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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 ><HEAD ><TITLE >SDL_WasInit</TITLE ><META NAME="GENERATOR" CONTENT="Modular DocBook HTML Stylesheet Version 1.64 "><LINK REL="HOME" TITLE="SDL Library Documentation" HREF="index.html"><LINK REL="UP" TITLE="General" HREF="general.html"><LINK REL="PREVIOUS" TITLE="SDL_Quit" HREF="sdlquit.html"><LINK REL="NEXT" TITLE="SDL_GetError" HREF="sdlgeterror.html"></HEAD ><BODY CLASS="REFENTRY" BGCOLOR="#FFF8DC" TEXT="#000000" LINK="#0000ee" VLINK="#551a8b" ALINK="#ff0000" ><DIV CLASS="NAVHEADER" ><TABLE WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TH COLSPAN="3" ALIGN="center" >SDL Library Documentation</TH ></TR ><TR ><TD WIDTH="10%" ALIGN="left" VALIGN="bottom" ><A HREF="sdlquit.html" >Prev</A ></TD ><TD WIDTH="80%" ALIGN="center" VALIGN="bottom" ></TD ><TD WIDTH="10%" ALIGN="right" VALIGN="bottom" ><A HREF="sdlgeterror.html" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><H1 ><A NAME="SDLWASINIT" >SDL_WasInit</A ></H1 ><DIV CLASS="REFNAMEDIV" ><A NAME="AEN617" ></A ><H2 >Name</H2 >SDL_WasInit -- Check which subsystems are initialized</DIV ><DIV CLASS="REFSYNOPSISDIV" ><A NAME="AEN620" ></A ><H2 >Synopsis</H2 ><DIV CLASS="FUNCSYNOPSIS" ><A NAME="AEN621" ></A ><P ></P ><PRE CLASS="FUNCSYNOPSISINFO" >#include "SDL.h"</PRE ><P ><CODE ><CODE CLASS="FUNCDEF" >Uint32 <B CLASS="FSFUNC" >SDL_WasInit</B ></CODE >(Uint32 flags);</CODE ></P ><P ></P ></DIV ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN627" ></A ><H2 >Description</H2 ><P ><TT CLASS="FUNCTION" >SDL_WasInit</TT > allows you to see which SDL subsytems have been <A HREF="sdlinit.html" >initialized</A >. <TT CLASS="PARAMETER" ><I >flags</I ></TT > is a bitwise OR'd combination of the subsystems you wish to check (see <A HREF="sdlinit.html" ><TT CLASS="FUNCTION" >SDL_Init</TT ></A > for a list of subsystem flags).</P ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN635" ></A ><H2 >Return Value</H2 ><P ><TT CLASS="FUNCTION" >SDL_WasInit</TT > returns a bitwised OR'd combination of the initialized subsystems.</P ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN639" ></A ><H2 >Examples</H2 ><PRE CLASS="PROGRAMLISTING" > /* Here are several ways you can use SDL_WasInit() */ /* Get init data on all the subsystems */ Uint32 subsystem_init; subsystem_init=SDL_WasInit(SDL_INIT_EVERYTHING); if(subsystem_init&SDL_INIT_VIDEO) printf("Video is initialized.\n"); else printf("Video is not initialized.\n"); /* Just check for one specfic subsystem */ if(SDL_WasInit(SDL_INIT_VIDEO)!=0) printf("Video is initialized.\n"); else printf("Video is not initialized.\n"); /* Check for two subsystems */ Uint32 subsystem_mask=SDL_INIT_VIDEO|SDL_INIT_AUDIO; if(SDL_WasInit(subsystem_mask)==subsystem_mask) printf("Video and Audio initialized.\n"); else printf("Video and Audio not initialized.\n"); </PRE ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN642" ></A ><H2 >See Also</H2 ><P ><A HREF="sdlinit.html" ><TT CLASS="FUNCTION" >SDL_Init</TT ></A >, <A HREF="sdlinitsubsystem.html" ><TT CLASS="FUNCTION" >SDL_Subsystem</TT ></A ></P ></DIV ><DIV CLASS="NAVFOOTER" ><HR ALIGN="LEFT" WIDTH="100%"><TABLE WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" ><A HREF="sdlquit.html" >Prev</A ></TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="index.html" >Home</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" ><A HREF="sdlgeterror.html" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >SDL_Quit</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="general.html" >Up</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >SDL_GetError</TD ></TR ></TABLE ></DIV ></BODY ></HTML >