Obsah

Grafickej režim (graphics mode)

Spustit grafickej režim se musí v reálnym režimu nebo ve virtual 8086 (Múže změnit GDT).
V chráněnym režimu se s obrazovkou pracuje přes linear frame buffer.

struct VbeInfoBlock{
  char VbeSignature[4] // "VESA"
  uns2 VbeVersion // 200h
  ptr4 OemStringPtr
  uns1 Capabilities[4]
  ptr4 VideoModePtr // real mode pointer to Video Mode List (array of words terminated -1)
  uns2 TotalMemory // Number of 64KiB memory blocks

  // VBE 2.0
  uns2 OemSoftwareRev
  ptr4 OemVendorNamePtr
  ptr4 OemProductNamePtr
  ptr4 OemProductRevPtr
  uns1 Reserved[222]
  uns1 OemData[256] // Data Area for OEM Strings
}

struct ModeInfoBlock{
  uns2 ModeAttributes
  uns1 WinAAttributes, WinBAttributes
  uns2 WinGranularity
  uns2 WinSize
  uns2 WinASegment, WinBSegment
  ptr4 WinFuncPtr // pointer to window function
  uns2 BytesPerScanLine // pitch

  // VBE 1.2
  uns2 XResolution, YResolution
  uns1 XCharSize, YCharSize
  uns1 NumberOfPlanes
  uns1 BitsPerPixel
  uns1 NumberOfBanks
  uns1 MemoryModel
  uns1 BankSize // bank size in KB
  uns1 NumberOfImagePages
  uns1 Reserved // reserved for page function

  // Direct Color fields (required for direct/6 and YUV/7 memory models)
  uns1 RedMaskSize, RedFieldPosition, GreenMaskSize, GreenFieldPosition
  uns1 BlueMaskSize, BlueFieldPosition, RsvdMaskSize, RsvdFieldPosition
  uns1 DirectColorModeInfo

  // VBE 2.0
  ptr4 PhysBasePtr // physical address for linear frame buffer
  uns4 OffScreenMemOffset // pointer to start of off screen memory
  uns2 OffScreenMemSize // amount of off screen memory in 1K units

  uns1 Reserved[206]
}

VbeInfoBlock vib
ModeInfoBlock mib

V reálnym režimu

// Return VBE Controller Information
mov ax, 4F00h
push ds
pop es
mov di, offset vib
int 10h
cmp al, 4Fh
jnz l_error

// Return VBE mode information (call for each vmode in VideoModePtr)
mov ax, 4F01h
mov cx, vmode
push ds
pop es
mov di, offset mib
int 10h
cmp al, 4Fh
jnz l_error

// Set VBE Mode
mov ax, 4F02h
mov bx, vmode
or bx, 4000h // create linear frame buffer
int 10h
cmp al, 4Fh
jnz l_error

V chráněnym režimu

Pokud nemáte zapnutý stránkování, použijte deskriptor s bází PhysBasePtr.
Pokud máte zapnutý stránkování, namapujte si libovolnou lineární adresu na fyzickou PhysBasePtr.
Pixel[x,y] najdete na adrese LA + (y * BytesPerScanLine) + (x * (BitsPerPixel / 8))