Bit position of reserved mask LSB */
    ULONG  MaximumPixelClock;          /* Maximum pixel clock for graphics video mode, in Hz */
    UCHAR  Reserved2[190];             /* 190 BYTEs  reserved (0) */
} SVGA_MODE_INFORMATION, *PSVGA_MODE_INFORMATION;
C_ASSERT(sizeof(SVGA_MODE_INFORMATION) == 256);
#include <poppack.h>
 
UCHAR MachDefaultTextColor = COLOR_GRAY;
 
static ULONG VideoCard = VIDEOCARD_CGA_OR_OTHER;        /* Type of video card installed on the system */
static USHORT BiosVideoMode = VIDEOMODE_NORMAL_TEXT;    /* Current video mode as known by BIOS */
static ULONG ScreenWidth = 80;                          /* Screen Width in characters */
static ULONG ScreenHeight = 25;                         /* Screen Height in characters */
static ULONG BytesPerScanLine = 160;                    /* Number of bytes per scanline (delta) */
static VIDEODISPLAYMODE DisplayMode = VideoTextMode;    /* Current display mode */
static BOOLEAN VesaVideoMode = FALSE;                   /* Are we using a VESA mode? */
static SVGA_MODE_INFORMATION VesaVideoModeInformation;  /* Only valid when in VESA mode */
static ULONG CurrentMemoryBank = 0;                     /* Currently selected VESA bank */
 
enum
{
    INT1FhFont = 0x00,
    INT43hFont = 0x01,
    ROM_8x14CharacterFont = 0x02,
    ROM_8x8DoubleDotFontLo = 0x03,
    ROM_8x8DoubleDotFontHi = 0x04,
    ROM_AlphaAlternate = 0x05,
    ROM_8x16Font = 0x06,
    ROM_Alternate9x16Font = 0x07,
    UltraVision_8x20Font = 0x11,
    UltraVision_8x10Font = 0x12,
};
 
static ULONG
PcVideoDetectVideoCard(VOID)
{
    REGS Regs;
 
    /* Int 10h AH=12h BL=10h
     * VIDEO - ALTERNATE FUNCTION SELECT (PS,EGA,VGA,MCGA) - GET EGA INFO
     *
     * AH = 12h
     * BL = 10h
     * Return:
     * BH = video state
     * 00h color mode in effect (I/O port 3Dxh)
     * 01h mono mode in effect (I/O port 3Bxh)
     * BL = installed memory (00h = 64K, 01h = 128K, 02h = 192K, 03h = 256K)
     * CH = feature connector bits
     * CL = switch settings
     * AH destroyed (at least by Tseng ET4000 BIOS v8.00n)
     *
     * Installation check;EGA
     */
    Regs.b.ah = 0x12;
    Regs.b.bl = 0x10;
    Int386(0x10, &Regs, &Regs);
 
    /* If BL is still equal to 0x10 then there is no EGA/VGA present */
    if (Regs.b.bl == 0x10)
        return VIDEOCARD_CGA_OR_OTHER;
 
    /* Int 10h AX=1A00h
     * VIDEO - GET DISPLAY COMBINATION CODE (PS,VGA/MCGA)
     *
     * AX = 1A00h
     * Return:
     * AL = 1Ah if function was supported
     * BL = active display code
     * BH = alternate display code
     *
     * This function is commonly used to check for the presence of a VGA.
     *
     * Installation check;VGA
     *
     * Values for display combination code:
     * 00h    no display
     * 01h    monochrome adapter w/ monochrome display
     * 02h    CGA w/ color display
     * 03h    reserved
     * 04h    EGA w/ color display
     * 05h    EGA w/ monochrome display
     * 06h    PGA w/ color display
     * 07h    VGA w/ monochrome analog display
     * 08h    VGA w/ color analog display
     * 09h    reserved
     * 0Ah    MCGA w/ digital color display
     * 0Bh    MCGA w/ monochrome analog display
     * 0Ch    MCGA w/ color analog display
     * FFh    unknown display type
     */
    Regs.w.ax = 0x1A00;
    Int386(0x10, &Regs, &Regs);
 
    if (Regs.b.al == 0x1a)
        return VIDEOCARD_VGA;
    else
        return VIDEOCARD_EGA;
}
 
static BOOLEAN
PcVideoVesaGetSVGAModeInformation(
    _In_ USHORT Mode,
    _Out_ PSVGA_MODE_INFORMATION ModeInformation)
{
    REGS Regs;
 
    RtlZeroMemory((PVOID)BIOSCALLBUFFER, sizeof(*ModeInformation));
 
    /* VESA SuperVGA BIOS - GET SuperVGA MODE INFORMATION
     * AX = 4F01h
     * CX = SuperVGA video mode (see #04082 for bitfields)
     * ES:DI -> 256-byte buffer for mode information (see #00079)
     * Return:
     * AL = 4Fh if function supported
     * AH = status
     * 00h successful
     * ES:DI buffer filled
     * 01h failed
     *
     * Desc: Determine the attributes of the specified video mode.
     *
     * Note: While VBE 1.1 and higher will zero out all unused bytes
     * of the buffer, v1.0 did not, so applications that want to be
     * backward compatible should clear the buffer before calling.
     */
    Regs.w.ax = 0x4F01;
    Regs.w.cx = Mode;
    Regs.w.es = BIOSCALLBUFSEGMENT;
    Regs.w.di = BIOSCALLBUFOFFSET;
    Int386(0x10, &Regs, &Regs);
 
    if (Regs.w.ax != 0x004F)
        return FALSE;
 
    RtlCopyMemory(ModeInformation, (PVOID)BIOSCALLBUFFER, sizeof(*ModeInformation));
 
    TRACE("\n");
    TRACE("BiosVesaGetSVGAModeInformation(Mode 0x%x)\n", Mode);
    TRACE("ModeAttributes = 0x%04x\n", ModeInformation->ModeAttributes);
    TRACE("WindowAttributesA = 0x%02x\n", ModeInformation->WindowAttributesA);
    TRACE("WindowAttributesB = 0x%02x\n", ModeInformation->WindowsAttributesB);
    TRACE("WindowGranularity = %huKB\n", ModeInformation->WindowGranularity);
    TRACE("WindowSize = %huKB\n", ModeInformation->WindowSize);
    TRACE("WindowAStartSegment = 0x%04x\n", ModeInformation->WindowAStartSegment);
    TRACE("WindowBStartSegment = 0x%04x\n", ModeInformation->WindowBStartSegment);
    TRACE("WindowPositioningFunction = 0x%x\n", ModeInformation->WindowPositioningFunction);
    TRACE("BytesPerScanLine = %hu\n", ModeInformation->BytesPerScanLine);
    TRACE("WidthInPixels = %hu\n", ModeInformation->WidthInPixels);
    TRACE("HeightInPixels = %hu\n", ModeInformation->HeightInPixels);
    TRACE("CharacterWidthInPixels = %u\n", ModeInformation->CharacterWidthInPixels);
    TRACE("CharacterHeightInPixels = %u\n", ModeInformation->CharacterHeightInPixels);
    TRACE("NumberOfMemoryPlanes = %u\n", ModeInformation->NumberOfMemoryPlanes);
    TRACE("BitsPerPixel = %u\n", ModeInformation->BitsPerPixel);
    TRACE("NumberOfBanks = %u\n", ModeInformation->NumberOfBanks);
    TRACE("MemoryModel = %u\n", ModeInformation->MemoryModel);
    TRACE("BankSize = %u\n", ModeInformation->BankSize);
    TRACE("NumberOfImagePanes = %u\n", ModeInformation->NumberOfImagePanes);
    TRACE("Reserved1 = 0x%02x\n", ModeInformation->Reserved1);
    TRACE("---VBE v1.2+ ---\n");
    TRACE("RedMaskSize = %u\n", ModeInformation->RedMaskSize);
    TRACE("RedMaskPosition = %u\n", ModeInformation->RedMaskPosition);
    TRACE("GreenMaskSize = %u\n", ModeInformation->GreenMaskSize);
    TRACE("GreenMaskPosition = %u\n", ModeInformation->GreenMaskPosition);
    TRACE("BlueMaskSize = %u\n", ModeInformation->BlueMaskSize);
    TRACE("BlueMaskPosition = %u\n", ModeInformation->BlueMaskPosition);
    TRACE("ReservedMaskSize = %u\n", ModeInformation->ReservedMaskSize);
    TRACE("ReservedMaskPosition = %u\n", ModeInformation->ReservedMaskPosition);
    TRACE("DirectColorModeInfo = 0x%02x\n", ModeInformation->DirectColorModeInfo);
    TRACE("---VBE v2.0+ ---\n");
    TRACE("LinearVideoBufferAddress = 0x%x\n", ModeInformation->LinearVideoBufferAddress);
    TRACE("OffscreenMemoryPointer = 0x%x\n", ModeInformation->OffscreenMemoryPointer);
    TRACE("OffscreenMemorySize = %huKB\n", ModeInformation->OffscreenMemorySize);
    TRACE("---VBE v3.0 ---\n");
    TRACE("LinearBytesPerScanLine = %hu\n", ModeInformation->LinearBytesPerScanLine);
    TRACE("BankedNumberOfImages = %u\n", ModeInformation->BankedNumberOfImages);
    TRACE("LinearNumberOfImages = %u\n", ModeInformation->LinearNumberOfImages);
    TRACE("LinearRedMaskSize = %u\n", ModeInformation->LinearRedMaskSize);
    TRACE("LinearRedMaskPosition = %u\n", ModeInformation->LinearRedMaskPosition);
    TRACE("LinearGreenMaskSize = %u\n", ModeInformation->LinearGreenMaskSize);
    TRACE("LinearGreenMaskPosition = %u\n", ModeInformation->LinearGreenMaskPosition);
    TRACE("LinearBlueMaskSize = %u\n", ModeInformation->LinearBlueMaskSize);
    TRACE("LinearBlueMaskPosition = %u\n", ModeInformation->LinearBlueMaskPosition);
    TRACE("LinearReservedMaskSize = %u\n", ModeInformation->LinearReservedMaskSize);
    TRACE("LinearReservedMaskPosition = %u\n", ModeInformation->LinearReservedMaskPosition);
    TRACE("MaximumPixelClock = %luHz\n", ModeInformation->MaximumPixelClock);
    TRACE("\n");
 
    return TRUE;
}
 
static BOOLEAN
PcVideoVesaGetCurrentSVGAMode(
    _Out_ PUSHORT Mode)
{
    REGS Regs;
 
    /*
     * VESA SuperVGA BIOS - GET CURRENT VIDEO MODE
     *
     * AX = 4F03h
     * Return:
     * AL = 4Fh if function supported
     * AH = status
     * 00h successful
     * BX = video mode (see #00083,#00084)
     *
     * bit 13:
     * VBE/AF v1.0P accelerated video mode
     *
     * bit 14:
     * Linear frame buffer enabled (VBE v2.0+)
     *
     * bit 15:
     * Don't clear video memory
     * 01h failed
     */
    Regs.w.ax = 0x4F03;
    Int386(0x10, &Regs, &Regs);
 
    if (Regs.w.ax != 0x004F)
        return FALSE;
 
    *Mode = Regs.w.bx;
    return TRUE;
}
 
static BOOLEAN
PcVideoGetBiosMode(
    _Out_ PUSHORT Mode)
{
    REGS Regs;
 
    /* Int 10h AH=0Fh
     * VIDEO - GET CURRENT VIDEO MODE
     *
     * AH = 0Fh
     * Return:
     * AH = number of character columns
     * AL = display mode (see #00010 at AH=00h)
     * BH = active page (see AH=05h)
     *
     * Notes: If mode was set with bit 7 set ("no blanking"), the returned
     * mode will also have bit 7 set. EGA, VGA, and UltraVision return either
     * AL=03h (color) or AL=07h (monochrome) in all extended-row text modes.
     * HP 200LX returns AL=07h (monochrome) if mode was set to AL=21h and
     * always 80 resp. 40 columns in all text modes regardless of current
     * zoom setting (see AH=D0h). When using a Hercules Graphics Card,
     * additional checks are necessary:
     *
     * mode 05h:
     * If WORD 0040h:0063h is 03B4h, may be in graphics page 1
     * (as set by DOSSHELL and other Microsoft software)
     *
     * mode 06h:
     * If WORD 0040h:0063h is 03B4h, may be in graphics page 0
     * (as set by DOSSHELL and other Microsoft software)
     *
     * mode 07h:
     * If BYTE 0040h:0065h bit 1 is set, Hercules card is in
     * graphics mode, with bit 7 indicating the page (mode set by
     * Hercules driver for Borland Turbo C).
     * The Tandy 2000 BIOS is only documented as returning AL, not AH or BH
     */
    Regs.b.ah = 0x0F;
    Int386(0x10, &Regs, &Regs);
 
    if (Regs.b.ah == 0)
        return FALSE;
 
    *Mode = Regs.b.al;
    return TRUE;
}
 
static VOID
PcVideoGetDisplayMode(VOID)
{
    USHORT Mode = 0;
 
    /* Is the current mode VESA? */
    if (PcVideoVesaGetCurrentSVGAMode(&Mode) &&
        PcVideoVesaGetSVGAModeInformation(Mode, &VesaVideoModeInformation))
    {
        TRACE("VESA mode detected\n");
        ScreenWidth = VesaVideoModeInformation.WidthInPixels;
        ScreenHeight = VesaVideoModeInformation.HeightInPixels;
        BytesPerScanLine = VesaVideoModeInformation.BytesPerScanLine;
        BiosVideoMode = Mode;
        DisplayMode = (0x0108 <= Mode && Mode <= 0x010C) ? VideoTextMode : VideoGraphicsMode;
        VesaVideoMode = TRUE;
    }
    /* If not, it should be a regular BIOS mode */
    else if (PcVideoGetBiosMode(&Mode))
    {
        /*
         * The BIOS data area 0x400 holds information about the current video mode.
         * Infos at: https://web.archive.org/web/20240119203029/http://www.bioscentral.com/misc/bda.htm
         * https://stanislavs.org/helppc/bios_data_area.html
         */
 
        UCHAR BiosMode = (*(PUCHAR)0x449) & 0x7F; /* Current video mode */
        ASSERT(BiosMode == Mode);
        BiosVideoMode = Mode;
        TRACE("BIOS mode detected\n");
 
        ScreenWidth = *(PUSHORT)0x44A; /* Number of screen columns */
        ScreenHeight = 1 + *(PUCHAR)0x484; /* 1 + "Rows on the screen (less 1, EGA+)" */
 
        /*
         * Select bits 7 and 4 of "Video display data area (MCGA and VGA)"
         * |7|6|5|4|3|2|1|0|
         *  |     `------ see table below
         *  `--------- alphanumeric scan lines (see table below)
         *
         * then convert to a number and map it to the scanline number:
         * Bit7  Bit4  Scan Lines
         * 0     0     350 line mode
         * 0     1     400 line mode
         * 1     0     200 line mode
         * 1     1     reserved
         */
        BytesPerScanLine = (*(PUCHAR)0x489) & 0x90;
        BytesPerScanLine = ((BytesPerScanLine & 0x80) >> 6) | ((BytesPerScanLine & 0x10) >> 4);
        switch (BytesPerScanLine)
        {
            case VERTRES_200_SCANLINES:
                BytesPerScanLine = 200; break;
            case VERTRES_350_SCANLINES:
                BytesPerScanLine = 350; break;
            case VERTRES_400_SCANLINES:
                BytesPerScanLine = 400; break;
            default:
                BytesPerScanLine = 160; break;
        }
 
        DisplayMode = VideoTextMode;
        VesaVideoMode = FALSE;
    }
    else
    {
        /* Set the values for the default text mode.
         * If a graphics mode is set, these values will be changed. */
        TRACE("Fallback mode detected\n");
        BiosVideoMode = VIDEOMODE_NORMAL_TEXT;
        ScreenWidth = 80;
        ScreenHeight = 25;
        BytesPerScanLine = 160;
        DisplayMode = VideoTextMode;
        VesaVideoMode = FALSE;
    }
 
    TRACE("This is a %s video mode\n", VesaVideoMode ? "VESA" : "BIOS");
    TRACE("BiosVideoMode    = 0x%x\n", BiosVideoMode);
    TRACE("DisplayMode      = %sMode\n", DisplayMode == VideoTextMode ? "Text" : "Graphics");
    TRACE("ScreenWidth      = %lu\n", ScreenWidth);
    TRACE("ScreenHeight     = %lu\n", ScreenHeight);
    TRACE("BytesPerScanLine = %lu\n", BytesPerScanLine);
}
 
static BOOLEAN
PcVideoSetBiosVesaMode(USHORT Mode)
{
    REGS Regs;
 
    /* Int 10h AX=4F02h
     * VESA SuperVGA BIOS - SET SuperVGA VIDEO MODE
     *
     * AX = 4F02h
     * BX = new video mode
     * ES:DI -> (VBE 3.0+) CRTC information block, bit mode bit 11 set
     * Return:
     * AL = 4Fh if function supported
     * AH = status
     * 00h successful
     * 01h failed
     *
     * Values for VESA video mode:
     * 00h-FFh OEM video modes (see #00010 at AH=00h)
     * 100h   640x400x256
     * 101h   640x480x256
     * 102h   800x600x16
     * 103h   800x600x256
     * 104h   1024x768x16
     * 105h   1024x768x256
     * 106h   1280x1024x16
     * 107h   1280x1024x256
     * 108h   80x60 text
     * 109h   132x25 text
     * 10Ah   132x43 text
     * 10Bh   132x50 text
     * 10Ch   132x60 text
     * ---VBE v1.2+ ---
     * 10Dh   320x200x32K
     * 10Eh   320x200x64K
     * 10Fh   320x200x16M
     * 110h   640x480x32K
     * 111h   640x480x64K
     * 112h   640x480x16M
     * 113h   800x600x32K
     * 114h   800x600x64K
     * 115h   800x600x16M
     * 116h   1024x768x32K
     * 117h   1024x768x64K
     * 118h   1024x768x16M
     * 119h   1280x1024x32K (1:5:5:5)
     * 11Ah   1280x1024x64K (5:6:5)
     * 11Bh   1280x1024x16M
     * ---VBE 2.0+ ---
     * 120h   1600x1200x256
     * 121h   1600x1200x32K
     * 122h   1600x1200x64K
     * 81FFh   special full-memory access mode
     *
     * Notes: The special mode 81FFh preserves the contents of the video memory and gives
     * access to all of the memory; VESA recommends that the special mode be a packed-pixel
     * mode. For VBE 2.0+, it is required that the VBE implement the mode, but not place it
     * in the list of available modes (mode information for this mode can be queried
     * directly, however). As of VBE 2.0, VESA will no longer define video mode numbers.
     */
    Regs.w.ax = 0x4F02;
    Regs.w.bx = Mode;
    Int386(0x10, &Regs, &Regs);
    return (Regs.w.ax == 0x004F);
}
 
static VOID
PcVideoSetBiosMode(UCHAR VideoMode)
{
    REGS Regs;
 
    /* Int 10h AH=00h
     * VIDEO - SET VIDEO MODE
     *
     * AH = 00h
     * AL = desired video mode
     * Return:
     * AL = video mode flag (Phoenix, AMI BIOS)
     * 20h mode > 7
     * 30h modes 0-5 and 7
     * 3Fh mode 6
     * AL = CRT controller mode byte (Phoenix 386 BIOS v1.10)
     */
    Regs.b.ah = 0x00;
    Regs.b.al = VideoMode;
    Int386(0x10, &Regs, &Regs);
}
 
static VOID
PcVideoSetFont8x8(VOID)
{
    REGS Regs;
 
    /* Int 10h AX=1112h
     * VIDEO - TEXT-MODE CHARGEN - LOAD ROM 8x8 DBL-DOT PATTERNS (PS,EGA,VGA)
     *
     * AX = 1112h
     * BL = block to load
     * Return:
     * Nothing
     */
    Regs.w.ax = 0x1112;
    Regs.b.bl = 0x00;
    Int386(0x10, &Regs, &Regs);
}
 
static VOID
PcVideoSetFont8x14(VOID)
{
    REGS Regs;
 
    /* Int 10h AX=1111h
     * VIDEO - TEXT-MODE CHARGEN - LOAD ROM MONOCHROME PATTERNS (PS,EGA,VGA)
     *
     * AX = 1111h
     * BL = block to load
     * Return:
     * Nothing
     */
    Regs.w.ax = 0x1111;
    Regs.b.bl = 0;
    Int386(0x10, &Regs, &Regs);
}
 
static VOID
PcVideoSelectAlternatePrintScreen(VOID)
{
    REGS Regs;
 
    /* Int 10h AH=12h BL=20h
     * VIDEO - ALTERNATE FUNCTION SELECT (PS,EGA,VGA,MCGA) - ALTERNATE PRTSC
     *
     * AH = 12h
     * BL = 20h select alternate print screen routine
     * Return:
     * Nothing
     *
     * Installs a PrtSc routine from the video card's BIOS to replace the
     * default PrtSc handler from the ROM BIOS, which usually does not
     * understand screen heights other than 25 lines.
     *
     * Some adapters disable print-screen instead of enhancing it.
     */
    Regs.b.ah = 0x12;
    Regs.b.bl = 0x20;
    Int386(0x10, &Regs, &Regs);
}
 
static VOID
PcVideoDisableCursorEmulation(VOID)
{
    REGS Regs;
 
    /* Int 10h AH=12h BL=34h
     * VIDEO - ALTERNATE FUNCTION SELECT (VGA) - CURSOR EMULATION
     *
     * AH = 12h
     * BL = 34h
     * AL = new state
     * 00h enable alphanumeric cursor emulation
     * 01h disable alphanumeric cursor emulation
     * Return:
     * AL = 12h if function supported
     *
     * Specify whether the BIOS should automatically remap cursor start/end
     * according to the current character height in text modes.
     */
    Regs.b.ah = 0x12;
    Regs.b.bl = 0x34;
    Regs.b.al = 0x01;
    Int386(0x10, &Regs, &Regs);
}
 
static VOID
PcVideoDefineCursor(UCHAR StartScanLine, UCHAR EndScanLine)
{
    REGS Regs;
 
    /* Int 10h AH=01h
     * VIDEO - SET TEXT-MODE CURSOR SHAPE
     *
     * AH = 01h
     * CH = cursor start and options
     * CL = bottom scan line containing cursor (bits 0-4)
     * Return:
     * Nothing
     *
     * Specify the starting and ending scan lines to be occupied
     * by the hardware cursor in text modes.
     *
     * AMI 386 BIOS and AST Premier 386 BIOS will lock up the
     * system if AL is not equal to the current video mode.
     *
     * Bitfields for cursor start and options:
     *
     * Bit(s)    Description
     * 7         should be zero
     * 6,5       cursor blink
     * (00=normal, 01=invisible, 10=erratic, 11=slow).
     * (00=normal, other=invisible on EGA/VGA)
     * 4-0       topmost scan line containing cursor
     */
    Regs.b.ah = 0x01;
    Regs.b.al = 0x03;
    Regs.b.ch = StartScanLine;
    Regs.b.cl = EndScanLine;
    Int386(0x10, &Regs, &Regs);
}
 
static VOID
PcVideoSetVerticalResolution(UCHAR VerticalResolutionMode)
{
    REGS Regs;
 
    /* Int 10h AH=12h BL=30h
     * VIDEO - ALTERNATE FUNCTION SELECT (VGA) - SELECT VERTICAL RESOLUTION
     *
     * AH = 12h
     * BL = 30h
     * AL = vertical resolution
     * 00h 200 scan lines
     * 01h 350 scan lines
     * 02h 400 scan lines
     * Return:
     * AL = 12h if function supported
     *
     * Specify the number of scan lines used to display text modes.
     *
     * The specified resolution will take effect on the next mode set.
     */
    Regs.b.ah = 0x12;
    Regs.b.bl = 0x30;
    Regs.b.al = VerticalResolutionMode;
    Int386(0x10, &Regs, &Regs);
}
 
static VOID
PcVideoSet480ScanLines(VOID)
{
    INT_PTR CRTC;
 
    /* Read CRTC port */
    CRTC = READ_PORT_UCHAR((PUCHAR)0x03CC);
    if (CRTC & 1)
        CRTC = 0x3D4;
    else
        CRTC = 0x3B4;
 
    /* Vertical sync end (also unlocks CR0-7) */
    WRITE_PORT_UCHAR((PUCHAR)CRTC, 0x11);
    WRITE_PORT_UCHAR((PUCHAR)CRTC+1, 0x0C);
 
    /* Vertical total */
    WRITE_PORT_UCHAR((PUCHAR)CRTC, 0x06);
    WRITE_PORT_UCHAR((PUCHAR)CRTC+1, 0x0B);
 
    /* (vertical) overflow */
    WRITE_PORT_UCHAR((PUCHAR)CRTC, 0x07);
    WRITE_PORT_UCHAR((PUCHAR)CRTC+1, 0x3E);
 
    /* Vertical sync start */
    WRITE_PORT_UCHAR((PUCHAR)CRTC, 0x10);
    WRITE_PORT_UCHAR((PUCHAR)CRTC+1, 0xEA);
 
    /* Vertical display end */
    WRITE_PORT_UCHAR((PUCHAR)CRTC, 0x12);
    WRITE_PORT_UCHAR((PUCHAR)CRTC+1, 0xDF);
 
    /* Vertical blank start */
    WRITE_PORT_UCHAR((PUCHAR)CRTC, 0x15);
    WRITE_PORT_UCHAR((PUCHAR)CRTC+1, 0xE7);
 
    /* Vertical blank end */
    WRITE_PORT_UCHAR((PUCHAR)CRTC, 0x16);
    WRITE_PORT_UCHAR((PUCHAR)CRTC+1, 0x04);
 
    /* Misc output register (read) */
    CRTC = READ_PORT_UCHAR((PUCHAR)0x03CC);
 
    /* Preserve clock select bits and color bit */
    CRTC = (CRTC & 0x0D);
    /* Set correct sync polarity */
    CRTC = (CRTC | 0xE2);
 
    /* (write) */
    WRITE_PORT_UCHAR((PUCHAR)0x03C2, (UCHAR)CRTC);
}
 
static VOID
PcVideoSetDisplayEnd(VOID)
{
    INT_PTR CRTC;
 
    /* Read CRTC port */
    CRTC = READ_PORT_UCHAR((PUCHAR)0x03CC);
    if (CRTC & 1)
        CRTC = 0x3D4;
    else
        CRTC = 0x3B4;
 
    /* Vertical display end */
    WRITE_PORT_UCHAR((PUCHAR)CRTC, 0x12);
    WRITE_PORT_UCHAR((PUCHAR)CRTC+1, 0xDF);
}
 
static BOOLEAN
PcVideoSetMode80x25(VOID)
{
    PcVideoSetBiosMode(0x03);
    ScreenWidth = 80;
    ScreenHeight = 25;
    return TRUE;
}
 
static BOOLEAN
PcVideoSetMode80x50_80x43(VOID)
{
    if (VideoCard == VIDEOCARD_VGA)
    {
        PcVideoSetBiosMode(0x03);
        PcVideoSetFont8x8();
        PcVideoSelectAlternatePrintScreen();
        PcVideoDisableCursorEmulation();
        PcVideoDefineCursor(6, 7);
        ScreenWidth = 80;
        ScreenHeight = 50;
    }
    else if (VideoCard == VIDEOCARD_EGA)
    {
        PcVideoSetBiosMode(0x03);
        PcVideoSetFont8x8();
        PcVideoSelectAlternatePrintScreen();
        PcVideoDisableCursorEmulation();
        PcVideoDefineCursor(6, 7);
        ScreenWidth = 80;
        ScreenHeight = 43;
    }
    else /* VIDEOCARD_CGA_OR_OTHER */
    {
        return FALSE;
    }
 
    return TRUE;
}
 
static BOOLEAN
PcVideoSetMode80x28(VOID)
{
    /* FIXME: Is this VGA-only? */
    PcVideoSetMode80x25();
    PcVideoSetFont8x14();
    PcVideoDefineCursor(11, 12);
    ScreenWidth = 80;
    ScreenHeight = 28;
    return TRUE;
}
 
static BOOLEAN
PcVideoSetMode80x30(VOID)
{
    /* FIXME: Is this VGA-only? */
    PcVideoSetMode80x25();
    PcVideoSet480ScanLines();
    ScreenWidth = 80;
    ScreenHeight = 30;
    return TRUE;
}
 
static BOOLEAN
PcVideoSetMode80x34(VOID)
{
    /* FIXME: Is this VGA-only? */
    PcVideoSetMode80x25();
    PcVideoSet480ScanLines();
    PcVideoSetFont8x14();
    PcVideoDefineCursor(11, 12);
    PcVideoSetDisplayEnd();
    ScreenWidth = 80;
    ScreenHeight = 34;
    return TRUE;
}
 
static BOOLEAN
PcVideoSetMode80x43(VOID)
{
    /* FIXME: Is this VGA-only? */
    PcVideoSetVerticalResolution(VERTRES_350_SCANLINES);
    PcVideoSetMode80x25();
    PcVideoSetFont8x8();
    PcVideoSelectAlternatePrintScreen();
    PcVideoDisableCursorEmulation();
    PcVideoDefineCursor(6, 7);
    ScreenWidth = 80;
    ScreenHeight = 43;
    return TRUE;
}
 
static BOOLEAN
PcVideoSetMode80x60(VOID)
{
    /* FIXME: Is this VGA-only? */
    PcVideoSetMode80x25();
    PcVideoSet480ScanLines();
    PcVideoSetFont8x8();
    PcVideoSelectAlternatePrintScreen();
    PcVideoDisableCursorEmulation();
    PcVideoDefineCursor(6, 7);
    PcVideoSetDisplayEnd();
    ScreenWidth = 80;
    ScreenHeight = 60;
    return TRUE;
}
 
static BOOLEAN
PcVideoSetMode(USHORT NewMode)
{
    CurrentMemoryBank = 0;
 
    /* Set the values for the default text modes
     * If they are setting a graphics mode then
     * these values will be changed. */
    BiosVideoMode = NewMode;
    ScreenWidth = 80;
    ScreenHeight = 25;
    BytesPerScanLine = 160;
    DisplayMode = VideoTextMode;
    VesaVideoMode = FALSE;
 
    switch (NewMode)
    {
        case VIDEOMODE_NORMAL_TEXT:
        case 0x03: /* BIOS 80x25 text mode number */
            return PcVideoSetMode80x25();
        case VIDEOMODE_EXTENDED_TEXT:
            return PcVideoSetMode80x50_80x43();
        case VIDEOMODE_80X28:
            return PcVideoSetMode80x28();
        case VIDEOMODE_80X30:
            return PcVideoSetMode80x30();
        case VIDEOMODE_80X34:
            return PcVideoSetMode80x34();
        case VIDEOMODE_80X43:
            return PcVideoSetMode80x43();
        case VIDEOMODE_80X60:
            return PcVideoSetMode80x60();
    }
 
    if (NewMode == 0x12)
    {
        /* 640x480x16 */
        PcVideoSetBiosMode((UCHAR)NewMode);
        WRITE_PORT_USHORT((USHORT*)0x03CE, 0x0F01); /* For some reason this is necessary? */
        ScreenWidth = 640;
        ScreenHeight = 480;
        BytesPerScanLine = 80;
        BiosVideoMode = NewMode;
        DisplayMode = VideoGraphicsMode;
 
        return TRUE;
    }
    else if (NewMode == 0x13)
    {
        /* 320x200x256 */
        PcVideoSetBiosMode((UCHAR)NewMode);
        ScreenWidth = 320;
        ScreenHeight = 200;
        BytesPerScanLine = 320;
        BiosVideoMode = NewMode;
        DisplayMode = VideoGraphicsMode;
 
        return TRUE;
    }
    else
    {
        /* VESA Text/Graphics Mode */
        if (!PcVideoVesaGetSVGAModeInformation(NewMode, &VesaVideoModeInformation))
            return FALSE;
 
        if (!PcVideoSetBiosVesaMode(NewMode))
            return FALSE;
 
        ScreenWidth = VesaVideoModeInformation.WidthInPixels;
        ScreenHeight = VesaVideoModeInformation.HeightInPixels;
        BytesPerScanLine = VesaVideoModeInformation.BytesPerScanLine;
        BiosVideoMode = NewMode;
        DisplayMode = (0x0108 <= NewMode && NewMode <= 0x010C) ? VideoTextMode : VideoGraphicsMode;
        VesaVideoMode = TRUE;
 
        return TRUE;
    }
 
    return FALSE;
}
 
static VOID
PcVideoSetBlinkBit(BOOLEAN Enable)
{
    REGS Regs;
 
    /* Int 10h AX=1003h
     * VIDEO - TOGGLE INTENSITY/BLINKING BIT (Jr, PS, TANDY 1000, EGA, VGA)
     *
     * AX = 1003h
     * BL = new state
     * 00h background intensity enabled
     * 01h blink enabled
     * BH = 00h to avoid problems on some adapters
     * Return:
     * Nothing
     *
     * Note: although there is no function to get
     * the current status, bit 5 of 0040h:0065h
     * indicates the state.
     */
    Regs.w.ax = 0x1003;
    Regs.w.bx = Enable ? 0x0001 : 0x0000;
    Int386(0x10, &Regs, &Regs);
}
 
static VOID
PcVideoSetMemoryBank(USHORT BankNumber)
{
    REGS Regs;
 
    if (CurrentMemoryBank == BankNumber)
        return;
 
    /* Int 10h AX=4F05h
     * VESA SuperVGA BIOS - CPU VIDEO MEMORY CONTROL
     *
     * AX = 4F05h
     * BH = subfunction
     * 00h select video memory window
     * 01h get video memory window
     * DX = window address in video memory (in granularity units)
     * Return:
     * DX = window address in video memory (in gran. units)
     * BL = window number
     * 00h window A
     * 01h window B.
     * Return:
     * AL = 4Fh if function supported
     * AH = status
     * 00h successful
     * 01h failed
     */
    Regs.w.ax = 0x4F05;
    Regs.w.bx = 0x0000;
    Regs.w.dx = BankNumber;
    Int386(0x10, &Regs, &Regs);
 
    if (Regs.w.ax == 0x004F)
        CurrentMemoryBank = BankNumber;
}
 
VOID
PcVideoInit(VOID)
{
    /* Detect the installed video card */
    VideoCard = PcVideoDetectVideoCard();
 
    /* Retrieve the initial display mode parameters */
    PcVideoGetDisplayMode();
 
    /* If any video options have been specified, try to set a display mode */
    if (BootMgrInfo.VideoOptions && *BootMgrInfo.VideoOptions)
        PcVideoSetDisplayMode(BootMgrInfo.VideoOptions, TRUE);
 
    // FIXME: We don't support graphics modes yet!
    // Revert to 80x25 text mode.
    if (DisplayMode != VideoTextMode)
        PcVideoSetMode(VIDEOMODE_NORMAL_TEXT);
}
 
#define TRACE_printf(Format, ...) \
do { \
    TRACE(Format, ##__VA_ARGS__); \
    printf(Format, ##__VA_ARGS__); \
} while (0)
 
VIDEODISPLAYMODE
PcVideoSetDisplayMode(PCSTR DisplayModeName, BOOLEAN Init)
{
    USHORT VideoMode = VIDEOMODE_NORMAL_TEXT;
 
    if (!DisplayModeName || *DisplayModeName == '\0')
        goto Quit;
 
    if (VideoCard == VIDEOCARD_CGA_OR_OTHER)
    {
        TRACE_printf("CGA or other display adapter detected.\n");
        TRACE_printf("Using 80x25 text mode.\n");
        VideoMode = VIDEOMODE_NORMAL_TEXT;
    }
    else if (VideoCard == VIDEOCARD_EGA)
    {
        TRACE_printf("EGA display adapter detected.\n");
        TRACE_printf("Using 80x25 text mode.\n");
        VideoMode = VIDEOMODE_NORMAL_TEXT;
    }
    else /* VIDEOCARD_VGA */
    {
        TRACE_printf("VGA display adapter detected.\n");
 
        /* Get the video option separator, if any */
        size_t NameLen = strcspn(DisplayModeName, ",");
        if (!NameLen)
            goto Quit;
 
        if (_strnicmp(DisplayModeName, "NORMAL_VGA", NameLen) == 0)
            VideoMode = VIDEOMODE_NORMAL_TEXT;
        else if (_strnicmp(DisplayModeName, "EXTENDED_VGA", NameLen) == 0)
            VideoMode = VIDEOMODE_EXTENDED_TEXT;
        else
            VideoMode = (USHORT)strtoul(DisplayModeName, NULL, 0);
    }
 
    if (!PcVideoSetMode(VideoMode))
    {
        TRACE_printf("Error: unable to set video display mode 0x%x\n", VideoMode);
        TRACE_printf("Defaulting to 80x25 text mode.\n");
        printf("Press any key to continue.\n");
        PcConsGetCh();
 
        PcVideoSetMode(VIDEOMODE_NORMAL_TEXT);
    }
 
Quit:
    PcVideoSetBlinkBit(!Init);
    return DisplayMode;
}
 
VOID
PcVideoGetDisplaySize(PULONG Width, PULONG Height, PULONG Depth)
{
    *Width = ScreenWidth;
    *Height = ScreenHeight;
    if (VideoGraphicsMode == DisplayMode && VesaVideoMode)
    {
        if (VesaVideoModeInformation.BitsPerPixel == 16)
        {
            /* 16-bit color modes give green an extra bit (5:6:5)
             * 15-bit color modes have just 5:5:5 for R:G:B */
            *Depth = (VesaVideoModeInformation.GreenMaskSize == 6 ? 16 : 15);
        }
        else
        {
            *Depth = VesaVideoModeInformation.BitsPerPixel;
        }
    }
    else
    {
        *Depth = 0;
    }
}
 
ULONG
PcVideoGetBufferSize(VOID)
{
    return ScreenHeight * BytesPerScanLine;
}
 
VOID
PcVideoGetFontsFromFirmware(PULONG RomFontPointers)
{
    REGS BiosRegs;
 
    /* Get the address of the BIOS ROM fonts.
     * Int 10h, AX=1130h, BH = pointer specifier
     * Returns: es:bp = address */
    BiosRegs.d.eax = 0x1130;
    BiosRegs.b.bh = ROM_8x14CharacterFont;
    Int386(0x10, &BiosRegs, &BiosRegs);
    RomFontPointers[0] = BiosRegs.w.es << 4 | BiosRegs.w.bp;
 
    BiosRegs.b.bh = ROM_8x8DoubleDotFontLo;
    Int386(0x10, &BiosRegs, &BiosRegs);
    RomFontPointers[1] = BiosRegs.w.es << 16 | BiosRegs.w.bp;
 
    BiosRegs.b.bh = ROM_8x8DoubleDotFontHi;
    Int386(0x10, &BiosRegs, &BiosRegs);
    RomFontPointers[2] = BiosRegs.w.es << 16 | BiosRegs.w.bp;
 
    BiosRegs.b.bh = ROM_AlphaAlternate;
    Int386(0x10, &BiosRegs, &BiosRegs);
    RomFontPointers[3] = BiosRegs.w.es << 16 | BiosRegs.w.bp;
 
    BiosRegs.b.bh = ROM_8x16Font;
    Int386(0x10, &BiosRegs, &BiosRegs);
    RomFontPointers[4] = BiosRegs.w.es << 16 | BiosRegs.w.bp;
 
    BiosRegs.b.bh = ROM_Alternate9x16Font;
    Int386(0x10, &BiosRegs, &BiosRegs);
    RomFontPointers[5] = BiosRegs.w.es << 16 | BiosRegs.w.bp;
}
 
VOID
PcVideoSetTextCursorPosition(UCHAR X, UCHAR Y)
{
    REGS Regs;
 
    /* Int 10h AH=02h
     * VIDEO - SET CURSOR POSITION
     *
     * AH = 02h
     * BH = page number
     * 0-3 in modes 2&3
     * 0-7 in modes 0&1
     * 0 in graphics modes
     * DH = row (00h is top)
     * DL = column (00h is left)
     * Return:
     * Nothing
     */
    Regs.b.ah = 0x02;
    Regs.b.bh = 0x00;
    Regs.b.dh = Y;
    Regs.b.dl = X;
    Int386(0x10, &Regs, &Regs);
}
 
VOID
PcVideoHideShowTextCursor(BOOLEAN Show)
{
    if (Show)
        PcVideoDefineCursor(0x0D, 0x0E);
    else
        PcVideoDefineCursor(0x20, 0x00);
}
 
VOID
PcVideoCopyOffScreenBufferToVRAM(PVOID Buffer)
{
    USHORT BanksToCopy;
    ULONG BytesInLastBank;
    USHORT CurrentBank;
    ULONG BankSize;
 
    /* PcVideoWaitForVerticalRetrace(); */
 
    /* Text mode (BIOS or VESA) */
    if (VideoTextMode == DisplayMode)
    {
        RtlCopyMemory((PVOID)VIDEOTEXT_MEM_ADDRESS, Buffer, PcVideoGetBufferSize());
    }
    /* VESA graphics mode */
    else if (VideoGraphicsMode == DisplayMode && VesaVideoMode)
    {
        BankSize = VesaVideoModeInformation.WindowGranularity << 10;
        BanksToCopy = (USHORT)((VesaVideoModeInformation.HeightInPixels * VesaVideoModeInformation.BytesPerScanLine) / BankSize);
        BytesInLastBank = (VesaVideoModeInformation.HeightInPixels * VesaVideoModeInformation.BytesPerScanLine) % BankSize;
 
        /* Copy all the banks but the last one because
         * it is probably a partial bank */
        for (CurrentBank = 0; CurrentBank < BanksToCopy; CurrentBank++)
        {
            PcVideoSetMemoryBank(CurrentBank);
            RtlCopyMemory((PVOID)VIDEOVGA_MEM_ADDRESS, (char*)Buffer + CurrentBank * BankSize, BankSize);
        }
 
        /* Copy the remaining bytes into the last bank */
        PcVideoSetMemoryBank(CurrentBank);
        RtlCopyMemory((PVOID)VIDEOVGA_MEM_ADDRESS, (char*)Buffer + CurrentBank * BankSize, BytesInLastBank);
    }
    /* BIOS graphics mode */
    else
    {
        UNIMPLEMENTED;
    }
}
 
VOID
PcVideoClearScreen(UCHAR Attr)
{
    USHORT AttrChar;
    USHORT *BufPtr;
 
    AttrChar = ((USHORT)Attr << 8) | ' ';
    for (BufPtr = (USHORT*)VIDEOTEXT_MEM_ADDRESS;
         BufPtr < (USHORT*)(VIDEOTEXT_MEM_ADDRESS + VIDEOTEXT_MEM_SIZE);
         BufPtr++)
    {
        _PRAGMA_WARNING_SUPPRESS(__WARNING_DEREF_NULL_PTR)
        *BufPtr = AttrChar;
    }
}
 
VOID
PcVideoPutChar(int Ch, UCHAR Attr, unsigned X, unsigned Y)
{
    USHORT *BufPtr;
 
    BufPtr = (USHORT*)(ULONG_PTR)(VIDEOTEXT_MEM_ADDRESS + Y * BytesPerScanLine + X * 2);
    *BufPtr = ((USHORT)Attr << 8) | (Ch & 0xff);
}
 
BOOLEAN
PcVideoIsPaletteFixed(VOID)
{
    return FALSE;
}
 
VOID
PcVideoSetPaletteColor(UCHAR Color, UCHAR Red, UCHAR Green, UCHAR Blue)
{
    WRITE_PORT_UCHAR((UCHAR*)VIDEOPORT_PALETTE_WRITE, Color);
    WRITE_PORT_UCHAR((UCHAR*)VIDEOPORT_PALETTE_DATA, Red);
    WRITE_PORT_UCHAR((UCHAR*)VIDEOPORT_PALETTE_DATA, Green);
    WRITE_PORT_UCHAR((UCHAR*)VIDEOPORT_PALETTE_DATA, Blue);
}
 
VOID
PcVideoGetPaletteColor(UCHAR Color, UCHAR* Red, UCHAR* Green, UCHAR* Blue)
{
    WRITE_PORT_UCHAR((UCHAR*)VIDEOPORT_PALETTE_READ, Color);
    *Red = READ_PORT_UCHAR((UCHAR*)VIDEOPORT_PALETTE_DATA);
    *Green = READ_PORT_UCHAR((UCHAR*)VIDEOPORT_PALETTE_DATA);
    *Blue = READ_PORT_UCHAR((UCHAR*)VIDEOPORT_PALETTE_DATA);
}
 
VOID
PcVideoSync(VOID)
{
    while ((READ_PORT_UCHAR((UCHAR*)VIDEOPORT_VERTICAL_RETRACE) & 0x08))
    {
        /*
         * Keep reading the port until bit 3 is clear
         * This waits for the current retrace to end and
         * we can catch the next one so we know we are
         * getting a full retrace.
         */
    }
 
    while (!(READ_PORT_UCHAR((UCHAR*)VIDEOPORT_VERTICAL_RETRACE) & 0x08))
    {
        /*
         * Keep reading the port until bit 3 is set
         * Now that we know we aren't doing a vertical
         * retrace we need to wait for the next one.
         */
    }
}
 
VOID
PcVideoPrepareForReactOS(VOID)
{
    // PcVideoSetMode80x50_80x43();
    PcVideoSetMode80x25();
    PcVideoHideShowTextCursor(FALSE);
}
 
/* EOF */