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Date: Sat, 15 Jan 2005 02:01:51 +0000 (UTC) From: jimrandomh Subject: [SDL] Re: Modifier keys pressed during initialization stick I wrote a simple test program which initializes SDL, prints the SDL version number, then prints any keydown and keyup events with their modifiers. (Source code below). Compilation was done using Visual Studio 6, release mode. My test sequence was: Start a command prompt. Type the name of the test program. shift down enter down (program starts) Wait for window to appear enter up shift up spacebar down spacebar up Under Windows 98, the output was correct: SDL 1.2.8 left shift down shift-return down shift-return up left shift up space down space up Under Windows 2000 and under Windows XP, the output was: SDL 1.2.8 shift-space down shift-space up Since shift was not held at the time space was pressed, this is incorrect. Similar results were observed with launching in different ways (including double-clicking in Windows Explorer), so it does not depend on the launching terminal.
author Sam Lantinga <slouken@libsdl.org>
date Sun, 29 Jan 2006 07:57:13 +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