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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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><TITLE
>SDL_KeyboardEvent</TITLE
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><H1
><A
NAME="SDLKEYBOARDEVENT"
>SDL_KeyboardEvent</A
></H1
><DIV
CLASS="REFNAMEDIV"
><A
NAME="AEN3627"
></A
><H2
>Name</H2
>SDL_KeyboardEvent&nbsp;--&nbsp;Keyboard event structure</DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN3630"
></A
><H2
>Structure Definition</H2
><PRE
CLASS="PROGRAMLISTING"
>typedef struct{
  Uint8 type;
  Uint8 state;
  SDL_keysym keysym;
} SDL_KeyboardEvent;</PRE
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN3633"
></A
><H2
>Structure Data</H2
><DIV
CLASS="INFORMALTABLE"
><A
NAME="AEN3635"
></A
><P
></P
><TABLE
BORDER="0"
CLASS="CALSTABLE"
><TBODY
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="STRUCTFIELD"
><I
>type</I
></TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="LITERAL"
>SDL_KEYDOWN</TT
> or <TT
CLASS="LITERAL"
>SDL_KEYUP</TT
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="STRUCTFIELD"
><I
>state</I
></TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="LITERAL"
>SDL_PRESSED</TT
> or <TT
CLASS="LITERAL"
>SDL_RELEASED</TT
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="STRUCTFIELD"
><I
>keysym</I
></TT
></TD
><TD
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VALIGN="TOP"
>Contains key press information</TD
></TR
></TBODY
></TABLE
><P
></P
></DIV
></DIV
><DIV
CLASS="REFSECT1"
><A
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></A
><H2
>Description</H2
><P
><SPAN
CLASS="STRUCTNAME"
>SDL_KeyboardEvent</SPAN
> is a member of the <A
HREF="sdlevent.html"
><SPAN
CLASS="STRUCTNAME"
>SDL_Event</SPAN
></A
> union and is used when an event of type <TT
CLASS="LITERAL"
>SDL_KEYDOWN</TT
> or <TT
CLASS="LITERAL"
>SDL_KEYUP</TT
> is reported.</P
><P
>The <TT
CLASS="STRUCTFIELD"
><I
>type</I
></TT
> and <TT
CLASS="STRUCTFIELD"
><I
>state</I
></TT
> actually report the same information, they just use different values to do it! A keyboard event occurs when a key is released (<TT
CLASS="STRUCTFIELD"
><I
>type</I
></TT
>=<TT
CLASS="LITERAL"
>SDK_KEYUP</TT
> or <TT
CLASS="STRUCTFIELD"
><I
>state</I
></TT
>=<TT
CLASS="LITERAL"
>SDL_RELEASED</TT
>) and when a key is pressed (<TT
CLASS="STRUCTFIELD"
><I
>type</I
></TT
>=<TT
CLASS="LITERAL"
>SDL_KEYDOWN</TT
> or <TT
CLASS="STRUCTFIELD"
><I
>state</I
></TT
>=<TT
CLASS="LITERAL"
>SDL_PRESSED</TT
>). The information on what key was pressed or released is in the <A
HREF="sdlkeysym.html"
><SPAN
CLASS="STRUCTNAME"
>keysym</SPAN
></A
> structure.</P
><DIV
CLASS="NOTE"
><BLOCKQUOTE
CLASS="NOTE"
><P
><B
>Note: </B
>Repeating <TT
CLASS="LITERAL"
>SDL_KEYDOWN</TT
> events will occur if key repeat is enabled (see <A
HREF="sdlenablekeyrepeat.html"
><TT
CLASS="FUNCTION"
>SDL_EnableKeyRepeat</TT
></A
>).</P
></BLOCKQUOTE
></DIV
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><A
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></A
><H2
>See Also</H2
><P
><A
HREF="sdlevent.html"
><SPAN
CLASS="STRUCTNAME"
>SDL_Event</SPAN
></A
>,
<A
HREF="sdlkeysym.html"
><SPAN
CLASS="STRUCTNAME"
>SDL_keysym</SPAN
></A
>,
<A
HREF="sdlenablekeyrepeat.html"
><TT
CLASS="FUNCTION"
>SDL_EnableKeyRepeat</TT
></A
>,
<A
HREF="sdlenableunicode.html"
><TT
CLASS="FUNCTION"
>SDL_EnableUNICODE</TT
></A
></P
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