Mercurial > sdl-ios-xcode

view docs/html/sdlsemtrywait.html @ 3191:91b335df6fc8

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
Fixed bug #750 Since many different event structures include windowID it should be placed near the beginning of the structure (preferably right after type) so it's position is the same between different events. This is to avoid code like this: if (event.type == SDL_WINDOWEVENT) win = event.window.windowID; else if ((SDL_EVENTMASK(event.type) & SDL_KEYEVENTMASK) != 0) win = event.key.windowID; else if (event.type == SDL_TEXTINPUT) win = event.text.windowID; else if (event.type == SDL_MOUSEMOTION) win = event.motion.windowID; else if ((SDL_EVENTMASK(event.type) & (SDL_MOUBUTTONDOWNMASK | SDL_MOUBUTTONUPMASK)) != 0) win = event.button.windowID; else if (event.type == SDL_MOUSEWHEEL) win = event.wheel.windowID; ... in favor of: win = event.window.windowID;
author Sam Lantinga <slouken@libsdl.org>
date Wed, 10 Jun 2009 14:00:21 +0000
parents 355632dca928
children
line wrap: on
line source

<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&nbsp;--&nbsp;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
>