| .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 |
