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| 5131 | clevermous | 1 | |
| 2 | > |
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| 3 | > |
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| 4 | >SDL_SemTryWait |
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| 5 | > |
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| 6 | NAME="GENERATOR" |
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| 7 | CONTENT="Modular DocBook HTML Stylesheet Version 1.64 |
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| 8 | "> |
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| 9 | REL="HOME" |
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| 10 | TITLE="SDL Library Documentation" |
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| 11 | HREF="index.html"> |
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| 12 | REL="UP" |
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| 13 | TITLE="Multi-threaded Programming" |
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| 14 | HREF="thread.html"> |
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| 15 | REL="PREVIOUS" |
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| 16 | TITLE="SDL_SemWait" |
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| 17 | HREF="sdlsemwait.html"> |
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| 18 | REL="NEXT" |
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| 19 | TITLE="SDL_SemWaitTimeout" |
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| 20 | HREF="sdlsemwaittimeout.html"> |
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| 21 | > |
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| 22 | CLASS="REFENTRY" |
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| 23 | BGCOLOR="#FFF8DC" |
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| 24 | TEXT="#000000" |
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| 25 | LINK="#0000ee" |
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| 26 | VLINK="#551a8b" |
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| 27 | ALINK="#ff0000" |
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| 28 | > |
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| 29 | CLASS="NAVHEADER" |
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| 30 | > |
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| 31 | WIDTH="100%" |
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| 32 | BORDER="0" |
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| 33 | CELLPADDING="0" |
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| 34 | CELLSPACING="0" |
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| 35 | > |
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| 36 | > |
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| 37 | COLSPAN="3" |
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| 38 | ALIGN="center" |
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| 39 | >SDL Library Documentation |
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| 40 | > |
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| 41 | > |
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| 42 | > |
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| 43 | WIDTH="10%" |
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| 44 | ALIGN="left" |
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| 45 | VALIGN="bottom" |
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| 46 | > |
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| 47 | HREF="sdlsemwait.html" |
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| 48 | >Prev |
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| 49 | > |
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| 50 | > |
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| 51 | WIDTH="80%" |
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| 52 | ALIGN="center" |
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| 53 | VALIGN="bottom" |
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| 54 | > |
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| 55 | > |
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| 56 | WIDTH="10%" |
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| 57 | ALIGN="right" |
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| 58 | VALIGN="bottom" |
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| 59 | > |
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| 60 | HREF="sdlsemwaittimeout.html" |
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| 61 | >Next |
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| 62 | > |
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| 63 | > |
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| 64 | > |
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| 65 | > |
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| 66 | ALIGN="LEFT" |
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| 67 | WIDTH="100%"> |
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| 68 | > |
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| 69 | > |
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| 70 | NAME="SDLSEMTRYWAIT" |
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| 71 | >SDL_SemTryWait |
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| 72 | > |
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| 73 | > |
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| 74 | CLASS="REFNAMEDIV" |
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| 75 | > |
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| 76 | NAME="AEN7520" |
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| 77 | > |
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| 78 | > |
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| 79 | >Name |
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| 80 | >SDL_SemTryWait -- Attempt to lock a semaphore but don't suspend the thread. |
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| 81 | > |
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| 82 | CLASS="REFSYNOPSISDIV" |
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| 83 | > |
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| 84 | NAME="AEN7523" |
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| 85 | > |
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| 86 | > |
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| 87 | >Synopsis |
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| 88 | > |
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| 89 | CLASS="FUNCSYNOPSIS" |
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| 90 | > |
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| 91 | NAME="AEN7524" |
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| 92 | > |
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| 93 | > |
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| 94 | > |
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| 95 | > |
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| 96 | CLASS="FUNCSYNOPSISINFO" |
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| 97 | >#include "SDL.h" |
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| 98 | #include "SDL_thread.h" |
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| 99 | > |
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| 100 | > |
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| 101 | > |
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| 102 | CLASS="FUNCDEF" |
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| 103 | >int |
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| 104 | CLASS="FSFUNC" |
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| 105 | >SDL_SemTryWait |
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| 106 | > |
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| 107 | >(SDL_sem *sem); |
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| 108 | > |
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| 109 | > |
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| 110 | > |
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| 111 | > |
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| 112 | > |
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| 113 | > |
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| 114 | CLASS="REFSECT1" |
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| 115 | > |
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| 116 | NAME="AEN7530" |
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| 117 | > |
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| 118 | > |
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| 119 | >Description |
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| 120 | > |
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| 121 | > |
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| 122 | CLASS="FUNCTION" |
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| 123 | >SDL_SemTryWait |
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| 124 | > is a non-blocking varient of |
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| 125 | |||
| 126 | HREF="sdlsemwait.html" |
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| 127 | > |
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| 128 | CLASS="FUNCTION" |
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| 129 | >SDL_SemWait |
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| 130 | > |
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| 131 | >. If the value of the semaphore |
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| 132 | pointed to by |
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| 133 | CLASS="PARAMETER" |
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| 134 | > |
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| 135 | >sem |
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| 136 | > |
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| 137 | > is positive it will atomically |
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| 138 | decrement the semaphore value and return 0, otherwise it will return |
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| 139 | |||
| 140 | CLASS="RETURNVALUE" |
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| 141 | >SDL_MUTEX_TIMEOUT |
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| 142 | > instead of suspending the thread. |
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| 143 | > |
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| 144 | >After |
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| 145 | CLASS="FUNCTION" |
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| 146 | >SDL_SemTryWait |
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| 147 | > is successful, the semaphore |
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| 148 | can be released and its count atomically incremented by a successful call to |
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| 149 | |||
| 150 | HREF="sdlsempost.html" |
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| 151 | >SDL_SemPost |
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| 152 | >. |
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| 153 | > |
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| 154 | > |
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| 155 | CLASS="REFSECT1" |
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| 156 | > |
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| 157 | NAME="AEN7541" |
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| 158 | > |
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| 159 | > |
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| 160 | >Return Value |
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| 161 | > |
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| 162 | >Returns |
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| 163 | CLASS="RETURNVALUE" |
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| 164 | >0 |
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| 165 | > if the semaphore was successfully locked or |
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| 166 | either |
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| 167 | CLASS="RETURNVALUE" |
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| 168 | >SDL_MUTEX_TIMEOUT |
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| 169 | > or |
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| 170 | CLASS="RETURNVALUE" |
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| 171 | >-1 |
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| 172 | > |
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| 173 | if the thread would have suspended or there was an error, respectivly. |
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| 174 | > |
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| 175 | >If the semaphore was not successfully locked, the semaphore will be unchanged. |
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| 176 | > |
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| 177 | > |
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| 178 | CLASS="REFSECT1" |
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| 179 | > |
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| 180 | NAME="AEN7548" |
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| 181 | > |
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| 182 | > |
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| 183 | >Examples |
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| 184 | > |
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| 185 | > |
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| 186 | CLASS="PROGRAMLISTING" |
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| 187 | >res = SDL_SemTryWait(my_sem); |
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| 188 | |||
| 189 | if (res == SDL_MUTEX_TIMEOUT) { |
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| 190 | return TRY_AGAIN; |
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| 191 | } |
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| 192 | if (res == -1) { |
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| 193 | return WAIT_ERROR; |
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| 194 | } |
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| 195 | |||
| 196 | ... |
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| 197 | |||
| 198 | SDL_SemPost(my_sem); |
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| 199 | > |
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| 200 | > |
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| 201 | > |
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| 202 | CLASS="REFSECT1" |
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| 203 | > |
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| 204 | NAME="AEN7552" |
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| 205 | > |
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| 206 | > |
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| 207 | >See Also |
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| 208 | > |
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| 209 | > |
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| 210 | HREF="sdlcreatesemaphore.html" |
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| 211 | > |
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| 212 | CLASS="FUNCTION" |
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| 213 | >SDL_CreateSemaphore |
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| 214 | > |
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| 215 | >, |
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| 216 | |||
| 217 | HREF="sdldestroysemaphore.html" |
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| 218 | > |
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| 219 | CLASS="FUNCTION" |
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| 220 | >SDL_DestroySemaphore |
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| 221 | > |
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| 222 | >, |
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| 223 | |||
| 224 | HREF="sdlsemwait.html" |
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| 225 | > |
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| 226 | CLASS="FUNCTION" |
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| 227 | >SDL_SemWait |
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| 228 | > |
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| 229 | >, |
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| 230 | |||
| 231 | HREF="sdlsemwaittimeout.html" |
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| 232 | > |
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| 233 | CLASS="FUNCTION" |
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| 234 | >SDL_SemWaitTimeout |
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| 235 | > |
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| 236 | >, |
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| 237 | |||
| 238 | HREF="sdlsempost.html" |
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| 239 | > |
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| 240 | CLASS="FUNCTION" |
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| 241 | >SDL_SemPost |
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| 242 | > |
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| 243 | >, |
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| 244 | |||
| 245 | HREF="sdlsemvalue.html" |
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| 246 | > |
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| 247 | CLASS="FUNCTION" |
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| 248 | >SDL_SemValue |
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| 249 | > |
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| 250 | > |
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| 251 | > |
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| 252 | > |
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| 253 | CLASS="NAVFOOTER" |
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| 254 | > |
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| 255 | ALIGN="LEFT" |
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| 256 | WIDTH="100%"> |
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| 257 | WIDTH="100%" |
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| 258 | BORDER="0" |
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| 259 | CELLPADDING="0" |
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| 260 | CELLSPACING="0" |
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| 261 | > |
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| 262 | > |
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| 263 | WIDTH="33%" |
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| 264 | ALIGN="left" |
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| 265 | VALIGN="top" |
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| 266 | > |
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| 267 | HREF="sdlsemwait.html" |
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| 268 | >Prev |
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| 269 | > |
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| 270 | > |
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| 271 | WIDTH="34%" |
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| 272 | ALIGN="center" |
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| 273 | VALIGN="top" |
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| 274 | > |
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| 275 | HREF="index.html" |
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| 276 | >Home |
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| 277 | > |
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| 278 | > |
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| 279 | WIDTH="33%" |
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| 280 | ALIGN="right" |
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| 281 | VALIGN="top" |
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| 282 | > |
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| 283 | HREF="sdlsemwaittimeout.html" |
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| 284 | >Next |
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| 285 | > |
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| 286 | > |
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| 287 | > |
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| 288 | > |
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| 289 | WIDTH="33%" |
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| 290 | ALIGN="left" |
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| 291 | VALIGN="top" |
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| 292 | >SDL_SemWait |
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| 293 | > |
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| 294 | WIDTH="34%" |
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| 295 | ALIGN="center" |
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| 296 | VALIGN="top" |
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| 297 | > |
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| 298 | HREF="thread.html" |
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| 299 | >Up |
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| 300 | > |
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| 301 | > |
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| 302 | WIDTH="33%" |
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| 303 | ALIGN="right" |
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| 304 | VALIGN="top" |
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| 305 | >SDL_SemWaitTimeout |
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| 306 | > |
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| 307 | > |
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| 308 | > |
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| 309 | > |
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| 310 | > |
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| 311 | > |