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Editors Note: The original patch was modified to use SDL_Delay() instead of nanosleep because nanosleep may not be portable to all systems using SDL with the ALSA backend. This may be a moot point with the switch to blocking writes anyway... Date: Sat, 27 Dec 2003 21:47:36 +0100 From: Michel Daenzer To: Debian Bug Tracking System Subject: [SDL] Bug#225252: [PATCH] ALSA fixes Package: libsdl1.2debian-all Version: 1.2.6-2 Severity: normal Tags: patch For SDL 1.2.6, the ALSA backend was changed to call snd_pcm_open() with SND_PCM_NONBLOCK. That's a good idea per se, however, it causes high CPU usage, interrupted sound and stuttering in some games here. Taking a nanosleep whenever snd_pcm_writei() returns -EAGAIN fixes this, but I think it's more efficient to use blocking mode for the actual sound playback. Feedback from the SDL and ALSA lists appreciated. The patch also fixes the default ALSA device to be used.
author Sam Lantinga <slouken@libsdl.org>
date Sun, 04 Jan 2004 15:40:50 +0000
parents e5bc29de3f0a
children 355632dca928
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<HTML
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><H1
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>SDL_UpdateRects</A
></H1
><DIV
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><A
NAME="AEN1008"
></A
><H2
>Name</H2
>SDL_UpdateRects&nbsp;--&nbsp;Makes sure the given list of rectangles is updated on the given screen.</DIV
><DIV
CLASS="REFSYNOPSISDIV"
><A
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><H2
>Synopsis</H2
><DIV
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><P
></P
><PRE
CLASS="FUNCSYNOPSISINFO"
>#include "SDL.h"</PRE
><P
><CODE
><CODE
CLASS="FUNCDEF"
>void <B
CLASS="FSFUNC"
>SDL_UpdateRects</B
></CODE
>(SDL_Surface *screen, int numrects, SDL_Rect *rects);</CODE
></P
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><H2
>Description</H2
><P
>Makes sure the given list of rectangles is updated on the given screen.
The rectangles must all be confined within the screen boundaries (no
clipping is done).</P
><P
>This function should not be called while <TT
CLASS="PARAMETER"
><I
>screen</I
></TT
> is
<A
HREF="sdllocksurface.html"
>locked</A
>.</P
><DIV
CLASS="NOTE"
><BLOCKQUOTE
CLASS="NOTE"
><P
><B
>Note: </B
>It is adviced to call this function only once per frame, since each
call has some processing overhead. This is no restriction since you
can pass any number of rectangles each time.</P
><P
>The rectangles are not automatically merged or checked for overlap. In
general, the programmer can use his knowledge about his particular
rectangles to merge them in an efficient way, to avoid overdraw.</P
></BLOCKQUOTE
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><H2
>See Also</H2
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><TT
CLASS="FUNCTION"
>SDL_UpdateRect</TT
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>,
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>SDL_Rect</SPAN
></A
>,
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>SDL_Surface</SPAN
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>,
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>SDL_LockSurface</TT
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