.TH "SDL_SemWait" "3" "Tue 11 Sep 2001, 23:00" "SDL" "SDL API Reference" 

.SH "NAME"

SDL_SemWait \- Lock a semaphore and suspend the thread if the semaphore value is zero\&.

.SH "SYNOPSIS"

.PP

\fB#include "SDL\&.h"

#include "SDL_thread\&.h"

.sp

\fBint \fBSDL_SemWait\fP\fR(\fBSDL_sem *sem\fR);

.SH "DESCRIPTION"

.PP

\fBSDL_SemWait()\fP suspends the calling thread until either the semaphore pointed to by \fBsem\fR has a positive value, the call is interrupted by a signal or error\&. If the call is successful it will atomically decrement the semaphore value\&.

.PP

After \fBSDL_SemWait()\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 successful or \fB-1\fR if there was an error (leaving the semaphore unchanged)\&.

.SH "EXAMPLES"

.PP

.PP

.nf

\f(CWif (SDL_SemWait(my_sem) == -1) {

        return WAIT_FAILED;

}

\&.\&.\&.

SDL_SemPost(my_sem);\fR

.fi

.PP

.SH "SEE ALSO"

.PP

\fI\fBSDL_CreateSemaphore\fP\fR, \fI\fBSDL_DestroySemaphore\fP\fR, \fI\fBSDL_SemTryWait\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