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| NAME="SDLSEMWAITTIMEOUT" |
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| >SDL_SemWaitTimeout</H1 |
| ><DIV |
| CLASS="REFNAMEDIV" |
| ><A |
| NAME="AEN8120" |
| ></A |
| ><H2 |
| >Name</H2 |
| >SDL_SemWaitTimeout -- Lock a semaphore, but only wait up to a specified maximum time.</DIV |
| ><DIV |
| CLASS="REFSYNOPSISDIV" |
| ><A |
| NAME="AEN8123" |
| ></A |
| ><H2 |
| >Synopsis</H2 |
| ><DIV |
| CLASS="FUNCSYNOPSIS" |
| ><A |
| NAME="AEN8124" |
| ></A |
| ><P |
| ></P |
| ><PRE |
| CLASS="FUNCSYNOPSISINFO" |
| >#include "SDL.h" |
| #include "SDL_thread.h"</PRE |
| ><P |
| ><CODE |
| ><CODE |
| CLASS="FUNCDEF" |
| >int <B |
| CLASS="FSFUNC" |
| >SDL_SemWaitTimeout</B |
| ></CODE |
| >(SDL_sem *sem, Uint32 timeout);</CODE |
| ></P |
| ><P |
| ></P |
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| ></DIV |
| ><DIV |
| CLASS="REFSECT1" |
| ><A |
| NAME="AEN8130" |
| ></A |
| ><H2 |
| >Description</H2 |
| ><P |
| ><TT |
| CLASS="FUNCTION" |
| >SDL_SemWaitTimeout()</TT |
| > is a varient of |
| <A |
| HREF="sdlsemwait.html" |
| >SDL_SemWait</A |
| > |
| with a maximum timeout value. |
| If the value of the semaphore pointed to by <TT |
| CLASS="PARAMETER" |
| ><I |
| >sem</I |
| ></TT |
| > is |
| positive (greater than zero) it will atomically decrement the semaphore value |
| and return 0, otherwise it will wait up to <TT |
| CLASS="PARAMETER" |
| ><I |
| >timeout</I |
| ></TT |
| > |
| milliseconds trying to lock the semaphore. This function is to be avoided if |
| possible since on some platforms it is implemented by polling the semaphore |
| every millisecond in a busy loop.</P |
| ><P |
| >After <TT |
| CLASS="FUNCTION" |
| >SDL_SemWaitTimeout()</TT |
| > is successful, the semaphore |
| can be released and its count atomically incremented by a successful call to |
| <A |
| HREF="sdlsempost.html" |
| >SDL_SemPost</A |
| >.</P |
| ></DIV |
| ><DIV |
| CLASS="REFSECT1" |
| ><A |
| NAME="AEN8140" |
| ></A |
| ><H2 |
| >Return Value</H2 |
| ><P |
| >Returns <SPAN |
| CLASS="RETURNVALUE" |
| >0</SPAN |
| > if the semaphore was successfully locked or |
| either <SPAN |
| CLASS="RETURNVALUE" |
| >SDL_MUTEX_TIMEDOUT</SPAN |
| > or <SPAN |
| CLASS="RETURNVALUE" |
| >-1</SPAN |
| > |
| if the timeout period was exceeded or there was an error, respectivly.</P |
| ><P |
| >If the semaphore was not successfully locked, the semaphore will be unchanged.</P |
| ></DIV |
| ><DIV |
| CLASS="REFSECT1" |
| ><A |
| NAME="AEN8147" |
| ></A |
| ><H2 |
| >Examples</H2 |
| ><P |
| ><PRE |
| CLASS="PROGRAMLISTING" |
| >res = SDL_SemWaitTimeout(my_sem, WAIT_TIMEOUT_MILLISEC); |
| |
| if (res == SDL_MUTEX_TIMEDOUT) { |
| return TRY_AGAIN; |
| } |
| if (res == -1) { |
| return WAIT_ERROR; |
| } |
| |
| ... |
| |
| SDL_SemPost(my_sem);</PRE |
| ></P |
| ></DIV |
| ><DIV |
| CLASS="REFSECT1" |
| ><A |
| NAME="AEN8151" |
| ></A |
| ><H2 |
| >See Also</H2 |
| ><P |
| ><A |
| HREF="sdlcreatesemaphore.html" |
| ><TT |
| CLASS="FUNCTION" |
| >SDL_CreateSemaphore</TT |
| ></A |
| >, |
| <A |
| HREF="sdldestroysemaphore.html" |
| ><TT |
| CLASS="FUNCTION" |
| >SDL_DestroySemaphore</TT |
| ></A |
| >, |
| <A |
| HREF="sdlsemwait.html" |
| ><TT |
| CLASS="FUNCTION" |
| >SDL_SemWait</TT |
| ></A |
| >, |
| <A |
| HREF="sdlsemtrywait.html" |
| ><TT |
| CLASS="FUNCTION" |
| >SDL_SemTryWait</TT |
| ></A |
| >, |
| <A |
| HREF="sdlsempost.html" |
| ><TT |
| CLASS="FUNCTION" |
| >SDL_SemPost</TT |
| ></A |
| >, |
| <A |
| HREF="sdlsemvalue.html" |
| ><TT |
| CLASS="FUNCTION" |
| >SDL_SemValue</TT |
| ></A |
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