view docs/html/sdlcdstatus.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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><H1
><A
NAME="SDLCDSTATUS"
>SDL_CDStatus</A
></H1
><DIV
CLASS="REFNAMEDIV"
><A
NAME="AEN6920"
></A
><H2
>Name</H2
>SDL_CDStatus&nbsp;--&nbsp;Returns the current status of the given drive.</DIV
><DIV
CLASS="REFSYNOPSISDIV"
><A
NAME="AEN6923"
></A
><H2
>Synopsis</H2
><DIV
CLASS="FUNCSYNOPSIS"
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><P
></P
><PRE
CLASS="FUNCSYNOPSISINFO"
>#include "SDL.h"</PRE
><P
><CODE
><CODE
CLASS="FUNCDEF"
>CDstatus <B
CLASS="FSFUNC"
>SDL_CDStatus</B
></CODE
>(SDL_CD *cdrom);</CODE
></P
><PRE
CLASS="FUNCSYNOPSISINFO"
>/* Given a status, returns true if there's a disk in the drive */
#define CD_INDRIVE(status)      ((int)status &#62; 0)</PRE
><P
></P
></DIV
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><DIV
CLASS="REFSECT1"
><A
NAME="AEN6931"
></A
><H2
>Description</H2
><P
>This function returns the current status of the given drive. Status is described like so:
<PRE
CLASS="PROGRAMLISTING"
>typedef enum {
  CD_TRAYEMPTY,
  CD_STOPPED,
  CD_PLAYING,
  CD_PAUSED,
  CD_ERROR = -1
} CDstatus;</PRE
></P
><P
>If the drive has a CD in it, the table of contents of the CD and current
play position of the CD will be stored in the SDL_CD structure.</P
><P
>The macro <TT
CLASS="LITERAL"
>CD_INDRIVE</TT
> is provided for convenience, 
and given a status returns true if there's a disk in the drive.</P
><DIV
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><BLOCKQUOTE
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><P
><B
>Note: </B
><TT
CLASS="FUNCTION"
>SDL_CDStatus</TT
> also updates the <A
HREF="sdlcd.html"
><SPAN
CLASS="STRUCTNAME"
>SDL_CD</SPAN
></A
> structure passed to it.</P
></BLOCKQUOTE
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><A
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></A
><H2
>Example</H2
><PRE
CLASS="PROGRAMLISTING"
>int playTrack(int track)
{
  int playing = 0;

  if ( CD_INDRIVE(SDL_CDStatus(cdrom)) ) {
  /* clamp to the actual number of tracks on the CD */
    if (track &#62;= cdrom-&#62;numtracks) {
      track = cdrom-&#62;numtracks-1;
    }

    if ( SDL_CDPlayTracks(cdrom, track, 0, 1, 0) == 0 ) {
      playing = 1;
    }
  }
  return playing;
}</PRE
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><A
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><H2
>See Also</H2
><P
><A
HREF="sdlcd.html"
><TT
CLASS="FUNCTION"
>SDL_CD</TT
></A
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