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view docs/man3/SDL_ListModes.3 @ 1544:ab1e4c41ab71
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 (2006-03-15) |
parents | e5bc29de3f0a |
children | 546f7c1eb755 |
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.TH "SDL_ListModes" "3" "Tue 11 Sep 2001, 23:01" "SDL" "SDL API Reference" .SH "NAME" SDL_ListModes\- Returns a pointer to an array of available screen dimensions for the given format and video flags .SH "SYNOPSIS" .PP \fB#include "SDL\&.h" .sp \fBSDL_Rect **\fBSDL_ListModes\fP\fR(\fBSDL_PixelFormat *format, Uint32 flags\fR); .SH "DESCRIPTION" .PP Return a pointer to an array of available screen dimensions for the given format and video flags, sorted largest to smallest\&. Returns \fBNULL\fP if there are no dimensions available for a particular format, or \fB-1\fR if any dimension is okay for the given format\&. .PP If \fBformat\fR is \fBNULL\fP, the mode list will be for the format returned by \fISDL_GetVideoInfo()\fR->\fBvfmt\fR\&. The \fBflag\fR parameter is an OR\&'d combination of \fIsurface\fR flags\&. The flags are the same as those used \fI\fBSDL_SetVideoMode\fP\fR and they play a strong role in deciding what modes are valid\&. For instance, if you pass \fBSDL_HWSURFACE\fP as a flag only modes that support hardware video surfaces will be returned\&. .SH "EXAMPLE" .PP .nf \f(CWSDL_Rect **modes; int i; \&. \&. \&. /* Get available fullscreen/hardware modes */ modes=SDL_ListModes(NULL, SDL_FULLSCREEN|SDL_HWSURFACE); /* Check is there are any modes available */ if(modes == (SDL_Rect **)0){ printf("No modes available! "); exit(-1); } /* Check if or resolution is restricted */ if(modes == (SDL_Rect **)-1){ printf("All resolutions available\&. "); } else{ /* Print valid modes */ printf("Available Modes "); for(i=0;modes[i];++i) printf(" %d x %d ", modes[i]->w, modes[i]->h); } \&. \&.\fR .fi .PP .SH "SEE ALSO" .PP \fI\fBSDL_SetVideoMode\fP\fR, \fI\fBSDL_GetVideoInfo\fP\fR, \fI\fBSDL_Rect\fR\fR, \fI\fBSDL_PixelFormat\fR\fR ...\" created by instant / docbook-to-man, Tue 11 Sep 2001, 23:01