Mercurial > sdl-ios-xcode
view docs/man3/SDL_Flip.3 @ 3899:081aecdb0911 SDL-1.2
From: Gabriel Gambetta
To: SDL Mailing List <sdl@libsdl.org>
Date: Fri, 17 Nov 2006 00:39:29 -0200
Subject: [SDL] Alpha blending bug - fixed?
It turns out mm5 never got the correct value. This failed :
[...]
"movd %1, %%mm5\n\t"
: : "m" (amask), "m" (sf->Ashift) );
mm5 got 0xFF000018 instead of 0x00000018. However I did this :
Uint32 ashift = sf->Ashift;
[...]
"movd %1, %%mm5\n\t"
: : "m" (amask), "m" (ashift) );
and everything worked fine.
The only thing I could find out was that ashift is 32-bit aligned but
sf->Ashift isn't:
printf("ashift %8X [%d]\n", &ashift, (int)(&ashift) % 4);
printf("sf->Ashift %8X [%d]\n", &sf->Ashift, (int)(&sf->Ashift) % 4);
ashift at BFF0E0C4 [0]
sf->Ashift at 08AFB9CD [1]
Could this be the problem? If it is, the fix is extremely trivial.
Should I submit a patch?
--Gabriel
| author | Ryan C. Gordon <icculus@icculus.org> |
|---|---|
| date | Tue, 21 Nov 2006 23:17:00 +0000 |
| parents | e5bc29de3f0a |
| children | 546f7c1eb755 |
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.TH "SDL_Flip" "3" "Tue 11 Sep 2001, 23:01" "SDL" "SDL API Reference" .SH "NAME" SDL_Flip\- Swaps screen buffers .SH "SYNOPSIS" .PP \fB#include "SDL\&.h" .sp \fBint \fBSDL_Flip\fP\fR(\fBSDL_Surface *screen\fR); .SH "DESCRIPTION" .PP On hardware that supports double-buffering, this function sets up a flip and returns\&. The hardware will wait for vertical retrace, and then swap video buffers before the next video surface blit or lock will return\&. On hardware that doesn\&'t support double-buffering, this is equivalent to calling \fISDL_UpdateRect\fR\fB(screen, 0, 0, 0, 0)\fR .PP The \fBSDL_DOUBLEBUF\fP flag must have been passed to \fISDL_SetVideoMode\fR, when setting the video mode for this function to perform hardware flipping\&. .SH "RETURN VALUE" .PP This function returns \fB0\fR if successful, or \fB-1\fR if there was an error\&. .SH "SEE ALSO" .PP \fI\fBSDL_SetVideoMode\fP\fR, \fI\fBSDL_UpdateRect\fP\fR, \fI\fBSDL_Surface\fR\fR ...\" created by instant / docbook-to-man, Tue 11 Sep 2001, 23:01