forked from KolibriOS/kolibrios
311 lines
4.1 KiB
HTML
311 lines
4.1 KiB
HTML
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<HTML
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><HEAD
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><TITLE
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>SDL_SemTryWait</TITLE
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><META
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NAME="GENERATOR"
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CONTENT="Modular DocBook HTML Stylesheet Version 1.64
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"><LINK
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REL="HOME"
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TITLE="SDL Library Documentation"
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HREF="index.html"><LINK
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REL="UP"
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TITLE="Multi-threaded Programming"
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HREF="thread.html"><LINK
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REL="PREVIOUS"
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TITLE="SDL_SemWait"
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HREF="sdlsemwait.html"><LINK
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REL="NEXT"
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TITLE="SDL_SemWaitTimeout"
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HREF="sdlsemwaittimeout.html"></HEAD
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><BODY
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CLASS="REFENTRY"
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BGCOLOR="#FFF8DC"
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TEXT="#000000"
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LINK="#0000ee"
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VLINK="#551a8b"
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ALINK="#ff0000"
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><DIV
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CLASS="NAVHEADER"
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><TABLE
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WIDTH="100%"
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BORDER="0"
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CELLPADDING="0"
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CELLSPACING="0"
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><TR
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><TH
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COLSPAN="3"
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ALIGN="center"
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>SDL Library Documentation</TH
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></TR
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><TR
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><TD
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WIDTH="10%"
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ALIGN="left"
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VALIGN="bottom"
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><A
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HREF="sdlsemwait.html"
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>Prev</A
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></TD
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><TD
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WIDTH="80%"
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ALIGN="center"
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VALIGN="bottom"
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></TD
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><TD
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WIDTH="10%"
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ALIGN="right"
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VALIGN="bottom"
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><A
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HREF="sdlsemwaittimeout.html"
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>Next</A
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></TD
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></TR
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></TABLE
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><HR
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ALIGN="LEFT"
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WIDTH="100%"></DIV
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><H1
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><A
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NAME="SDLSEMTRYWAIT"
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>SDL_SemTryWait</A
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></H1
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><DIV
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CLASS="REFNAMEDIV"
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><A
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NAME="AEN7520"
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></A
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><H2
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>Name</H2
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>SDL_SemTryWait -- Attempt to lock a semaphore but don't suspend the thread.</DIV
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><DIV
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CLASS="REFSYNOPSISDIV"
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><A
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NAME="AEN7523"
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></A
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><H2
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>Synopsis</H2
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><DIV
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CLASS="FUNCSYNOPSIS"
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><A
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NAME="AEN7524"
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></A
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><P
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></P
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><PRE
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CLASS="FUNCSYNOPSISINFO"
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>#include "SDL.h"
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#include "SDL_thread.h"</PRE
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><P
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><CODE
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><CODE
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CLASS="FUNCDEF"
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>int <B
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CLASS="FSFUNC"
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>SDL_SemTryWait</B
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></CODE
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>(SDL_sem *sem);</CODE
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></P
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><P
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></P
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></DIV
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></DIV
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><DIV
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CLASS="REFSECT1"
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><A
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NAME="AEN7530"
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></A
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><H2
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>Description</H2
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><P
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><TT
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CLASS="FUNCTION"
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>SDL_SemTryWait</TT
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> is a non-blocking varient of
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<A
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HREF="sdlsemwait.html"
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><TT
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CLASS="FUNCTION"
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>SDL_SemWait</TT
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></A
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>. If the value of the semaphore
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pointed to by <TT
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CLASS="PARAMETER"
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><I
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>sem</I
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></TT
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> is positive it will atomically
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decrement the semaphore value and return 0, otherwise it will return
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<SPAN
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CLASS="RETURNVALUE"
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>SDL_MUTEX_TIMEOUT</SPAN
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> instead of suspending the thread.</P
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><P
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>After <TT
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CLASS="FUNCTION"
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>SDL_SemTryWait</TT
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> is successful, the semaphore
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can be released and its count atomically incremented by a successful call to
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<A
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HREF="sdlsempost.html"
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>SDL_SemPost</A
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>.</P
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></DIV
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><DIV
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CLASS="REFSECT1"
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><A
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NAME="AEN7541"
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></A
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><H2
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>Return Value</H2
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><P
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>Returns <SPAN
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CLASS="RETURNVALUE"
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>0</SPAN
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> if the semaphore was successfully locked or
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either <SPAN
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CLASS="RETURNVALUE"
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>SDL_MUTEX_TIMEOUT</SPAN
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> or <SPAN
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CLASS="RETURNVALUE"
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>-1</SPAN
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>
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if the thread would have suspended or there was an error, respectivly.</P
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><P
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>If the semaphore was not successfully locked, the semaphore will be unchanged.</P
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></DIV
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><DIV
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CLASS="REFSECT1"
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><A
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NAME="AEN7548"
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></A
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><H2
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>Examples</H2
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><P
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><PRE
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CLASS="PROGRAMLISTING"
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>res = SDL_SemTryWait(my_sem);
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if (res == SDL_MUTEX_TIMEOUT) {
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return TRY_AGAIN;
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}
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if (res == -1) {
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return WAIT_ERROR;
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}
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...
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SDL_SemPost(my_sem);</PRE
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></P
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></DIV
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><DIV
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CLASS="REFSECT1"
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><A
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NAME="AEN7552"
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></A
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><H2
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>See Also</H2
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><P
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><A
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HREF="sdlcreatesemaphore.html"
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><TT
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CLASS="FUNCTION"
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>SDL_CreateSemaphore</TT
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></A
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>,
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<A
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HREF="sdldestroysemaphore.html"
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><TT
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CLASS="FUNCTION"
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>SDL_DestroySemaphore</TT
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></A
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>,
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<A
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HREF="sdlsemwait.html"
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><TT
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CLASS="FUNCTION"
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>SDL_SemWait</TT
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></A
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>,
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<A
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HREF="sdlsemwaittimeout.html"
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><TT
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CLASS="FUNCTION"
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>SDL_SemWaitTimeout</TT
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></A
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>,
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<A
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HREF="sdlsempost.html"
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><TT
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CLASS="FUNCTION"
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>SDL_SemPost</TT
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></A
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>,
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<A
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HREF="sdlsemvalue.html"
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><TT
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CLASS="FUNCTION"
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>SDL_SemValue</TT
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></A
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></P
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></DIV
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><DIV
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CLASS="NAVFOOTER"
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><HR
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ALIGN="LEFT"
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WIDTH="100%"><TABLE
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WIDTH="100%"
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BORDER="0"
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CELLPADDING="0"
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CELLSPACING="0"
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><TR
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><TD
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WIDTH="33%"
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ALIGN="left"
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VALIGN="top"
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><A
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HREF="sdlsemwait.html"
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>Prev</A
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></TD
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><TD
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WIDTH="34%"
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ALIGN="center"
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VALIGN="top"
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><A
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HREF="index.html"
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>Home</A
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></TD
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><TD
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WIDTH="33%"
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ALIGN="right"
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VALIGN="top"
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><A
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HREF="sdlsemwaittimeout.html"
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>Next</A
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></TD
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></TR
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><TR
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><TD
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WIDTH="33%"
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ALIGN="left"
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VALIGN="top"
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>SDL_SemWait</TD
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><TD
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WIDTH="34%"
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ALIGN="center"
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VALIGN="top"
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><A
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HREF="thread.html"
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>Up</A
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></TD
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><TD
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WIDTH="33%"
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ALIGN="right"
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VALIGN="top"
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>SDL_SemWaitTimeout</TD
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></TR
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></TABLE
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></DIV
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></BODY
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></HTML
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>
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