Mercurial > sdl-ios-xcode
view docs/html/sdlsemwait.html @ 2429:2c55b72ba46e gsoc2008_iphone
testdyngles is exactly what it sounds like -- a version of testdyngl that uses OpenGL ES calls instead of OpenGL. Was necessary to create because glOrtho is called glOrthof in OpenGL ES, and OpenGL ES doesn't have glBegin() type semantics for specifying geometry.
author | Holmes Futrell <hfutrell@umail.ucsb.edu> |
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date | Fri, 15 Aug 2008 00:52:52 +0000 |
parents | 355632dca928 |
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<HTML ><HEAD ><TITLE >SDL_SemWait</TITLE ><META NAME="GENERATOR" CONTENT="Modular DocBook HTML Stylesheet Version 1.76b+ "><LINK REL="HOME" TITLE="SDL Library Documentation" HREF="index.html"><LINK REL="UP" TITLE="Multi-threaded Programming" HREF="thread.html"><LINK REL="PREVIOUS" TITLE="SDL_DestroySemaphore" HREF="sdldestroysemaphore.html"><LINK REL="NEXT" TITLE="SDL_SemTryWait" HREF="sdlsemtrywait.html"></HEAD ><BODY CLASS="REFENTRY" BGCOLOR="#FFF8DC" TEXT="#000000" LINK="#0000ee" VLINK="#551a8b" ALINK="#ff0000" ><DIV CLASS="NAVHEADER" ><TABLE SUMMARY="Header navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TH COLSPAN="3" ALIGN="center" >SDL Library Documentation</TH ></TR ><TR ><TD WIDTH="10%" ALIGN="left" VALIGN="bottom" ><A HREF="sdldestroysemaphore.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="80%" ALIGN="center" VALIGN="bottom" ></TD ><TD WIDTH="10%" ALIGN="right" VALIGN="bottom" ><A HREF="sdlsemtrywait.html" ACCESSKEY="N" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><H1 ><A NAME="SDLSEMWAIT" ></A >SDL_SemWait</H1 ><DIV CLASS="REFNAMEDIV" ><A NAME="AEN8023" ></A ><H2 >Name</H2 >SDL_SemWait -- Lock a semaphore and suspend the thread if the semaphore value is zero.</DIV ><DIV CLASS="REFSYNOPSISDIV" ><A NAME="AEN8026" ></A ><H2 >Synopsis</H2 ><DIV CLASS="FUNCSYNOPSIS" ><A NAME="AEN8027" ></A ><P ></P ><PRE CLASS="FUNCSYNOPSISINFO" >#include "SDL.h" #include "SDL_thread.h"</PRE ><P ><CODE ><CODE CLASS="FUNCDEF" >int <B CLASS="FSFUNC" >SDL_SemWait</B ></CODE >(SDL_sem *sem);</CODE ></P ><P ></P ></DIV ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN8033" ></A ><H2 >Description</H2 ><P ><TT CLASS="FUNCTION" >SDL_SemWait()</TT > suspends the calling thread until either the semaphore pointed to by <TT CLASS="PARAMETER" ><I >sem</I ></TT > has a positive value, the call is interrupted by a signal or error. If the call is successful it will atomically decrement the semaphore value.</P ><P >After <TT CLASS="FUNCTION" >SDL_SemWait()</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="AEN8041" ></A ><H2 >Return Value</H2 ><P >Returns <SPAN CLASS="RETURNVALUE" >0</SPAN > if successful or <SPAN CLASS="RETURNVALUE" >-1</SPAN > if there was an error (leaving the semaphore unchanged).</P ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN8046" ></A ><H2 >Examples</H2 ><P ><PRE CLASS="PROGRAMLISTING" >if (SDL_SemWait(my_sem) == -1) { return WAIT_FAILED; } ... SDL_SemPost(my_sem);</PRE ></P ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN8050" ></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="sdlsemtrywait.html" ><TT CLASS="FUNCTION" >SDL_SemTryWait</TT ></A >, <A HREF="sdlsemwaittimeout.html" ><TT CLASS="FUNCTION" >SDL_SemWaitTimeout</TT ></A >, <A HREF="sdlsempost.html" ><TT CLASS="FUNCTION" >SDL_SemPost</TT ></A >, <A HREF="sdlsemvalue.html" ><TT CLASS="FUNCTION" >SDL_SemValue</TT ></A ></P ></DIV ><DIV CLASS="NAVFOOTER" ><HR ALIGN="LEFT" WIDTH="100%"><TABLE SUMMARY="Footer navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" ><A HREF="sdldestroysemaphore.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="index.html" ACCESSKEY="H" >Home</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" ><A HREF="sdlsemtrywait.html" ACCESSKEY="N" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >SDL_DestroySemaphore</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="thread.html" ACCESSKEY="U" >Up</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >SDL_SemTryWait</TD ></TR ></TABLE ></DIV ></BODY ></HTML >