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* Added configure option --enable-screensaver, to allow enabling the screensaver by default. * Use XResetScreenSaver() instead of disabling screensaver entirely. Full discussion summary from Erik on the SDL mailing list: Current behaviour ================= SDL changes the user's display power management settings without permission from the user and without telling the user. The interface that it uses to do so is DPMSDisable/DPMSEnable, which should only ever be used by configuration utilities like KControl, never by normal application programs, let alone by the libraries that they use. Using an interface that is not at all intended for what SDL tries to achieve means that it will not work as it should. Firstly, the power management is completely disabled during the whole lifetime of the SDL program, not only when it should be. Secondly, it makes SDL non-reentrant, meaning that things will break when multiple SDL programs are clients of the same X server simultaneously. Thirdly, no cleanup mechanism ensures that the setting is restored if the client does not do that (for example if it crashes). In addition to that, this interface is broken on xorg, [http://bugs.freedesktop.org/show_bug.cgi?id=13962], so what SDL tries to do does not work at all on that implementation of the X Window System. (The reason that the DPMSEnable works in KControl is that it calls DPMSSetTimeout immediately after, [http://websvn.kde.org/tags/KDE/3.5.9/kdebase/kcontrol/energy/energy.cpp?annotate=774532#l343]). The problems that the current behaviour causes ============================================== 1. Information leak. When the user is away, someone might see what the user has on the display when the user counts on the screensaver preventing this. This does not even require physical access to the workstation, it is enough to see it from a distance. 2. Draining battery. An SDL program that runs on a laptop will quickly drain the battery while the user is away. The system will soon shut down and require recharging before being usable again, while it should in fact have consumed very little energy if the user's settings would have been obeyed. 3. Wasting energy. Even if battery issues are not considered, energy as such is wasted. 4. Display wear. The display may be worn out. The problems that the current behaviour tries to solve ====================================================== 1. Preventing screensaver while playing movies. Many SDL applications are media players. They have reasons to prevent screensavers from being activated while a movie is being played. When a user clicks on the play button it can be interpreted as saying "play this movie, but do not turn off the display while playing it, because I will watch it even though I do not interact with the system". 2. Preventing screensaver when some input bypasses X. Sometimes SDL uses input from another source than the X server, so that the X server is bypassed. This obviously breaks the screensaver handling. SDL tries to work around that. 3. Preventing screensaver when all input bypasses X. There is something called Direct Graphics Access mode, where a program takes control of both the display and the input devices from the X server. This obviously means that the X server can not handle the screensaver alone, since screensaver handling depends on input handling. SDL does not do what it should to help the X server to handle the screensaver. Nor does SDL take care of screeensaver handling itself. SDL simply disables the screensaver completely. How the problems should be solved ================================= The correct way for an application program to prevent the screensaver under X is to call XResetScreenSaver. This was recently discovered and implemented by the mplayer developers, [http://svn.mplayerhq.hu/mplayer?view=rev&revision=25637]. SDL needs to wrap this in an API call (SDL_ResetScreenSaver) and implement it for the other video targets (if they do not have a corresponding call, SDL should do what it takes on that particular target, for example sending fake key events). 1. When a movie is played, the player should reset the screensaver when the animation is advanced to a new frame. The same applies to anything similar, like slideshows. 2. When the X server is handling input, it must handle all input (keyboards, mice, gamepads, ...). This is necessary, not only to be able to handle the screensaver, but also so that it can send the events to the correct (the currently active) client. If there is an input device that the X server can not handle for some reason (such as lack of Plug and Play capability), the program that handles the device as a workaround must simulate what would happen if the X server would have handled the device, by calling XResetScreenSaver when input is received from the device. 3. When the X server is not handling the input, it depends on the program that does to call XResetScreenSaver whenever an input event occurs. Alternatively the program must handle the screensaver countdown internally and call XActivateScreenSaver.
author Sam Lantinga <slouken@libsdl.org>
date Fri, 29 Feb 2008 13:55:44 +0000
parents b1fd24d62e55
children 0660995cdd3b
line wrap: on
line source

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><H1
><A
NAME="SDLENVVARS"
></A
>SDL_envvars</H1
><DIV
CLASS="REFNAMEDIV"
><A
NAME="AEN675"
></A
><H2
>Name</H2
>SDL_envvars&nbsp;--&nbsp;SDL environment variables</DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN678"
></A
><H2
>Description</H2
><P
>Not a function, set using setenv()</P
><P
>Several environment variables are available to modify the
behaviour of SDL. Using these variables isn't recommened and the names
and presence of these variables aren't guaranteed from one release to
the next. However, they can be very useful for debugging
purposes.</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN682"
></A
><H2
>Video</H2
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
><TT
CLASS="LITERAL"
>SDL_FBACCEL</TT
></DT
><DD
><P
>If set to 0, disable hardware acceleration in the linux fbcon driver.</P
></DD
><DT
><TT
CLASS="LITERAL"
>SDL_FBDEV</TT
></DT
><DD
><P
>Frame buffer device to use in the linux fbcon driver, instead of /dev/fb0</P
></DD
><DT
><TT
CLASS="LITERAL"
>SDL_FULLSCREEN_UPDATE</TT
></DT
><DD
><P
>In the ps2gs driver, sets the <TT
CLASS="LITERAL"
>SDL_ASYNCBLIT</TT
> flag on the
display surface.</P
></DD
><DT
><TT
CLASS="LITERAL"
>SDL_VIDEODRIVER</TT
></DT
><DD
><P
>Selectes the video driver for SDL to use. Possible values, in the
order they are tried if this variable is not set:</P
><DIV
CLASS="INFORMALTABLE"
><A
NAME="AEN706"
></A
><P
></P
><TABLE
BORDER="0"
CLASS="CALSTABLE"
><TBODY
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="LITERAL"
>x11</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
></P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="LITERAL"
>dga</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
>(the XFree86 DGA2)</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="LITERAL"
>nanox</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
>(Linux)</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="LITERAL"
>fbcon</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
>(Linux)</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="LITERAL"
>directfb</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
>(Linux)</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="LITERAL"
>ps2gs</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
>(Playstation 2)</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="LITERAL"
>ggi</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
></P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="LITERAL"
>vgl</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
>(BSD)</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="LITERAL"
>svgalib</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
>(Linux)</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="LITERAL"
>aalib</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
></P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="LITERAL"
>directx</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
>(Win32)</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="LITERAL"
>windib</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
>(Win32)</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="LITERAL"
>bwindow</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
>(BeOS)</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="LITERAL"
>toolbox</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
>(MacOS Classic)</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="LITERAL"
>DSp</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
>(MacOS Classic)</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="LITERAL"
>Quartz</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
>(Mac OS X)</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="LITERAL"
>CGX</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
>(Amiga)</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="LITERAL"
>photon</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
>(QNX)</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="LITERAL"
>dummy</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
></P
></TD
></TR
></TBODY
></TABLE
><P
></P
></DIV
></DD
><DT
><TT
CLASS="LITERAL"
>SDL_VIDEO_CENTERED</TT
></DT
><DD
><P
>If set, tries to center the SDL window when running in X11 windowed
mode, or using the CyberGrafix driver.</P
></DD
><DT
><TT
CLASS="LITERAL"
>SDL_VIDEO_GL_DRIVER</TT
></DT
><DD
><P
>The openGL driver (shared library) to use for X11. Default is libGL.so.1</P
></DD
><DT
><TT
CLASS="LITERAL"
>SDL_VIDEO_X11_DGAMOUSE</TT
></DT
><DD
><P
>With XFree86, enables use of DGA mouse if set.</P
></DD
><DT
><TT
CLASS="LITERAL"
>SDL_VIDEO_X11_MOUSEACCEL</TT
></DT
><DD
><P
>For X11, sets the mouse acceleration. The value should be a string
on the form:</P
><P
>"<TT
CLASS="PARAMETER"
><I
>n</I
></TT
>/<TT
CLASS="PARAMETER"
><I
>d</I
></TT
>/<TT
CLASS="PARAMETER"
><I
>t</I
></TT
>"</P
><P
>where <TT
CLASS="PARAMETER"
><I
>n</I
></TT
> and <TT
CLASS="PARAMETER"
><I
>d</I
></TT
> are the
acceleration numerator/denumerators (so	mouse movement is accelerated by
<TT
CLASS="PARAMETER"
><I
>n</I
></TT
>/<TT
CLASS="PARAMETER"
><I
>d</I
></TT
>), and
<TT
CLASS="PARAMETER"
><I
>t</I
></TT
> is the threshold above which acceleration applies
(counted as number of pixels the mouse moves at once).</P
></DD
><DT
><TT
CLASS="LITERAL"
>SDL_VIDEO_X11_NODIRECTCOLOR</TT
></DT
><DD
><P
>If set, don't attempt to use DirectColor visuals even if they are
present. (SDL will use them otherwise for gamma correction).
This is needed with older X servers when using the XVideo extension.</P
></DD
><DT
><TT
CLASS="LITERAL"
>SDL_VIDEO_X11_VISUALID</TT
></DT
><DD
><P
>ID of an X11 visual to use, overriding SDL's default visual selection
algorithm. It can be in decimal or in hex (prefixed by 0x).</P
></DD
><DT
><TT
CLASS="LITERAL"
>SDL_VIDEO_YUV_DIRECT</TT
></DT
><DD
><P
>If set, display YUV overlay directly on the video surface if possible,
instead of on the surface passed to
<A
HREF="sdlcreateyuvoverlay.html"
><TT
CLASS="FUNCTION"
>SDL_CreateYUVOverlay</TT
></A
>.</P
></DD
><DT
><TT
CLASS="LITERAL"
>SDL_VIDEO_YUV_HWACCEL</TT
></DT
><DD
><P
>If not set or set to a nonzero value, SDL will attempt to use
hardware YUV acceleration for video playback.</P
></DD
><DT
><TT
CLASS="LITERAL"
>SDL_WINDOWID</TT
></DT
><DD
><P
>For X11 or Win32, contains the ID number of the window to be used by
SDL instead of creating its own window. Either in decimal or
in hex (prefixed by 0x).</P
></DD
></DL
></DIV
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN866"
></A
><H2
>Events/Input</H2
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
><TT
CLASS="LITERAL"
>SDL_MOUSE_RELATIVE</TT
></DT
><DD
><P
>If set to 0, do not use mouse relative mode in X11. The default is
to use it if the mouse is hidden and input is grabbed.</P
></DD
><DT
><TT
CLASS="LITERAL"
>SDL_MOUSEDEV</TT
></DT
><DD
><P
>The mouse device to use for the linux fbcon driver. If not set,
SDL first tries to use GPM in repeater mode, then various other
devices (/dev/pcaux, /dev/adbmouse, /dev/mouse etc).</P
></DD
><DT
><TT
CLASS="LITERAL"
>SDL_MOUSEDEV_IMPS2</TT
></DT
><DD
><P
>If set, SDL will not try to auto-detect	the IMPS/2 protocol of
a PS/2 mouse but use it right away. For the fbcon and ps2gs drivers.</P
></DD
><DT
><TT
CLASS="LITERAL"
>SDL_MOUSEDRV</TT
></DT
><DD
><P
>For the linux fbcon driver: if set to ELO, use the ELO touchscreen
controller as a pointer device</P
></DD
><DT
><TT
CLASS="LITERAL"
>SDL_NO_RAWKBD</TT
></DT
><DD
><P
>For the libvga driver: If set, do not attempt to put the keyboard in raw mode.</P
></DD
><DT
><TT
CLASS="LITERAL"
>SDL_NOMOUSE</TT
></DT
><DD
><P
>If set, the linux fbcon driver will not use a mouse at all.</P
></DD
><DT
><TT
CLASS="LITERAL"
>SDL_NO_LOCK_KEYS</TT
></DT
><DD
><P
>Disable CAPS-LOCK and NUM-LOCK suppression of down+up key events,
suitable for games where the player needs these keys to do more than just toggle.
A value of 1 will effect both CAPS-LOCK and NUM-LOCK.
A value of 2 will effect only CAPS-LOCK.
A value of 3 will effect only NUM-LOCK.
All other values have no effect.
</P
></DD
></DL
></DIV
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN899"
></A
><H2
>Audio</H2
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
><TT
CLASS="LITERAL"
>AUDIODEV</TT
></DT
><DD
><P
>The audio device to use, if <TT
CLASS="LITERAL"
>SDL_PATH_DSP</TT
> isn't set.</P
></DD
><DT
><TT
CLASS="LITERAL"
>SDL_AUDIODRIVER</TT
></DT
><DD
><P
>Selects the audio driver for SDL to use. Possible values, in the
order they are tried if this variable is not set:</P
><DIV
CLASS="INFORMALTABLE"
><A
NAME="AEN913"
></A
><P
></P
><TABLE
BORDER="0"
CLASS="CALSTABLE"
><TBODY
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="LITERAL"
>openbsd</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
>(OpenBSD)</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="LITERAL"
>dsp</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
>(OSS /dev/dsp: Linux, Solaris, BSD etc)</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="LITERAL"
>alsa</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
>(Linux)</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="LITERAL"
>audio</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
>(Unix style /dev/audio: SunOS, Solaris etc)</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="LITERAL"
>AL</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
>(Irix)</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="LITERAL"
>artsc</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
>(ARTS audio daemon)</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="LITERAL"
>esd</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
>(esound audio daemon)</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="LITERAL"
>nas</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
>(NAS audio daemon)</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="LITERAL"
>dma</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
>(OSS /dev/dsp, using DMA)</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="LITERAL"
>dsound</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
>(Win32 DirectX)</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="LITERAL"
>waveout</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
>(Win32 WaveOut)</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="LITERAL"
>baudio</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
>(BeOS)</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="LITERAL"
>sndmgr</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
>(MacOS SoundManager)</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="LITERAL"
>paud</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
>(AIX)</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="LITERAL"
>AHI</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
>(Amiga)</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="LITERAL"
>disk</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
>(all; output to file)</P
></TD
></TR
></TBODY
></TABLE
><P
></P
></DIV
></DD
><DT
><TT
CLASS="LITERAL"
>SDL_DISKAUDIOFILE</TT
></DT
><DD
><P
>The name of the output file for the "disk" audio driver. If not
set, the name <TT
CLASS="LITERAL"
>sdlaudio.raw</TT
> is used.</P
></DD
><DT
><TT
CLASS="LITERAL"
>SDL_DISKAUDIODELAY</TT
></DT
><DD
><P
>For the "disk" audio driver, how long to wait (in ms) before writing
a full sound buffer. The default is 150 ms.</P
></DD
><DT
><TT
CLASS="LITERAL"
>SDL_DSP_NOSELECT</TT
></DT
><DD
><P
>For some audio drivers (alsa, paud, dma and dsp), don't use select()
but a timed method instead. May cure some audio problems, or cause
others.</P
></DD
><DT
><TT
CLASS="LITERAL"
>SDL_PATH_DSP</TT
></DT
><DD
><P
>The audio device to use. If not set, SDL tries AUDIODEV and then
a platform-dependent default value (/dev/audio on Solaris,
/dev/dsp on Linux etc).</P
></DD
></DL
></DIV
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN1017"
></A
><H2
>CD-ROM</H2
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
><TT
CLASS="LITERAL"
>SDL_CDROM</TT
></DT
><DD
><P
>A colon-separated list of CD-ROM devices to use, in addition to
the standard devices (typically /dev/cdrom, platform-dependent).</P
></DD
></DL
></DIV
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN1025"
></A
><H2
>Debugging</H2
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
><TT
CLASS="LITERAL"
>SDL_DEBUG</TT
></DT
><DD
><P
>If set, causes every call to <TT
CLASS="FUNCTION"
>SDL_SetError</TT
> (that
is, every time SDL signals an error) to also print an error message on
stderr.</P
></DD
></DL
></DIV
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN1034"
></A
><H2
>Joystick</H2
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
><TT
CLASS="LITERAL"
>SDL_JOYSTICK_DEVICE</TT
></DT
><DD
><P
>Joystick device to use in the linux joystick driver, in addition
to the usual: /dev/js*, /dev/input/event*, /dev/input/js*</P
></DD
><DT
><TT
CLASS="LITERAL"
>SDL_LINUX_JOYSTICK</TT
></DT
><DD
><P
>Special joystick configuration string for linux. The format is</P
><P
>"<TT
CLASS="PARAMETER"
><I
>name</I
></TT
> <TT
CLASS="PARAMETER"
><I
>numaxes</I
></TT
> <TT
CLASS="PARAMETER"
><I
>numhats</I
></TT
> <TT
CLASS="PARAMETER"
><I
>numballs</I
></TT
>"</P
><P
>where <TT
CLASS="PARAMETER"
><I
>name</I
></TT
> is the name string of the joystick
(possibly in single quotes), and the rest are the number of axes, hats
and balls respectively.</P
></DD
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