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<div class="toc"><dl>
<dt><span class="section"><a href="appendices.html#chrono.appendices.history">Appendix: History</a></span></dt>
<dt><span class="section"><a href="appendices.html#chrono.appendices.rationale">Appendix: Rationale</a></span></dt>
<dt><span class="section"><a href="appendices.html#chrono.appendices.implementation">Appendix: Implementation
Notes</a></span></dt>
<dt><span class="section"><a href="appendices.html#chrono.appendices.faq">Appendix: FAQ</a></span></dt>
<dt><span class="section"><a href="appendices.html#chrono.appendices.acknowledgements">Appendix: Acknowledgements</a></span></dt>
<dt><span class="section"><a href="appendices.html#chrono.appendices.todo">Appendix: Future plans</a></span></dt>
</dl></div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="chrono.appendices.history"></a><a class="link" href="appendices.html#chrono.appendices.history" title="Appendix: History">Appendix: History</a>
</h3></div></div></div>
<div class="toc"><dl>
<dt><span class="section"><a href="appendices.html#chrono.appendices.history.__version_1_2_3__august_1__2012___1_51__"><span class="bold"><strong>Version 1.2.3, August 1, 2012 - 1.51</strong></span> </a></span></dt>
<dt><span class="section"><a href="appendices.html#chrono.appendices.history.__version_1_2_2__april_1__2012___1_50__"><span class="bold"><strong>Version 1.2.2, April 1, 2012 - 1.50</strong></span> </a></span></dt>
<dt><span class="section"><a href="appendices.html#chrono.appendices.history.__version_1_2_1__february_1__2012___1_49__"><span class="bold"><strong>Version 1.2.1, February 1, 2012 - 1.49</strong></span> </a></span></dt>
<dt><span class="section"><a href="appendices.html#chrono.appendices.history.__version_1_2_0__october_17__2011___1_48___"><span class="bold"><strong>Version 1.2.0, October 17, 2011 - 1.48 </strong></span> </a></span></dt>
<dt><span class="section"><a href="appendices.html#chrono.appendices.history.__version_1_1_0__mars_17__2011___1_47__"><span class="bold"><strong>Version 1.1.0, Mars 17, 2011 - 1.47</strong></span> </a></span></dt>
<dt><span class="section"><a href="appendices.html#chrono.appendices.history.__version_1_0_0__january_6__2011__"><span class="bold"><strong>Version 1.0.0, January 6, 2011</strong></span> </a></span></dt>
</dl></div>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="chrono.appendices.history.__version_1_2_3__august_1__2012___1_51__"></a><a class="link" href="appendices.html#chrono.appendices.history.__version_1_2_3__august_1__2012___1_51__" title="Version 1.2.3, August 1, 2012 - 1.51"><span class="bold"><strong>Version 1.2.3, August 1, 2012 - 1.51</strong></span> </a>
</h4></div></div></div>
<p>
<span class="bold"><strong>Fixes:</strong></span>
</p>
<div class="itemizedlist"><ul class="itemizedlist" type="disc">
<li class="listitem">
<a href="http://svn.boost.org/trac/boost/ticket/6918" target="_top">#6918</a>
Boost Chrono compilation failure on HP uX due to undefined pthread_getcpuclockid.
</li>
<li class="listitem">
<a href="http://svn.boost.org/trac/boost/ticket/6241" target="_top">#6241</a>
boost::chrono compilation problems without std::wstring support.
</li>
<li class="listitem">
<a href="http://svn.boost.org/trac/boost/ticket/6987" target="_top">#6987</a>
Documentation & C++11.
</li>
<li class="listitem">
<a href="http://svn.boost.org/trac/boost/ticket/7041" target="_top">#7041</a>
time_point.hpp depends on Boost.System.
</li>
<li class="listitem">
<a href="http://svn.boost.org/trac/boost/ticket/7042" target="_top">#7042</a>
Avoiding time_point and duration dependency on time.h and CLOCK_REALTIME.
</li>
<li class="listitem">
<a href="http://svn.boost.org/trac/boost/ticket/7058" target="_top">#7058</a>
Make it work when BOOST_NO_EXCEPTIONS is defined.
</li>
<li class="listitem">
<a href="http://svn.boost.org/trac/boost/ticket/7069" target="_top">#7069</a>
Misspellings in clock_string<thread_clock>.
</li>
<li class="listitem">
<a href="http://svn.boost.org/trac/boost/ticket/7081" target="_top">#7081</a>
WinError.h capitalization in boost/detail/win/basic_types.hpp.
</li>
</ul></div>
</div>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="chrono.appendices.history.__version_1_2_2__april_1__2012___1_50__"></a><a class="link" href="appendices.html#chrono.appendices.history.__version_1_2_2__april_1__2012___1_50__" title="Version 1.2.2, April 1, 2012 - 1.50"><span class="bold"><strong>Version 1.2.2, April 1, 2012 - 1.50</strong></span> </a>
</h4></div></div></div>
<p>
<span class="bold"><strong>Fixes:</strong></span>
</p>
<div class="itemizedlist"><ul class="itemizedlist" type="disc">
<li class="listitem">
<a href="http://svn.boost.org/trac/boost/ticket/6361" target="_top">#6361</a>
integer overflow in boost::chrono::process_real_cpu_clock::now() under
Windows 32bits.
</li>
<li class="listitem">
<a href="http://svn.boost.org/trac/boost/ticket/6628" target="_top">#6628</a>
compiler warning in process_cpu_clocks.hpp.
</li>
<li class="listitem">
<a href="http://svn.boost.org/trac/boost/ticket/6666" target="_top">#6666</a>
thread_clock.hpp needs pthread.h.
</li>
</ul></div>
</div>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="chrono.appendices.history.__version_1_2_1__february_1__2012___1_49__"></a><a class="link" href="appendices.html#chrono.appendices.history.__version_1_2_1__february_1__2012___1_49__" title="Version 1.2.1, February 1, 2012 - 1.49"><span class="bold"><strong>Version 1.2.1, February 1, 2012 - 1.49</strong></span> </a>
</h4></div></div></div>
<p>
<span class="bold"><strong>Fixes:</strong></span>
</p>
<div class="itemizedlist"><ul class="itemizedlist" type="disc">
<li class="listitem">
<a href="http://svn.boost.org/trac/boost/ticket/6092" target="_top">#6092</a>
Input from non integral durations makes the compiler fail.
</li>
<li class="listitem">
<a href="http://svn.boost.org/trac/boost/ticket/6093" target="_top">#6093</a>
[1/3]second fails as valid duration input.
</li>
<li class="listitem">
<a href="http://svn.boost.org/trac/boost/ticket/6113" target="_top">#6113</a>
duplicate symbol when BOOST_CHRONO_HEADER_ONLY is defined.
</li>
<li class="listitem">
<a href="http://svn.boost.org/trac/boost/ticket/6243" target="_top">#6243</a>
Sandia-pgi-11.9: more than one instance of overloaded function "min"
matches.
</li>
<li class="listitem">
<a href="http://svn.boost.org/trac/boost/ticket/6257" target="_top">#6257</a>
process_cpu_clock::now() on linux gives time_points 1/1000 times.
</li>
</ul></div>
</div>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="chrono.appendices.history.__version_1_2_0__october_17__2011___1_48___"></a><a class="link" href="appendices.html#chrono.appendices.history.__version_1_2_0__october_17__2011___1_48___" title="Version 1.2.0, October 17, 2011 - 1.48"><span class="bold"><strong>Version 1.2.0, October 17, 2011 - 1.48 </strong></span> </a>
</h4></div></div></div>
<p>
<span class="bold"><strong>New Features:</strong></span>
</p>
<div class="itemizedlist"><ul class="itemizedlist" type="disc">
<li class="listitem">
<a href="http://svn.boost.org/trac/boost/ticket/5979" target="_top">#5979</a>
Added chrono rounding utilities as defined By Howard Hinnant <a href="http://home.roadrunner.com/~hinnant/duration_io/chrono_util.html" target="_top">here</a>.
</li>
<li class="listitem">
<a href="http://svn.boost.org/trac/boost/ticket/5978" target="_top">#5978</a>
Add BOOST_CHRONO_HAS_PROCESS_CLOCKS to know if process clocks are available.
</li>
<li class="listitem">
<a href="http://svn.boost.org/trac/boost/ticket/5998" target="_top">#5998</a>
Make possible to don't provide hybrid error handling.
</li>
<li class="listitem">
<a href="http://svn.boost.org/trac/boost/ticket/5906" target="_top">#5906</a>
Take in account the constexpr as defined in the standard.
</li>
<li class="listitem">
<a href="http://svn.boost.org/trac/boost/ticket/5907" target="_top">#5907</a>
Take in account noexcept for compilers supporting it.
</li>
</ul></div>
<p>
<span class="bold"><strong>Fixes:</strong></span>
</p>
<div class="itemizedlist"><ul class="itemizedlist" type="disc">
<li class="listitem">
<a href="http://svn.boost.org/trac/boost/ticket/5669" target="_top">#5669</a>
Intel compiler failure to compile duration.hpp
</li>
<li class="listitem">
<a href="http://svn.boost.org/trac/boost/ticket/2114" target="_top">#2114</a>
Enable visibility support (Boost.Chrono part)
</li>
<li class="listitem">
<a href="http://svn.boost.org/trac/boost/ticket/5909" target="_top">#5909</a>
process_cpu_clock::now() on MAC gives time_points 1/1000 times.
</li>
<li class="listitem">
<a href="http://svn.boost.org/trac/boost/ticket/5946" target="_top">#5946</a>
Process real cpu clock returns the system steady clock (windows).
</li>
<li class="listitem">
<a href="http://svn.boost.org/trac/boost/ticket/5974" target="_top">#5974</a>
Process real cpu clock should use clock() instead of times() in MAC
which is twice faster and have better resolution.
</li>
</ul></div>
<p>
<span class="bold"><strong>Cleanup:</strong></span>
</p>
<div class="itemizedlist"><ul class="itemizedlist" type="disc">
<li class="listitem">
<a href="http://svn.boost.org/trac/boost/ticket/5975" target="_top">#5975</a>
Reduce the combinations of header-only, shared, static link to reduce
test time by 50%.
</li>
<li class="listitem">
<a href="http://svn.boost.org/trac/boost/ticket/5976" target="_top">#5976</a>
chrono_accuracy_test is not deterministic and should be removed from
the regression tests
</li>
<li class="listitem">
<a href="http://svn.boost.org/trac/boost/ticket/5977" target="_top">#5977</a>
Remove old files from Beman's version. Some old files included in the
Beman's version and not documented in the reviewed version that have
been definitely removed from the repository as
<div class="itemizedlist"><ul class="itemizedlist" type="circle">
<li class="listitem">
boost/chrono/timer.hpp,
</li>
<li class="listitem">
boost/chrono/process_times.hpp
</li>
<li class="listitem">
boost/chrono/detail/process_clock.hpp,
</li>
<li class="listitem">
boost/chrono/detail/mac/process_clock.hpp,
</li>
<li class="listitem">
boost/chrono/detail/posix/process_clock.hpp,
</li>
<li class="listitem">
boost/chrono/detail/win/process_clock.hpp,
</li>
<li class="listitem">
boost/chrono/detail/run_timer.hpp,
</li>
<li class="listitem">
boost/chrono/detail/run_timer_static.hpp,
</li>
</ul></div>
</li>
</ul></div>
</div>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="chrono.appendices.history.__version_1_1_0__mars_17__2011___1_47__"></a><a class="link" href="appendices.html#chrono.appendices.history.__version_1_1_0__mars_17__2011___1_47__" title="Version 1.1.0, Mars 17, 2011 - 1.47"><span class="bold"><strong>Version 1.1.0, Mars 17, 2011 - 1.47</strong></span> </a>
</h4></div></div></div>
<p>
<span class="bold"><strong>New Features:</strong></span>
</p>
<div class="itemizedlist"><ul class="itemizedlist" type="disc">
<li class="listitem">
<a href="http://svn.boost.org/trac/boost/ticket/????" target="_top">#????</a>
Added time_point unary operators +,-,++,-- and binary operators +<code class="literal">,-</code>
with Rep al RHS.
</li>
<li class="listitem">
<a href="http://svn.boost.org/trac/boost/ticket/5323" target="_top">#5323</a>
Add Associated type difference_type for chrono::time_point.
</li>
</ul></div>
<p>
<span class="bold"><strong>Fixes:</strong></span>
</p>
<div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem">
<a href="http://svn.boost.org/trac/boost/ticket/5322" target="_top">#5322</a>
Explicit default constructed chrono::durations are uninitialized
</li></ul></div>
</div>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="chrono.appendices.history.__version_1_0_0__january_6__2011__"></a><a class="link" href="appendices.html#chrono.appendices.history.__version_1_0_0__january_6__2011__" title="Version 1.0.0, January 6, 2011"><span class="bold"><strong>Version 1.0.0, January 6, 2011</strong></span> </a>
</h4></div></div></div>
<div class="itemizedlist"><ul class="itemizedlist" type="disc">
<li class="listitem">
Moved chrono to trunk taking in account the review remarks.
</li>
<li class="listitem">
Documentation revision.
</li>
</ul></div>
<p>
<span class="bold"><strong>Features:</strong></span>
</p>
<div class="itemizedlist"><ul class="itemizedlist" type="disc">
<li class="listitem">
Boost_Chrono is now a configurable header-only library version (that
also allows the user to choose if the <code class="computeroutput"><span class="identifier">windows</span><span class="special">.</span><span class="identifier">h</span></code>
file is included or not).
</li>
<li class="listitem">
Added clock_string<> traits.
</li>
<li class="listitem">
Define chrono-io for all the clocks.
</li>
<li class="listitem">
Add input of process_times representation.
</li>
</ul></div>
<p>
<span class="bold"><strong>Implementation:</strong></span>
</p>
<div class="itemizedlist"><ul class="itemizedlist" type="disc">
<li class="listitem">
Use of detail/win files to avoid the use of windows.h file.
</li>
<li class="listitem">
Completed the error_code handling.
</li>
<li class="listitem">
Works now with BOOST_SYSTEM_NO_DEPRECATED.
</li>
</ul></div>
<p>
<span class="bold"><strong>Fixes:</strong></span>
</p>
<div class="itemizedlist"><ul class="itemizedlist" type="disc">
<li class="listitem">
Fix some warnings.
</li>
<li class="listitem">
Fix original errors on Mac
</li>
<li class="listitem">
Don't fix the link with boost_system to static.
</li>
</ul></div>
<p>
<span class="bold"><strong>Test:</strong></span>
</p>
<div class="itemizedlist"><ul class="itemizedlist" type="disc">
<li class="listitem">
Added test on process and thread clocks.
</li>
<li class="listitem">
Moved to lightweight_test.hpp.
</li>
<li class="listitem">
Able to test multiple configurations.
</li>
</ul></div>
<p>
<span class="bold"><strong>Doc:</strong></span>
</p>
<div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem">
Removed some not useful parts as the test and the tickets.
</li></ul></div>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="chrono.appendices.rationale"></a><a class="link" href="appendices.html#chrono.appendices.rationale" title="Appendix: Rationale">Appendix: Rationale</a>
</h3></div></div></div>
<p>
See <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2008/n2661.htm" target="_top"><span class="bold"><strong>N2661 - A Foundation to Sleep On</strong></span></a> which is
very informative and provides motivation for key design decisions. This section
contains some extracts from this document.
</p>
<h5>
<a name="chrono.appendices.rationale.h0"></a>
<span><a name="chrono.appendices.rationale.why_duration_needs_operator_"></a></span><a class="link" href="appendices.html#chrono.appendices.rationale.why_duration_needs_operator_">Why duration
needs operator%</a>
</h5>
<p>
This operator is convenient for computing where in a time frame a given duration
lies. A motivating example is converting a duration into a "broken-down"
time duration such as hours::minutes::seconds:
</p>
<pre class="programlisting"><span class="keyword">class</span> <span class="identifier">ClockTime</span>
<span class="special">{</span>
<span class="keyword">typedef</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">hours</span> <span class="identifier">hours</span><span class="special">;</span>
<span class="keyword">typedef</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">minutes</span> <span class="identifier">minutes</span><span class="special">;</span>
<span class="keyword">typedef</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">seconds</span> <span class="identifier">seconds</span><span class="special">;</span>
<span class="keyword">public</span><span class="special">:</span>
<span class="identifier">hours</span> <span class="identifier">hours_</span><span class="special">;</span>
<span class="identifier">minutes</span> <span class="identifier">minutes_</span><span class="special">;</span>
<span class="identifier">seconds</span> <span class="identifier">seconds_</span><span class="special">;</span>
<span class="keyword">template</span> <span class="special"><</span><span class="keyword">class</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Period</span><span class="special">></span>
<span class="keyword">explicit</span> <span class="identifier">ClockTime</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span><span class="special"><</span><span class="identifier">Rep</span><span class="special">,</span> <span class="identifier">Period</span><span class="special">>&</span> <span class="identifier">d</span><span class="special">)</span>
<span class="special">:</span> <span class="identifier">hours_</span> <span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration_cast</span><span class="special"><</span><span class="identifier">hours</span><span class="special">></span> <span class="special">(</span><span class="identifier">d</span><span class="special">)),</span>
<span class="identifier">minutes_</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration_cast</span><span class="special"><</span><span class="identifier">minutes</span><span class="special">>(</span><span class="identifier">d</span> <span class="special">%</span> <span class="identifier">hours</span><span class="special">(</span><span class="number">1</span><span class="special">))),</span>
<span class="identifier">seconds_</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration_cast</span><span class="special"><</span><span class="identifier">seconds</span><span class="special">>(</span><span class="identifier">d</span> <span class="special">%</span> <span class="identifier">minutes</span><span class="special">(</span><span class="number">1</span><span class="special">)))</span>
<span class="special">{}</span>
<span class="special">};</span>
</pre>
</div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="chrono.appendices.implementation"></a><a class="link" href="appendices.html#chrono.appendices.implementation" title="Appendix: Implementation Notes">Appendix: Implementation
Notes</a>
</h3></div></div></div>
<h5>
<a name="chrono.appendices.implementation.h0"></a>
<span><a name="chrono.appendices.implementation.which_apis_have_been_chosen_to_implement_each_clock_on_each_platform_"></a></span><a class="link" href="appendices.html#chrono.appendices.implementation.which_apis_have_been_chosen_to_implement_each_clock_on_each_platform_">Which
APIs have been chosen to implement each clock on each platform?</a>
</h5>
<p>
The following table presents a resume of which API is uused for each clock
on each platform
</p>
<div class="table">
<a name="chrono.appendices.implementation.clock_api_correspondence"></a><p class="title"><b>Table 4.3. Clock API correspondence</b></p>
<div class="table-contents"><table class="table" summary="Clock API correspondence">
<colgroup>
<col>
<col>
<col>
<col>
</colgroup>
<thead><tr>
<th>
<p>
Clock
</p>
</th>
<th>
<p>
Windows Platform
</p>
</th>
<th>
<p>
Posix Platform
</p>
</th>
<th>
<p>
Mac Platform
</p>
</th>
</tr></thead>
<tbody>
<tr>
<td>
<p>
<a class="link" href="reference.html#chrono.reference.cpp0x.system_clocks_hpp.system_clock" title="Class system_clock"><code class="computeroutput"><span class="identifier">system_clock</span></code></a>
</p>
</td>
<td>
<p>
GetSystemTimeAsFileTime
</p>
</td>
<td>
<p>
clock_gettime( CLOCK_REALTIME)
</p>
</td>
<td>
<p>
gettimeofday
</p>
</td>
</tr>
<tr>
<td>
<p>
<a class="link" href="reference.html#chrono.reference.cpp0x.system_clocks_hpp.steady_clock" title="Class steady_clock"><code class="computeroutput"><span class="identifier">steady_clock</span></code></a>
</p>
</td>
<td>
<p>
QueryPerformanceCounter and QueryPerformanceFrequency
</p>
</td>
<td>
<p>
clock_gettime( CLOCK_STEADY)
</p>
</td>
<td>
<p>
mach_timebase_info,mach_absolute_time
</p>
</td>
</tr>
<tr>
<td>
<p>
<a class="link" href="reference.html#chrono.reference.other_clocks.process_cpu_clocks_hpp.process_real_cpu_clock" title="Class process_real_cpu_clock"><code class="computeroutput"><span class="identifier">process_real_cpu_clock</span></code></a>
</p>
</td>
<td>
<p>
GetProcessTimes
</p>
</td>
<td>
<p>
times
</p>
</td>
<td>
<p>
times
</p>
</td>
</tr>
<tr>
<td>
<p>
<a class="link" href="reference.html#chrono.reference.other_clocks.process_cpu_clocks_hpp.process_system_cpu_clock" title="Class process_system_cpu_clock"><code class="computeroutput"><span class="identifier">process_system_cpu_clock</span></code></a>
</p>
</td>
<td>
<p>
GetProcessTimes
</p>
</td>
<td>
<p>
times
</p>
</td>
<td>
<p>
times
</p>
</td>
</tr>
<tr>
<td>
<p>
<a class="link" href="reference.html#chrono.reference.other_clocks.process_cpu_clocks_hpp.process_user_cpu_clock" title="Class process_user_cpu_clock"><code class="computeroutput"><span class="identifier">process_user_cpu_clock</span></code></a>
</p>
</td>
<td>
<p>
GetProcessTimes
</p>
</td>
<td>
<p>
times
</p>
</td>
<td>
<p>
times
</p>
</td>
</tr>
<tr>
<td>
<p>
<a class="link" href="reference.html#chrono.reference.other_clocks.process_cpu_clocks_hpp.process_cpu_clock" title="Class process_cpu_clock"><code class="computeroutput"><span class="identifier">process_cpu_clock</span></code></a>
</p>
</td>
<td>
<p>
GetProcessTimes
</p>
</td>
<td>
<p>
times
</p>
</td>
<td>
<p>
times
</p>
</td>
</tr>
<tr>
<td>
<p>
<a class="link" href="reference.html#chrono.reference.other_clocks.thread_clock_hpp.thread_clock" title="Class thread_clock"><code class="computeroutput"><span class="identifier">thread_clock</span></code></a>
</p>
</td>
<td>
<p>
GetThreadTimes
</p>
</td>
<td>
<p>
clock_gettime(pthread_getcpuclockid)
</p>
</td>
<td>
<p>
clock_gettime(pthread_getcpuclockid)
</p>
</td>
</tr>
</tbody>
</table></div>
</div>
<br class="table-break">
</div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="chrono.appendices.faq"></a><a class="link" href="appendices.html#chrono.appendices.faq" title="Appendix: FAQ">Appendix: FAQ</a>
</h3></div></div></div>
<h5>
<a name="chrono.appendices.faq.h0"></a>
<span><a name="chrono.appendices.faq.why_does_process_cpu_clock_sometimes_give_more_cpu_seconds_than_real_seconds_"></a></span><a class="link" href="appendices.html#chrono.appendices.faq.why_does_process_cpu_clock_sometimes_give_more_cpu_seconds_than_real_seconds_">Why
does process_cpu_clock sometimes give more cpu seconds than real seconds?</a>
</h5>
<p>
Ask your operating system supplier. The results have been inspected with
a debugger, and both for Windows and Linux, that's what the OS appears to
be reporting at times.
</p>
<h5>
<a name="chrono.appendices.faq.h1"></a>
<span><a name="chrono.appendices.faq.are_integer_overflows_in_the_duration_arithmetic_detected_and_reported_"></a></span><a class="link" href="appendices.html#chrono.appendices.faq.are_integer_overflows_in_the_duration_arithmetic_detected_and_reported_">Are
integer overflows in the duration arithmetic detected and reported?</a>
</h5>
<p>
<span class="bold"><strong>Boost.Ratio</strong></span> avoids all kind of overflow
that could result of arithmetic operation and that can be simplified. The
typedefs durations don't detect overflow. You will need a duration representation
that handles overflow.
</p>
<h5>
<a name="chrono.appendices.faq.h2"></a>
<span><a name="chrono.appendices.faq.which_clocks_should_be_used_to_benchmarking_"></a></span><a class="link" href="appendices.html#chrono.appendices.faq.which_clocks_should_be_used_to_benchmarking_">Which
clocks should be used to benchmarking?</a>
</h5>
<p>
Each clock has his own features. It depends on what do you need to benchmark.
Most of the time, you could be interested in using a thread clock, but if
you need to measure code subject to synchronization a process clock would
be better. If you have a multi-process application, a system-wide clock could
be needed.
</p>
<h5>
<a name="chrono.appendices.faq.h3"></a>
<span><a name="chrono.appendices.faq.which_clocks_should_be_used_for_watching_"></a></span><a class="link" href="appendices.html#chrono.appendices.faq.which_clocks_should_be_used_for_watching_">Which
clocks should be used for watching?</a>
</h5>
<p>
For trace purposes, it is probably best to use a system-wide clock.
</p>
</div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="chrono.appendices.acknowledgements"></a><a class="link" href="appendices.html#chrono.appendices.acknowledgements" title="Appendix: Acknowledgements">Appendix: Acknowledgements</a>
</h3></div></div></div>
<p>
The library's code was derived from Howard Hinnant's time2_demo prototype.
Many thanks to Howard for making his code available under the Boost license.
The original code was modified by Beman Dawes to conform to Boost conventions.
</p>
<p>
time2_demo contained this comment:
</p>
<p>
Much thanks to Andrei Alexandrescu, Walter Brown, Peter Dimov, Jeff Garland,
Terry Golubiewski, Daniel Krugler, Anthony Williams.
</p>
<p>
The file <boost/chrono_io.hpp> has been adapted from the experimental
header <code class="computeroutput"><span class="special"><</span><span class="identifier">chrono_io</span><span class="special">></span></code> from Howard Hinnant. Thanks for all Howard.
</p>
<p>
Howard Hinnant, who is the real author of the library, has provided valuable
feedback and suggestions during the development of the library. In particular,
The chrono_io_io.hpp source has been adapted from the experimental header
<code class="computeroutput"><span class="special"><</span><span class="identifier">chrono_io</span><span class="special">></span></code> from Howard Hinnant.
</p>
<p>
The acceptance review of Boost.Ratio took place between November 5th and
15th 2010. Many thanks to Anthony Williams, the review manager, and to all
the reviewers: David Deakins, John Bytheway, Roland Bock and Paul A. Bristow.
</p>
<p>
Thanks to Ronald Bock, Andrew Chinoff, Paul A. Bristow and John Bytheway
for his help polishing the documentation.
</p>
<p>
Thanks to Tom Tan for reporting some compiler issues with MSVC V10 beta and
MinGW-gcc-4.4.0 and for the many pushing for an homogeneous <code class="computeroutput"><span class="identifier">process_cpu_clock</span></code> clock.
</p>
<p>
Thanks to Ronald Bock for reporting Valgind issues and for the many suggestions
he made concerning the documentation.
</p>
</div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="chrono.appendices.todo"></a><a class="link" href="appendices.html#chrono.appendices.todo" title="Appendix: Future plans">Appendix: Future plans</a>
</h3></div></div></div>
<h5>
<a name="chrono.appendices.todo.h0"></a>
<span><a name="chrono.appendices.todo.for_later_releases"></a></span><a class="link" href="appendices.html#chrono.appendices.todo.for_later_releases">For
later releases</a>
</h5>
<div class="itemizedlist"><ul class="itemizedlist" type="disc">
<li class="listitem">
Enhance chrono I/O
<div class="itemizedlist"><ul class="itemizedlist" type="circle">
<li class="listitem">
<a href="http://svn.boost.org/trac/boost/ticket/5980" target="_top">#5980</a>
Take care of the Howard Hinnant <a href="http://home.roadrunner.com/~hinnant/bloomington/chrono_io.html" target="_top">proposal</a>
which has the advantage to provide I/O for system clocks using
the Gregorian Calendar.
</li>
<li class="listitem">
<a href="http://svn.boost.org/trac/boost/ticket/5981" target="_top">#5981</a>
Added i/o state savers.
</li>
</ul></div>
</li>
<li class="listitem">
Deprecate:
<div class="itemizedlist"><ul class="itemizedlist" type="circle">
<li class="listitem">
chrono I/O: The manipulators duration_short, duration long are
depreceated. You should use the parameterized form duration_fmt
instead.
</li>
<li class="listitem">
chrono I/O: The duraction_punc<> facet observers is_short_name,
is_long_name are depreceated. You should use is_prefix and is_symbol
instead.
</li>
<li class="listitem">
chrono I/O: The duraction_punc<> facet constructors taking
as argument the literals duraction_punc<>::use_long or use
short are depreceated. You should use duration_style::prefix and
duration_style::symbol instead.
</li>
<li class="listitem">
chrono I/O: The duraction_punc<> facet constructors taking
the long names for seconds, minutes and hours and the associated
observers short_name, long_name and name are depreceated. Boost.Chrono
allows the user to use an interface that could be customized to
take care of locale issues. The default behavior been to return
the English words.
</li>
</ul></div>
</li>
</ul></div>
<p>
When BOOST_CHRONO_IO_V1_DONT_PROVIDE_DEPRECATED is defined the preceding
deprecated functions are not available. In addition, the user needs to define
the macro BOOST_CHRONO_IO_USES_EXTERNAL_LOCALIZATION to be able to customize
the locale interface.
</p>
<div class="itemizedlist"><ul class="itemizedlist" type="disc">
<li class="listitem">
Include Stopwatches.
</li>
<li class="listitem">
Include chrono::date as defined by Howard Hinnant <a href="http://home.roadrunner.com/~hinnant/bloomington/date.html" target="_top">here</a>.
</li>
</ul></div>
</div>
</div>
<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
<td align="left"></td>
<td align="right"><div class="copyright-footer">Copyright © 2008 Howard Hinnant<br>Copyright © 2006, 2008 Beman Dawes<br>Copyright © 2009-2011 Vicente J. Botet
Escriba<p>
Distributed under the Boost Software License, Version 1.0. (See accompanying
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>)
</p>
</div></td>
</tr></table>
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