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view docs/html/sdljoystickopen.html @ 1542:a8bf1aa21020
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_JoystickOpen</TITLE ><META NAME="GENERATOR" CONTENT="Modular DocBook HTML Stylesheet Version 1.76b+ "><LINK REL="HOME" TITLE="SDL Library Documentation" HREF="index.html"><LINK REL="UP" TITLE="Joystick" HREF="joystick.html"><LINK REL="PREVIOUS" TITLE="SDL_JoystickName" HREF="sdljoystickname.html"><LINK REL="NEXT" TITLE="SDL_JoystickOpened" HREF="sdljoystickopened.html"></HEAD ><BODY CLASS="REFENTRY" BGCOLOR="#FFF8DC" TEXT="#000000" LINK="#0000ee" VLINK="#551a8b" ALINK="#ff0000" ><DIV CLASS="NAVHEADER" ><TABLE SUMMARY="Header navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TH COLSPAN="3" ALIGN="center" >SDL Library Documentation</TH ></TR ><TR ><TD WIDTH="10%" ALIGN="left" VALIGN="bottom" ><A HREF="sdljoystickname.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="80%" ALIGN="center" VALIGN="bottom" ></TD ><TD WIDTH="10%" ALIGN="right" VALIGN="bottom" ><A HREF="sdljoystickopened.html" ACCESSKEY="N" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><H1 ><A NAME="SDLJOYSTICKOPEN" ></A >SDL_JoystickOpen</H1 ><DIV CLASS="REFNAMEDIV" ><A NAME="AEN6096" ></A ><H2 >Name</H2 >SDL_JoystickOpen -- Opens a joystick for use.</DIV ><DIV CLASS="REFSYNOPSISDIV" ><A NAME="AEN6099" ></A ><H2 >Synopsis</H2 ><DIV CLASS="FUNCSYNOPSIS" ><A NAME="AEN6100" ></A ><P ></P ><PRE CLASS="FUNCSYNOPSISINFO" >#include "SDL.h"</PRE ><P ><CODE ><CODE CLASS="FUNCDEF" >SDL_Joystick *<B CLASS="FSFUNC" >SDL_JoystickOpen</B ></CODE >(int index);</CODE ></P ><P ></P ></DIV ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN6106" ></A ><H2 >Description</H2 ><P >Opens a joystick for use within SDL. The <TT CLASS="PARAMETER" ><I >index</I ></TT > refers to the N'th joystick in the system. A joystick must be opened before it game be used.</P ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN6110" ></A ><H2 >Return Value</H2 ><P >Returns a <SPAN CLASS="STRUCTNAME" >SDL_Joystick</SPAN > structure on success. <SPAN CLASS="RETURNVALUE" >NULL</SPAN > on failure.</P ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN6115" ></A ><H2 >Examples</H2 ><P ><PRE CLASS="PROGRAMLISTING" >SDL_Joystick *joy; // Check for joystick if(SDL_NumJoysticks()>0){ // Open joystick joy=SDL_JoystickOpen(0); if(joy) { printf("Opened Joystick 0\n"); printf("Name: %s\n", SDL_JoystickName(0)); printf("Number of Axes: %d\n", SDL_JoystickNumAxes(joy)); printf("Number of Buttons: %d\n", SDL_JoystickNumButtons(joy)); printf("Number of Balls: %d\n", SDL_JoystickNumBalls(joy)); } else printf("Couldn't open Joystick 0\n"); // Close if opened if(SDL_JoystickOpened(0)) SDL_JoystickClose(joy); }</PRE ></P ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN6119" ></A ><H2 >See Also</H2 ><P ><A HREF="sdljoystickclose.html" ><TT CLASS="FUNCTION" >SDL_JoystickClose</TT ></A ></P ></DIV ><DIV CLASS="NAVFOOTER" ><HR ALIGN="LEFT" WIDTH="100%"><TABLE SUMMARY="Footer navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" ><A HREF="sdljoystickname.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="index.html" ACCESSKEY="H" >Home</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" ><A HREF="sdljoystickopened.html" ACCESSKEY="N" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >SDL_JoystickName</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="joystick.html" ACCESSKEY="U" >Up</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >SDL_JoystickOpened</TD ></TR ></TABLE ></DIV ></BODY ></HTML >