Mercurial > sdl-ios-xcode

view docs/man3/SDL_SemTryWait.3 @ 937:1e6366bde299

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
Date: Tue, 27 Jul 2004 17:14:00 +0200 From: "Eckhard Stolberg" Subject: Controller names in SDL for Windows I'm working on an Atari 2600 emulator for different systems that uses the SDL. Some time ago someone created an adaptor that lets you use your old Atari controllers with your computer through the USB port. Some of the Atari controllers require special handling by the emulator, so it would be nice, if it would be possible to detect if any of the controllers connected to the computer is this adaptor. SDL would allow that with the SDL_JoystickName function, but unfortunately it doesn't work properly on Windows. On Linux and MacOSX this function returns the name of the controller, but on Windows you'll only get the name of the joystick driver. Most joysticks nowadays use the generic Microsoft driver, so they all return the same name. In an old MSDN article (http://msdn.microsoft.com/archive/default.asp?url=/archive/en-us/dnarinput/html/msdn_extdirect.asp) Microsoft describes how to read out the OEM controller names from the registry. I have implemented this for the SDL controller handler on Windows, and now reading the joystick name works properly there too.
author Sam Lantinga <slouken@libsdl.org>
date Sat, 21 Aug 2004 03:45:58 +0000
parents e5bc29de3f0a
children 546f7c1eb755
line wrap: on
line source

.TH "SDL_SemTryWait" "3" "Tue 11 Sep 2001, 23:00" "SDL" "SDL API Reference" 
.SH "NAME"
SDL_SemTryWait\- Attempt to lock a semaphore but don\&'t suspend the thread\&.
.SH "SYNOPSIS"
.PP
\fB#include "SDL\&.h"
#include "SDL_thread\&.h"
.sp
\fBint \fBSDL_SemTryWait\fP\fR(\fBSDL_sem *sem\fR);
.SH "DESCRIPTION"
.PP
\fBSDL_SemTryWait\fP is a non-blocking varient of \fI\fBSDL_SemWait\fP\fR\&. If the value of the semaphore pointed to by \fBsem\fR is positive it will atomically decrement the semaphore value and return 0, otherwise it will return \fBSDL_MUTEX_TIMEOUT\fR instead of suspending the thread\&.
.PP
After \fBSDL_SemTryWait\fP is successful, the semaphore can be released and its count atomically incremented by a successful call to \fISDL_SemPost\fR\&.
.SH "RETURN VALUE"
.PP
Returns \fB0\fR if the semaphore was successfully locked or either \fBSDL_MUTEX_TIMEOUT\fR or \fB-1\fR if the thread would have suspended or there was an error, respectivly\&.
.PP
If the semaphore was not successfully locked, the semaphore will be unchanged\&.
.SH "EXAMPLES"
.PP
.PP
.nf
\f(CWres = SDL_SemTryWait(my_sem);

if (res == SDL_MUTEX_TIMEOUT) {
        return TRY_AGAIN;
}
if (res == -1) {
        return WAIT_ERROR;
}

\&.\&.\&.

SDL_SemPost(my_sem);\fR
.fi
.PP
.SH "SEE ALSO"
.PP
\fI\fBSDL_CreateSemaphore\fP\fR, \fI\fBSDL_DestroySemaphore\fP\fR, \fI\fBSDL_SemWait\fP\fR, \fI\fBSDL_SemWaitTimeout\fP\fR, \fI\fBSDL_SemPost\fP\fR, \fI\fBSDL_SemValue\fP\fR
...\" created by instant / docbook-to-man, Tue 11 Sep 2001, 23:00