view docs/man3/SDL_GetKeyState.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
line wrap: on
line source

.TH "SDL_GetKeyState" "3" "Tue 11 Sep 2001, 22:59" "SDL" "SDL API Reference" 
.SH "NAME"
SDL_GetKeyState\- Get a snapshot of the current keyboard state
.SH "SYNOPSIS"
.PP
\fB#include "SDL\&.h"
.sp
\fBUint8 *\fBSDL_GetKeyState\fP\fR(\fBint *numkeys\fR);
.SH "DESCRIPTION"
.PP
Gets a snapshot of the current keyboard state\&. The current state is return as a pointer to an array, the size of this array is stored in \fBnumkeys\fR\&. The array is indexed by the \fI\fBSDLK_*\fP\fR symbols\&. A value of 1 means the key is pressed and a value of 0 means its not\&. The pointer returned is a pointer to an internal SDL array and should not be freed by the caller\&.
.PP
.RS
\fBNote:  
.PP
Use \fI\fBSDL_PumpEvents\fP\fR to update the state array\&.
.RE
.SH "EXAMPLE"
.PP
.PP
.nf
\f(CWUint8 *keystate = SDL_GetKeyState(NULL);
if ( keystate[SDLK_RETURN] ) printf("Return Key Pressed\&.
");\fR
.fi
.PP
.SH "SEE ALSO"
.PP
\fI\fBSDL Key Symbols\fP\fR, \fI\fBSDL_PumpEvents\fP\fR
...\" created by instant / docbook-to-man, Tue 11 Sep 2001, 22:59