Mercurial > sdl-ios-xcode
annotate docs/html/sdlsemtrywait.html @ 3958:85b6fb6a5e3c SDL-1.2
Actually, this is a better fix...clear the error state once if everything we
need loaded; it's more efficient, and works even if the last unnecessary
xrandr symbol failed to load. Otherwise, leave the original loadso error, so
the end user can find out what symbol failed.
| author | Ryan C. Gordon <icculus@icculus.org> |
|---|---|
| date | Wed, 13 Jun 2007 08:00:10 +0000 |
| parents | 355632dca928 |
| children |
| rev | line source |
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| 0 | 1 <HTML |
| 2 ><HEAD | |
| 3 ><TITLE | |
| 4 >SDL_SemTryWait</TITLE | |
| 5 ><META | |
| 6 NAME="GENERATOR" | |
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7 CONTENT="Modular DocBook HTML Stylesheet Version 1.76b+ |
| 0 | 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_SemWait" | |
| 17 HREF="sdlsemwait.html"><LINK | |
| 18 REL="NEXT" | |
| 19 TITLE="SDL_SemWaitTimeout" | |
| 20 HREF="sdlsemwaittimeout.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 | |
|
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31 SUMMARY="Header navigation table" |
| 0 | 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="sdlsemwait.html" | |
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49 ACCESSKEY="P" |
| 0 | 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="sdlsemwaittimeout.html" | |
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63 ACCESSKEY="N" |
| 0 | 64 >Next</A |
| 65 ></TD | |
| 66 ></TR | |
| 67 ></TABLE | |
| 68 ><HR | |
| 69 ALIGN="LEFT" | |
| 70 WIDTH="100%"></DIV | |
| 71 ><H1 | |
| 72 ><A | |
| 73 NAME="SDLSEMTRYWAIT" | |
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74 ></A |
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75 >SDL_SemTryWait</H1 |
| 0 | 76 ><DIV |
| 77 CLASS="REFNAMEDIV" | |
| 78 ><A | |
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79 NAME="AEN8069" |
| 0 | 80 ></A |
| 81 ><H2 | |
| 82 >Name</H2 | |
| 83 >SDL_SemTryWait -- Attempt to lock a semaphore but don't suspend the thread.</DIV | |
| 84 ><DIV | |
| 85 CLASS="REFSYNOPSISDIV" | |
| 86 ><A | |
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87 NAME="AEN8072" |
| 0 | 88 ></A |
| 89 ><H2 | |
| 90 >Synopsis</H2 | |
| 91 ><DIV | |
| 92 CLASS="FUNCSYNOPSIS" | |
| 93 ><A | |
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94 NAME="AEN8073" |
| 0 | 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_SemTryWait</B | |
| 109 ></CODE | |
| 110 >(SDL_sem *sem);</CODE | |
| 111 ></P | |
| 112 ><P | |
| 113 ></P | |
| 114 ></DIV | |
| 115 ></DIV | |
| 116 ><DIV | |
| 117 CLASS="REFSECT1" | |
| 118 ><A | |
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119 NAME="AEN8079" |
| 0 | 120 ></A |
| 121 ><H2 | |
| 122 >Description</H2 | |
| 123 ><P | |
| 124 ><TT | |
| 125 CLASS="FUNCTION" | |
| 126 >SDL_SemTryWait</TT | |
| 127 > is a non-blocking varient of | |
| 128 <A | |
| 129 HREF="sdlsemwait.html" | |
| 130 ><TT | |
| 131 CLASS="FUNCTION" | |
| 132 >SDL_SemWait</TT | |
| 133 ></A | |
| 134 >. If the value of the semaphore | |
| 135 pointed to by <TT | |
| 136 CLASS="PARAMETER" | |
| 137 ><I | |
| 138 >sem</I | |
| 139 ></TT | |
| 140 > is positive it will atomically | |
| 141 decrement the semaphore value and return 0, otherwise it will return | |
| 142 <SPAN | |
| 143 CLASS="RETURNVALUE" | |
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144 >SDL_MUTEX_TIMEDOUT</SPAN |
| 0 | 145 > instead of suspending the thread.</P |
| 146 ><P | |
| 147 >After <TT | |
| 148 CLASS="FUNCTION" | |
| 149 >SDL_SemTryWait</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 | |
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160 NAME="AEN8090" |
| 0 | 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" | |
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171 >SDL_MUTEX_TIMEDOUT</SPAN |
| 0 | 172 > or <SPAN |
| 173 CLASS="RETURNVALUE" | |
| 174 >-1</SPAN | |
| 175 > | |
| 176 if the thread would have suspended 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 | |
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183 NAME="AEN8097" |
| 0 | 184 ></A |
| 185 ><H2 | |
| 186 >Examples</H2 | |
| 187 ><P | |
| 188 ><PRE | |
| 189 CLASS="PROGRAMLISTING" | |
| 190 >res = SDL_SemTryWait(my_sem); | |
| 191 | |
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192 if (res == SDL_MUTEX_TIMEDOUT) { |
| 0 | 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 | |
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207 NAME="AEN8101" |
| 0 | 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="sdlsemwaittimeout.html" | |
| 235 ><TT | |
| 236 CLASS="FUNCTION" | |
| 237 >SDL_SemWaitTimeout</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 | |
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260 SUMMARY="Footer navigation table" |
| 0 | 261 WIDTH="100%" |
| 262 BORDER="0" | |
| 263 CELLPADDING="0" | |
| 264 CELLSPACING="0" | |
| 265 ><TR | |
| 266 ><TD | |
| 267 WIDTH="33%" | |
| 268 ALIGN="left" | |
| 269 VALIGN="top" | |
| 270 ><A | |
| 271 HREF="sdlsemwait.html" | |
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272 ACCESSKEY="P" |
| 0 | 273 >Prev</A |
| 274 ></TD | |
| 275 ><TD | |
| 276 WIDTH="34%" | |
| 277 ALIGN="center" | |
| 278 VALIGN="top" | |
| 279 ><A | |
| 280 HREF="index.html" | |
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281 ACCESSKEY="H" |
| 0 | 282 >Home</A |
| 283 ></TD | |
| 284 ><TD | |
| 285 WIDTH="33%" | |
| 286 ALIGN="right" | |
| 287 VALIGN="top" | |
| 288 ><A | |
| 289 HREF="sdlsemwaittimeout.html" | |
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290 ACCESSKEY="N" |
| 0 | 291 >Next</A |
| 292 ></TD | |
| 293 ></TR | |
| 294 ><TR | |
| 295 ><TD | |
| 296 WIDTH="33%" | |
| 297 ALIGN="left" | |
| 298 VALIGN="top" | |
| 299 >SDL_SemWait</TD | |
| 300 ><TD | |
| 301 WIDTH="34%" | |
| 302 ALIGN="center" | |
| 303 VALIGN="top" | |
| 304 ><A | |
| 305 HREF="thread.html" | |
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306 ACCESSKEY="U" |
| 0 | 307 >Up</A |
| 308 ></TD | |
| 309 ><TD | |
| 310 WIDTH="33%" | |
| 311 ALIGN="right" | |
| 312 VALIGN="top" | |
| 313 >SDL_SemWaitTimeout</TD | |
| 314 ></TR | |
| 315 ></TABLE | |
| 316 ></DIV | |
| 317 ></BODY | |
| 318 ></HTML | |
| 319 > |