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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_LockYUVOverlay</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_CreateYUVOverlay"
HREF="sdlcreateyuvoverlay.html"><LINK
REL="NEXT"
TITLE="SDL_UnlockYUVOverlay"
HREF="sdlunlockyuvoverlay.html"></HEAD
><BODY
CLASS="REFENTRY"
BGCOLOR="#FFF8DC"
TEXT="#000000"
LINK="#0000ee"
VLINK="#551a8b"
ALINK="#ff0000"
><DIV
CLASS="NAVHEADER"
><TABLE
SUMMARY="Header navigation table"
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BORDER="0"
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><TR
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>SDL Library Documentation</TH
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><HR
ALIGN="LEFT"
WIDTH="100%"></DIV
><H1
><A
NAME="SDLLOCKYUVOVERLAY"
></A
>SDL_LockYUVOverlay</H1
><DIV
CLASS="REFNAMEDIV"
><A
NAME="AEN2844"
></A
><H2
>Name</H2
>SDL_LockYUVOverlay&nbsp;--&nbsp;Lock an overlay</DIV
><DIV
CLASS="REFSYNOPSISDIV"
><A
NAME="AEN2847"
></A
><H2
>Synopsis</H2
><DIV
CLASS="FUNCSYNOPSIS"
><A
NAME="AEN2848"
></A
><P
></P
><PRE
CLASS="FUNCSYNOPSISINFO"
>#include "SDL.h"</PRE
><P
><CODE
><CODE
CLASS="FUNCDEF"
>int <B
CLASS="FSFUNC"
>SDL_LockYUVOverlay</B
></CODE
>(SDL_Overlay *overlay);</CODE
></P
><P
></P
></DIV
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN2854"
></A
><H2
>Description</H2
><P
>Much the same as <A
HREF="sdllocksurface.html"
><TT
CLASS="FUNCTION"
>SDL_LockSurface</TT
></A
>, <TT
CLASS="FUNCTION"
>SDL_LockYUVOverlay</TT
> locks the <A
HREF="sdloverlay.html"
><TT
CLASS="PARAMETER"
><I
>overlay</I
></TT
></A
> for direct access to pixel data.</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN2862"
></A
><H2
>Return Value</H2
><P
>Returns <SPAN
CLASS="RETURNVALUE"
>0</SPAN
> on success, or <SPAN
CLASS="RETURNVALUE"
>-1</SPAN
> on an error.</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN2867"
></A
><H2
>See Also</H2
><P
><A
HREF="sdlunlockyuvoverlay.html"
><TT
CLASS="FUNCTION"
>SDL_UnlockYUVOverlay</TT
></A
>,
<A
HREF="sdlcreateyuvoverlay.html"
><TT
CLASS="FUNCTION"
>SDL_CreateYUVOverlay</TT
></A
>,
<A
HREF="sdloverlay.html"
><SPAN
CLASS="STRUCTNAME"
>SDL_Overlay</SPAN
></A
></P
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>Prev</A
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>