From: Felix Natter <f DOT natter AT ndh DOT net>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: Windows 2000: __dpmi_physical_address_mapping fails II
Date: 07 Nov 2001 17:00:30 +0100
Organization: Customer of Pironet NDH AG, Germany
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Message-ID: <874ro6woyp.fsf@mybaby.home.felix>
References: <87668rssr2 DOT fsf AT mybaby DOT home DOT felix> <8632-Sat03Nov2001214441+0200-eliz AT is DOT elta DOT co DOT il>
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"Eli Zaretskii" <eliz AT is DOT elta DOT co DOT il> writes:

> > From: Felix Natter <f DOT natter AT ndh DOT net>
> > Newsgroups: comp.os.msdos.djgpp
> > Date: 03 Nov 2001 17:50:57 +0100
> > 
> >   __dpmi_meminfo meminf;
> >   meminf.address = vbe_modeinfo.PhysicalBasePtr;
> >   meminf.size	= screensize;
> >   if (__dpmi_physical_address_mapping(&meminf) ==	- 1)
> >     => error
> > 
> > __dpmi_physical_address_mapping fails on Windows 2000 (both with
> > cwsdpmi 4/5 and when I select Dos on startup).
> 
> It's not surprising that W2K doesn't let you do this (it disallows
> access to hardware), but it should work on DOS.
> 
> However, without knowing the values of vbe_modeinfo.PhysicalBasePtr
> and screensize, it's very hard to say something intelligent.

Sorry, my fault. the address was 0.

the getVBEModeInfo function returns true, but
vbe_modeinfo.PhysicalBasePtr is 0 !

So either that graphics card isn't VESA 1.2 compliant or my code is wrong.
(It's a matrox card so I guess I'm wrong :-()

static bool	getVBEModeInfo(unsigned	short	mode)
{
  __dpmi_regs	regs;
  regs.x.ax =	0x4F01;
  regs.x.cx =	mode;
  regs.x.es =	__tb / 16;
  regs.x.di =	0x0000;
  safe_int(0x10, &regs);
  dosmemget(__tb, sizeof(VBE_MODEINFO), &vbe_modeinfo);
  if (regs.x.ax != 0x004F	|| !(vbe_modeinfo.ModeAttributes & vbeModeAvailablewithLFB))
    return false;
  else
    return true;
};

struct VBE_MODEINFO
{
  unsigned short ModeAttributes PACKED;
  unsigned char WinAAttributes PACKED; 
  unsigned char WinBAttributes PACKED; 
  unsigned short WinGranularity PACKED;
  unsigned short WinSize PACKED;     
  unsigned short WinASegment PACKED; 
  unsigned short WinBSegment PACKED; 
  unsigned short WinFuncPtrOffset PACKED;
  unsigned short WinFuncPtrSegment PACKED; 
  unsigned short BytesPerScanline PACKED;  
  // VBE 1.2+
  unsigned short XResolution PACKED;       
  unsigned short YResolution PACKED;       
  unsigned char XCharSize PACKED;          
  unsigned char YCharSize PACKED;          
  unsigned char NumberOfPlanes PACKED;     
  unsigned char BitsPerPixel PACKED;       
  unsigned char NumberOfBanks PACKED;      
  unsigned char MemoryModel PACKED;        
  unsigned char BankSize PACKED;           
  unsigned char NumberOfImagePages PACKED; 
  unsigned char reserved1 PACKED;          
  // required for direct color memory models (RGB, YUV)
  unsigned char RedMaskSize PACKED;        
  unsigned char RedFieldPosition PACKED;   
  unsigned char GreenMaskSize PACKED;      
  unsigned char GreenFieldPosition PACKED; 
  unsigned char BlueMaskSize PACKED;       
  unsigned char BlueFieldPosition PACKED;  
  unsigned char RsvdMaskSize PACKED;       
  unsigned char RsvdFieldPosition PACKED;  
  unsigned char DirectColorModeInfo PACKED;
  // VBE 2.0+
  unsigned long PhysicalBasePtr PACKED; /* Physical address for LFB         */
  unsigned long OffScreenMemOffset PACKED;/* Pointer to Offscreen-memory   */
  unsigned short OffScreenMemSize PACKED; /* Size of Offscreen-memory in K  */
  unsigned char reserved2[206] PACKED;
};

here is the beginning of the openVBE-function:

bool openVBE(int width,	int height,	unsigned char bpp	= 8)
{
  if (!initVBE())
    {
      printf("\nNo VBE 2.0 loaded.\n");
      abort();
    }
  int modeidx	= 0;
  unsigned short mode;
  while	(1)
    {
      mode = AvailableModes[modeidx++];
      if (mode ==	0xFFFF)
	return false;
      if (getVBEModeInfo(mode) == false)
	continue;
      if (vbe_modeinfo.XResolution != width)
	continue;
      if (vbe_modeinfo.YResolution != height)
	continue;
      if (vbe_modeinfo.BitsPerPixel	!= bpp)
	continue;
      break;
    }
  xres = vbe_modeinfo.XResolution;
  yres = vbe_modeinfo.YResolution;
  BPP =	vbe_modeinfo.BitsPerPixel;
  BytesPerScanline = vbe_modeinfo.BytesPerScanline;
  unsigned long screensize = BytesPerScanline * yres;
  if (screensize % 4)
    ErrorMessage::handleError(ErrorMessage("Screensize [PARAM1] isn't dword-aligned.", "", screensize));
  offscreen =	(char*)malloc(screensize);
  screensize_dword = screensize	/ 4;

  __dpmi_meminfo meminf;
  meminf.address = vbe_modeinfo.PhysicalBasePtr;
  meminf.size	= screensize;
  // TODO: fails on Windows 2000
  if (__dpmi_physical_address_mapping(&meminf) ==	- 1)
=> this fails because meminf.address is 0

The complete source is here:
http://www.ndh.net/home/natter/vbetest.cpp

-- 
Felix Natter