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  81 CLASS="SECT1"
  82 ><H1
  83 CLASS="SECT1"
  84 ><A
  85 NAME="POSIX-SYNCHRONIZATION">Synchronization &#0091;POSIX Section 11&#0093;</H1
  86 ><DIV
  87 CLASS="SECT2"
  88 ><H2
  89 CLASS="SECT2"
  90 ><A
  91 NAME="AEN13150">Functions Implemented</H2
  92 ><TABLE
  93 BORDER="5"
  94 BGCOLOR="#E0E0F0"
  95 WIDTH="70%"
  96 ><TR
  97 ><TD
  98 ><PRE
  99 CLASS="SCREEN"
 100 >int sem&#0095;init(sem&#0095;t &#0042;sem, int pshared, unsigned int value);
 101 int sem&#0095;destroy(sem&#0095;t &#0042;sem);
 102 int sem&#0095;wait(sem&#0095;t &#0042;sem);
 103 int sem&#0095;trywait(sem&#0095;t &#0042;sem);
 104 int sem&#0095;post(sem&#0095;t &#0042;sem);
 105 int sem&#0095;getvalue(sem&#0095;t &#0042;sem, int &#0042;sval);
 106 int pthread&#0095;mutexattr&#0095;init( pthread&#0095;mutexattr&#0095;t &#0042;attr);
 107 int pthread&#0095;mutexattr&#0095;destroy( pthread&#0095;mutexattr&#0095;t &#0042;attr);
 108 int pthread&#0095;mutex&#0095;init(pthread&#0095;mutex&#0095;t &#0042;mutex,
 109                        const pthread&#0095;mutexattr&#0095;t &#0042;mutex&#0095;attr);
 110 int pthread&#0095;mutex&#0095;destroy(pthread&#0095;mutex&#0095;t &#0042;mutex);
 111 int pthread&#0095;mutex&#0095;lock(pthread&#0095;mutex&#0095;t &#0042;mutex);
 112 int pthread&#0095;mutex&#0095;trylock(pthread&#0095;mutex&#0095;t &#0042;mutex);
 113 int pthread&#0095;mutex&#0095;unlock(pthread&#0095;mutex&#0095;t &#0042;mutex);
 114 int pthread&#0095;condattr&#0095;init(pthread&#0095;condattr&#0095;t &#0042;attr);
 115 int pthread&#0095;condattr&#0095;destroy(pthread&#0095;condattr&#0095;t &#0042;attr);
 116 int pthread&#0095;cond&#0095;init(pthread&#0095;cond&#0095;t &#0042;cond,
 117                        const pthread&#0095;condattr&#0095;t &#0042;attr);
 118 int pthread&#0095;cond&#0095;destroy(pthread&#0095;cond&#0095;t &#0042;cond);
 119 int pthread&#0095;cond&#0095;signal(pthread&#0095;cond&#0095;t &#0042;cond);
 120 int pthread&#0095;cond&#0095;broadcast(pthread&#0095;cond&#0095;t &#0042;cond);
 121 int pthread&#0095;cond&#0095;wait(pthread&#0095;cond&#0095;t &#0042;cond,
 122                        pthread&#0095;mutex&#0095;t &#0042;mutex);
 123 int pthread&#0095;cond&#0095;timedwait(pthread&#0095;cond&#0095;t &#0042;cond,
 124                            pthread&#0095;mutex&#0095;t &#0042;mutex,
 125                            const struct timespec &#0042;abstime);</PRE
 126 ></TD
 127 ></TR
 128 ></TABLE
 129 ></DIV
 130 ><DIV
 131 CLASS="SECT2"
 132 ><H2
 133 CLASS="SECT2"
 134 ><A
 135 NAME="AEN13153">Functions Omitted</H2
 136 ><TABLE
 137 BORDER="5"
 138 BGCOLOR="#E0E0F0"
 139 WIDTH="70%"
 140 ><TR
 141 ><TD
 142 ><PRE
 143 CLASS="SCREEN"
 144 >sem&#0095;t &#0042;sem&#0095;open(const char &#0042;name, int oflag, ...);             &#0047;&#0047; TBA
 145 int sem&#0095;close(sem&#0095;t &#0042;sem);                                    &#0047;&#0047; TBA
 146 int sem&#0095;unlink(const char &#0042;name);                           &#0047;&#0047; TBA
 147 int pthread&#0095;mutexattr&#0095;getpshared( const pthread&#0095;mutexattr&#0095;t &#0042;attr,
 148                                   int &#0042;pshared );
 149 int pthread&#0095;mutexattr&#0095;setpshared( const pthread&#0095;mutexattr&#0095;t &#0042;attr,
 150                                   int pshared );
 151 int  pthread&#0095;condattr&#0095;getpshared( const pthread&#0095;condattr&#0095;t &#0042;attr,
 152                                   int &#0042;pshared);
 153 int  pthread&#0095;condattr&#0095;setpshared( const pthread&#0095;condattr&#0095;t &#0042;attr,
 154                                   int pshared);</PRE
 155 ></TD
 156 ></TR
 157 ></TABLE
 158 ></DIV
 159 ><DIV
 160 CLASS="SECT2"
 161 ><H2
 162 CLASS="SECT2"
 163 ><A
 164 NAME="AEN13156">Notes</H2
 165 ><P
 166 ></P
 167 ><UL
 168 ><LI
 169 ><P
 170 >           The presence of semaphores is controlled by the
 171             CYGPKG&#0095;POSIX&#0095;SEMAPHORES option. This in turn
 172             causes the &#0095;POSIX&#0095;SEMAPHORES feature test
 173             macro to be defined and the semaphore API to be made
 174             available.
 175             </P
 176 ></LI
 177 ><LI
 178 ><P
 179 >           The <SPAN
 180 CLASS="strong"
 181 ><B
 182 CLASS="EMPHASIS"
 183 >pshared</B
 184 ></SPAN
 185 > argument to
 186             <SPAN
 187 CLASS="emphasis"
 188 ><I
 189 CLASS="EMPHASIS"
 190 >sem&#0095;init()</I
 191 ></SPAN
 192 > is not implemented,
 193             its value is ignored.
 194             </P
 195 ></LI
 196 ><LI
 197 ><P
 198 >           Functions <SPAN
 199 CLASS="emphasis"
 200 ><I
 201 CLASS="EMPHASIS"
 202 >sem&#0095;open()</I
 203 ></SPAN
 204 >,
 205             <SPAN
 206 CLASS="emphasis"
 207 ><I
 208 CLASS="EMPHASIS"
 209 >sem&#0095;close()</I
 210 ></SPAN
 211 > and
 212             <SPAN
 213 CLASS="emphasis"
 214 ><I
 215 CLASS="EMPHASIS"
 216 >sem&#0095;unlink()</I
 217 ></SPAN
 218 > are present but
 219             always return an error (ENOSYS).
 220             </P
 221 ></LI
 222 ><LI
 223 ><P
 224 >           The exact priority inversion protocols supported may be
 225             controlled with the
 226             &#0095;POSIX&#0095;THREAD&#0095;PRIO&#0095;INHERIT and
 227             &#0095;POSIX&#0095;THREAD&#0095;PRIO&#0095;PROTECT
 228             configuration options.
 229             </P
 230 ></LI
 231 ><LI
 232 ><P
 233 >           &#0123;&#0095;POSIX&#0095;THREAD&#0095;PROCESS&#0095;SHARED&#0125; is
 234             not defined, so the
 235             <SPAN
 236 CLASS="strong"
 237 ><B
 238 CLASS="EMPHASIS"
 239 >process-shared</B
 240 ></SPAN
 241 > mutex
 242             and condition variable attributes are not supported, and
 243             neither are the functions
 244             <SPAN
 245 CLASS="emphasis"
 246 ><I
 247 CLASS="EMPHASIS"
 248 >pthread&#0095;mutexattr&#0095;getpshared()</I
 249 ></SPAN
 250 >,
 251             <SPAN
 252 CLASS="emphasis"
 253 ><I
 254 CLASS="EMPHASIS"
 255 >pthread&#0095;mutexattr&#0095;setpshared()</I
 256 ></SPAN
 257 >,
 258             <SPAN
 259 CLASS="emphasis"
 260 ><I
 261 CLASS="EMPHASIS"
 262 >pthread&#0095;condattr&#0095;getpshared()</I
 263 ></SPAN
 264 > and
 265             <SPAN
 266 CLASS="emphasis"
 267 ><I
 268 CLASS="EMPHASIS"
 269 >pthread&#0095;condattr&#0095;setpshared()</I
 270 ></SPAN
 271 >.
 272             </P
 273 ></LI
 274 ><LI
 275 ><P
 276 >           Condition variables do not become bound to a particular
 277             mutex when
 278             <SPAN
 279 CLASS="emphasis"
 280 ><I
 281 CLASS="EMPHASIS"
 282 >pthread&#0095;cond&#0095;wait()</I
 283 ></SPAN
 284 > is
 285             called. Hence different threads may wait on a condition
 286             variable with different mutexes. This is at variance with
 287             the standard, which requires a condition variable to
 288             become (dynamically) bound by the first waiter, and
 289             unbound when the last finishes. However, this difference
 290             is largely benign, and the cost of policing this feature
 291             is non-trivial.
 292           </P
 293 ></LI
 294 ></UL
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