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Date: Mon, 11 Oct 2004 15:17:27 +0300 (EEST) From: Hannu Savolainen Subject: Re: SDL uses obsolete OSS features I did some work on getting OSS to work better with SDL. There have been some problems with select which should be fixed now. I'm having some problems in understanding what is the purpose of the DSP_WaitAudio() routine. I added a return to the very beginning of this routine and commendted out the define for USE_BLOCKING_WRITES. At least lbreakout2 seems to work as well as earlier. The latencies are the same. An ordinary blocking write does exactly the same thing than DSP_WaitAudio does. So I would recommend using the USE_BLOCKING_WRITES approach and removing everything from the DSP_WaitAudio routine. Also enabling USE_BLOCKING_WRITES makes it possible to simplify DSP_PlayAudio() because you don't need to handle the partial writes (the do-while loop). Attached is a patch against SDL-1.2.7. After these changes SDL will use OSS as it's designed to be used (make it as simple as possible). This code should work with all OSS implementations because it uses only the very fundamental features that have been there since the jurassic times.
author Sam Lantinga <slouken@libsdl.org>
date Fri, 12 Nov 2004 21:39:04 +0000
parents 355632dca928
children
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<HTML
><HEAD
><TITLE
>SDL_CD</TITLE
><META
NAME="GENERATOR"
CONTENT="Modular DocBook HTML Stylesheet Version 1.76b+
"><LINK
REL="HOME"
TITLE="SDL Library Documentation"
HREF="index.html"><LINK
REL="UP"
TITLE="CD-ROM"
HREF="cdrom.html"><LINK
REL="PREVIOUS"
TITLE="SDL_CDClose"
HREF="sdlcdclose.html"><LINK
REL="NEXT"
TITLE="SDL_CDtrack"
HREF="sdlcdtrack.html"></HEAD
><BODY
CLASS="REFENTRY"
BGCOLOR="#FFF8DC"
TEXT="#000000"
LINK="#0000ee"
VLINK="#551a8b"
ALINK="#ff0000"
><DIV
CLASS="NAVHEADER"
><TABLE
SUMMARY="Header navigation 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="sdlcdclose.html"
ACCESSKEY="P"
>Prev</A
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><TD
WIDTH="80%"
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WIDTH="10%"
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VALIGN="bottom"
><A
HREF="sdlcdtrack.html"
ACCESSKEY="N"
>Next</A
></TD
></TR
></TABLE
><HR
ALIGN="LEFT"
WIDTH="100%"></DIV
><H1
><A
NAME="SDLCD"
></A
>SDL_CD</H1
><DIV
CLASS="REFNAMEDIV"
><A
NAME="AEN7566"
></A
><H2
>Name</H2
>SDL_CD&nbsp;--&nbsp;CDROM Drive Information</DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN7569"
></A
><H2
>Structure Definition</H2
><PRE
CLASS="PROGRAMLISTING"
>typedef struct{
  int id;
  CDstatus status;
  int numtracks;
  int cur_track;
  int cur_frame;
  SDL_CDtrack track[SDL_MAX_TRACKS+1];
} SDL_CD;</PRE
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN7572"
></A
><H2
>Structure Data</H2
><DIV
CLASS="INFORMALTABLE"
><A
NAME="AEN7574"
></A
><P
></P
><TABLE
BORDER="0"
CLASS="CALSTABLE"
><TBODY
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="STRUCTFIELD"
><I
>id</I
></TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>Private drive identifier</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="STRUCTFIELD"
><I
>status</I
></TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>Drive <A
HREF="sdlcdstatus.html"
>status</A
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="STRUCTFIELD"
><I
>numtracks</I
></TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>Number of tracks on the CD</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="STRUCTFIELD"
><I
>cur_track</I
></TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>Current track</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="STRUCTFIELD"
><I
>cur_frame</I
></TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>Current frame offset within the track</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="STRUCTFIELD"
><I
>track</I
></TT
>[SDL_MAX_TRACKS+1]</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>Array of track descriptions. (see <A
HREF="sdlcdtrack.html"
><SPAN
CLASS="STRUCTNAME"
>SDL_CDtrack</SPAN
></A
>)</TD
></TR
></TBODY
></TABLE
><P
></P
></DIV
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN7604"
></A
><H2
>Description</H2
><P
>An <SPAN
CLASS="STRUCTNAME"
>SDL_CD</SPAN
> structure is returned by <A
HREF="sdlcdopen.html"
><TT
CLASS="FUNCTION"
>SDL_CDOpen</TT
></A
>. It represents an opened CDROM device and stores information on the layout of the tracks on the disc.</P
><P
>A frame is the base data unit of a CD. <TT
CLASS="LITERAL"
>CD_FPS</TT
> frames is equal to 1 second of music. SDL provides two macros for converting between time and frames: <TT
CLASS="LITERAL"
>FRAMES_TO_MSF(f, M,S,F)</TT
> and <TT
CLASS="LITERAL"
>MSF_TO_FRAMES</TT
>.</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN7614"
></A
><H2
>Examples</H2
><PRE
CLASS="PROGRAMLISTING"
>int min, sec, frame;
int frame_offset;

FRAMES_TO_MSF(cdrom-&#62;cur_frame, &#38;min, &#38;sec, &#38;frame);
printf("Current Position: %d minutes, %d seconds, %d frames\n", min, sec, frame);

frame_offset=MSF_TO_FRAMES(min, sec, frame);</PRE
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN7617"
></A
><H2
>See Also</H2
><P
><A
HREF="sdlcdopen.html"
><TT
CLASS="FUNCTION"
>SDL_CDOpen</TT
></A
>,
<A
HREF="sdlcdtrack.html"
><SPAN
CLASS="STRUCTNAME"
>SDL_CDtrack</SPAN
></A
></P
></DIV
><DIV
CLASS="NAVFOOTER"
><HR
ALIGN="LEFT"
WIDTH="100%"><TABLE
SUMMARY="Footer navigation table"
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><A
HREF="sdlcdclose.html"
ACCESSKEY="P"
>Prev</A
></TD
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WIDTH="34%"
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><A
HREF="index.html"
ACCESSKEY="H"
>Home</A
></TD
><TD
WIDTH="33%"
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><A
HREF="sdlcdtrack.html"
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>Next</A
></TD
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><TR
><TD
WIDTH="33%"
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>SDL_CDClose</TD
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>