Mercurial > sdl-ios-xcode
annotate docs/html/sdlcreatesemaphore.html @ 641:df178851293b
Date: 28 Jun 2003 22:42:52 +0100
From: Alan Swanson
Subject: Re: [SDL] New XFree 4.3 Video Mode Patch
I have a wee amendment that moves the qsort in set_best_resolution
to only occur after failing to find an exact match only. This would
make absolutely sure we get a user set mode.
While I've never had any problems for my normal resolutions (1280x1024,
1024x768, 800x600 & 640,480) while closely examining the output from
qsort I've noticed it doesn't seem to sort the modes fully. These is
one definite wrong at 1152x768 and a few that just look wrong to me.
From a program (attached) I made to examine this more easily. X has
sorted its mode list using the same method as ours (plus frequency),
and our user modes get inserted without any other movement.
On the patch I've made I've also changed cmpmodes to sort on vertical
resolution and then horizontal. Ie vertical is now most significant
bit.
| author | Sam Lantinga <slouken@libsdl.org> |
|---|---|
| date | Sat, 28 Jun 2003 21:52:26 +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 > |