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view docs/html/sdlgetkeystate.html @ 765:4c2ba6161939
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_GetKeyState</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="Event Functions." HREF="eventfunctions.html"><LINK REL="PREVIOUS" TITLE="SDL_EventState" HREF="sdleventstate.html"><LINK REL="NEXT" TITLE="SDL_GetModState" HREF="sdlgetmodstate.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="sdleventstate.html" >Prev</A ></TD ><TD WIDTH="80%" ALIGN="center" VALIGN="bottom" ></TD ><TD WIDTH="10%" ALIGN="right" VALIGN="bottom" ><A HREF="sdlgetmodstate.html" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><H1 ><A NAME="SDLGETKEYSTATE" >SDL_GetKeyState</A ></H1 ><DIV CLASS="REFNAMEDIV" ><A NAME="AEN5298" ></A ><H2 >Name</H2 >SDL_GetKeyState -- Get a snapshot of the current keyboard state</DIV ><DIV CLASS="REFSYNOPSISDIV" ><A NAME="AEN5301" ></A ><H2 >Synopsis</H2 ><DIV CLASS="FUNCSYNOPSIS" ><A NAME="AEN5302" ></A ><P ></P ><PRE CLASS="FUNCSYNOPSISINFO" >#include "SDL.h"</PRE ><P ><CODE ><CODE CLASS="FUNCDEF" >Uint8 *<B CLASS="FSFUNC" >SDL_GetKeyState</B ></CODE >(int *numkeys);</CODE ></P ><P ></P ></DIV ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN5308" ></A ><H2 >Description</H2 ><P >Gets a snapshot of the current keyboard state. The current state is return as a pointer to an array, the size of this array is stored in <TT CLASS="PARAMETER" ><I >numkeys</I ></TT >. The array is indexed by the <A HREF="sdlkey.html" ><TT CLASS="LITERAL" >SDLK_*</TT ></A > symbols. A value of 1 means the key is pressed and a value of 0 means its not. The pointer returned is a pointer to an internal SDL array and should not be freed by the caller.</P ><DIV CLASS="NOTE" ><BLOCKQUOTE CLASS="NOTE" ><P ><B >Note: </B >Use <A HREF="sdlpumpevents.html" ><TT CLASS="FUNCTION" >SDL_PumpEvents</TT ></A > to update the state array.</P ></BLOCKQUOTE ></DIV ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN5318" ></A ><H2 >Example</H2 ><P ><PRE CLASS="PROGRAMLISTING" >Uint8 *keystate = SDL_GetKeyState(NULL); if ( keystate[SDLK_RETURN] ) printf("Return Key Pressed.\n");</PRE ></P ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN5322" ></A ><H2 >See Also</H2 ><P ><A HREF="sdlkey.html" ><TT CLASS="LITERAL" >SDL Key Symbols</TT ></A >, <A HREF="sdlpumpevents.html" ><TT CLASS="FUNCTION" >SDL_PumpEvents</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="sdleventstate.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="sdlgetmodstate.html" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >SDL_EventState</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="eventfunctions.html" >Up</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >SDL_GetModState</TD ></TR ></TABLE ></DIV ></BODY ></HTML >