Mercurial > sdl-ios-xcode
view docs/man3/SDL_JoystickOpen.3 @ 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 | e5bc29de3f0a |
children | 546f7c1eb755 |
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.TH "SDL_JoystickOpen" "3" "Tue 11 Sep 2001, 23:00" "SDL" "SDL API Reference" .SH "NAME" SDL_JoystickOpen\- Opens a joystick for use\&. .SH "SYNOPSIS" .PP \fB#include "SDL\&.h" .sp \fBSDL_Joystick *\fBSDL_JoystickOpen\fP\fR(\fBint index\fR); .SH "DESCRIPTION" .PP Opens a joystick for use within SDL\&. The \fBindex\fR refers to the N\&'th joystick in the system\&. A joystick must be opened before it game be used\&. .SH "RETURN VALUE" .PP Returns a \fBSDL_Joystick\fR structure on success\&. \fBNULL\fR on failure\&. .SH "EXAMPLES" .PP .PP .nf \f(CWSDL_Joystick *joy; // Check for joystick if(SDL_NumJoysticks()>0){ // Open joystick joy=SDL_JoystickOpen(0); if(joy) { printf("Opened Joystick 0 "); printf("Name: %s ", SDL_JoystickName(0)); printf("Number of Axes: %d ", SDL_JoystickNumAxes(joy)); printf("Number of Buttons: %d ", SDL_JoystickNumButtons(joy)); printf("Number of Balls: %d ", SDL_JoystickNumBalls(joy)); } else printf("Couldn\&'t open Joystick 0 "); // Close if opened if(SDL_JoystickOpened(0)) SDL_JoystickClose(joy); }\fR .fi .PP .SH "SEE ALSO" .PP \fI\fBSDL_JoystickClose\fP\fR ...\" created by instant / docbook-to-man, Tue 11 Sep 2001, 23:00