Mercurial > sdl-ios-xcode
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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 | f02e673ffc5f |
children | f12379c41042 |
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Wish list for the 1.3 development branch: http://bugzilla.libsdl.org/ * Add mousewheel events (new unified event architecture?) * DirectInput joystick support needs to be implemented * Be able to enumerate and select available audio and video drivers * Fullscreen video mode support for MacOS X * Explicit vertical retrace wait (maybe separate from SDL_Flip?) * Shaped windows, windows without borders * Multiple windows, multiple display support * SDL_INIT_EVENTTHREAD on Windows and MacOS? * Add a timestamp to events * Add audio input API * Add hardware accelerated scaled blit * Add hardware accelerated alpha blits * Redesign blitting architecture to allow blit plugins In the jump from 1.2 to 1.3, we should change the SDL_Rect members to int and evaluate all the rest of the datatypes. This is the only place we should do it though, since the 1.2 series should not break binary compatibility in this way. Requests: * PCM and CDROM volume control (deprecated, but possible)