Mercurial > sdl-ios-xcode
view docs/html/sdlsemtrywait.html @ 1643:51038e80ae59
More general fix for bug #189
The clipping is done at a higher level, and the low level functions are
passed clipped rectangles. Drivers which don't support source clipping
have not been changed, so the image will be squished instead of clipped,
but at least they will no longer crash when the destination rect was out
of bounds.
author | Sam Lantinga <slouken@libsdl.org> |
---|---|
date | Mon, 17 Apr 2006 06:47:23 +0000 |
parents | 355632dca928 |
children |
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<HTML ><HEAD ><TITLE >SDL_SemTryWait</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_SemWait" HREF="sdlsemwait.html"><LINK REL="NEXT" TITLE="SDL_SemWaitTimeout" HREF="sdlsemwaittimeout.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="sdlsemwait.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="80%" ALIGN="center" VALIGN="bottom" ></TD ><TD WIDTH="10%" ALIGN="right" VALIGN="bottom" ><A HREF="sdlsemwaittimeout.html" ACCESSKEY="N" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><H1 ><A NAME="SDLSEMTRYWAIT" ></A >SDL_SemTryWait</H1 ><DIV CLASS="REFNAMEDIV" ><A NAME="AEN8069" ></A ><H2 >Name</H2 >SDL_SemTryWait -- Attempt to lock a semaphore but don't suspend the thread.</DIV ><DIV CLASS="REFSYNOPSISDIV" ><A NAME="AEN8072" ></A ><H2 >Synopsis</H2 ><DIV CLASS="FUNCSYNOPSIS" ><A NAME="AEN8073" ></A ><P ></P ><PRE CLASS="FUNCSYNOPSISINFO" >#include "SDL.h" #include "SDL_thread.h"</PRE ><P ><CODE ><CODE CLASS="FUNCDEF" >int <B CLASS="FSFUNC" >SDL_SemTryWait</B ></CODE >(SDL_sem *sem);</CODE ></P ><P ></P ></DIV ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN8079" ></A ><H2 >Description</H2 ><P ><TT CLASS="FUNCTION" >SDL_SemTryWait</TT > is a non-blocking varient of <A HREF="sdlsemwait.html" ><TT CLASS="FUNCTION" >SDL_SemWait</TT ></A >. If the value of the semaphore pointed to by <TT CLASS="PARAMETER" ><I >sem</I ></TT > is positive it will atomically decrement the semaphore value and return 0, otherwise it will return <SPAN CLASS="RETURNVALUE" >SDL_MUTEX_TIMEDOUT</SPAN > instead of suspending the thread.</P ><P >After <TT CLASS="FUNCTION" >SDL_SemTryWait</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="AEN8090" ></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 thread would have suspended 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="AEN8097" ></A ><H2 >Examples</H2 ><P ><PRE CLASS="PROGRAMLISTING" >res = SDL_SemTryWait(my_sem); 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="AEN8101" ></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="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="sdlsemwait.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="sdlsemwaittimeout.html" ACCESSKEY="N" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >SDL_SemWait</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_SemWaitTimeout</TD ></TR ></TABLE ></DIV ></BODY ></HTML >