Mercurial > sdl-ios-xcode
annotate docs/html/sdlcreatesemaphore.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_CreateSemaphore</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_mutexV" | |
| 17 HREF="sdlmutexv.html"><LINK | |
| 18 REL="NEXT" | |
| 19 TITLE="SDL_DestroySemaphore" | |
| 20 HREF="sdldestroysemaphore.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="sdlmutexv.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="sdldestroysemaphore.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="SDLCREATESEMAPHORE" | |
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74 ></A |
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75 >SDL_CreateSemaphore</H1 |
| 0 | 76 ><DIV |
| 77 CLASS="REFNAMEDIV" | |
| 78 ><A | |
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79 NAME="AEN7936" |
| 0 | 80 ></A |
| 81 ><H2 | |
| 82 >Name</H2 | |
| 83 >SDL_CreateSemaphore -- Creates a new semaphore and assigns an initial value to it.</DIV | |
| 84 ><DIV | |
| 85 CLASS="REFSYNOPSISDIV" | |
| 86 ><A | |
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87 NAME="AEN7939" |
| 0 | 88 ></A |
| 89 ><H2 | |
| 90 >Synopsis</H2 | |
| 91 ><DIV | |
| 92 CLASS="FUNCSYNOPSIS" | |
| 93 ><A | |
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94 NAME="AEN7940" |
| 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 >SDL_sem *<B | |
| 107 CLASS="FSFUNC" | |
| 108 >SDL_CreateSemaphore</B | |
| 109 ></CODE | |
| 110 >(Uint32 initial_value);</CODE | |
| 111 ></P | |
| 112 ><P | |
| 113 ></P | |
| 114 ></DIV | |
| 115 ></DIV | |
| 116 ><DIV | |
| 117 CLASS="REFSECT1" | |
| 118 ><A | |
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119 NAME="AEN7946" |
| 0 | 120 ></A |
| 121 ><H2 | |
| 122 >Description</H2 | |
| 123 ><P | |
| 124 ><TT | |
| 125 CLASS="FUNCTION" | |
| 126 >SDL_CreateSemaphore()</TT | |
| 127 > creates a new semaphore and | |
| 128 initializes it with the value <TT | |
| 129 CLASS="PARAMETER" | |
| 130 ><I | |
| 131 >initial_value</I | |
| 132 ></TT | |
| 133 >. | |
| 134 Each locking operation on the semaphore by | |
| 135 <A | |
| 136 HREF="sdlsemwait.html" | |
| 137 >SDL_SemWait</A | |
| 138 >, | |
| 139 <A | |
| 140 HREF="sdlsemtrywait.html" | |
| 141 >SDL_SemTryWait</A | |
| 142 > or | |
| 143 <A | |
| 144 HREF="sdlsemwaittimeout.html" | |
| 145 >SDL_SemWaitTimeout</A | |
| 146 > | |
| 147 will atomically decrement the semaphore value. The locking operation will be blocked | |
| 148 if the semaphore value is not positive (greater than zero). Each unlock operation by | |
| 149 <A | |
| 150 HREF="sdlsempost.html" | |
| 151 >SDL_SemPost</A | |
| 152 > | |
| 153 will atomically increment the semaphore value.</P | |
| 154 ></DIV | |
| 155 ><DIV | |
| 156 CLASS="REFSECT1" | |
| 157 ><A | |
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158 NAME="AEN7955" |
| 0 | 159 ></A |
| 160 ><H2 | |
| 161 >Return Value</H2 | |
| 162 ><P | |
| 163 >Returns a pointer to an initialized semaphore or | |
| 164 <SPAN | |
| 165 CLASS="RETURNVALUE" | |
| 166 >NULL</SPAN | |
| 167 > if there was an error.</P | |
| 168 ></DIV | |
| 169 ><DIV | |
| 170 CLASS="REFSECT1" | |
| 171 ><A | |
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172 NAME="AEN7959" |
| 0 | 173 ></A |
| 174 ><H2 | |
| 175 >Examples</H2 | |
| 176 ><P | |
| 177 ><PRE | |
| 178 CLASS="PROGRAMLISTING" | |
| 179 >SDL_sem *my_sem; | |
| 180 | |
| 181 my_sem = SDL_CreateSemaphore(INITIAL_SEM_VALUE); | |
| 182 | |
| 183 if (my_sem == NULL) { | |
| 184 return CREATE_SEM_FAILED; | |
| 185 }</PRE | |
| 186 ></P | |
| 187 ></DIV | |
| 188 ><DIV | |
| 189 CLASS="REFSECT1" | |
| 190 ><A | |
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191 NAME="AEN7963" |
| 0 | 192 ></A |
| 193 ><H2 | |
| 194 >See Also</H2 | |
| 195 ><P | |
| 196 ><A | |
| 197 HREF="sdldestroysemaphore.html" | |
| 198 ><TT | |
| 199 CLASS="FUNCTION" | |
| 200 >SDL_DestroySemaphore</TT | |
| 201 ></A | |
| 202 >, | |
| 203 <A | |
| 204 HREF="sdlsemwait.html" | |
| 205 ><TT | |
| 206 CLASS="FUNCTION" | |
| 207 >SDL_SemWait</TT | |
| 208 ></A | |
| 209 >, | |
| 210 <A | |
| 211 HREF="sdlsemtrywait.html" | |
| 212 ><TT | |
| 213 CLASS="FUNCTION" | |
| 214 >SDL_SemTryWait</TT | |
| 215 ></A | |
| 216 >, | |
| 217 <A | |
| 218 HREF="sdlsemwaittimeout.html" | |
| 219 ><TT | |
| 220 CLASS="FUNCTION" | |
| 221 >SDL_SemWaitTimeout</TT | |
| 222 ></A | |
| 223 >, | |
| 224 <A | |
| 225 HREF="sdlsempost.html" | |
| 226 ><TT | |
| 227 CLASS="FUNCTION" | |
| 228 >SDL_SemPost</TT | |
| 229 ></A | |
| 230 >, | |
| 231 <A | |
| 232 HREF="sdlsemvalue.html" | |
| 233 ><TT | |
| 234 CLASS="FUNCTION" | |
| 235 >SDL_SemValue</TT | |
| 236 ></A | |
| 237 ></P | |
| 238 ></DIV | |
| 239 ><DIV | |
| 240 CLASS="NAVFOOTER" | |
| 241 ><HR | |
| 242 ALIGN="LEFT" | |
| 243 WIDTH="100%"><TABLE | |
|
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244 SUMMARY="Footer navigation table" |
| 0 | 245 WIDTH="100%" |
| 246 BORDER="0" | |
| 247 CELLPADDING="0" | |
| 248 CELLSPACING="0" | |
| 249 ><TR | |
| 250 ><TD | |
| 251 WIDTH="33%" | |
| 252 ALIGN="left" | |
| 253 VALIGN="top" | |
| 254 ><A | |
| 255 HREF="sdlmutexv.html" | |
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256 ACCESSKEY="P" |
| 0 | 257 >Prev</A |
| 258 ></TD | |
| 259 ><TD | |
| 260 WIDTH="34%" | |
| 261 ALIGN="center" | |
| 262 VALIGN="top" | |
| 263 ><A | |
| 264 HREF="index.html" | |
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265 ACCESSKEY="H" |
| 0 | 266 >Home</A |
| 267 ></TD | |
| 268 ><TD | |
| 269 WIDTH="33%" | |
| 270 ALIGN="right" | |
| 271 VALIGN="top" | |
| 272 ><A | |
| 273 HREF="sdldestroysemaphore.html" | |
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274 ACCESSKEY="N" |
| 0 | 275 >Next</A |
| 276 ></TD | |
| 277 ></TR | |
| 278 ><TR | |
| 279 ><TD | |
| 280 WIDTH="33%" | |
| 281 ALIGN="left" | |
| 282 VALIGN="top" | |
| 283 >SDL_mutexV</TD | |
| 284 ><TD | |
| 285 WIDTH="34%" | |
| 286 ALIGN="center" | |
| 287 VALIGN="top" | |
| 288 ><A | |
| 289 HREF="thread.html" | |
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290 ACCESSKEY="U" |
| 0 | 291 >Up</A |
| 292 ></TD | |
| 293 ><TD | |
| 294 WIDTH="33%" | |
| 295 ALIGN="right" | |
| 296 VALIGN="top" | |
| 297 >SDL_DestroySemaphore</TD | |
| 298 ></TR | |
| 299 ></TABLE | |
| 300 ></DIV | |
| 301 ></BODY | |
| 302 ></HTML | |
| 303 > |