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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 |