| e14743d1 |
1 | .TH "SDL_SemTryWait" "3" "Tue 11 Sep 2001, 23:00" "SDL" "SDL API Reference" |
| 2 | .SH "NAME" |
| 3 | SDL_SemTryWait \- Attempt to lock a semaphore but don\&'t suspend the thread\&. |
| 4 | .SH "SYNOPSIS" |
| 5 | .PP |
| 6 | \fB#include "SDL\&.h" |
| 7 | #include "SDL_thread\&.h" |
| 8 | .sp |
| 9 | \fBint \fBSDL_SemTryWait\fP\fR(\fBSDL_sem *sem\fR); |
| 10 | .SH "DESCRIPTION" |
| 11 | .PP |
| 12 | \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\&. |
| 13 | .PP |
| 14 | After \fBSDL_SemTryWait\fP is successful, the semaphore can be released and its count atomically incremented by a successful call to \fISDL_SemPost\fR\&. |
| 15 | .SH "RETURN VALUE" |
| 16 | .PP |
| 17 | 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\&. |
| 18 | .PP |
| 19 | If the semaphore was not successfully locked, the semaphore will be unchanged\&. |
| 20 | .SH "EXAMPLES" |
| 21 | .PP |
| 22 | .PP |
| 23 | .nf |
| 24 | \f(CWres = SDL_SemTryWait(my_sem); |
| 25 | |
| 26 | if (res == SDL_MUTEX_TIMEOUT) { |
| 27 | return TRY_AGAIN; |
| 28 | } |
| 29 | if (res == -1) { |
| 30 | return WAIT_ERROR; |
| 31 | } |
| 32 | |
| 33 | \&.\&.\&. |
| 34 | |
| 35 | SDL_SemPost(my_sem);\fR |
| 36 | .fi |
| 37 | .PP |
| 38 | .SH "SEE ALSO" |
| 39 | .PP |
| 40 | \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 |
| 41 | .\" created by instant / docbook-to-man, Tue 11 Sep 2001, 23:00 |
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