Mercurial > sdl-ios-xcode
annotate docs/html/sdlcreatesemaphore.html @ 612:0648505b1f8b
Fixed video intitialization problem on Qtopia (thanks David!)
| author | Sam Lantinga <slouken@libsdl.org> |
|---|---|
| date | Tue, 15 Apr 2003 16:04:31 +0000 |
| parents | e5bc29de3f0a |
| children | 355632dca928 |
| rev | line source |
|---|---|
| 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 1.64 |
| 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 | |
| 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="sdlmutexv.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="sdldestroysemaphore.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="SDLCREATESEMAPHORE" | |
| 71 >SDL_CreateSemaphore</A | |
| 72 ></H1 | |
| 73 ><DIV | |
| 74 CLASS="REFNAMEDIV" | |
| 75 ><A | |
|
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76 NAME="AEN7548" |
| 0 | 77 ></A |
| 78 ><H2 | |
| 79 >Name</H2 | |
| 80 >SDL_CreateSemaphore -- Creates a new semaphore and assigns an initial value to it.</DIV | |
| 81 ><DIV | |
| 82 CLASS="REFSYNOPSISDIV" | |
| 83 ><A | |
|
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84 NAME="AEN7551" |
| 0 | 85 ></A |
| 86 ><H2 | |
| 87 >Synopsis</H2 | |
| 88 ><DIV | |
| 89 CLASS="FUNCSYNOPSIS" | |
| 90 ><A | |
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91 NAME="AEN7552" |
| 0 | 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 >SDL_sem *<B | |
| 104 CLASS="FSFUNC" | |
| 105 >SDL_CreateSemaphore</B | |
| 106 ></CODE | |
| 107 >(Uint32 initial_value);</CODE | |
| 108 ></P | |
| 109 ><P | |
| 110 ></P | |
| 111 ></DIV | |
| 112 ></DIV | |
| 113 ><DIV | |
| 114 CLASS="REFSECT1" | |
| 115 ><A | |
|
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116 NAME="AEN7558" |
| 0 | 117 ></A |
| 118 ><H2 | |
| 119 >Description</H2 | |
| 120 ><P | |
| 121 ><TT | |
| 122 CLASS="FUNCTION" | |
| 123 >SDL_CreateSemaphore()</TT | |
| 124 > creates a new semaphore and | |
| 125 initializes it with the value <TT | |
| 126 CLASS="PARAMETER" | |
| 127 ><I | |
| 128 >initial_value</I | |
| 129 ></TT | |
| 130 >. | |
| 131 Each locking operation on the semaphore by | |
| 132 <A | |
| 133 HREF="sdlsemwait.html" | |
| 134 >SDL_SemWait</A | |
| 135 >, | |
| 136 <A | |
| 137 HREF="sdlsemtrywait.html" | |
| 138 >SDL_SemTryWait</A | |
| 139 > or | |
| 140 <A | |
| 141 HREF="sdlsemwaittimeout.html" | |
| 142 >SDL_SemWaitTimeout</A | |
| 143 > | |
| 144 will atomically decrement the semaphore value. The locking operation will be blocked | |
| 145 if the semaphore value is not positive (greater than zero). Each unlock operation by | |
| 146 <A | |
| 147 HREF="sdlsempost.html" | |
| 148 >SDL_SemPost</A | |
| 149 > | |
| 150 will atomically increment the semaphore value.</P | |
| 151 ></DIV | |
| 152 ><DIV | |
| 153 CLASS="REFSECT1" | |
| 154 ><A | |
|
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155 NAME="AEN7567" |
| 0 | 156 ></A |
| 157 ><H2 | |
| 158 >Return Value</H2 | |
| 159 ><P | |
| 160 >Returns a pointer to an initialized semaphore or | |
| 161 <SPAN | |
| 162 CLASS="RETURNVALUE" | |
| 163 >NULL</SPAN | |
| 164 > if there was an error.</P | |
| 165 ></DIV | |
| 166 ><DIV | |
| 167 CLASS="REFSECT1" | |
| 168 ><A | |
|
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169 NAME="AEN7571" |
| 0 | 170 ></A |
| 171 ><H2 | |
| 172 >Examples</H2 | |
| 173 ><P | |
| 174 ><PRE | |
| 175 CLASS="PROGRAMLISTING" | |
| 176 >SDL_sem *my_sem; | |
| 177 | |
| 178 my_sem = SDL_CreateSemaphore(INITIAL_SEM_VALUE); | |
| 179 | |
| 180 if (my_sem == NULL) { | |
| 181 return CREATE_SEM_FAILED; | |
| 182 }</PRE | |
| 183 ></P | |
| 184 ></DIV | |
| 185 ><DIV | |
| 186 CLASS="REFSECT1" | |
| 187 ><A | |
|
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188 NAME="AEN7575" |
| 0 | 189 ></A |
| 190 ><H2 | |
| 191 >See Also</H2 | |
| 192 ><P | |
| 193 ><A | |
| 194 HREF="sdldestroysemaphore.html" | |
| 195 ><TT | |
| 196 CLASS="FUNCTION" | |
| 197 >SDL_DestroySemaphore</TT | |
| 198 ></A | |
| 199 >, | |
| 200 <A | |
| 201 HREF="sdlsemwait.html" | |
| 202 ><TT | |
| 203 CLASS="FUNCTION" | |
| 204 >SDL_SemWait</TT | |
| 205 ></A | |
| 206 >, | |
| 207 <A | |
| 208 HREF="sdlsemtrywait.html" | |
| 209 ><TT | |
| 210 CLASS="FUNCTION" | |
| 211 >SDL_SemTryWait</TT | |
| 212 ></A | |
| 213 >, | |
| 214 <A | |
| 215 HREF="sdlsemwaittimeout.html" | |
| 216 ><TT | |
| 217 CLASS="FUNCTION" | |
| 218 >SDL_SemWaitTimeout</TT | |
| 219 ></A | |
| 220 >, | |
| 221 <A | |
| 222 HREF="sdlsempost.html" | |
| 223 ><TT | |
| 224 CLASS="FUNCTION" | |
| 225 >SDL_SemPost</TT | |
| 226 ></A | |
| 227 >, | |
| 228 <A | |
| 229 HREF="sdlsemvalue.html" | |
| 230 ><TT | |
| 231 CLASS="FUNCTION" | |
| 232 >SDL_SemValue</TT | |
| 233 ></A | |
| 234 ></P | |
| 235 ></DIV | |
| 236 ><DIV | |
| 237 CLASS="NAVFOOTER" | |
| 238 ><HR | |
| 239 ALIGN="LEFT" | |
| 240 WIDTH="100%"><TABLE | |
| 241 WIDTH="100%" | |
| 242 BORDER="0" | |
| 243 CELLPADDING="0" | |
| 244 CELLSPACING="0" | |
| 245 ><TR | |
| 246 ><TD | |
| 247 WIDTH="33%" | |
| 248 ALIGN="left" | |
| 249 VALIGN="top" | |
| 250 ><A | |
| 251 HREF="sdlmutexv.html" | |
| 252 >Prev</A | |
| 253 ></TD | |
| 254 ><TD | |
| 255 WIDTH="34%" | |
| 256 ALIGN="center" | |
| 257 VALIGN="top" | |
| 258 ><A | |
| 259 HREF="index.html" | |
| 260 >Home</A | |
| 261 ></TD | |
| 262 ><TD | |
| 263 WIDTH="33%" | |
| 264 ALIGN="right" | |
| 265 VALIGN="top" | |
| 266 ><A | |
| 267 HREF="sdldestroysemaphore.html" | |
| 268 >Next</A | |
| 269 ></TD | |
| 270 ></TR | |
| 271 ><TR | |
| 272 ><TD | |
| 273 WIDTH="33%" | |
| 274 ALIGN="left" | |
| 275 VALIGN="top" | |
| 276 >SDL_mutexV</TD | |
| 277 ><TD | |
| 278 WIDTH="34%" | |
| 279 ALIGN="center" | |
| 280 VALIGN="top" | |
| 281 ><A | |
| 282 HREF="thread.html" | |
| 283 >Up</A | |
| 284 ></TD | |
| 285 ><TD | |
| 286 WIDTH="33%" | |
| 287 ALIGN="right" | |
| 288 VALIGN="top" | |
| 289 >SDL_DestroySemaphore</TD | |
| 290 ></TR | |
| 291 ></TABLE | |
| 292 ></DIV | |
| 293 ></BODY | |
| 294 ></HTML | |
| 295 > |