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Fixed bug #33
Mike Frysinger wrote:
> with libsdl-1.2.9, some games (like bomberclone) started
> segfaulting in Gentoo
[...snip...]
> the last change in the last hunk:
[...snip...]
> if i change the statement to read:
> (table[which].blit_features & GetBlitFeatures()) == GetBlitFeatures()
> bomberclone no longer segfaults on my box
Alex Volkov wrote:
> The test "(table[which].blit_features & GetBlitFeatures()) ==
> table[which].blit_features)" is correct, and the previous
> "(table[which].cpu_mmx == SDL_HasMMX())" was actually broken.
I think there is potentially a slightly different cause of the above problem.
During the introduction of the Altivec code, the blit_table struct field
'alpha' got changed from a straightforward enum to a bitmask, which makes
perfect sense by itself. However, now the table driven blitter selection code
in SDL_CalculateBlitN() can choose the wrong blitters when searching for a
NO_ALPHA blitter because of the following code:
int a_need = 0;
...
(a_need & table[which].alpha) == a_need &&
When searching through the normal_blit_2[] table, a SET_ALPHA blitter (like
Blit_RGB565_ARGB8888) can now be selected instead of a NO_ALPHA one, causing
alpha channel bits to appear in a non-alpha destination surface. I suppose this
could theoretically be an indirect cause of the segfault mentioned above.
I *think* this can be fixed by changing to
int a_need = NO_ALPHA;
author | Sam Lantinga <slouken@libsdl.org> |
---|---|
date | Wed, 15 Mar 2006 15:47:49 +0000 |
parents | 355632dca928 |
children |
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<HTML ><HEAD ><TITLE >SDL_SysWMEvent</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="SDL Event Structures." HREF="eventstructures.html"><LINK REL="PREVIOUS" TITLE="SDL_ExposeEvent" HREF="sdlexposeevent.html"><LINK REL="NEXT" TITLE="SDL_UserEvent" HREF="sdluserevent.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="sdlexposeevent.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="80%" ALIGN="center" VALIGN="bottom" ></TD ><TD WIDTH="10%" ALIGN="right" VALIGN="bottom" ><A HREF="sdluserevent.html" ACCESSKEY="N" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><H1 ><A NAME="SDLSYSWMEVENT" ></A >SDL_SysWMEvent</H1 ><DIV CLASS="REFNAMEDIV" ><A NAME="AEN4538" ></A ><H2 >Name</H2 >SDL_SysWMEvent -- Platform-dependent window manager event.</DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN4541" ></A ><H2 >Description</H2 ><P >The system window manager event contains a pointer to system-specific information about unknown window manager events. If you enable this event using <A HREF="sdleventstate.html" ><TT CLASS="FUNCTION" >SDL_EventState()</TT ></A >, it will be generated whenever unhandled events are received from the window manager. This can be used, for example, to implement cut-and-paste in your application. <PRE CLASS="PROGRAMLISTING" >typedef struct { Uint8 type; /* Always SDL_SYSWMEVENT */ SDL_SysWMmsg *msg; } SDL_SysWMEvent;</PRE > If you want to obtain system-specific information about the window manager, you can fill the version member of a <SPAN CLASS="STRUCTNAME" >SDL_SysWMinfo</SPAN > structure (details can be found in <TT CLASS="FILENAME" >SDL_syswm.h</TT >, which must be included) using the <TT CLASS="FUNCTION" >SDL_VERSION()</TT > macro found in <TT CLASS="FILENAME" >SDL_version.h</TT >, and pass it to the function: <DIV CLASS="FUNCSYNOPSIS" ><A NAME="AEN4551" ></A ><P ></P ><P ><CODE ><CODE CLASS="FUNCDEF" >int <B CLASS="FSFUNC" >SDL_GetWMInfo</B ></CODE >(SDL_SysWMinfo *info);</CODE ></P ><P ></P ></DIV ></P ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN4556" ></A ><H2 >See Also</H2 ><P ><A HREF="sdleventstate.html" ><TT CLASS="FUNCTION" >SDL_EventState</TT ></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="sdlexposeevent.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="sdluserevent.html" ACCESSKEY="N" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >SDL_ExposeEvent</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="eventstructures.html" ACCESSKEY="U" >Up</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >SDL_UserEvent</TD ></TR ></TABLE ></DIV ></BODY ></HTML >