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te: Thu, 17 Apr 2003 11:25:26 -0700 From: "Jim" Subject: [SDL] Frame buffer patches... Would seem that GCC 3.2.2 promotes all signed values to unsigned if any single vlaue is unsigned in an expression... for instance when calculating an elo touch position....evertyhign is an (int) except for cach_vinfo.xres which is unsigned. THerefore if y ou reverse the SDL_ELO_MIN_X and SDL_ELO_MAX_X values the resulging negative value pegs the expression to it's max. Attached it the accumu lated patch to typecast the unsigned values to (int) - *dx = (cache_vinfo.xres - (cache_vinfo.xres * (input_x - ELO_MIN_X)) / width); + *dx = ((int)cache_vinfo.xres - ((int)cache_vinfo.xres * (input_x - ELO_MIN_X)) / width); and also to provide quite failure to operations which have the screen currently locked... The touch screen I'm using the original values were exactly opposite of any position I touched on the screen - evaluating the math the expr ession SHOULD have handled reversing the min and max values - and after casting the unsigned .xres and .yres to a signed int - worked well. .. Jim
author Sam Lantinga <slouken@libsdl.org>
date Tue, 24 Jan 2006 06:36:43 +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
></TD
><TD
WIDTH="80%"
ALIGN="center"
VALIGN="bottom"
></TD
><TD
WIDTH="10%"
ALIGN="right"
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"
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
><TR
><TD
WIDTH="33%"
ALIGN="left"
VALIGN="top"
><A
HREF="sdlcdclose.html"
ACCESSKEY="P"
>Prev</A
></TD
><TD
WIDTH="34%"
ALIGN="center"
VALIGN="top"
><A
HREF="index.html"
ACCESSKEY="H"
>Home</A
></TD
><TD
WIDTH="33%"
ALIGN="right"
VALIGN="top"
><A
HREF="sdlcdtrack.html"
ACCESSKEY="N"
>Next</A
></TD
></TR
><TR
><TD
WIDTH="33%"
ALIGN="left"
VALIGN="top"
>SDL_CDClose</TD
><TD
WIDTH="34%"
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VALIGN="top"
><A
HREF="cdrom.html"
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>Up</A
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><TD
WIDTH="33%"
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>SDL_CDtrack</TD
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>