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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_Color</TITLE
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><H1
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>SDL_Color</H1
><DIV
CLASS="REFNAMEDIV"
><A
NAME="AEN3082"
></A
><H2
>Name</H2
>SDL_Color&nbsp;--&nbsp;Format independent color description</DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN3085"
></A
><H2
>Structure Definition</H2
><PRE
CLASS="PROGRAMLISTING"
>typedef struct{
  Uint8 r;
  Uint8 g;
  Uint8 b;
  Uint8 unused;
} SDL_Color;</PRE
></DIV
><DIV
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>Structure Data</H2
><DIV
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><TABLE
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><TT
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><I
>r</I
></TT
></TD
><TD
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>Red intensity</TD
></TR
><TR
><TD
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><TT
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><I
>g</I
></TT
></TD
><TD
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>Green intensity</TD
></TR
><TR
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><TT
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><I
>b</I
></TT
></TD
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>Blue intensity</TD
></TR
><TR
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><TT
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><I
>unused</I
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></TD
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>Unused</TD
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><P
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><H2
>Description</H2
><P
><SPAN
CLASS="STRUCTNAME"
>SDL_Color</SPAN
> describes a color in a format independent way. You can convert a <SPAN
CLASS="STRUCTNAME"
>SDL_Color</SPAN
> to a pixel value for a certain pixel format using <A
HREF="sdlmaprgb.html"
><TT
CLASS="FUNCTION"
>SDL_MapRGB</TT
></A
>.</P
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><H2
>See Also</H2
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><SPAN
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>SDL_PixelFormat</SPAN
></A
>,
<A
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><TT
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>SDL_SetColors</TT
></A
>,
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><TT
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>SDL_Palette</TT
></A
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