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Date: Sun, 29 Feb 2004 15:14:22 +0200 From: Martin_Storsj Subject: Dynamic loading of ALSA I recently discovered that SDL can dynamically load ESD and aRts, and made a patch which adds this same functionality to ALSA. The update for configure.in isn't too good (it should e.g. look for libasound.so in other directories than /usr/lib), because I'm not too good at shellscripting and autoconf. The reason for using dlfcn.h and dlopen instead of SDL_LoadLibrary and SDL_LoadFunction is that libasound uses versioned symbols, and it is necessary to load the correct version using dlvsym. This isn't probably any real portability issue, because ALSA is linux-only.
author Sam Lantinga <slouken@libsdl.org>
date Tue, 02 Mar 2004 12:49:16 +0000
parents 355632dca928
children
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<HTML
><HEAD
><TITLE
>SDL_SetTimer</TITLE
><META
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><H1
><A
NAME="SDLSETTIMER"
></A
>SDL_SetTimer</H1
><DIV
CLASS="REFNAMEDIV"
><A
NAME="AEN8557"
></A
><H2
>Name</H2
>SDL_SetTimer&nbsp;--&nbsp;Set a callback to run after the specified number of milliseconds has
elapsed.</DIV
><DIV
CLASS="REFSYNOPSISDIV"
><A
NAME="AEN8560"
></A
><H2
>Synopsis</H2
><DIV
CLASS="FUNCSYNOPSIS"
><A
NAME="AEN8561"
></A
><P
></P
><PRE
CLASS="FUNCSYNOPSISINFO"
>#include "SDL.h"</PRE
><P
><CODE
><CODE
CLASS="FUNCDEF"
>int <B
CLASS="FSFUNC"
>SDL_SetTimer</B
></CODE
>(Uint32 interval, SDL_TimerCallback callback);</CODE
></P
><P
></P
></DIV
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="SDLTIMERCALLBACK"
></A
><H2
>Callback</H2
><P
>/* Function prototype for the timer callback function */
typedef Uint32 (*SDL_TimerCallback)(Uint32 interval);</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN8570"
></A
><H2
>Description</H2
><P
>Set a callback to run after the specified number of milliseconds has
elapsed. The callback function is passed the current timer interval
and returns the next timer interval.  If the returned value is the
same as the one passed in, the periodic alarm continues, otherwise a
new alarm is scheduled.</P
><P
>To cancel a currently running timer, call
<TT
CLASS="FUNCTION"
>SDL_SetTimer(0, NULL);</TT
></P
><P
>The timer callback function may run in a different thread than your
main constant, and so shouldn't call any functions from within itself.</P
><P
>The maximum resolution of this timer is 10 ms, which means that if
you request a 16 ms timer, your callback will run approximately 20 ms
later on an unloaded system.  If you wanted to set a flag signaling
a frame update at 30 frames per second (every 33 ms), you might set a
timer for 30 ms (see example below).</P
><P
>If you use this function, you need to pass <TT
CLASS="LITERAL"
>SDL_INIT_TIMER</TT
>
to <TT
CLASS="FUNCTION"
>SDL_Init()</TT
>.</P
><DIV
CLASS="NOTE"
><BLOCKQUOTE
CLASS="NOTE"
><P
><B
>Note: </B
>This function is kept for compatibility but has been superseded
by the new timer functions
<A
HREF="sdladdtimer.html"
>SDL_AddTimer</A
> and
<A
HREF="sdlremovetimer.html"
>SDL_RemoveTimer</A
> which support
multiple timers.</P
></BLOCKQUOTE
></DIV
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN8584"
></A
><H2
>Examples</H2
><P
><PRE
CLASS="PROGRAMLISTING"
>SDL_SetTimer((33/10)*10, my_callback);</PRE
></P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN8588"
></A
><H2
>See Also</H2
><P
><A
HREF="sdladdtimer.html"
><TT
CLASS="FUNCTION"
>SDL_AddTimer</TT
></A
></P
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