Mercurial > sdl-ios-xcode
view docs/man3/SDL_CD.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 |
parents | e5bc29de3f0a |
children | 546f7c1eb755 |
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.TH "SDL_CD" "3" "Tue 11 Sep 2001, 22:58" "SDL" "SDL API Reference" .SH "NAME" SDL_CD\- CDROM Drive Information .SH "STRUCTURE DEFINITION" .PP .nf \f(CWtypedef struct{ int id; CDstatus status; int numtracks; int cur_track; int cur_frame; SDL_CDtrack track[SDL_MAX_TRACKS+1]; } SDL_CD;\fR .fi .PP .SH "STRUCTURE DATA" .TP 20 \fBid\fR Private drive identifier .TP 20 \fBstatus\fR Drive \fIstatus\fR .TP 20 \fBnumtracks\fR Number of tracks on the CD .TP 20 \fBcur_track\fR Current track .TP 20 \fBcur_frame\fR Current frame offset within the track .TP 20 \fBtrack\fR[SDL_MAX_TRACKS+1] Array of track descriptions\&. (see \fI\fBSDL_CDtrack\fR\fR) .SH "DESCRIPTION" .PP An \fBSDL_CD\fR structure is returned by \fI\fBSDL_CDOpen\fP\fR\&. It represents an opened CDROM device and stores information on the layout of the tracks on the disc\&. .PP A frame is the base data unit of a CD\&. \fBCD_FPS\fP frames is equal to 1 second of music\&. SDL provides two macros for converting between time and frames: \fBFRAMES_TO_MSF(f, M,S,F)\fP and \fBMSF_TO_FRAMES\fP\&. .SH "EXAMPLES" .PP .nf \f(CWint min, sec, frame; int frame_offset; FRAMES_TO_MSF(cdrom->cur_frame, &min, &sec, &frame); printf("Current Position: %d minutes, %d seconds, %d frames ", min, sec, frame); frame_offset=MSF_TO_FRAMES(min, sec, frame);\fR .fi .PP .SH "SEE ALSO" .PP \fI\fBSDL_CDOpen\fP\fR, \fI\fBSDL_CDtrack\fR\fR ...\" created by instant / docbook-to-man, Tue 11 Sep 2001, 22:58