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Initial revision
author Sam Lantinga <slouken@lokigames.com>
date Thu, 26 Apr 2001 16:45:43 +0000
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children 55f1f1b3e27d
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-1:000000000000 0:74212992fb08
1 <HTML
2 ><HEAD
3 ><TITLE
4 >SDL_SemWaitTimeout</TITLE
5 ><META
6 NAME="GENERATOR"
7 CONTENT="Modular DocBook HTML Stylesheet Version 1.61
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 WIDTH="100%"
32 BORDER="0"
33 CELLPADDING="0"
34 CELLSPACING="0"
35 ><TR
36 ><TH
37 COLSPAN="3"
38 ALIGN="center"
39 >SDL Library Documentation</TH
40 ></TR
41 ><TR
42 ><TD
43 WIDTH="10%"
44 ALIGN="left"
45 VALIGN="bottom"
46 ><A
47 HREF="sdlsemtrywait.html"
48 >Prev</A
49 ></TD
50 ><TD
51 WIDTH="80%"
52 ALIGN="center"
53 VALIGN="bottom"
54 ></TD
55 ><TD
56 WIDTH="10%"
57 ALIGN="right"
58 VALIGN="bottom"
59 ><A
60 HREF="sdlsempost.html"
61 >Next</A
62 ></TD
63 ></TR
64 ></TABLE
65 ><HR
66 ALIGN="LEFT"
67 WIDTH="100%"></DIV
68 ><H1
69 ><A
70 NAME="SDLSEMWAITTIMEOUT"
71 >SDL_SemWaitTimeout</A
72 ></H1
73 ><DIV
74 CLASS="REFNAMEDIV"
75 ><A
76 NAME="AEN7495"
77 ></A
78 ><H2
79 >Name</H2
80 >SDL_SemWaitTimeout&nbsp;--&nbsp;Lock a semaphore, but only wait up to a specified maximum time.</DIV
81 ><DIV
82 CLASS="REFSYNOPSISDIV"
83 ><A
84 NAME="AEN7498"
85 ></A
86 ><H2
87 >Synopsis</H2
88 ><DIV
89 CLASS="FUNCSYNOPSIS"
90 ><A
91 NAME="AEN7499"
92 ></A
93 ><P
94 ></P
95 ><PRE
96 CLASS="FUNCSYNOPSISINFO"
97 >#include "SDL.h"
98 #include "SDL_thread.h"</PRE
99 ><P
100 ><CODE
101 ><CODE
102 CLASS="FUNCDEF"
103 >int <B
104 CLASS="FSFUNC"
105 >SDL_SemWaitTimeout</B
106 ></CODE
107 >(SDL_sem *sem, Uint32 timeout);</CODE
108 ></P
109 ><P
110 ></P
111 ></DIV
112 ></DIV
113 ><DIV
114 CLASS="REFSECT1"
115 ><A
116 NAME="AEN7505"
117 ></A
118 ><H2
119 >Description</H2
120 ><P
121 ><TT
122 CLASS="FUNCTION"
123 >SDL_SemWaitTimeout()</TT
124 > is a varient of
125 <A
126 HREF="sdlsemwait.html"
127 >SDL_SemWait</A
128 >
129 with a maximum timeout value.
130 If the value of the semaphore pointed to by <TT
131 CLASS="PARAMETER"
132 ><I
133 >sem</I
134 ></TT
135 > is
136 positive (greater than zero) it will atomically decrement the semaphore value
137 and return 0, otherwise it will wait up to <TT
138 CLASS="PARAMETER"
139 ><I
140 >timeout</I
141 ></TT
142 >
143 milliseconds trying to lock the semaphore. This function is to be avoided if
144 possible since on some platforms it is implemented by polling the semaphore
145 every millisecond in a busy loop.</P
146 ><P
147 >After <TT
148 CLASS="FUNCTION"
149 >SDL_SemWaitTimeout()</TT
150 > is successful, the semaphore
151 can be released and its count atomically incremented by a successful call to
152 <A
153 HREF="sdlsempost.html"
154 >SDL_SemPost</A
155 >.</P
156 ></DIV
157 ><DIV
158 CLASS="REFSECT1"
159 ><A
160 NAME="AEN7515"
161 ></A
162 ><H2
163 >Return Value</H2
164 ><P
165 >Returns <SPAN
166 CLASS="RETURNVALUE"
167 >0</SPAN
168 > if the semaphore was successfully locked or
169 either <SPAN
170 CLASS="RETURNVALUE"
171 >SDL_MUTEX_TIMEOUT</SPAN
172 > or <SPAN
173 CLASS="RETURNVALUE"
174 >-1</SPAN
175 >
176 if the timeout period was exceeded or there was an error, respectivly.</P
177 ><P
178 >If the semaphore was not successfully locked, the semaphore will be unchanged.</P
179 ></DIV
180 ><DIV
181 CLASS="REFSECT1"
182 ><A
183 NAME="AEN7522"
184 ></A
185 ><H2
186 >Examples</H2
187 ><P
188 ><PRE
189 CLASS="PROGRAMLISTING"
190 >res = SDL_SemWaitTimeout(my_sem, WAIT_TIMEOUT_MILLISEC);
191
192 if (res == SDL_MUTEX_TIMEOUT) {
193 return TRY_AGAIN;
194 }
195 if (res == -1) {
196 return WAIT_ERROR;
197 }
198
199 ...
200
201 SDL_SemPost(my_sem);</PRE
202 ></P
203 ></DIV
204 ><DIV
205 CLASS="REFSECT1"
206 ><A
207 NAME="AEN7526"
208 ></A
209 ><H2
210 >See Also</H2
211 ><P
212 ><A
213 HREF="sdlcreatesemaphore.html"
214 ><TT
215 CLASS="FUNCTION"
216 >SDL_CreateSemaphore</TT
217 ></A
218 >,
219 <A
220 HREF="sdldestroysemaphore.html"
221 ><TT
222 CLASS="FUNCTION"
223 >SDL_DestroySemaphore</TT
224 ></A
225 >,
226 <A
227 HREF="sdlsemwait.html"
228 ><TT
229 CLASS="FUNCTION"
230 >SDL_SemWait</TT
231 ></A
232 >,
233 <A
234 HREF="sdlsemtrywait.html"
235 ><TT
236 CLASS="FUNCTION"
237 >SDL_SemTryWait</TT
238 ></A
239 >,
240 <A
241 HREF="sdlsempost.html"
242 ><TT
243 CLASS="FUNCTION"
244 >SDL_SemPost</TT
245 ></A
246 >,
247 <A
248 HREF="sdlsemvalue.html"
249 ><TT
250 CLASS="FUNCTION"
251 >SDL_SemValue</TT
252 ></A
253 ></P
254 ></DIV
255 ><DIV
256 CLASS="NAVFOOTER"
257 ><HR
258 ALIGN="LEFT"
259 WIDTH="100%"><TABLE
260 WIDTH="100%"
261 BORDER="0"
262 CELLPADDING="0"
263 CELLSPACING="0"
264 ><TR
265 ><TD
266 WIDTH="33%"
267 ALIGN="left"
268 VALIGN="top"
269 ><A
270 HREF="sdlsemtrywait.html"
271 >Prev</A
272 ></TD
273 ><TD
274 WIDTH="34%"
275 ALIGN="center"
276 VALIGN="top"
277 ><A
278 HREF="index.html"
279 >Home</A
280 ></TD
281 ><TD
282 WIDTH="33%"
283 ALIGN="right"
284 VALIGN="top"
285 ><A
286 HREF="sdlsempost.html"
287 >Next</A
288 ></TD
289 ></TR
290 ><TR
291 ><TD
292 WIDTH="33%"
293 ALIGN="left"
294 VALIGN="top"
295 >SDL_SemTryWait</TD
296 ><TD
297 WIDTH="34%"
298 ALIGN="center"
299 VALIGN="top"
300 ><A
301 HREF="thread.html"
302 >Up</A
303 ></TD
304 ><TD
305 WIDTH="33%"
306 ALIGN="right"
307 VALIGN="top"
308 >SDL_SemPost</TD
309 ></TR
310 ></TABLE
311 ></DIV
312 ></BODY
313 ></HTML
314 >