e14743d1 |
1 | <HTML |
2 | ><HEAD |
3 | ><TITLE |
4 | >SDL_SemWaitTimeout</TITLE |
5 | ><META |
6 | NAME="GENERATOR" |
7 | CONTENT="Modular DocBook HTML Stylesheet Version 1.76b+ |
8 | "><LINK |
9 | REL="HOME" |
10 | TITLE="SDL Library Documentation" |
11 | HREF="index.html"><LINK |
12 | REL="UP" |
13 | TITLE="Multi-threaded Programming" |
14 | HREF="thread.html"><LINK |
15 | REL="PREVIOUS" |
16 | TITLE="SDL_SemTryWait" |
17 | HREF="sdlsemtrywait.html"><LINK |
18 | REL="NEXT" |
19 | TITLE="SDL_SemPost" |
20 | HREF="sdlsempost.html"></HEAD |
21 | ><BODY |
22 | CLASS="REFENTRY" |
23 | BGCOLOR="#FFF8DC" |
24 | TEXT="#000000" |
25 | LINK="#0000ee" |
26 | VLINK="#551a8b" |
27 | ALINK="#ff0000" |
28 | ><DIV |
29 | CLASS="NAVHEADER" |
30 | ><TABLE |
31 | SUMMARY="Header navigation table" |
32 | WIDTH="100%" |
33 | BORDER="0" |
34 | CELLPADDING="0" |
35 | CELLSPACING="0" |
36 | ><TR |
37 | ><TH |
38 | COLSPAN="3" |
39 | ALIGN="center" |
40 | >SDL Library Documentation</TH |
41 | ></TR |
42 | ><TR |
43 | ><TD |
44 | WIDTH="10%" |
45 | ALIGN="left" |
46 | VALIGN="bottom" |
47 | ><A |
48 | HREF="sdlsemtrywait.html" |
49 | ACCESSKEY="P" |
50 | >Prev</A |
51 | ></TD |
52 | ><TD |
53 | WIDTH="80%" |
54 | ALIGN="center" |
55 | VALIGN="bottom" |
56 | ></TD |
57 | ><TD |
58 | WIDTH="10%" |
59 | ALIGN="right" |
60 | VALIGN="bottom" |
61 | ><A |
62 | HREF="sdlsempost.html" |
63 | ACCESSKEY="N" |
64 | >Next</A |
65 | ></TD |
66 | ></TR |
67 | ></TABLE |
68 | ><HR |
69 | ALIGN="LEFT" |
70 | WIDTH="100%"></DIV |
71 | ><H1 |
72 | ><A |
73 | NAME="SDLSEMWAITTIMEOUT" |
74 | ></A |
75 | >SDL_SemWaitTimeout</H1 |
76 | ><DIV |
77 | CLASS="REFNAMEDIV" |
78 | ><A |
79 | NAME="AEN8120" |
80 | ></A |
81 | ><H2 |
82 | >Name</H2 |
83 | >SDL_SemWaitTimeout -- Lock a semaphore, but only wait up to a specified maximum time.</DIV |
84 | ><DIV |
85 | CLASS="REFSYNOPSISDIV" |
86 | ><A |
87 | NAME="AEN8123" |
88 | ></A |
89 | ><H2 |
90 | >Synopsis</H2 |
91 | ><DIV |
92 | CLASS="FUNCSYNOPSIS" |
93 | ><A |
94 | NAME="AEN8124" |
95 | ></A |
96 | ><P |
97 | ></P |
98 | ><PRE |
99 | CLASS="FUNCSYNOPSISINFO" |
100 | >#include "SDL.h" |
101 | #include "SDL_thread.h"</PRE |
102 | ><P |
103 | ><CODE |
104 | ><CODE |
105 | CLASS="FUNCDEF" |
106 | >int <B |
107 | CLASS="FSFUNC" |
108 | >SDL_SemWaitTimeout</B |
109 | ></CODE |
110 | >(SDL_sem *sem, Uint32 timeout);</CODE |
111 | ></P |
112 | ><P |
113 | ></P |
114 | ></DIV |
115 | ></DIV |
116 | ><DIV |
117 | CLASS="REFSECT1" |
118 | ><A |
119 | NAME="AEN8130" |
120 | ></A |
121 | ><H2 |
122 | >Description</H2 |
123 | ><P |
124 | ><TT |
125 | CLASS="FUNCTION" |
126 | >SDL_SemWaitTimeout()</TT |
127 | > is a varient of |
128 | <A |
129 | HREF="sdlsemwait.html" |
130 | >SDL_SemWait</A |
131 | > |
132 | with a maximum timeout value. |
133 | If the value of the semaphore pointed to by <TT |
134 | CLASS="PARAMETER" |
135 | ><I |
136 | >sem</I |
137 | ></TT |
138 | > is |
139 | positive (greater than zero) it will atomically decrement the semaphore value |
140 | and return 0, otherwise it will wait up to <TT |
141 | CLASS="PARAMETER" |
142 | ><I |
143 | >timeout</I |
144 | ></TT |
145 | > |
146 | milliseconds trying to lock the semaphore. This function is to be avoided if |
147 | possible since on some platforms it is implemented by polling the semaphore |
148 | every millisecond in a busy loop.</P |
149 | ><P |
150 | >After <TT |
151 | CLASS="FUNCTION" |
152 | >SDL_SemWaitTimeout()</TT |
153 | > is successful, the semaphore |
154 | can be released and its count atomically incremented by a successful call to |
155 | <A |
156 | HREF="sdlsempost.html" |
157 | >SDL_SemPost</A |
158 | >.</P |
159 | ></DIV |
160 | ><DIV |
161 | CLASS="REFSECT1" |
162 | ><A |
163 | NAME="AEN8140" |
164 | ></A |
165 | ><H2 |
166 | >Return Value</H2 |
167 | ><P |
168 | >Returns <SPAN |
169 | CLASS="RETURNVALUE" |
170 | >0</SPAN |
171 | > if the semaphore was successfully locked or |
172 | either <SPAN |
173 | CLASS="RETURNVALUE" |
174 | >SDL_MUTEX_TIMEDOUT</SPAN |
175 | > or <SPAN |
176 | CLASS="RETURNVALUE" |
177 | >-1</SPAN |
178 | > |
179 | if the timeout period was exceeded or there was an error, respectivly.</P |
180 | ><P |
181 | >If the semaphore was not successfully locked, the semaphore will be unchanged.</P |
182 | ></DIV |
183 | ><DIV |
184 | CLASS="REFSECT1" |
185 | ><A |
186 | NAME="AEN8147" |
187 | ></A |
188 | ><H2 |
189 | >Examples</H2 |
190 | ><P |
191 | ><PRE |
192 | CLASS="PROGRAMLISTING" |
193 | >res = SDL_SemWaitTimeout(my_sem, WAIT_TIMEOUT_MILLISEC); |
194 | |
195 | if (res == SDL_MUTEX_TIMEDOUT) { |
196 | return TRY_AGAIN; |
197 | } |
198 | if (res == -1) { |
199 | return WAIT_ERROR; |
200 | } |
201 | |
202 | ... |
203 | |
204 | SDL_SemPost(my_sem);</PRE |
205 | ></P |
206 | ></DIV |
207 | ><DIV |
208 | CLASS="REFSECT1" |
209 | ><A |
210 | NAME="AEN8151" |
211 | ></A |
212 | ><H2 |
213 | >See Also</H2 |
214 | ><P |
215 | ><A |
216 | HREF="sdlcreatesemaphore.html" |
217 | ><TT |
218 | CLASS="FUNCTION" |
219 | >SDL_CreateSemaphore</TT |
220 | ></A |
221 | >, |
222 | <A |
223 | HREF="sdldestroysemaphore.html" |
224 | ><TT |
225 | CLASS="FUNCTION" |
226 | >SDL_DestroySemaphore</TT |
227 | ></A |
228 | >, |
229 | <A |
230 | HREF="sdlsemwait.html" |
231 | ><TT |
232 | CLASS="FUNCTION" |
233 | >SDL_SemWait</TT |
234 | ></A |
235 | >, |
236 | <A |
237 | HREF="sdlsemtrywait.html" |
238 | ><TT |
239 | CLASS="FUNCTION" |
240 | >SDL_SemTryWait</TT |
241 | ></A |
242 | >, |
243 | <A |
244 | HREF="sdlsempost.html" |
245 | ><TT |
246 | CLASS="FUNCTION" |
247 | >SDL_SemPost</TT |
248 | ></A |
249 | >, |
250 | <A |
251 | HREF="sdlsemvalue.html" |
252 | ><TT |
253 | CLASS="FUNCTION" |
254 | >SDL_SemValue</TT |
255 | ></A |
256 | ></P |
257 | ></DIV |
258 | ><DIV |
259 | CLASS="NAVFOOTER" |
260 | ><HR |
261 | ALIGN="LEFT" |
262 | WIDTH="100%"><TABLE |
263 | SUMMARY="Footer navigation table" |
264 | WIDTH="100%" |
265 | BORDER="0" |
266 | CELLPADDING="0" |
267 | CELLSPACING="0" |
268 | ><TR |
269 | ><TD |
270 | WIDTH="33%" |
271 | ALIGN="left" |
272 | VALIGN="top" |
273 | ><A |
274 | HREF="sdlsemtrywait.html" |
275 | ACCESSKEY="P" |
276 | >Prev</A |
277 | ></TD |
278 | ><TD |
279 | WIDTH="34%" |
280 | ALIGN="center" |
281 | VALIGN="top" |
282 | ><A |
283 | HREF="index.html" |
284 | ACCESSKEY="H" |
285 | >Home</A |
286 | ></TD |
287 | ><TD |
288 | WIDTH="33%" |
289 | ALIGN="right" |
290 | VALIGN="top" |
291 | ><A |
292 | HREF="sdlsempost.html" |
293 | ACCESSKEY="N" |
294 | >Next</A |
295 | ></TD |
296 | ></TR |
297 | ><TR |
298 | ><TD |
299 | WIDTH="33%" |
300 | ALIGN="left" |
301 | VALIGN="top" |
302 | >SDL_SemTryWait</TD |
303 | ><TD |
304 | WIDTH="34%" |
305 | ALIGN="center" |
306 | VALIGN="top" |
307 | ><A |
308 | HREF="thread.html" |
309 | ACCESSKEY="U" |
310 | >Up</A |
311 | ></TD |
312 | ><TD |
313 | WIDTH="33%" |
314 | ALIGN="right" |
315 | VALIGN="top" |
316 | >SDL_SemPost</TD |
317 | ></TR |
318 | ></TABLE |
319 | ></DIV |
320 | ></BODY |
321 | ></HTML |
322 | > |