| 1 | <HTML |
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| 4 | >SDL_SemWaitTimeout</TITLE |
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| 40 | >SDL Library Documentation</TH |
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| 48 | HREF="sdlsemtrywait.html" |
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| 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 |
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| 302 | >SDL_SemTryWait</TD |
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| 316 | >SDL_SemPost</TD |
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