OSDev

//Get Video Info
UCHAR* pBuf = pSysInfo->pDiskBuf + g0MegPtr;
memset4(pBuf, 0, 0x200 / 4);
pBuf[0] = 'V'; pBuf[1] = 'B'; pBuf[2] = 'E'; pBuf[3] = '2';
_ThreadRegs BiosRegs;
BiosRegs.eax = 0x4F00; //GET SuperVGA INFORMATION
BiosRegs.es = pSysInfo->segDiskBuf;
BiosRegs.edi = 0;
syscall2(SYSCALL::BiosIntCall, 0x10, (UINT)&BiosRegs);
if((USHORT)BiosRegs.eax == 0x4F)
{
   pSysInfo->VesaCapab = pBuf[0xA];
   pSysInfo->VesaVbeVer = *(USHORT*)&pBuf[0x22];
      pSysInfo->VesaModes[0] = 0xFFFF;
   USHORT* pModes = (USHORT*)(*(USHORT*)&pBuf[0x10] * 0x10 + *(USHORT*)&pBuf[0xE]);
       for(UINT iSrc = 0, iDst = 0;; iSrc++)
  {
  if(pModes[iSrc] < 0x100u) { continue; }
  pSysInfo->VesaModes[iDst] = pModes[iSrc];
  if(pModes[iSrc] == 0xFFFF || iDst == 0xFF) { break; }
  iDst++;
  }
}
//Set Graphic mode
USHORT* pModes = pSysInfo->VesaModes;
for(UINT i = 0; i < 0x100u && pModes[i] != 0xFFFF; i++)
{
 BiosRegs.eax = 0x4F01; //GET SuperVGA MODE INFORMATION
 BiosRegs.ecx = pModes[i];
      BiosRegs.es = pSysInfo->segDiskBuf;
        BiosRegs.edi = 0;
      syscall2(SYSCALL::BiosIntCall, 0x10, (UINT)&BiosRegs);
 if((USHORT)BiosRegs.eax != 0x4F) { break; }
        if((pBuf[0] & 2) &&
  *(USHORT*)&pBuf[0x12] == 800 && *(USHORT*)&pBuf[0x14] == 600 && pBuf[0x19] == 16 &&
  pBuf[0x21] == 6)
       {
  UINT ConfigMode = pModes[i];
  if(pSysInfo->VesaCapab & 8) { ConfigMode |= 0x2000; } //Init VBE/AF
  pSysInfo->VesaConfigMode = ConfigMode;
  pSysInfo->VesaPixelsX = *(USHORT*)&pBuf[0x12];
  pSysInfo->VesaPixelsY = *(USHORT*)&pBuf[0x14];
  pSysInfo->VesaPixelBits = pBuf[0x19];
  pSysInfo->VesaLineBytes = *(USHORT*)&pBuf[0x10];
  if(pBuf[0] & 0x80) //With LFB
  {
   ConfigMode |= 0x4000; //Enable LFB
         ULONG VesaPhysLfb = *(ULONG*)&pBuf[0x28];
      pSysInfo->VesaPhysLfb = VesaPhysLfb;
   pSysInfo->VesaLfb = K_MapPhysMem(VesaPhysLfb, pSysInfo->VesaPixelsX * pSysInfo->VesaPixelsY * 2);
  }
  BiosRegs.eax = 0x4F02; //SET SuperVGA MODE
  BiosRegs.ebx = ConfigMode;
  syscall2(SYSCALL::BiosIntCall, 0x10, (UINT)&BiosRegs);
  break;
  }
}