view docs/man3/SDL_SemTryWait.3 @ 1258:b2283b0ded26

Date: Thu, 19 Jan 2006 20:02:29 +0200 From: Vassilis Virvilis <vasvir@iit.demokritos.gr> Subject: [SDL] Request: Please reconsider adding tag in SDL_Event Hi, Patch in question: --- include/SDL_events.h 20 Aug 2004 18:57:01 -0000 1.11 +++ include/SDL_events.h 19 Jan 2006 17:35:09 -0000 @@ -214,7 +214,7 @@ } SDL_SysWMEvent; /* General event structure */ -typedef union { +typedef union SDL_Event { Uint8 type; SDL_ActiveEvent active; SDL_KeyboardEvent key; Reasoning: ---------- 1) Allows forward declaration of the SDL_Event union in C++. Please note that in plain C it is possible to forward declare it. 2) Forward declaration is good because it allows encapsulation. It hides the specific implementation and does not necessarily exposes SDL staff to my appication's namespace 3) It can't harm plain C because tags are living in a different namespace than typenames 4) It is already done like this in other places in SDL. Check for example SDL_KeySym, and SDL_.*Event structures. 5) Right now I have to include SDL/event.h from a C++ header file. See 2)
author Sam Lantinga <slouken@libsdl.org>
date Fri, 20 Jan 2006 13:07:25 +0000 (2006-01-20)
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