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;

/* Test program to compare the compile-time version of SDL with the linked
   version of SDL
*/

#include <stdio.h>
#include <stdlib.h>

#include "SDL.h"

int main(int argc, char *argv[])
{
	SDL_version compiled;

	/* Initialize SDL */
	if ( SDL_Init(0) < 0 ) {
		fprintf(stderr, "Couldn't initialize SDL: %s\n",SDL_GetError());
		exit(1);
	}
#ifdef DEBUG
	fprintf(stderr, "SDL initialized\n");
#endif
#if SDL_VERSION_ATLEAST(1, 2, 0)
	printf("Compiled with SDL 1.2 or newer\n");
#else
	printf("Compiled with SDL older than 1.2\n");
#endif
	SDL_VERSION(&compiled);
	printf("Compiled version: %d.%d.%d\n",
			compiled.major, compiled.minor, compiled.patch);
	printf("Linked version: %d.%d.%d\n",
			SDL_Linked_Version()->major,
			SDL_Linked_Version()->minor,
			SDL_Linked_Version()->patch);
	SDL_Quit();
	return(0);
}