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view docs/html/sdlconvertsurface.html @ 3899:081aecdb0911 SDL-1.2
From: Gabriel Gambetta
To: SDL Mailing List <sdl@libsdl.org>
Date: Fri, 17 Nov 2006 00:39:29 -0200
Subject: [SDL] Alpha blending bug - fixed?
It turns out mm5 never got the correct value. This failed :
[...]
"movd %1, %%mm5\n\t"
: : "m" (amask), "m" (sf->Ashift) );
mm5 got 0xFF000018 instead of 0x00000018. However I did this :
Uint32 ashift = sf->Ashift;
[...]
"movd %1, %%mm5\n\t"
: : "m" (amask), "m" (ashift) );
and everything worked fine.
The only thing I could find out was that ashift is 32-bit aligned but
sf->Ashift isn't:
printf("ashift %8X [%d]\n", &ashift, (int)(&ashift) % 4);
printf("sf->Ashift %8X [%d]\n", &sf->Ashift, (int)(&sf->Ashift) % 4);
ashift at BFF0E0C4 [0]
sf->Ashift at 08AFB9CD [1]
Could this be the problem? If it is, the fix is extremely trivial.
Should I submit a patch?
--Gabriel
author | Ryan C. Gordon <icculus@icculus.org> |
---|---|
date | Tue, 21 Nov 2006 23:17:00 +0000 |
parents | 355632dca928 |
children |
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<HTML ><HEAD ><TITLE >SDL_ConvertSurface</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="Video" HREF="video.html"><LINK REL="PREVIOUS" TITLE="SDL_GetClipRect" HREF="sdlgetcliprect.html"><LINK REL="NEXT" TITLE="SDL_BlitSurface" HREF="sdlblitsurface.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="sdlgetcliprect.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="80%" ALIGN="center" VALIGN="bottom" ></TD ><TD WIDTH="10%" ALIGN="right" VALIGN="bottom" ><A HREF="sdlblitsurface.html" ACCESSKEY="N" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><H1 ><A NAME="SDLCONVERTSURFACE" ></A >SDL_ConvertSurface</H1 ><DIV CLASS="REFNAMEDIV" ><A NAME="AEN2258" ></A ><H2 >Name</H2 >SDL_ConvertSurface -- Converts a surface to the same format as another surface.</DIV ><DIV CLASS="REFSYNOPSISDIV" ><A NAME="AEN2261" ></A ><H2 >Synopsis</H2 ><DIV CLASS="FUNCSYNOPSIS" ><A NAME="AEN2262" ></A ><P ></P ><PRE CLASS="FUNCSYNOPSISINFO" >#include "SDL/SDL.h"</PRE ><P ><CODE ><CODE CLASS="FUNCDEF" >SDL_Surface *<B CLASS="FSFUNC" >SDL_ConvertSurface</B ></CODE >(SDL_Surface *src, SDL_PixelFormat *fmt, Uint32 flags);</CODE ></P ><P ></P ></DIV ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN2268" ></A ><H2 >Description</H2 ><P >Creates a new surface of the specified format, and then copies and maps the given surface to it. If this function fails, it returns <TT CLASS="LITERAL" >NULL</TT >.</P ><P >The <TT CLASS="PARAMETER" ><I >flags</I ></TT > parameter is passed to <A HREF="sdlcreatergbsurface.html" ><TT CLASS="FUNCTION" >SDL_CreateRGBSurface</TT ></A > and has those semantics.</P ><P >This function is used internally by <A HREF="sdldisplayformat.html" ><TT CLASS="FUNCTION" >SDL_DisplayFormat</TT ></A >.</P ><P >This function can only be called after SDL_Init.</P ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN2280" ></A ><H2 >Return Value</H2 ><P >Returns either a pointer to the new surface, or <TT CLASS="LITERAL" >NULL</TT > on error.</P ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN2284" ></A ><H2 >See Also</H2 ><P ><A HREF="sdlcreatergbsurface.html" ><TT CLASS="FUNCTION" >SDL_CreateRGBSurface</TT ></A >, <A HREF="sdldisplayformat.html" ><TT CLASS="FUNCTION" >SDL_DisplayFormat</TT ></A >, <A HREF="sdlpixelformat.html" ><SPAN CLASS="STRUCTNAME" >SDL_PixelFormat</SPAN ></A >, <A HREF="sdlsurface.html" ><SPAN CLASS="STRUCTNAME" >SDL_Surface</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="sdlgetcliprect.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="sdlblitsurface.html" ACCESSKEY="N" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >SDL_GetClipRect</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="video.html" ACCESSKEY="U" >Up</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >SDL_BlitSurface</TD ></TR ></TABLE ></DIV ></BODY ></HTML >