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Fixed bug #15 SDL_blit_A.mmx-speed.patch.txt -- Speed improvements and a bugfix for the current GCC inline mmx asm code: - Changed some ops and removed some resulting useless ones. - Added some instruction parallelism (some gain) The resulting speed on my Xeon improved upto 35% depending on the function (measured in fps). - Fixed a bug where BlitRGBtoRGBSurfaceAlphaMMX() was setting the alpha component on the destination surfaces (to opaque-alpha) even when the surface had none. SDL_blit_A.mmx-msvc.patch.txt -- MSVC mmx intrinsics version of the same GCC asm code. MSVC compiler tries to parallelize the code and to avoid register stalls, but does not always do a very good job. Per-surface blending MSVC functions run quite a bit faster than their pure-asm counterparts (upto 55% faster for 16bit ones), but the per-pixel blending runs somewhat slower than asm. - BlitRGBtoRGBSurfaceAlphaMMX and BlitRGBtoRGBPixelAlphaMMX (and all variants) can now also handle formats other than (A)RGB8888. Formats like RGBA8888 and some quite exotic ones are allowed -- like RAGB8888, or actually anything having channels aligned on 8bit boundary and full 8bit alpha (for per-pixel alpha blending). The performance cost of this change is virtually 0 for per-surface alpha blending (no extra ops inside the loop) and a single non-MMX op inside the loop for per-pixel blending. In testing, the per-pixel alpha blending takes a ~2% performance hit, but it still runs much faster than the current code in CVS. If necessary, a separate function with this functionality can be made. This code requires Processor Pack for VC6.
author Sam Lantinga <slouken@libsdl.org>
date Wed, 15 Mar 2006 15:39:29 +0000
parents 355632dca928
children
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<HTML
><HEAD
><TITLE
>SDL_Flip</TITLE
><META
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><H1
><A
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></A
>SDL_Flip</H1
><DIV
CLASS="REFNAMEDIV"
><A
NAME="AEN1426"
></A
><H2
>Name</H2
>SDL_Flip&nbsp;--&nbsp;Swaps screen buffers</DIV
><DIV
CLASS="REFSYNOPSISDIV"
><A
NAME="AEN1429"
></A
><H2
>Synopsis</H2
><DIV
CLASS="FUNCSYNOPSIS"
><A
NAME="AEN1430"
></A
><P
></P
><PRE
CLASS="FUNCSYNOPSISINFO"
>#include "SDL.h"</PRE
><P
><CODE
><CODE
CLASS="FUNCDEF"
>int <B
CLASS="FSFUNC"
>SDL_Flip</B
></CODE
>(SDL_Surface *screen);</CODE
></P
><P
></P
></DIV
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN1436"
></A
><H2
>Description</H2
><P
>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 <A
HREF="sdlupdaterect.html"
>SDL_UpdateRect</A
><TT
CLASS="PARAMETER"
><I
>(screen, 0, 0, 0, 0)</I
></TT
></P
><P
>The <TT
CLASS="LITERAL"
>SDL_DOUBLEBUF</TT
> flag must have been passed to 
<A
HREF="sdlsetvideomode.html"
>SDL_SetVideoMode</A
>,
 when
setting the video mode for this function to perform hardware flipping.</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN1444"
></A
><H2
>Return Value</H2
><P
>This function returns <SPAN
CLASS="RETURNVALUE"
>0</SPAN
> if successful, or 
<SPAN
CLASS="RETURNVALUE"
>-1</SPAN
> if there was an error.</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN1449"
></A
><H2
>See Also</H2
><P
><A
HREF="sdlsetvideomode.html"
><TT
CLASS="FUNCTION"
>SDL_SetVideoMode</TT
></A
>,
<A
HREF="sdlupdaterect.html"
><TT
CLASS="FUNCTION"
>SDL_UpdateRect</TT
></A
>,
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HREF="sdlsurface.html"
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>SDL_Surface</SPAN
></A
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