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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
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>SDL_UpdateRects</TITLE
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><H1
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>SDL_UpdateRects</H1
><DIV
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><H2
>Name</H2
>SDL_UpdateRects&nbsp;--&nbsp;Makes sure the given list of rectangles is updated on the given screen.</DIV
><DIV
CLASS="REFSYNOPSISDIV"
><A
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><H2
>Synopsis</H2
><DIV
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><P
></P
><PRE
CLASS="FUNCSYNOPSISINFO"
>#include "SDL.h"</PRE
><P
><CODE
><CODE
CLASS="FUNCDEF"
>void <B
CLASS="FSFUNC"
>SDL_UpdateRects</B
></CODE
>(SDL_Surface *screen, int numrects, SDL_Rect *rects);</CODE
></P
><P
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><DIV
CLASS="REFSECT1"
><A
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><H2
>Description</H2
><P
>Makes sure the given list of rectangles is updated on the given screen.
The rectangles must all be confined within the screen boundaries (no
clipping is done).</P
><P
>This function should not be called while <TT
CLASS="PARAMETER"
><I
>screen</I
></TT
> is
<A
HREF="sdllocksurface.html"
>locked</A
>.</P
><DIV
CLASS="NOTE"
><BLOCKQUOTE
CLASS="NOTE"
><P
><B
>Note: </B
>It is adviced to call this function only once per frame, since each
call has some processing overhead. This is no restriction since you
can pass any number of rectangles each time.</P
><P
>The rectangles are not automatically merged or checked for overlap. In
general, the programmer can use his knowledge about his particular
rectangles to merge them in an efficient way, to avoid overdraw.</P
></BLOCKQUOTE
></DIV
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><DIV
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><A
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><H2
>See Also</H2
><P
><A
HREF="sdlupdaterect.html"
><TT
CLASS="FUNCTION"
>SDL_UpdateRect</TT
></A
>,
<A
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><SPAN
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>SDL_Rect</SPAN
></A
>,
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HREF="sdlsurface.html"
><SPAN
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>SDL_Surface</SPAN
></A
>,
<A
HREF="sdllocksurface.html"
><TT
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>SDL_LockSurface</TT
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