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MAP_SCREEN_AT_DEPTH(9r)
NAME
  MAP_SCREEN_AT_DEPTH - Graphics: Maps a graphics device's memory and its
  registers to the server's virtual address space

SYNOPSIS
  #include sys/ioctl.h
  #include sys/workstation.h

  int ioctl(
	  int gfx_fd,
	  unsigned long MAP_SCREEN_AT_DEPTH,
	  void *ws_driver_structure_pointer );

ARGUMENTS
  gfx_fd
      Specifies the file descriptor of the graphics device-special file (by
      convention /dev/ws0) that the open system call returns when the server
      is initialized.  The server uses this file descriptor in subsequent
      ioctl calls to the Workstation Subsystem.

  MAP_SCREEN_AT_DEPTH
      Specifies the ioctl command used to access the ws_map_control
      structure.

  ws_driver_structure_pointer
      Specifies a pointer to the ws_map_control structure.

DESCRIPTION
  The MAP_SCREEN_AT_DEPTH ioctl command tells the graphics driver to map the
  graphics device's memory and its registers into the virtual address space
  of the server. This allows the server to access the graphics hardware
  directly. The virtual addresses that are allocated when MAP_SCREEN_AT_DEPTH
  is invoked are returned in a subsequent call to GET_DEPTH_INFO. The
  MAP_SCREEN_AT_DEPTH ioctl command maps frame buffer memory; GET_DEPTH_INFO
  returns the virtual address of the mapping.

  This ioctl command accesses the ws_map_control data structure defined in
  /usr/sys/include/sys/workstation.h.

RESTRICTIONS
  The graphics subsystem supports only one workstation per machine.

  Although most VGA devices support more than one depth of display with 16-
  bit pixels and 24-bit pixels (also known as TrueColor), the Compaq VGA
  controllers currently support only a single depth (8-bit pixels for all but
  the generic VGA driver, which supports 4-bit pixels).



RETURN VALUES
  If successful, the MAP_SCREEN_AT_DEPTH ioctl command returns 0 (zero). If
  unsuccessful, it returns -1.


EXAMPLES
  The following example shows how the generic VGA DDX issues a
  MAP_SCREEN_AT_DEPTH ioctl command from the genInitVGA routine:

       static ws_map_control * map;

       void genInitVGA(int index)
       {

       .
       .
       .

	   if (map == NULL)
	       map = (ws_map_control *) Xcalloc(sizeof(map));

	   if (!init_flags[index]) {
	       map->map_unmap = MAP_SCREEN;
	       map->screen = index;
	       if ((err=ioctl(wsFd, MAP_SCREEN_AT_DEPTH, map))) {
		   perror("Failed to map screen at depth");
		   exit (1);
	       }
	       init_flags[index] = 1;
	   }

       .
       .
       .


FILES
  /usr/sys/include/sys/ioctl.h

  /usr/sys/include/sys/workstation.h

SEE ALSO
  ioctl Commands: CURSOR_ON_OFF(9r), GET_DEPTH_INFO(9r),
  MAP_SCREEN_AT_DEPTH(9r), VIDEO_ON_OFF(9r)

Index for Section 9

Alphabetical listing for M

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