source: downloads/boost_1_34_1/libs/thread/doc/xtime-ref.xml @ 35

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE library PUBLIC "-//Boost//DTD BoostBook XML V1.0//EN"
  "http://www.boost.org/tools/boostbook/dtd/boostbook.dtd" [
  <!ENTITY % thread.entities SYSTEM "entities.xml">
  %thread.entities;
]>
<!-- Copyright (c) 2002-2003 William E. Kempf, Michael Glassford
     Subject to the Boost Software License, Version 1.0. 
     (See accompanying file LICENSE-1.0 or  http://www.boost.org/LICENSE-1.0)
-->
<header name="boost/thread/xtime.hpp"
  last-revision="$Date: 2006/10/15 14:52:54 $">
  <namespace name="boost">
    <enum name="xtime_clock_types">
                <enumvalue name="TIME_UTC" />

                <purpose>
                        <para>Specifies the clock type to use when creating
                        an object of type <classname>xtime</classname>.</para>
                </purpose>

                <description>
                        <para>The only clock type supported by &Boost.Thread; is 
                        <code>TIME_UTC</code>. The epoch for <code>TIME_UTC</code>
                        is 1970-01-01 00:00:00.</para>
                </description>
        </enum>

    <struct name="xtime">
                <purpose>
                        <simpara>An object of type <classname>xtime</classname>
                        defines a time that is used to perform high-resolution time operations.
                        This is a temporary solution that will be replaced by a more robust time 
                        library once available in Boost.</simpara>
                </purpose>

                <description>
                        <simpara>The <classname>xtime</classname> type is used to represent a point on 
                        some time scale or a duration in time. This type may be proposed for the C standard by 
                        Markus Kuhn. &Boost.Thread; provides only a very minimal implementation of this
                        proposal; it is expected that a full implementation (or some other time
                        library) will be provided in Boost as a separate library, at which time &Boost.Thread;
                        will deprecate its own implementation.</simpara>
                        
                        <simpara><emphasis role="bold">Note</emphasis> that the resolution is 
                        implementation specific. For many implementations the best resolution 
                        of time is far more than one nanosecond, and even when the resolution 
                        is reasonably good, the latency of a call to <code>xtime_get()</code>
                        may be significant. For maximum portability, avoid durations of less than
                        one second.</simpara>
                </description>

                <free-function-group name="creation">
                        <function name="xtime_get">
                                <type>int</type>
                                
                                <parameter name="xtp">
                                        <paramtype><classname>xtime</classname>*</paramtype>
                                </parameter>

                                <parameter name="clock_type">
                                        <paramtype>int</paramtype>
                                </parameter>
                                
                                <postconditions>
                                        <simpara><code>xtp</code> represents the current point in
                                        time as a duration since the epoch specified by
                                        <code>clock_type</code>.</simpara>
                                </postconditions>
                                
                                <returns>
                                        <simpara><code>clock_type</code> if successful, otherwise 0.</simpara>
                                </returns>
                        </function>
                </free-function-group>

                <data-member name="sec">
                        <type><emphasis>platform-specific-type</emphasis></type>
                </data-member>
        </struct>
  </namespace>
</header>