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  26 <div class="titlepage"><div><div><h3 class="title">
  27 <a name="boost_asio.reference.SerialPortService"></a><a class="link" href="SerialPortService.html" title="Serial port service requirements">Serial port service
  28       requirements</a>
  29 </h3></div></div></div>
  30 <p>
  31         A serial port service must meet the requirements for an <a class="link" href="IoObjectService.html" title="I/O object service requirements">I/O
  32         object service</a> with support for movability, as well as the additional
  33         requirements listed below.
  34       </p>
  35 <p>
  36         In the table below, <code class="computeroutput"><span class="identifier">X</span></code> denotes
  37         a serial port service class, <code class="computeroutput"><span class="identifier">a</span></code>
  38         and <code class="computeroutput"><span class="identifier">ao</span></code> denote values of type
  39         <code class="computeroutput"><span class="identifier">X</span></code>, <code class="computeroutput"><span class="identifier">d</span></code>
  40         denotes a serial port device name of type <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span></code>,
  41         <code class="computeroutput"><span class="identifier">b</span></code> and <code class="computeroutput"><span class="identifier">c</span></code>
  42         denote values of type <code class="computeroutput"><span class="identifier">X</span><span class="special">::</span><span class="identifier">implementation_type</span></code>, <code class="computeroutput"><span class="identifier">n</span></code>
  43         denotes a value of type <code class="computeroutput"><span class="identifier">X</span><span class="special">::</span><span class="identifier">native_handle_type</span></code>,
  44         <code class="computeroutput"><span class="identifier">ec</span></code> denotes a value of type
  45         <code class="computeroutput"><span class="identifier">error_code</span></code>, <code class="computeroutput"><span class="identifier">s</span></code> denotes a value meeting <a class="link" href="SettableSerialPortOption.html" title="Settable serial port option requirements"><code class="computeroutput"><span class="identifier">SettableSerialPortOption</span></code></a> requirements,
  46         <code class="computeroutput"><span class="identifier">g</span></code> denotes a value meeting
  47         <a class="link" href="GettableSerialPortOption.html" title="Gettable serial port option requirements"><code class="computeroutput"><span class="identifier">GettableSerialPortOption</span></code></a> requirements,
  48         <code class="computeroutput"><span class="identifier">mb</span></code> denotes a value satisfying
  49         <a class="link" href="MutableBufferSequence.html" title="Mutable buffer sequence requirements">mutable buffer
  50         sequence</a> requirements, <code class="computeroutput"><span class="identifier">rh</span></code>
  51         denotes a value meeting <a class="link" href="ReadHandler.html" title="Read handler requirements"><code class="computeroutput"><span class="identifier">ReadHandler</span></code></a> requirements, <code class="computeroutput"><span class="identifier">cb</span></code> denotes a value satisfying <a class="link" href="ConstBufferSequence.html" title="Constant buffer sequence requirements">constant
  52         buffer sequence</a> requirements, and <code class="computeroutput"><span class="identifier">wh</span></code>
  53         denotes a value meeting <a class="link" href="WriteHandler.html" title="Write handler requirements"><code class="computeroutput"><span class="identifier">WriteHandler</span></code></a> requirements. and
  54         <code class="computeroutput"><span class="identifier">u</span></code> and <code class="computeroutput"><span class="identifier">v</span></code>
  55         denote identifiers.
  56       </p>
  57 <div class="table">
  58 <a name="boost_asio.reference.SerialPortService.t0"></a><p class="title"><b>Table&#160;25.&#160;SerialPortService requirements</b></p>
  59 <div class="table-contents"><table class="table" summary="SerialPortService requirements">
  60 <colgroup>
  61 <col>
  62 <col>
  63 <col>
  64 </colgroup>
  65 <thead><tr>
  66 <th>
  67                 <p>
  68                   expression
  69                 </p>
  70               </th>
  71 <th>
  72                 <p>
  73                   return type
  74                 </p>
  75               </th>
  76 <th>
  77                 <p>
  78                   assertion/note<br> pre/post-condition
  79                 </p>
  80               </th>
  81 </tr></thead>
  82 <tbody>
  83 <tr>
  84 <td>
  85                 <p>
  86                   <code class="computeroutput"><span class="identifier">X</span><span class="special">::</span><span class="identifier">native_handle_type</span></code>
  87                 </p>
  88               </td>
  89 <td>
  90               </td>
  91 <td>
  92                 <p>
  93                   The implementation-defined native representation of a serial port.
  94                   Must satisfy the requirements of <code class="computeroutput"><span class="identifier">CopyConstructible</span></code>
  95                   types (C++ Std, 20.1.3), and the requirements of <code class="computeroutput"><span class="identifier">Assignable</span></code> types (C++ Std, 23.1).
  96                 </p>
  97               </td>
  98 </tr>
  99 <tr>
 100 <td>
 101                 <p>
 102                   <code class="computeroutput"><span class="identifier">a</span><span class="special">.</span><span class="identifier">construct</span><span class="special">(</span><span class="identifier">b</span><span class="special">);</span></code>
 103                 </p>
 104               </td>
 105 <td>
 106               </td>
 107 <td>
 108                 <p>
 109                   From <a class="link" href="IoObjectService.html" title="I/O object service requirements">IoObjectService</a>
 110                   requirements.<br> post: <code class="computeroutput"><span class="special">!</span><span class="identifier">a</span><span class="special">.</span><span class="identifier">is_open</span><span class="special">(</span><span class="identifier">b</span><span class="special">)</span></code>.
 111                 </p>
 112               </td>
 113 </tr>
 114 <tr>
 115 <td>
 116                 <p>
 117                   <code class="computeroutput"><span class="identifier">a</span><span class="special">.</span><span class="identifier">destroy</span><span class="special">(</span><span class="identifier">b</span><span class="special">);</span></code>
 118                 </p>
 119               </td>
 120 <td>
 121               </td>
 122 <td>
 123                 <p>
 124                   From <a class="link" href="IoObjectService.html" title="I/O object service requirements">IoObjectService</a>
 125                   requirements. Implicitly cancels asynchronous operations, as if
 126                   by calling <code class="computeroutput"><span class="identifier">a</span><span class="special">.</span><span class="identifier">close</span><span class="special">(</span><span class="identifier">b</span><span class="special">,</span>
 127                   <span class="identifier">ec</span><span class="special">)</span></code>.
 128                 </p>
 129               </td>
 130 </tr>
 131 <tr>
 132 <td>
 133                 <p>
 134 </p>
 135 <pre class="programlisting"><span class="identifier">a</span><span class="special">.</span><span class="identifier">move_construct</span><span class="special">(</span><span class="identifier">b</span><span class="special">,</span> <span class="identifier">c</span><span class="special">);</span>
 136 </pre>
 137 <p>
 138                 </p>
 139               </td>
 140 <td>
 141               </td>
 142 <td>
 143                 <p>
 144                   From <a class="link" href="IoObjectService.html" title="I/O object service requirements">IoObjectService</a>
 145                   requirements. The underlying native representation is moved from
 146                   <code class="computeroutput"><span class="identifier">c</span></code> to <code class="computeroutput"><span class="identifier">b</span></code>.
 147                 </p>
 148               </td>
 149 </tr>
 150 <tr>
 151 <td>
 152                 <p>
 153 </p>
 154 <pre class="programlisting"><span class="identifier">a</span><span class="special">.</span><span class="identifier">move_assign</span><span class="special">(</span><span class="identifier">b</span><span class="special">,</span> <span class="identifier">ao</span><span class="special">,</span> <span class="identifier">c</span><span class="special">);</span>
 155 </pre>
 156 <p>
 157                 </p>
 158               </td>
 159 <td>
 160               </td>
 161 <td>
 162                 <p>
 163                   From <a class="link" href="IoObjectService.html" title="I/O object service requirements">IoObjectService</a>
 164                   requirements. Implicitly cancels asynchronous operations associated
 165                   with <code class="computeroutput"><span class="identifier">b</span></code>, as if by
 166                   calling <code class="computeroutput"><span class="identifier">a</span><span class="special">.</span><span class="identifier">close</span><span class="special">(</span><span class="identifier">b</span><span class="special">,</span>
 167                   <span class="identifier">ec</span><span class="special">)</span></code>.
 168                   Then the underlying native representation is moved from <code class="computeroutput"><span class="identifier">c</span></code> to <code class="computeroutput"><span class="identifier">b</span></code>.
 169                 </p>
 170               </td>
 171 </tr>
 172 <tr>
 173 <td>
 174                 <p>
 175 </p>
 176 <pre class="programlisting"><span class="keyword">const</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span><span class="special">&amp;</span> <span class="identifier">u</span> <span class="special">=</span> <span class="identifier">d</span><span class="special">;</span>
 177 <span class="identifier">a</span><span class="special">.</span><span class="identifier">open</span><span class="special">(</span><span class="identifier">b</span><span class="special">,</span> <span class="identifier">u</span><span class="special">,</span> <span class="identifier">ec</span><span class="special">);</span>
 178 </pre>
 179 <p>
 180                 </p>
 181               </td>
 182 <td>
 183                 <p>
 184                   <code class="computeroutput"><span class="identifier">error_code</span></code>
 185                 </p>
 186               </td>
 187 <td>
 188                 <p>
 189                   pre: <code class="computeroutput"><span class="special">!</span><span class="identifier">a</span><span class="special">.</span><span class="identifier">is_open</span><span class="special">(</span><span class="identifier">b</span><span class="special">)</span></code>.<br> post: <code class="computeroutput"><span class="special">!!</span><span class="identifier">ec</span> <span class="special">||</span>
 190                   <span class="identifier">a</span><span class="special">.</span><span class="identifier">is_open</span><span class="special">(</span><span class="identifier">b</span><span class="special">)</span></code>.
 191                 </p>
 192               </td>
 193 </tr>
 194 <tr>
 195 <td>
 196                 <p>
 197 </p>
 198 <pre class="programlisting"><span class="identifier">a</span><span class="special">.</span><span class="identifier">assign</span><span class="special">(</span><span class="identifier">b</span><span class="special">,</span> <span class="identifier">n</span><span class="special">,</span> <span class="identifier">ec</span><span class="special">);</span>
 199 </pre>
 200 <p>
 201                 </p>
 202               </td>
 203 <td>
 204                 <p>
 205                   <code class="computeroutput"><span class="identifier">error_code</span></code>
 206                 </p>
 207               </td>
 208 <td>
 209                 <p>
 210                   pre: <code class="computeroutput"><span class="special">!</span><span class="identifier">a</span><span class="special">.</span><span class="identifier">is_open</span><span class="special">(</span><span class="identifier">b</span><span class="special">)</span></code>.<br> post: <code class="computeroutput"><span class="special">!!</span><span class="identifier">ec</span> <span class="special">||</span>
 211                   <span class="identifier">a</span><span class="special">.</span><span class="identifier">is_open</span><span class="special">(</span><span class="identifier">b</span><span class="special">)</span></code>.
 212                 </p>
 213               </td>
 214 </tr>
 215 <tr>
 216 <td>
 217                 <p>
 218 </p>
 219 <pre class="programlisting"><span class="identifier">a</span><span class="special">.</span><span class="identifier">is_open</span><span class="special">(</span><span class="identifier">b</span><span class="special">);</span>
 220 </pre>
 221 <p>
 222                 </p>
 223               </td>
 224 <td>
 225                 <p>
 226                   <code class="computeroutput"><span class="keyword">bool</span></code>
 227                 </p>
 228               </td>
 229 <td>
 230               </td>
 231 </tr>
 232 <tr>
 233 <td>
 234                 <p>
 235 </p>
 236 <pre class="programlisting"><span class="keyword">const</span> <span class="identifier">X</span><span class="special">&amp;</span> <span class="identifier">u</span> <span class="special">=</span> <span class="identifier">a</span><span class="special">;</span>
 237 <span class="keyword">const</span> <span class="identifier">X</span><span class="special">::</span><span class="identifier">implementation_type</span><span class="special">&amp;</span> <span class="identifier">v</span> <span class="special">=</span> <span class="identifier">b</span><span class="special">;</span>
 238 <span class="identifier">u</span><span class="special">.</span><span class="identifier">is_open</span><span class="special">(</span><span class="identifier">v</span><span class="special">);</span>
 239 </pre>
 240 <p>
 241                 </p>
 242               </td>
 243 <td>
 244                 <p>
 245                   <code class="computeroutput"><span class="keyword">bool</span></code>
 246                 </p>
 247               </td>
 248 <td>
 249               </td>
 250 </tr>
 251 <tr>
 252 <td>
 253                 <p>
 254 </p>
 255 <pre class="programlisting"><span class="identifier">a</span><span class="special">.</span><span class="identifier">close</span><span class="special">(</span><span class="identifier">b</span><span class="special">,</span> <span class="identifier">ec</span><span class="special">);</span>
 256 </pre>
 257 <p>
 258                 </p>
 259               </td>
 260 <td>
 261                 <p>
 262                   <code class="computeroutput"><span class="identifier">error_code</span></code>
 263                 </p>
 264               </td>
 265 <td>
 266                 <p>
 267                   If <code class="computeroutput"><span class="identifier">a</span><span class="special">.</span><span class="identifier">is_open</span><span class="special">()</span></code>
 268                   is true, causes any outstanding asynchronous operations to complete
 269                   as soon as possible. Handlers for cancelled operations shall be
 270                   passed the error code <code class="computeroutput"><span class="identifier">error</span><span class="special">::</span><span class="identifier">operation_aborted</span></code>.<br>
 271                   post: <code class="computeroutput"><span class="special">!</span><span class="identifier">a</span><span class="special">.</span><span class="identifier">is_open</span><span class="special">(</span><span class="identifier">b</span><span class="special">)</span></code>.
 272                 </p>
 273               </td>
 274 </tr>
 275 <tr>
 276 <td>
 277                 <p>
 278 </p>
 279 <pre class="programlisting"><span class="identifier">a</span><span class="special">.</span><span class="identifier">native_handle</span><span class="special">(</span><span class="identifier">b</span><span class="special">);</span>
 280 </pre>
 281 <p>
 282                 </p>
 283               </td>
 284 <td>
 285                 <p>
 286                   <code class="computeroutput"><span class="identifier">X</span><span class="special">::</span><span class="identifier">native_handle_type</span></code>
 287                 </p>
 288               </td>
 289 <td>
 290               </td>
 291 </tr>
 292 <tr>
 293 <td>
 294                 <p>
 295 </p>
 296 <pre class="programlisting"><span class="identifier">a</span><span class="special">.</span><span class="identifier">cancel</span><span class="special">(</span><span class="identifier">b</span><span class="special">,</span> <span class="identifier">ec</span><span class="special">);</span>
 297 </pre>
 298 <p>
 299                 </p>
 300               </td>
 301 <td>
 302                 <p>
 303                   <code class="computeroutput"><span class="identifier">error_code</span></code>
 304                 </p>
 305               </td>
 306 <td>
 307                 <p>
 308                   pre: <code class="computeroutput"><span class="identifier">a</span><span class="special">.</span><span class="identifier">is_open</span><span class="special">(</span><span class="identifier">b</span><span class="special">)</span></code>.<br>
 309                   Causes any outstanding asynchronous operations to complete as soon
 310                   as possible. Handlers for cancelled operations shall be passed
 311                   the error code <code class="computeroutput"><span class="identifier">error</span><span class="special">::</span><span class="identifier">operation_aborted</span></code>.
 312                 </p>
 313               </td>
 314 </tr>
 315 <tr>
 316 <td>
 317                 <p>
 318 </p>
 319 <pre class="programlisting"><span class="identifier">a</span><span class="special">.</span><span class="identifier">set_option</span><span class="special">(</span><span class="identifier">b</span><span class="special">,</span> <span class="identifier">s</span><span class="special">,</span> <span class="identifier">ec</span><span class="special">);</span>
 320 </pre>
 321 <p>
 322                 </p>
 323               </td>
 324 <td>
 325                 <p>
 326                   <code class="computeroutput"><span class="identifier">error_code</span></code>
 327                 </p>
 328               </td>
 329 <td>
 330                 <p>
 331                   pre: <code class="computeroutput"><span class="identifier">a</span><span class="special">.</span><span class="identifier">is_open</span><span class="special">(</span><span class="identifier">b</span><span class="special">)</span></code>.
 332                 </p>
 333               </td>
 334 </tr>
 335 <tr>
 336 <td>
 337                 <p>
 338 </p>
 339 <pre class="programlisting"><span class="identifier">a</span><span class="special">.</span><span class="identifier">get_option</span><span class="special">(</span><span class="identifier">b</span><span class="special">,</span> <span class="identifier">g</span><span class="special">,</span> <span class="identifier">ec</span><span class="special">);</span>
 340 </pre>
 341 <p>
 342                 </p>
 343               </td>
 344 <td>
 345                 <p>
 346                   <code class="computeroutput"><span class="identifier">error_code</span></code>
 347                 </p>
 348               </td>
 349 <td>
 350                 <p>
 351                   pre: <code class="computeroutput"><span class="identifier">a</span><span class="special">.</span><span class="identifier">is_open</span><span class="special">(</span><span class="identifier">b</span><span class="special">)</span></code>.
 352                 </p>
 353               </td>
 354 </tr>
 355 <tr>
 356 <td>
 357                 <p>
 358 </p>
 359 <pre class="programlisting"><span class="keyword">const</span> <span class="identifier">X</span><span class="special">&amp;</span> <span class="identifier">u</span> <span class="special">=</span> <span class="identifier">a</span><span class="special">;</span>
 360 <span class="keyword">const</span> <span class="identifier">X</span><span class="special">::</span><span class="identifier">implementation_type</span><span class="special">&amp;</span> <span class="identifier">v</span> <span class="special">=</span> <span class="identifier">b</span><span class="special">;</span>
 361 <span class="identifier">u</span><span class="special">.</span><span class="identifier">get_option</span><span class="special">(</span><span class="identifier">v</span><span class="special">,</span> <span class="identifier">g</span><span class="special">,</span> <span class="identifier">ec</span><span class="special">);</span>
 362 </pre>
 363 <p>
 364                 </p>
 365               </td>
 366 <td>
 367                 <p>
 368                   <code class="computeroutput"><span class="identifier">error_code</span></code>
 369                 </p>
 370               </td>
 371 <td>
 372                 <p>
 373                   pre: <code class="computeroutput"><span class="identifier">a</span><span class="special">.</span><span class="identifier">is_open</span><span class="special">(</span><span class="identifier">b</span><span class="special">)</span></code>.
 374                 </p>
 375               </td>
 376 </tr>
 377 <tr>
 378 <td>
 379                 <p>
 380 </p>
 381 <pre class="programlisting"><span class="identifier">a</span><span class="special">.</span><span class="identifier">send_break</span><span class="special">(</span><span class="identifier">b</span><span class="special">,</span> <span class="identifier">ec</span><span class="special">);</span>
 382 </pre>
 383 <p>
 384                 </p>
 385               </td>
 386 <td>
 387                 <p>
 388                   <code class="computeroutput"><span class="identifier">error_code</span></code>
 389                 </p>
 390               </td>
 391 <td>
 392                 <p>
 393                   pre: <code class="computeroutput"><span class="identifier">a</span><span class="special">.</span><span class="identifier">is_open</span><span class="special">(</span><span class="identifier">b</span><span class="special">)</span></code>.
 394                 </p>
 395               </td>
 396 </tr>
 397 <tr>
 398 <td>
 399                 <p>
 400                   <code class="computeroutput"><span class="identifier">a</span><span class="special">.</span><span class="identifier">read_some</span><span class="special">(</span><span class="identifier">b</span><span class="special">,</span>
 401                   <span class="identifier">mb</span><span class="special">,</span>
 402                   <span class="identifier">ec</span><span class="special">);</span></code>
 403                 </p>
 404               </td>
 405 <td>
 406                 <p>
 407                   <code class="computeroutput"><span class="identifier">size_t</span></code>
 408                 </p>
 409               </td>
 410 <td>
 411                 <p>
 412                   pre: <code class="computeroutput"><span class="identifier">a</span><span class="special">.</span><span class="identifier">is_open</span><span class="special">(</span><span class="identifier">b</span><span class="special">)</span></code>.<br>
 413                   <br> Reads one or more bytes of data from a serial port <code class="computeroutput"><span class="identifier">b</span></code>.<br> <br> The mutable buffer
 414                   sequence <code class="computeroutput"><span class="identifier">mb</span></code> specifies
 415                   memory where the data should be placed. The operation shall always
 416                   fill a buffer in the sequence completely before proceeding to the
 417                   next.<br> <br> If successful, returns the number of bytes read.
 418                   Otherwise returns <code class="computeroutput"><span class="number">0</span></code>.
 419                   If the total size of all buffers in the sequence <code class="computeroutput"><span class="identifier">mb</span></code> is <code class="computeroutput"><span class="number">0</span></code>,
 420                   the function shall return <code class="computeroutput"><span class="number">0</span></code>
 421                   immediately.<br> <br> If the operation completes due to graceful
 422                   connection closure by the peer, the operation shall fail with
 423                   <code class="computeroutput"><span class="identifier">error</span><span class="special">::</span><span class="identifier">eof</span></code>.
 424                 </p>
 425               </td>
 426 </tr>
 427 <tr>
 428 <td>
 429                 <p>
 430                   <code class="computeroutput"><span class="identifier">a</span><span class="special">.</span><span class="identifier">async_read_some</span><span class="special">(</span><span class="identifier">b</span><span class="special">,</span>
 431                   <span class="identifier">mb</span><span class="special">,</span>
 432                   <span class="identifier">rh</span><span class="special">);</span></code>
 433                 </p>
 434               </td>
 435 <td>
 436                 <p>
 437                   <code class="computeroutput"><span class="keyword">void</span></code>
 438                 </p>
 439               </td>
 440 <td>
 441                 <p>
 442                   pre: <code class="computeroutput"><span class="identifier">a</span><span class="special">.</span><span class="identifier">is_open</span><span class="special">(</span><span class="identifier">b</span><span class="special">)</span></code>.<br>
 443                   <br> Initiates an asynchronous operation to read one or more
 444                   bytes of data from a serial port <code class="computeroutput"><span class="identifier">b</span></code>.
 445                   The operation is performed via the <code class="computeroutput"><span class="identifier">io_service</span></code>
 446                   object <code class="computeroutput"><span class="identifier">a</span><span class="special">.</span><span class="identifier">get_io_service</span><span class="special">()</span></code>
 447                   and behaves according to <a class="link" href="asynchronous_operations.html" title="Requirements on asynchronous operations">asynchronous
 448                   operation</a> requirements.<br> <br> The mutable buffer
 449                   sequence <code class="computeroutput"><span class="identifier">mb</span></code> specifies
 450                   memory where the data should be placed. The operation shall always
 451                   fill a buffer in the sequence completely before proceeding to the
 452                   next.<br> <br> The implementation shall maintain one or more
 453                   copies of <code class="computeroutput"><span class="identifier">mb</span></code> until
 454                   such time as the read operation no longer requires access to the
 455                   memory specified by the buffers in the sequence. The program must
 456                   ensure the memory is valid until:<br> <br> &#8212; the last copy of
 457                   <code class="computeroutput"><span class="identifier">mb</span></code> is destroyed,
 458                   or<br> <br> &#8212; the handler for the asynchronous operation is invoked,<br>
 459                   <br> whichever comes first. If the total size of all buffers
 460                   in the sequence <code class="computeroutput"><span class="identifier">mb</span></code>
 461                   is <code class="computeroutput"><span class="number">0</span></code>, the asynchronous
 462                   read operation shall complete immediately and pass <code class="computeroutput"><span class="number">0</span></code> as the argument to the handler
 463                   that specifies the number of bytes read.<br> <br> If the operation
 464                   completes due to graceful connection closure by the peer, the operation
 465                   shall fail with <code class="computeroutput"><span class="identifier">error</span><span class="special">::</span><span class="identifier">eof</span></code>.<br>
 466                   <br> If the operation completes successfully, the <code class="computeroutput"><span class="identifier">ReadHandler</span></code> object <code class="computeroutput"><span class="identifier">rh</span></code> is invoked with the number
 467                   of bytes transferred. Otherwise it is invoked with <code class="computeroutput"><span class="number">0</span></code>.
 468                 </p>
 469               </td>
 470 </tr>
 471 <tr>
 472 <td>
 473                 <p>
 474                   <code class="computeroutput"><span class="identifier">a</span><span class="special">.</span><span class="identifier">write_some</span><span class="special">(</span><span class="identifier">b</span><span class="special">,</span>
 475                   <span class="identifier">cb</span><span class="special">,</span>
 476                   <span class="identifier">ec</span><span class="special">);</span></code>
 477                 </p>
 478               </td>
 479 <td>
 480                 <p>
 481                   <code class="computeroutput"><span class="identifier">size_t</span></code>
 482                 </p>
 483               </td>
 484 <td>
 485                 <p>
 486                   pre: <code class="computeroutput"><span class="identifier">a</span><span class="special">.</span><span class="identifier">is_open</span><span class="special">(</span><span class="identifier">b</span><span class="special">)</span></code>.<br>
 487                   <br> Writes one or more bytes of data to a serial port <code class="computeroutput"><span class="identifier">b</span></code>.<br> <br> The constant
 488                   buffer sequence <code class="computeroutput"><span class="identifier">cb</span></code>
 489                   specifies memory where the data to be written is located. The operation
 490                   shall always write a buffer in the sequence completely before proceeding
 491                   to the next.<br> <br> If successful, returns the number of
 492                   bytes written. Otherwise returns <code class="computeroutput"><span class="number">0</span></code>.
 493                   If the total size of all buffers in the sequence <code class="computeroutput"><span class="identifier">cb</span></code> is <code class="computeroutput"><span class="number">0</span></code>,
 494                   the function shall return <code class="computeroutput"><span class="number">0</span></code>
 495                   immediately.
 496                 </p>
 497               </td>
 498 </tr>
 499 <tr>
 500 <td>
 501                 <p>
 502                   <code class="computeroutput"><span class="identifier">a</span><span class="special">.</span><span class="identifier">async_write_some</span><span class="special">(</span><span class="identifier">b</span><span class="special">,</span>
 503                   <span class="identifier">cb</span><span class="special">,</span>
 504                   <span class="identifier">wh</span><span class="special">);</span></code>
 505                 </p>
 506               </td>
 507 <td>
 508                 <p>
 509                   <code class="computeroutput"><span class="keyword">void</span></code>
 510                 </p>
 511               </td>
 512 <td>
 513                 <p>
 514                   pre: <code class="computeroutput"><span class="identifier">a</span><span class="special">.</span><span class="identifier">is_open</span><span class="special">(</span><span class="identifier">b</span><span class="special">)</span></code>.<br>
 515                   <br> Initiates an asynchronous operation to write one or more
 516                   bytes of data to a serial port <code class="computeroutput"><span class="identifier">b</span></code>.
 517                   The operation is performed via the <code class="computeroutput"><span class="identifier">io_service</span></code>
 518                   object <code class="computeroutput"><span class="identifier">a</span><span class="special">.</span><span class="identifier">get_io_service</span><span class="special">()</span></code>
 519                   and behaves according to <a class="link" href="asynchronous_operations.html" title="Requirements on asynchronous operations">asynchronous
 520                   operation</a> requirements.<br> <br> The constant buffer
 521                   sequence <code class="computeroutput"><span class="identifier">cb</span></code> specifies
 522                   memory where the data to be written is located. The operation shall
 523                   always write a buffer in the sequence completely before proceeding
 524                   to the next.<br> <br> The implementation shall maintain one
 525                   or more copies of <code class="computeroutput"><span class="identifier">cb</span></code>
 526                   until such time as the write operation no longer requires access
 527                   to the memory specified by the buffers in the sequence. The program
 528                   must ensure the memory is valid until:<br> <br> &#8212; the last copy
 529                   of <code class="computeroutput"><span class="identifier">cb</span></code> is destroyed,
 530                   or<br> <br> &#8212; the handler for the asynchronous operation is invoked,<br>
 531                   <br> whichever comes first. If the total size of all buffers
 532                   in the sequence <code class="computeroutput"><span class="identifier">cb</span></code>
 533                   is <code class="computeroutput"><span class="number">0</span></code>, the asynchronous
 534                   operation shall complete immediately and pass <code class="computeroutput"><span class="number">0</span></code>
 535                   as the argument to the handler that specifies the number of bytes
 536                   read.<br> <br> If the operation completes successfully, the
 537                   <code class="computeroutput"><span class="identifier">WriteHandler</span></code> object
 538                   <code class="computeroutput"><span class="identifier">wh</span></code> is invoked with
 539                   the number of bytes transferred. Otherwise it is invoked with
 540                   <code class="computeroutput"><span class="number">0</span></code>.
 541                 </p>
 542               </td>
 543 </tr>
 544 </tbody>
 545 </table></div>
 546 </div>
 547 <br class="table-break">
 548 </div>
 549 <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
 550 <td align="left"></td>
 551 <td align="right"><div class="copyright-footer">Copyright &#169; 2003-2014 Christopher M. Kohlhoff<p>
 552         Distributed under the Boost Software License, Version 1.0. (See accompanying
 553         file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
 554       </p>
 555 </div></td>
 556 </tr></table>
 557 <hr>
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