view docs/man3/SDL_SemTryWait.3 @ 1438:1f4f09641645

Date: Sun, 26 Feb 2006 11:25:09 +0900 From: Hayashi Naoyuki Subject: Re: [SDL] CVS stable again, please update SDL ports Some problems are caused on Tru64 UNIX. If applying SDL12-osf1.path, these problems are fixed. 1. configure-script say "recursive mutexes... no" and "pthread semaphores... no". checking for pthreads... yes checking for recursive mutexes... no checking for pthread semaphores... no This is because it compiled without pthread_cflags and pthread_lib when checking recursive mutexes and pthread semaphores. 2. Compiling src/audio/mme/SDL_mmeaudio.c fails. cc: Severe: ./src/audio/mme/SDL_mmeaudio.c, line 25: Cannot find file <mme_api.h> specified in #include directive. (noinclfilef) #include <mme_api.h> -^ This is because BUILD_CFLAGS is wrong. 3. Compiling src/cdrom/osf/SDL_syscdrom.c fails. cc: Warning: ./src/cdrom/osf/SDL_syscdrom.c, line 176: Too few actual parameters in the invocation of the macro "SDL_stack_alloc". (toofewactuals) cdpath = SDL_stack_alloc(len); ------------------------------------^ cc: Error: ./src/cdrom/osf/SDL_syscdrom.c, line 176: Invalid expression. (badexpr) cdpath = SDL_stack_alloc(len); -----------------^ SDL_stack_alloc is defined in include/SDL_stdinc.h. #define SDL_stack_alloc(type, count) (type*)alloca(sizeof(type)*count) 4. Linking fails if running configure with --enable-x11-shared=yes. /usr/ccs/bin/ld: Warning: Unresolved: p_XData32 5. Compiling src/video/x11/SDL_x11dyn.c fails if running configure with --enable-x11-shared=no. cc: Error: ./src/video/x11/SDL_x11sym.h, line 149: In this statement, "_SmtBufferOverflow" is not declared. (undeclared) SDL_X11_SYM(1,void,_SmtBufferOverflow,(Display *dpy,register smtDisplayPtr)) ^ cc: Error: ./src/video/x11/SDL_x11sym.h, line 150: In this statement, "_SmtBufferOverflow" is not declared. (undeclared) SDL_X11_SYM(1,void,_SmtBufferOverflow,(Display *dpy,register smtDisplayPtr)) ^ cc: Error: ./src/video/x11/SDL_x11sym.h, line 150: In this statement, "_SmtIpError" is not declared. (undeclared) SDL_X11_SYM(1,void,_SmtIpError,(Display *dpy,register smtDisplayPtr, int)) ^
author Sam Lantinga <slouken@libsdl.org>
date Sun, 26 Feb 2006 04:54:01 +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