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NAME

       X11::Protocol::Ext::XFree86_DGA - direct video memory access

SYNOPSIS

        use X11::Protocol;
        my $X = X11::Protocol->new;
        $X->init_extension('XFree86-DGA')
          or print "XFree86-DGA extension not available";

DESCRIPTION

       The XFree86-DGA extension provides direct access to the video RAM of
       the server display.  A client program running on the same machine can
       use this to read or write directly instead of going through the X
       protocol.

       Accessing video memory will require some system-dependent trickery.
       Under the Linux kernel for example video RAM is part of the /dev/mem
       physical address space and can be brought into program address space
       with an "mmap()" or accessed with "sysread()" and "syswrite()".  This
       normally requires root permissions.

       The requests offered here are only XFree86-DGA version 1.0 as yet and
       they don't say anything about the pixel layout etc in the memory --
       that has to be divined separately.  (Version 2.0 has more for that.)

REQUESTS

       The following requests are made available with an "init_extension()",
       as per "EXTENSIONS" in X11::Protocol.

           my $ext_available = $X->init_extension('XFree86-DGA');

   XFree86-DGA 1.0
       "($server_major, $server_minor) = $X->XF86DGAQueryVersion()"
           Return the DGA protocol version implemented by the server.

       "$flags = $X->XF86DGAQueryDirectVideo ($screen_num)"
           Get flags describing direct video access on $screen_num (integer 0
           upwards).  The only flag bit is

               0x0001   direct video available

           It's possible to have the extension available but no direct video
           on a particular screen, or even on no screens at all.  When no
           direct video the requests below give protocol error
           "XF86DGANoDirectVideoMode".

       "($address, $width, $bank_size_bytes, $ram_size_kbytes) =
       $X->XF86DGAGetVideoLL ($screen_num)"
           Return the location and size of the video memory for $screen_num
           (integer 0 upwards).

           $address is a raw physical 32-bit address as an integer.  $width is
           in pixels.

           $bank_size_bytes is the size in bytes accessible at a given time.
           $ram_size_kbytes is the total memory in 1024 byte blocks.  If
           "$ram_size_kbytes*1024" is bigger than $bank_size_bytes then
           "$X->XF86DGASetVidPage()" below must be used to switch among the
           banks to access all the RAM.

       "$X->XF86DGADirectVideo ($screen_num, $flags)"
           Enable or disable direct video access on $screen_num (integer 0
           upwards).  $flags is bits

               0x0002    enable direct video graphics
               0x0004    enable mouse pointer reporting as relative
               0x0008    enable direct keyboard event reporting

           When direct video graphics is enabled (bit 0x0002) the server gives
           up control to the client program.

           If the graphics card doesn't have a direct video mode then an
           "XF86DGANoDirectVideoMode" error results, or if the screen is not
           active (eg. switched away to a different virtual terminal) then
           "XF86DGAScreenNotActive".

       "($width, $height) = $X->XF86DGAGetViewPortSize ($screen_num)"
           Get the size of the viewport on $screen_num (integer 0 upwards).
           This is the part of the video memory actually visible on the
           monitor.  The memory might be bigger than the monitor.

       "$X->XF86DGASetViewPort ($screen_num, $x, $y)"
           Set the coordinates of the top-left corner of the visible part of
           the video memory on $screen_num (integer 0 upwards).

           This can be used when the video memory is bigger than the monitor
           to pan around that bigger area.  It can also be used for some
           double-buffering to display one part of memory while drawing to
           another.

       "$vidpage = $X->XF86DGAGetVidPage ($screen_num)"
       "$X->XF86DGASetVidPage ($screen_num, $vidpage)"
           Get or set the video page (bank) on $screen_num (integer 0
           upwards).  $vidpage is an integer 0 upwards.

           This is used to access all the RAM when when the bank size is less
           than the total memory size (per "XF86DGAGetVideoLL()" above).

       "$vidpage = $X->XF86DGAInstallColormap ($screen_num, $colormap)"
           Set the colormap on $screen_num to $colormap (integer XID).

           This can only be used while direct video is enabled (per
           "XF86DGADirectVideo()" above) or an error "XF86DGAScreenNotActive"
           or "XF86DGADirectNotActivated" results.

       "$bool = $X->XF86DGAViewPortChanged ($screen_num, $num_pages)"
           Check whether a previous "XF86DGASetViewPort()" on $screen_num
           (integer 0 upwards) has completed, meaning a vertical retrace has
           occurred since that viewport location was set.

           This is used for double-buffering (or N-multi-buffering) to check a
           viewport change has become visible.  $num_pages should be 2 for
           double-buffering and can be higher for multi-buffering.

SEE ALSO

       X11::Protocol

       /usr/share/doc/xserver-xfree86/README.DGA.gz

HOME PAGE

       <http://user42.tuxfamily.org/x11-protocol-other/index.php>

LICENSE

       Copyright 2011, 2012, 2013 Kevin Ryde

       X11-Protocol-Other is free software; you can redistribute it and/or
       modify it under the terms of the GNU General Public License as
       published by the Free Software Foundation; either version 3, or (at
       your option) any later version.

       X11-Protocol-Other is distributed in the hope that it will be useful,
       but WITHOUT ANY WARRANTY; without even the implied warranty of
       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
       General Public License for more details.

       You should have received a copy of the GNU General Public License along
       with X11-Protocol-Other.  If not, see <http://www.gnu.org/licenses/>.

perl v5.18.2                      2013-11-X11::Protocol::Ext::XFree86_DGA(3pm)



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