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Date: Mon, 10 Oct 2005 13:09:32 +0300 From: Tommi Kyntola <tommi.kyntola@ray.fi> To: sdl@libsdl.org Subject: [SDL] [RFC] get_ticks broken on linux It uses gettimeofday to calculate the timedifference. Gettimeofday returns current time which is seldom monotonous. This breaks SDL timer subsystem. (time callbacks and all that get borked when the time difference ms is suddenly ~ 2^32) I posted a message about this earlier but got no response. Some thoughts on this matter would be appreciated. (Or even an explanation for the lack of interest.) A patch below would use the posix timers that have been around since posix 93 and do provide a good source of monotonous time on linux boxes (and on few others too). The following patch is also availabe at: http://www.hut.fi/u/tkyntola/SDL-1.2.9-clockfix.patch It's against 1.2.9, but I can easily rediffit against the cvs branch is needed. cheers, Tommi Kyntola tommi.kyntola@ray.fi
author Ryan C. Gordon <icculus@icculus.org>
date Tue, 11 Oct 2005 18:16:12 +0000
parents 355632dca928
children
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<HTML
><HEAD
><TITLE
>Time</TITLE
><META
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>Chapter 13. Time</H1
><DIV
CLASS="TOC"
><DL
><DT
><B
>Table of Contents</B
></DT
><DT
><A
HREF="sdlgetticks.html"
>SDL_GetTicks</A
>&nbsp;--&nbsp;Get the number of milliseconds since the SDL library initialization.</DT
><DT
><A
HREF="sdldelay.html"
>SDL_Delay</A
>&nbsp;--&nbsp;Wait a specified number of milliseconds before returning.</DT
><DT
><A
HREF="sdladdtimer.html"
>SDL_AddTimer</A
>&nbsp;--&nbsp;Add a timer which will call a callback after the specified number of milliseconds has
elapsed.</DT
><DT
><A
HREF="sdlremovetimer.html"
>SDL_RemoveTimer</A
>&nbsp;--&nbsp;Remove a timer which was added with
<A
HREF="sdladdtimer.html"
>SDL_AddTimer</A
>.</DT
><DT
><A
HREF="sdlsettimer.html"
>SDL_SetTimer</A
>&nbsp;--&nbsp;Set a callback to run after the specified number of milliseconds has
elapsed.</DT
></DL
></DIV
><P
>SDL provides several cross-platform functions for dealing with time.
It provides a way to get the current time, a way to wait a little while,
and a simple timer mechanism.  These functions give you two ways of moving an
object every x milliseconds:

<P
></P
><UL
><LI
><P
>Use a timer callback function.  This may have the bad effect that it runs in a seperate thread or uses alarm signals, but it's easier to implement.</P
></LI
><LI
><P
>Or you can get the number of milliseconds passed, and move the object if, for example, 30 ms passed.</P
></LI
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>&#13;</P
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