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| 5131 | clevermous | 1 | |
| 2 | > |
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| 3 | > |
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| 4 | >SDL_SemWait |
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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_DestroySemaphore" |
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| 17 | HREF="sdldestroysemaphore.html"> |
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| 18 | REL="NEXT" |
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| 19 | TITLE="SDL_SemTryWait" |
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| 20 | HREF="sdlsemtrywait.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="sdldestroysemaphore.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="sdlsemtrywait.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="SDLSEMWAIT" |
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| 71 | >SDL_SemWait |
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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="AEN7474" |
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| 77 | > |
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| 78 | > |
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| 79 | >Name |
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| 80 | >SDL_SemWait -- Lock a semaphore and suspend the thread if the semaphore value is zero. |
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| 81 | > |
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| 82 | CLASS="REFSYNOPSISDIV" |
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| 83 | > |
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| 84 | NAME="AEN7477" |
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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="AEN7478" |
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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_SemWait |
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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="AEN7484" |
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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_SemWait() |
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| 124 | > suspends the calling thread until either |
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| 125 | the semaphore pointed to by |
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| 126 | CLASS="PARAMETER" |
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| 127 | > |
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| 128 | >sem |
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| 129 | > |
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| 130 | > has a positive value, |
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| 131 | the call is interrupted by a signal or error. If the call is successful it |
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| 132 | will atomically decrement the semaphore value. |
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| 133 | > |
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| 134 | >After |
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| 135 | CLASS="FUNCTION" |
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| 136 | >SDL_SemWait() |
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| 137 | > is successful, the semaphore |
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| 138 | can be released and its count atomically incremented by a successful call to |
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| 139 | |||
| 140 | HREF="sdlsempost.html" |
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| 141 | >SDL_SemPost |
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| 142 | >. |
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| 143 | > |
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| 144 | > |
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| 145 | CLASS="REFSECT1" |
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| 146 | > |
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| 147 | NAME="AEN7492" |
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| 148 | > |
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| 149 | > |
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| 150 | >Return Value |
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| 151 | > |
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| 152 | >Returns |
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| 153 | CLASS="RETURNVALUE" |
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| 154 | >0 |
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| 155 | > if successful or |
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| 156 | |||
| 157 | CLASS="RETURNVALUE" |
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| 158 | >-1 |
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| 159 | > if there was an error (leaving the semaphore unchanged). |
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| 160 | > |
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| 161 | > |
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| 162 | CLASS="REFSECT1" |
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| 163 | > |
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| 164 | NAME="AEN7497" |
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| 165 | > |
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| 166 | > |
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| 167 | >Examples |
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| 168 | > |
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| 169 | > |
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| 170 | CLASS="PROGRAMLISTING" |
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| 171 | >if (SDL_SemWait(my_sem) == -1) { |
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| 172 | return WAIT_FAILED; |
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| 173 | } |
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| 174 | |||
| 175 | ... |
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| 176 | |||
| 177 | SDL_SemPost(my_sem); |
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| 178 | > |
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| 179 | > |
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| 180 | > |
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| 181 | CLASS="REFSECT1" |
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| 182 | > |
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| 183 | NAME="AEN7501" |
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| 184 | > |
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| 185 | > |
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| 186 | >See Also |
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| 187 | > |
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| 188 | > |
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| 189 | HREF="sdlcreatesemaphore.html" |
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| 190 | > |
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| 191 | CLASS="FUNCTION" |
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| 192 | >SDL_CreateSemaphore |
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| 193 | > |
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| 194 | >, |
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| 195 | |||
| 196 | HREF="sdldestroysemaphore.html" |
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| 197 | > |
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| 198 | CLASS="FUNCTION" |
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| 199 | >SDL_DestroySemaphore |
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| 200 | > |
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| 201 | >, |
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| 202 | |||
| 203 | HREF="sdlsemtrywait.html" |
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| 204 | > |
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| 205 | CLASS="FUNCTION" |
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| 206 | >SDL_SemTryWait |
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| 207 | > |
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| 208 | >, |
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| 209 | |||
| 210 | HREF="sdlsemwaittimeout.html" |
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| 211 | > |
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| 212 | CLASS="FUNCTION" |
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| 213 | >SDL_SemWaitTimeout |
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| 214 | > |
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| 215 | >, |
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| 216 | |||
| 217 | HREF="sdlsempost.html" |
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| 218 | > |
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| 219 | CLASS="FUNCTION" |
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| 220 | >SDL_SemPost |
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| 221 | > |
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| 222 | >, |
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| 223 | |||
| 224 | HREF="sdlsemvalue.html" |
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| 225 | > |
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| 226 | CLASS="FUNCTION" |
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| 227 | >SDL_SemValue |
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| 228 | > |
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| 229 | > |
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| 230 | > |
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| 231 | > |
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| 232 | CLASS="NAVFOOTER" |
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| 233 | > |
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| 234 | ALIGN="LEFT" |
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| 235 | WIDTH="100%"> |
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| 236 | WIDTH="100%" |
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| 237 | BORDER="0" |
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| 238 | CELLPADDING="0" |
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| 239 | CELLSPACING="0" |
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| 240 | > |
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| 241 | > |
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| 242 | WIDTH="33%" |
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| 243 | ALIGN="left" |
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| 244 | VALIGN="top" |
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| 245 | > |
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| 246 | HREF="sdldestroysemaphore.html" |
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| 247 | >Prev |
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| 248 | > |
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| 249 | > |
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| 250 | WIDTH="34%" |
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| 251 | ALIGN="center" |
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| 252 | VALIGN="top" |
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| 253 | > |
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| 254 | HREF="index.html" |
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| 255 | >Home |
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| 256 | > |
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| 257 | > |
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| 258 | WIDTH="33%" |
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| 259 | ALIGN="right" |
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| 260 | VALIGN="top" |
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| 261 | > |
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| 262 | HREF="sdlsemtrywait.html" |
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| 263 | >Next |
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| 264 | > |
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| 265 | > |
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| 266 | > |
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| 267 | > |
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| 268 | WIDTH="33%" |
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| 269 | ALIGN="left" |
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| 270 | VALIGN="top" |
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| 271 | >SDL_DestroySemaphore |
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| 272 | > |
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| 273 | WIDTH="34%" |
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| 274 | ALIGN="center" |
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| 275 | VALIGN="top" |
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| 276 | > |
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| 277 | HREF="thread.html" |
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| 278 | >Up |
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| 279 | > |
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| 280 | > |
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| 281 | WIDTH="33%" |
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| 282 | ALIGN="right" |
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| 283 | VALIGN="top" |
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| 284 | >SDL_SemTryWait |
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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 | > |
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| 290 | > |