subsystems/ntvdm/vga.c

   1 /*
   2  * COPYRIGHT:       GPL - See COPYING in the top level directory
   3  * PROJECT:         ReactOS Virtual DOS Machine
   4  * FILE:            vga.c
   5  * PURPOSE:         VGA hardware emulation
   6  * PROGRAMMERS:     Aleksandar Andrejevic <theflash AT sdf DOT lonestar DOT org>
   7  */
   8
   9 /* INCLUDES *******************************************************************/
  10
  11 #define NDEBUG
  12
  13 #include "vga.h"
  14 #include "bios.h"
  15
  16 /* PRIVATE VARIABLES **********************************************************/
  17
  18 static CONST DWORD MemoryBase[] = { 0xA0000, 0xA0000, 0xB0000, 0xB8000 };
  19 static CONST DWORD MemoryLimit[] = { 0xAFFFF, 0xAFFFF, 0xB7FFF, 0xBFFFF };
  20
  21 static BYTE VgaMemory[VGA_NUM_BANKS * VGA_BANK_SIZE];
  22 static BYTE VgaMiscRegister;
  23 static BYTE VgaSeqIndex = VGA_SEQ_RESET_REG;
  24 static BYTE VgaSeqRegisters[VGA_SEQ_MAX_REG];
  25 static BYTE VgaGcIndex = VGA_GC_RESET_REG;
  26 static BYTE VgaGcRegisters[VGA_GC_MAX_REG];
  27 static BYTE VgaCrtcIndex = VGA_CRTC_HORZ_TOTAL_REG;
  28 static BYTE VgaCrtcRegisters[VGA_CRTC_MAX_REG];
  29 static BYTE VgaAcIndex = VGA_AC_PAL_0_REG;
  30 static BOOLEAN VgaAcLatch = FALSE;
  31 static BYTE VgaAcRegisters[VGA_AC_MAX_REG];
  32 static BYTE VgaDacIndex = 0;
  33 static BOOLEAN VgaDacReadWrite = FALSE;
  34 static BYTE VgaDacRegisters[VGA_PALETTE_SIZE];
  35 static BOOLEAN InVerticalRetrace = FALSE;
  36 static BOOLEAN InHorizontalRetrace = FALSE;
  37 static HANDLE TextConsoleBuffer = NULL;
  38 static HANDLE GraphicsConsoleBuffer = NULL;
  39 static LPVOID ConsoleFramebuffer = NULL;
  40 static HANDLE ConsoleMutex = NULL;
  41 static BOOLEAN NeedsUpdate = FALSE;
  42 static BOOLEAN ModeChanged = TRUE;
  43 static BOOLEAN CursorMoved = FALSE;
  44 static BOOLEAN TextMode = TRUE;
  45 static SMALL_RECT UpdateRectangle = { 0, 0, 0, 0 };
  46
  47 /* PRIVATE FUNCTIONS **********************************************************/
  48
  49 static inline INT VgaGetAddressSize(VOID)
  50 {
  51     if (VgaCrtcRegisters[VGA_CRTC_UNDERLINE_REG] & VGA_CRTC_UNDERLINE_DWORD)
  52     {
  53         /* Double-word addressing */
  54         return 4;
  55     }
  56
  57     if (VgaCrtcRegisters[VGA_CRTC_MODE_CONTROL_REG] & VGA_CRTC_MODE_CONTROL_BYTE)
  58     {
  59         /* Byte addressing */
  60         return 1;
  61     }
  62
  63     /* Word addressing */
  64     return 2;
  65 }
  66
  67 static inline DWORD VgaTranslateReadAddress(DWORD Address)
  68 {
  69     DWORD Offset = Address - VgaGetVideoBaseAddress();
  70     BYTE Plane;
  71
  72     /* Check for chain-4 and odd-even mode */
  73     if (VgaSeqRegisters[VGA_SEQ_MEM_REG] & VGA_SEQ_MEM_C4)
  74     {
  75         /* The lowest two bits are the plane number */
  76         Plane = Offset & 3;
  77         Offset >>= 2;
  78     }
  79     else if (VgaGcRegisters[VGA_GC_MODE_REG] & VGA_GC_MODE_OE)
  80     {
  81         /* The LSB is the plane number */
  82         Plane = Offset & 1;
  83         Offset >>= 1;
  84     }
  85     else
  86     {
  87         /* Use the read mode */
  88         Plane = VgaGcRegisters[VGA_GC_READ_MAP_SEL_REG] & 0x03;
  89     }
  90
  91     /* Multiply the offset by the address size */
  92     Offset *= VgaGetAddressSize();
  93
  94     return Offset + Plane * VGA_BANK_SIZE;
  95 }
  96
  97 static inline DWORD VgaTranslateWriteAddress(DWORD Address)
  98 {
  99     DWORD Offset = Address - VgaGetVideoBaseAddress();
 100
 101     /* Check for chain-4 and odd-even mode */
 102     if (VgaSeqRegisters[VGA_SEQ_MEM_REG] & VGA_SEQ_MEM_C4)
 103     {
 104         /* Shift the offset to the right by 2 */
 105         Offset >>= 2;
 106     }
 107     else if (VgaGcRegisters[VGA_GC_MODE_REG] & VGA_GC_MODE_OE)
 108     {
 109         /* Shift the offset to the right by 1 */
 110         Offset >>= 1;
 111     }
 112
 113     /* Multiply the offset by the address size */
 114     Offset *= VgaGetAddressSize();
 115
 116     /* Return the offset on plane 0 */
 117     return Offset;
 118 }
 119
 120 static inline VOID VgaMarkForUpdate(SHORT Row, SHORT Column)
 121 {
 122     DPRINT("VgaMarkForUpdate: Row %d, Column %d\n", Row, Column);
 123
 124     /* Check if this is the first time the rectangle is updated */
 125     if (!NeedsUpdate)
 126     {
 127         UpdateRectangle.Left = UpdateRectangle.Top = SHRT_MAX;
 128         UpdateRectangle.Right = UpdateRectangle.Bottom = SHRT_MIN;
 129     }
 130
 131     /* Expand the rectangle to include the point */
 132     UpdateRectangle.Left = min(UpdateRectangle.Left, Column);
 133     UpdateRectangle.Right = max(UpdateRectangle.Right, Column);
 134     UpdateRectangle.Top = min(UpdateRectangle.Top, Row);
 135     UpdateRectangle.Bottom = max(UpdateRectangle.Bottom, Row);
 136
 137     /* Set the update request flag */
 138     NeedsUpdate = TRUE;
 139 }
 140
 141 static VOID VgaWriteSequencer(BYTE Data)
 142 {
 143     ASSERT(VgaSeqIndex < VGA_SEQ_MAX_REG);
 144
 145     /* Save the value */
 146     VgaSeqRegisters[VgaSeqIndex] = Data;
 147 }
 148
 149 static VOID VgaWriteGc(BYTE Data)
 150 {
 151     ASSERT(VgaGcIndex < VGA_GC_MAX_REG);
 152
 153     /* Save the value */
 154     VgaGcRegisters[VgaGcIndex] = Data;
 155
 156     /* Check the index */
 157     switch (VgaGcIndex)
 158     {
 159         case VGA_GC_MISC_REG:
 160         {
 161             /* The GC misc register decides if it's text or graphics mode */
 162             ModeChanged = TRUE;
 163
 164             break;
 165         }
 166     }
 167 }
 168
 169 static VOID VgaWriteCrtc(BYTE Data)
 170 {
 171     ASSERT(VgaGcIndex < VGA_CRTC_MAX_REG);
 172
 173     /* Save the value */
 174     VgaCrtcRegisters[VgaCrtcIndex] = Data;
 175
 176     /* Check the index */
 177     switch (VgaCrtcIndex)
 178     {
 179         case VGA_CRTC_END_HORZ_DISP_REG:
 180         case VGA_CRTC_VERT_DISP_END_REG:
 181         case VGA_CRTC_OVERFLOW_REG:
 182         {
 183             /* The video mode has changed */
 184             ModeChanged = TRUE;
 185
 186             break;
 187         }
 188
 189         case VGA_CRTC_CURSOR_LOC_LOW_REG:
 190         case VGA_CRTC_CURSOR_LOC_HIGH_REG:
 191         case VGA_CRTC_CURSOR_START_REG:
 192         case VGA_CRTC_CURSOR_END_REG:
 193         {
 194             /* Set the cursor moved flag */
 195             CursorMoved = TRUE;
 196
 197             break;
 198         }
 199     }
 200 }
 201
 202 static VOID VgaWriteDac(BYTE Data)
 203 {
 204     /* Set the value */
 205     VgaDacRegisters[VgaDacIndex++] = Data;
 206     VgaDacIndex %= VGA_PALETTE_SIZE;
 207
 208     // TODO: Change the palette!
 209 }
 210
 211 static VOID VgaWriteAc(BYTE Data)
 212 {
 213     ASSERT(VgaAcIndex < VGA_AC_MAX_REG);
 214
 215     /* Save the value */
 216     VgaAcRegisters[VgaAcIndex] = Data;
 217 }
 218
 219 static BOOL VgaEnterGraphicsMode(PCOORD Resolution)
 220 {
 221     DWORD i;
 222     CONSOLE_GRAPHICS_BUFFER_INFO GraphicsBufferInfo;
 223     BYTE BitmapInfoBuffer[VGA_BITMAP_INFO_SIZE];
 224     LPBITMAPINFO BitmapInfo = (LPBITMAPINFO)BitmapInfoBuffer;
 225     LPWORD PaletteIndex = (LPWORD)(BitmapInfoBuffer + sizeof(BITMAPINFOHEADER));
 226
 227     /* Fill the bitmap info header */
 228     ZeroMemory(&BitmapInfo->bmiHeader, sizeof(BITMAPINFOHEADER));
 229     BitmapInfo->bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
 230     BitmapInfo->bmiHeader.biWidth = Resolution->X;
 231     BitmapInfo->bmiHeader.biHeight = Resolution->Y;
 232     BitmapInfo->bmiHeader.biBitCount = 8;
 233     BitmapInfo->bmiHeader.biPlanes = 1;
 234     BitmapInfo->bmiHeader.biCompression = BI_RGB;
 235     BitmapInfo->bmiHeader.biSizeImage = Resolution->X * Resolution->Y;
 236
 237     /* Fill the palette data */
 238     for (i = 0; i < (VGA_PALETTE_SIZE / 3); i++) PaletteIndex[i] = (WORD)i;
 239
 240     /* Fill the console graphics buffer info */
 241     GraphicsBufferInfo.dwBitMapInfoLength = VGA_BITMAP_INFO_SIZE;
 242     GraphicsBufferInfo.lpBitMapInfo = BitmapInfo;
 243     GraphicsBufferInfo.dwUsage = DIB_PAL_COLORS;
 244
 245     /* Create the buffer */
 246     GraphicsConsoleBuffer = CreateConsoleScreenBuffer(GENERIC_READ | GENERIC_WRITE,
 247                                                       FILE_SHARE_READ | FILE_SHARE_WRITE,
 248                                                       NULL,
 249                                                       CONSOLE_GRAPHICS_BUFFER,
 250                                                       &GraphicsBufferInfo);
 251     if (GraphicsConsoleBuffer == INVALID_HANDLE_VALUE) return FALSE;
 252
 253     /* Save the framebuffer address and mutex */
 254     ConsoleFramebuffer = GraphicsBufferInfo.lpBitMap;
 255     ConsoleMutex = GraphicsBufferInfo.hMutex;
 256
 257     /* Clear the framebuffer */
 258     ZeroMemory(ConsoleFramebuffer, BitmapInfo->bmiHeader.biSizeImage);
 259
 260     /* Set the active buffer */
 261     SetConsoleActiveScreenBuffer(GraphicsConsoleBuffer);
 262
 263     return TRUE;
 264 }
 265
 266 static VOID VgaLeaveGraphicsMode(VOID)
 267 {
 268     /* Switch back to the text buffer */
 269     SetConsoleActiveScreenBuffer(TextConsoleBuffer);
 270
 271     /* Cleanup the video data */
 272     CloseHandle(ConsoleMutex);
 273     CloseHandle(GraphicsConsoleBuffer);
 274     GraphicsConsoleBuffer = NULL;
 275 }
 276
 277 static BOOL VgaEnterTextMode(PCOORD Resolution)
 278 {
 279     /* Resize the console */
 280     SetConsoleScreenBufferSize(TextConsoleBuffer, *Resolution);
 281
 282     /* Allocate a framebuffer */
 283     ConsoleFramebuffer = HeapAlloc(GetProcessHeap(),
 284                                    HEAP_ZERO_MEMORY,
 285                                    Resolution->X * Resolution->Y
 286                                    * sizeof(CHAR_INFO));
 287     if (ConsoleFramebuffer == NULL)
 288     {
 289         DisplayMessage(L"An unexpected error occurred!\n");
 290         VdmRunning = FALSE;
 291         return FALSE;
 292     }
 293
 294     return TRUE;
 295 }
 296
 297 static VOID VgaLeaveTextMode(VOID)
 298 {
 299     /* Free the old framebuffer */
 300     HeapFree(GetProcessHeap(), 0, ConsoleFramebuffer);
 301     ConsoleFramebuffer = NULL;
 302 }
 303
 304 static VOID VgaUpdateMode(VOID)
 305 {
 306     COORD Resolution = VgaGetDisplayResolution();
 307
 308     if (!TextMode)
 309     {
 310         /* Leave the current graphics mode */
 311         VgaLeaveGraphicsMode();
 312     }
 313     else
 314     {
 315         /* Leave the current text mode */
 316         VgaLeaveTextMode();
 317     }
 318
 319     /* Check if the new mode is alphanumeric */
 320     if (!(VgaGcRegisters[VGA_GC_MISC_REG] & VGA_GC_MISC_NOALPHA))
 321     {
 322         /* Enter new text mode */
 323         if (!VgaEnterTextMode(&Resolution)) return;
 324
 325         /* Set the text mode flag */
 326         TextMode = TRUE;
 327     }
 328     else
 329     {
 330         /* Enter 8-bit graphics mode */
 331         if (!VgaEnterGraphicsMode(&Resolution)) return;
 332
 333         /* Clear the text mode flag */
 334         TextMode = FALSE;
 335     }
 336
 337     /* Perform a full update */
 338     NeedsUpdate = TRUE;
 339     UpdateRectangle.Left = 0;
 340     UpdateRectangle.Top = 0;
 341     UpdateRectangle.Right = Resolution.X;
 342     UpdateRectangle.Bottom = Resolution.Y;
 343 }
 344
 345 static VOID VgaUpdateFramebuffer(VOID)
 346 {
 347     INT i, j, k;
 348     COORD Resolution = VgaGetDisplayResolution();
 349     INT AddressSize = VgaGetAddressSize();
 350     DWORD Address = (VgaCrtcRegisters[VGA_CRTC_START_ADDR_HIGH_REG] << 8)
 351                     + VgaCrtcRegisters[VGA_CRTC_START_ADDR_LOW_REG];
 352     DWORD ScanlineSize = (DWORD)VgaCrtcRegisters[VGA_CRTC_OFFSET_REG] * 2;
 353     PCHAR_INFO CharBuffer = (PCHAR_INFO)ConsoleFramebuffer;
 354     PBYTE GraphicsBuffer = (PBYTE)ConsoleFramebuffer;
 355
 356     /* Loop through the scanlines */
 357     for (i = 0; i < Resolution.Y; i++)
 358     {
 359         /* Check if this is text mode or graphics mode */
 360         if (VgaGcRegisters[VGA_GC_MISC_REG] & VGA_GC_MISC_NOALPHA)
 361         {
 362             /* Graphics mode */
 363
 364             /* Loop through the pixels */
 365             for (j = 0; j < Resolution.X; j++)
 366             {
 367                 BYTE PixelData = 0;
 368
 369                 /* Check the shifting mode */
 370                 if (VgaGcRegisters[VGA_GC_MODE_REG] & VGA_GC_MODE_SHIFT256)
 371                 {
 372                     /* 4 bits shifted from each plane */
 373
 374                     /* Check if this is 16 or 256 color mode */
 375                     if (VgaAcRegisters[VGA_AC_CONTROL_REG] & VGA_AC_CONTROL_8BIT)
 376                     {
 377                         /* One byte per pixel */
 378                         PixelData = VgaMemory[(j % VGA_NUM_BANKS) * VGA_BANK_SIZE
 379                                               + (Address + (j / VGA_NUM_BANKS))
 380                                               * AddressSize];
 381                     }
 382                     else
 383                     {
 384                         /* 4-bits per pixel */
 385
 386                         PixelData = VgaMemory[(j % VGA_NUM_BANKS) * VGA_BANK_SIZE
 387                                               + (Address + (j / (VGA_NUM_BANKS * 2)))
 388                                               * AddressSize];
 389
 390                         /* Check if we should use the highest 4 bits or lowest 4 */
 391                         if (((j / VGA_NUM_BANKS) % 2) == 0)
 392                         {
 393                             /* Highest 4 */
 394                             PixelData >>= 4;
 395                         }
 396                         else
 397                         {
 398                             /* Lowest 4 */
 399                             PixelData &= 0x0F;
 400                         }
 401                     }
 402                 }
 403                 else if (VgaGcRegisters[VGA_GC_MODE_REG] & VGA_GC_MODE_SHIFTREG)
 404                 {
 405                     /*
 406                      * 2 bits shifted from plane 0 and 2 for the first 4 pixels,
 407                      * then 2 bits shifted from plane 1 and 3 for the next 4
 408                      */
 409
 410                     // TODO: NOT IMPLEMENTED!
 411                     DPRINT1("Interleaved shift mode is not implemented!\n");
 412                 }
 413                 else
 414                 {
 415                     /* 1 bit shifted from each plane */
 416
 417                     /* Check if this is 16 or 256 color mode */
 418                     if (VgaAcRegisters[VGA_AC_CONTROL_REG] & VGA_AC_CONTROL_8BIT)
 419                     {
 420                         /* 8 bits per pixel, 2 on each plane */
 421
 422                         for (k = 0; k < VGA_NUM_BANKS; k++)
 423                         {
 424                             /* The data is on plane k, 4 pixels per byte */
 425                             BYTE PlaneData = VgaMemory[k * VGA_BANK_SIZE
 426                                                        + (Address + (j / 4)) * AddressSize];
 427
 428                             /* The mask of the first bit in the pair */
 429                             BYTE BitMask = 1 << (((3 - (j % 4)) * 2) + 1);
 430
 431                             /* Bits 0, 1, 2 and 3 come from the first bit of the pair */
 432                             if (PlaneData & BitMask) PixelData |= 1 << k;
 433
 434                             /* Bits 4, 5, 6 and 7 come from the second bit of the pair */
 435                             if (PlaneData & (BitMask >> 1)) PixelData |= 1 << (k + 4);
 436                         }
 437                     }
 438                     else
 439                     {
 440                         /* 4 bits per pixel, 1 on each plane */
 441
 442                         for (k = 0; k < VGA_NUM_BANKS; k++)
 443                         {
 444                             BYTE PlaneData = VgaMemory[k * VGA_BANK_SIZE
 445                                                        + (Address + (j / 8)) * AddressSize];
 446
 447                             /* If the bit on that plane is set, set it */
 448                             if (PlaneData & (1 << (7 - (j % 8)))) PixelData |= 1 << k;
 449                         }
 450                     }
 451                 }
 452
 453                 /* Now check if the resulting pixel data has changed */
 454                 if (GraphicsBuffer[i * Resolution.X + j] != PixelData)
 455                 {
 456                     /* Yes, write the new value */
 457                     GraphicsBuffer[i * Resolution.X + j] = PixelData;
 458
 459                     /* Mark the specified pixel as changed */
 460                     VgaMarkForUpdate(i, j);
 461                 }
 462             }
 463         }
 464         else
 465         {
 466             /* Text mode */
 467
 468             /* Loop through the characters */
 469             for (j = 0; j < Resolution.X; j++)
 470             {
 471                 DWORD CurrentAddr = LOWORD((Address + j) * AddressSize);
 472                 CHAR_INFO CharInfo;
 473
 474                 /* Plane 0 holds the character itself */
 475                 CharInfo.Char.AsciiChar = VgaMemory[CurrentAddr];
 476
 477                 /* Plane 1 holds the attribute */
 478                 CharInfo.Attributes = VgaMemory[CurrentAddr + VGA_BANK_SIZE];
 479
 480                 /* Now check if the resulting character data has changed */
 481                 if ((CharBuffer[i * Resolution.X + j].Char.AsciiChar != CharInfo.Char.AsciiChar)
 482                     || (CharBuffer[i * Resolution.X + j].Attributes != CharInfo.Attributes))
 483                 {
 484                     /* Yes, write the new value */
 485                     CharBuffer[i * Resolution.X + j] = CharInfo;
 486
 487                     /* Mark the specified pixel as changed */
 488                     VgaMarkForUpdate(i, j);
 489                 }
 490             }
 491         }
 492
 493         /* Move to the next scanline */
 494         Address += ScanlineSize;
 495     }
 496 }
 497
 498 static VOID VgaUpdateTextCursor(VOID)
 499 {
 500     COORD Position;
 501     CONSOLE_CURSOR_INFO CursorInfo;
 502     BYTE CursorStart = VgaCrtcRegisters[VGA_CRTC_CURSOR_START_REG] & 0x3F;
 503     BYTE CursorEnd = VgaCrtcRegisters[VGA_CRTC_CURSOR_END_REG] & 0x1F;
 504     DWORD ScanlineSize = (DWORD)VgaCrtcRegisters[VGA_CRTC_OFFSET_REG] * 2;
 505     WORD Location = MAKEWORD(VgaCrtcRegisters[VGA_CRTC_CURSOR_LOC_LOW_REG],
 506                              VgaCrtcRegisters[VGA_CRTC_CURSOR_LOC_HIGH_REG]);
 507
 508     if (CursorStart < CursorEnd)
 509     {
 510         /* Visible cursor */
 511         CursorInfo.bVisible = TRUE;
 512         CursorInfo.dwSize = (100 * (CursorEnd - CursorStart)) >> 5;
 513     }
 514     else
 515     {
 516         /* No cursor */
 517         CursorInfo.bVisible = FALSE;
 518         CursorInfo.dwSize = 0;
 519     }
 520
 521     /* Add the cursor skew to the location */
 522     Location += (VgaCrtcRegisters[VGA_CRTC_CURSOR_END_REG] >> 5) & 3;
 523
 524     /* Find the coordinates of the new position */
 525     Position.X = (WORD)(Location % ScanlineSize);
 526     Position.Y = (WORD)(Location / ScanlineSize);
 527
 528     /* Update the physical cursor */
 529     SetConsoleCursorInfo(TextConsoleBuffer, &CursorInfo);
 530     SetConsoleCursorPosition(TextConsoleBuffer, Position);
 531 }
 532
 533 /* PUBLIC FUNCTIONS ***********************************************************/
 534
 535 DWORD VgaGetVideoBaseAddress(VOID)
 536 {
 537     return MemoryBase[(VgaGcRegisters[VGA_GC_MISC_REG] >> 2) & 0x03];
 538 }
 539
 540 DWORD VgaGetVideoLimitAddress(VOID)
 541 {
 542     return MemoryLimit[(VgaGcRegisters[VGA_GC_MISC_REG] >> 2) & 0x03];
 543 }
 544
 545 COORD VgaGetDisplayResolution(VOID)
 546 {
 547     COORD Resolution;
 548
 549     /* The low 8 bits are in the display registers */
 550     Resolution.X = VgaCrtcRegisters[VGA_CRTC_END_HORZ_DISP_REG];
 551     Resolution.Y = VgaCrtcRegisters[VGA_CRTC_VERT_DISP_END_REG];
 552
 553     /* Set the top bits from the overflow register */
 554     if (VgaCrtcRegisters[VGA_CRTC_OVERFLOW_REG] & VGA_CRTC_OVERFLOW_VDE8)
 555     {
 556         Resolution.Y |= 1 << 8;
 557     }
 558     if (VgaCrtcRegisters[VGA_CRTC_OVERFLOW_REG] & VGA_CRTC_OVERFLOW_VDE9)
 559     {
 560         Resolution.Y |= 1 << 9;
 561     }
 562
 563     /* Increase the values by 1 */
 564     Resolution.X++;
 565     Resolution.Y++;
 566
 567     if (VgaGcRegisters[VGA_GC_MISC_REG] & VGA_GC_MISC_NOALPHA)
 568     {
 569         /* Multiply the horizontal resolution by the 9/8 dot mode */
 570         Resolution.X *= (VgaSeqRegisters[VGA_SEQ_CLOCK_REG] & VGA_SEQ_CLOCK_98DM)
 571                         ? 8 : 9;
 572
 573         /* The horizontal resolution is halved in 8-bit mode */
 574         if (VgaAcRegisters[VGA_AC_CONTROL_REG] & VGA_AC_CONTROL_8BIT) Resolution.X /= 2;
 575
 576         /* Divide the vertical resolution by the maximum scan line */
 577         Resolution.Y /= ((DWORD)VgaCrtcRegisters[VGA_CRTC_MAX_SCAN_LINE_REG] & 0x1F) + 1;
 578     }
 579     else
 580     {
 581         /* Divide the number of scanlines by the font size */
 582         Resolution.Y /= 16;
 583     }
 584
 585     /* Return the resolution */
 586     return Resolution;
 587 }
 588
 589 VOID VgaRefreshDisplay(VOID)
 590 {
 591     COORD Resolution = VgaGetDisplayResolution();
 592
 593     DPRINT("VgaRefreshDisplay\n");
 594
 595     if (ModeChanged)
 596     {
 597         /* Change the display mode */
 598         VgaUpdateMode();
 599
 600         /* Reset the mode change flag */
 601         ModeChanged = FALSE;
 602     }
 603
 604     if (CursorMoved)
 605     {
 606         /* Change the text cursor location */
 607         VgaUpdateTextCursor();
 608
 609         /* Reset the cursor move flag */
 610         CursorMoved = FALSE;
 611     }
 612
 613     /* Update the contents of the framebuffer */
 614     VgaUpdateFramebuffer();
 615
 616     /* Set the vertical retrace flag */
 617     InVerticalRetrace = TRUE;
 618
 619     /* Ignore if there's nothing to update */
 620     if (!NeedsUpdate) return;
 621
 622     DPRINT("Updating screen rectangle (%d, %d, %d, %d)\n",
 623            UpdateRectangle.Left,
 624            UpdateRectangle.Top,
 625            UpdateRectangle.Right,
 626            UpdateRectangle.Bottom);
 627
 628     /* Check if this is text mode or graphics mode */
 629     if (VgaGcRegisters[VGA_GC_MISC_REG] & VGA_GC_MISC_NOALPHA)
 630     {
 631         /* Graphics mode */
 632
 633         /* Redraw the screen */
 634         InvalidateConsoleDIBits(GraphicsConsoleBuffer, &UpdateRectangle);
 635     }
 636     else
 637     {
 638         /* Text mode */
 639         COORD Origin = { UpdateRectangle.Left, UpdateRectangle.Top };
 640
 641         /* Write the data to the console */
 642         WriteConsoleOutputA(TextConsoleBuffer,
 643                             (PCHAR_INFO)ConsoleFramebuffer,
 644                             Resolution,
 645                             Origin,
 646                             &UpdateRectangle);
 647
 648     }
 649
 650     /* Clear the update flag */
 651     NeedsUpdate = FALSE;
 652 }
 653
 654 VOID VgaHorizontalRetrace(VOID)
 655 {
 656     /* Set the flag */
 657     InHorizontalRetrace = TRUE;
 658 }
 659
 660 VOID VgaReadMemory(DWORD Address, LPBYTE Buffer, DWORD Size)
 661 {
 662     DWORD i;
 663     DWORD VideoAddress;
 664
 665     DPRINT("VgaReadMemory: Address 0x%08X, Size %lu\n",
 666            Address,
 667            Size);
 668
 669     /* Ignore if video RAM access is disabled */
 670     if (!(VgaMiscRegister & VGA_MISC_RAM_ENABLED)) return;
 671
 672     /* Loop through each byte */
 673     for (i = 0; i < Size; i++)
 674     {
 675         VideoAddress = VgaTranslateReadAddress(Address + i);
 676
 677         /* Copy the value to the buffer */
 678         Buffer[i] = VgaMemory[VideoAddress];
 679     }
 680 }
 681
 682 VOID VgaWriteMemory(DWORD Address, LPBYTE Buffer, DWORD Size)
 683 {
 684     DWORD i, j;
 685     DWORD VideoAddress;
 686
 687     DPRINT("VgaWriteMemory: Address 0x%08X, Size %lu\n",
 688            Address,
 689            Size);
 690
 691     /* Ignore if video RAM access is disabled */
 692     if (!(VgaMiscRegister & VGA_MISC_RAM_ENABLED)) return;
 693
 694     /* Also ignore if write access to all planes is disabled */
 695     if ((VgaSeqRegisters[VGA_SEQ_MASK_REG] & 0x0F) == 0x00) return;
 696
 697     /* Loop through each byte */
 698     for (i = 0; i < Size; i++)
 699     {
 700         VideoAddress = VgaTranslateWriteAddress(Address + i);
 701
 702         for (j = 0; j < VGA_NUM_BANKS; j++)
 703         {
 704             /* Make sure the page is writeable */
 705             if (!(VgaSeqRegisters[VGA_SEQ_MASK_REG] & (1 << j))) continue;
 706
 707             /* Check if this is chain-4 mode */
 708             if (VgaSeqRegisters[VGA_SEQ_MEM_REG] & VGA_SEQ_MEM_C4)
 709             {
 710                 if (((Address + i) & 3) != j)
 711                 {
 712                     /* This plane will not be accessed */
 713                     continue;
 714                 }
 715             }
 716
 717             /* Check if this is odd-even mode */
 718             if (VgaGcRegisters[VGA_GC_MODE_REG] & VGA_GC_MODE_OE)
 719             {
 720                 if (((Address + i) & 1) != (j & 1))
 721                 {
 722                     /* This plane will not be accessed */
 723                     continue;
 724                 }
 725             }
 726
 727             /* Copy the value to the VGA memory */
 728             VgaMemory[VideoAddress + j * VGA_BANK_SIZE] = Buffer[i];
 729         }
 730     }
 731 }
 732
 733 BYTE VgaReadPort(WORD Port)
 734 {
 735     DPRINT("VgaReadPort: Port 0x%04X\n", Port);
 736
 737     switch (Port)
 738     {
 739         case VGA_AC_INDEX:
 740         {
 741             return VgaAcIndex;
 742         }
 743
 744         case VGA_AC_READ:
 745         {
 746             return VgaAcRegisters[VgaAcIndex];
 747         }
 748
 749         case VGA_SEQ_INDEX:
 750         {
 751             return VgaSeqIndex;
 752         }
 753
 754         case VGA_SEQ_DATA:
 755         {
 756             return VgaSeqRegisters[VgaSeqIndex];
 757         }
 758
 759         case VGA_DAC_READ_INDEX:
 760         {
 761             /* This returns the read/write state */
 762             return VgaDacReadWrite ? 0 : 3;
 763         }
 764
 765         case VGA_DAC_WRITE_INDEX:
 766         {
 767             return VgaDacIndex;
 768         }
 769
 770         case VGA_DAC_DATA:
 771         {
 772             /* Ignore reads in write mode */
 773             if (!VgaDacReadWrite)
 774             {
 775                 BYTE Data = VgaDacRegisters[VgaDacIndex++];
 776                 VgaDacIndex %= VGA_PALETTE_SIZE;
 777                 return Data;
 778             }
 779
 780             break;
 781         }
 782
 783         case VGA_MISC_READ:
 784         {
 785             return VgaMiscRegister;
 786         }
 787
 788         case VGA_CRTC_INDEX:
 789         {
 790             return VgaCrtcIndex;
 791         }
 792
 793         case VGA_CRTC_DATA:
 794         {
 795             return VgaCrtcRegisters[VgaCrtcIndex];
 796         }
 797
 798         case VGA_GC_INDEX:
 799         {
 800             return VgaGcIndex;
 801         }
 802
 803         case VGA_GC_DATA:
 804         {
 805             return VgaGcRegisters[VgaGcIndex];
 806         }
 807
 808         case VGA_STAT_MONO:
 809         case VGA_STAT_COLOR:
 810         {
 811             BYTE Result = 0;
 812
 813             /* Reset the AC latch */
 814             VgaAcLatch = FALSE;
 815
 816             /* Set a flag if there is a vertical or horizontal retrace */
 817             if (InVerticalRetrace || InHorizontalRetrace) Result |= VGA_STAT_DD;
 818
 819             /* Set an additional flag if there was a vertical retrace */
 820             if (InVerticalRetrace) Result |= VGA_STAT_VRETRACE;
 821
 822             /* Clear the flags */
 823             InHorizontalRetrace = InVerticalRetrace = FALSE;
 824
 825             return Result;
 826         }
 827     }
 828
 829     return 0;
 830 }
 831
 832 VOID VgaWritePort(WORD Port, BYTE Data)
 833 {
 834     DPRINT("VgaWritePort: Port 0x%04X, Data 0x%02X\n", Port, Data);
 835
 836     switch (Port)
 837     {
 838         case VGA_AC_INDEX:
 839         {
 840             if (!VgaAcLatch)
 841             {
 842                 /* Change the index */
 843                 if (Data < VGA_AC_MAX_REG) VgaAcIndex = Data;
 844             }
 845             else
 846             {
 847                 /* Write the data */
 848                 VgaWriteAc(Data);
 849             }
 850
 851             /* Toggle the latch */
 852             VgaAcLatch = !VgaAcLatch;
 853
 854             break;
 855         }
 856
 857         case VGA_SEQ_INDEX:
 858         {
 859             /* Set the sequencer index register */
 860             if (Data < VGA_SEQ_MAX_REG) VgaSeqIndex = Data;
 861
 862             break;
 863         }
 864
 865         case VGA_SEQ_DATA:
 866         {
 867             /* Call the sequencer function */
 868             VgaWriteSequencer(Data);
 869
 870             break;
 871         }
 872
 873         case VGA_DAC_READ_INDEX:
 874         {
 875             VgaDacReadWrite = FALSE;
 876             VgaDacIndex = Data % VGA_PALETTE_SIZE;
 877
 878             break;
 879         }
 880
 881         case VGA_DAC_WRITE_INDEX:
 882         {
 883             VgaDacReadWrite = TRUE;
 884             VgaDacIndex = Data % VGA_PALETTE_SIZE;
 885
 886             break;
 887         }
 888
 889         case VGA_DAC_DATA:
 890         {
 891             /* Ignore writes in read mode */
 892             if (VgaDacReadWrite) VgaWriteDac(Data & 0x3F);
 893
 894             break;
 895         }
 896
 897         case VGA_MISC_WRITE:
 898         {
 899             VgaMiscRegister = Data;
 900
 901             break;
 902         }
 903
 904         case VGA_CRTC_INDEX:
 905         {
 906             /* Set the CRTC index register */
 907             if (Data < VGA_CRTC_MAX_REG) VgaCrtcIndex = Data;
 908
 909             break;
 910         }
 911
 912         case VGA_CRTC_DATA:
 913         {
 914             /* Call the CRTC function */
 915             VgaWriteCrtc(Data);
 916
 917             break;
 918         }
 919
 920         case VGA_GC_INDEX:
 921         {
 922             /* Set the GC index register */
 923             if (Data < VGA_GC_MAX_REG) VgaGcIndex = Data;
 924             break;
 925         }
 926
 927         case VGA_GC_DATA:
 928         {
 929             /* Call the GC function */
 930             VgaWriteGc(Data);
 931
 932             break;
 933         }
 934     }
 935 }
 936
 937 VOID VgaInitialize(HANDLE TextHandle)
 938 {
 939     INT i, j;
 940     COORD Resolution;
 941     INT AddressSize;
 942     DWORD ScanlineSize;
 943     COORD Origin = { 0, 0 };
 944     SMALL_RECT ScreenRect;
 945     PCHAR_INFO CharBuffer;
 946     DWORD Address = 0;
 947     DWORD CurrentAddr;
 948
 949     /* Set the global handle */
 950     TextConsoleBuffer = TextHandle;
 951
 952     /* Clear the VGA memory */
 953     ZeroMemory(VgaMemory, VGA_NUM_BANKS * VGA_BANK_SIZE);
 954
 955     /* Set the default video mode */
 956     BiosSetVideoMode(BIOS_DEFAULT_VIDEO_MODE);
 957     VgaUpdateMode();
 958     ModeChanged = FALSE;
 959
 960     /* Get the data */
 961     Resolution = VgaGetDisplayResolution();
 962     CharBuffer = (PCHAR_INFO)ConsoleFramebuffer;
 963     AddressSize = VgaGetAddressSize();
 964     ScreenRect.Left = ScreenRect.Top = 0;
 965     ScreenRect.Right = Resolution.X;
 966     ScreenRect.Bottom = Resolution.Y;
 967     ScanlineSize = (DWORD)VgaCrtcRegisters[VGA_CRTC_OFFSET_REG] * 2;
 968
 969     /* Read the data from the console into the framebuffer */
 970     ReadConsoleOutputA(TextConsoleBuffer,
 971                        CharBuffer,
 972                        Resolution,
 973                        Origin,
 974                        &ScreenRect);
 975
 976     /* Loop through the scanlines */
 977     for (i = 0; i < Resolution.Y; i++)
 978     {
 979         /* Loop through the characters */
 980         for (j = 0; j < Resolution.X; j++)
 981         {
 982             CurrentAddr = LOWORD((Address + j) * AddressSize);
 983
 984             /* Store the character in plane 0 */
 985             VgaMemory[CurrentAddr] = CharBuffer[i * Resolution.X + j].Char.AsciiChar;
 986
 987             /* Store the attribute in plane 1 */
 988             VgaMemory[CurrentAddr + VGA_BANK_SIZE] = (BYTE)CharBuffer[i * Resolution.X + j].Attributes;
 989         }
 990
 991         /* Move to the next scanline */
 992         Address += ScanlineSize;
 993     }
 994 }
 995
 996 /* EOF */