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;

.TH "SDL_InitSubSystem" "3" "Tue 11 Sep 2001, 23:00" "SDL" "SDL API Reference" +
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.SH "NAME"+
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SDL_InitSubSystem\- Initialize subsystems+
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.SH "SYNOPSIS"+
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.PP+
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\fB#include "SDL\&.h"+
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.sp+
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\fBint \fBSDL_InitSubSystem\fP\fR(\fBUint32 flags\fR);+
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.SH "DESCRIPTION"+
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.PP+
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After SDL has been initialized with \fI\fBSDL_Init\fP\fR you may initialize uninitialized subsystems with \fBSDL_InitSubSystem\fP\&. The \fBflags\fR parameter is the same as that used in \fI\fBSDL_Init\fP\fR\&.+
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.SH "EXAMPLES"+
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.PP+
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.nf+
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\f(CW/* Seperating Joystick and Video initialization\&. */+
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SDL_Init(SDL_INIT_VIDEO);+
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\&.+
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\&.+
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SDL_SetVideoMode(640, 480, 16, SDL_DOUBLEBUF|SDL_FULLSCREEN);+
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\&.+
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/* Do Some Video stuff */+
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\&.+
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\&.+
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/* Initialize the joystick subsystem */+
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SDL_InitSubSystem(SDL_INIT_JOYSTICK);+
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+
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/* Do some stuff with video and joystick */+
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\&.+
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\&.+
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\&.+
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/* Shut them both down */+
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SDL_Quit();\fR+
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.fi+
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.PP+
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.SH "RETURN VALUE"+
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.PP+
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Returns \fB-1\fR on an error or \fB0\fR on success\&.+
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.SH "SEE ALSO"+
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.PP+
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\fI\fBSDL_Init\fP\fR, \fI\fBSDL_Quit\fP\fR, \fI\fBSDL_QuitSubSystem\fP\fR+
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...\" created by instant / docbook-to-man, Tue 11 Sep 2001, 23:00+
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