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annotate docs/html/sdlcreatesemaphore.html @ 1125:a6011e1394d9
Apparently MacOS X will sometimes pass command line arguments to a Cocoa
app as an openFile() message, so we have to make sure we were launched from
the Finder before accepting these as drag'n'drop documents, or they will just
duplicate what's already in argc/argv.
| author | Ryan C. Gordon <icculus@icculus.org> |
|---|---|
| date | Mon, 22 Aug 2005 14:18:15 +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 > |