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| <div class="titlepage"><div><div><h3 class="title"> |
| <a name="context.stack.segmented"></a><a class="link" href="segmented.html" title="Class segmented_stack">Class <span class="emphasis"><em>segmented_stack</em></span></a> |
| </h3></div></div></div> |
| <p> |
| <span class="bold"><strong>Boost.Context</strong></span> supports usage of a <span class="emphasis"><em>segmented_stack</em></span>, |
| e. g. the size of the stack grows on demand. The coroutine is created with |
| a minimal stack size and will be increased as required. Class <span class="emphasis"><em>segmented_stack</em></span> |
| models the <span class="emphasis"><em>stack-allocator concept</em></span>. In contrast to |
| <span class="emphasis"><em>protected_fixedsize_stack</em></span> and <span class="emphasis"><em>fixedsize_stack</em></span> |
| it creates a stack which grows on demand. |
| </p> |
| <div class="note"><table border="0" summary="Note"> |
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| <td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../../../../doc/src/images/note.png"></td> |
| <th align="left">Note</th> |
| </tr> |
| <tr><td align="left" valign="top"><p> |
| Segmented stacks are currently only supported by <span class="bold"><strong>gcc</strong></span> |
| from version <span class="bold"><strong>4.7</strong></span> <span class="bold"><strong>clang</strong></span> |
| from version <span class="bold"><strong>3.4</strong></span> onwards. In order to |
| use a __segmented_stack__ <span class="bold"><strong>Boost.Context</strong></span> |
| must be built with <span class="bold"><strong>toolset=gcc segmented-stacks=on</strong></span> |
| at b2/bjam command-line. Applications must be compiled with compiler-flags |
| <span class="bold"><strong>-fsplit-stack -DBOOST_USE_SEGMENTED_STACKS</strong></span>. |
| </p></td></tr> |
| </table></div> |
| <pre class="programlisting"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">context</span><span class="special">/</span><span class="identifier">segmented_stack</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> |
| |
| <span class="keyword">template</span><span class="special"><</span> <span class="keyword">typename</span> <span class="identifier">traitsT</span> <span class="special">></span> |
| <span class="keyword">struct</span> <span class="identifier">basic_segmented_stack</span> |
| <span class="special">{</span> |
| <span class="keyword">typedef</span> <span class="identifier">traitT</span> <span class="identifier">traits_type</span><span class="special">;</span> |
| |
| <span class="identifier">basic_segmented_stack</span><span class="special">(</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">size</span> <span class="special">=</span> <span class="identifier">traits_type</span><span class="special">::</span><span class="identifier">default_size</span><span class="special">());</span> |
| |
| <span class="identifier">stack_context</span> <span class="identifier">allocate</span><span class="special">();</span> |
| |
| <span class="keyword">void</span> <span class="identifier">deallocate</span><span class="special">(</span> <span class="identifier">stack_context</span> <span class="special">&);</span> |
| <span class="special">}</span> |
| |
| <span class="keyword">typedef</span> <span class="identifier">basic_segmented_stack</span><span class="special"><</span> <span class="identifier">stack_traits</span> <span class="special">></span> <span class="identifier">segmented_stack</span><span class="special">;</span> |
| </pre> |
| <h5> |
| <a name="context.stack.segmented.h0"></a> |
| <span class="phrase"><a name="context.stack.segmented._code__phrase_role__identifier__stack_context__phrase___phrase_role__identifier__allocate__phrase__phrase_role__special______phrase___code_"></a></span><a class="link" href="segmented.html#context.stack.segmented._code__phrase_role__identifier__stack_context__phrase___phrase_role__identifier__allocate__phrase__phrase_role__special______phrase___code_"><code class="computeroutput"><span class="identifier">stack_context</span> <span class="identifier">allocate</span><span class="special">()</span></code></a> |
| </h5> |
| <div class="variablelist"> |
| <p class="title"><b></b></p> |
| <dl class="variablelist"> |
| <dt><span class="term">Preconditions:</span></dt> |
| <dd><p> |
| <code class="computeroutput"><span class="identifier">traits_type</span><span class="special">::</span><span class="identifier">minimum</span><span class="special">:</span><span class="identifier">size</span><span class="special">()</span> |
| <span class="special"><=</span> <span class="identifier">size</span></code> |
| and <code class="computeroutput"><span class="special">!</span> <span class="identifier">traits_type</span><span class="special">::</span><span class="identifier">is_unbounded</span><span class="special">()</span> <span class="special">&&</span> |
| <span class="special">(</span> <span class="identifier">traits_type</span><span class="special">::</span><span class="identifier">maximum</span><span class="special">:</span><span class="identifier">size</span><span class="special">()</span> <span class="special">>=</span> <span class="identifier">size</span><span class="special">)</span></code>. |
| </p></dd> |
| <dt><span class="term">Effects:</span></dt> |
| <dd><p> |
| Allocates memory of at least <code class="computeroutput"><span class="identifier">size</span></code> |
| Bytes and stores a pointer to the stack and its actual size in <code class="computeroutput"><span class="identifier">sctx</span></code>. Depending on the architecture |
| (the stack grows downwards/upwards) the stored address is the highest/lowest |
| address of the stack. |
| </p></dd> |
| </dl> |
| </div> |
| <h5> |
| <a name="context.stack.segmented.h1"></a> |
| <span class="phrase"><a name="context.stack.segmented._code__phrase_role__keyword__void__phrase___phrase_role__identifier__deallocate__phrase__phrase_role__special_____phrase___phrase_role__identifier__stack_context__phrase___phrase_role__special___amp___phrase___phrase_role__identifier__sctx__phrase__phrase_role__special_____phrase___code_"></a></span><a class="link" href="segmented.html#context.stack.segmented._code__phrase_role__keyword__void__phrase___phrase_role__identifier__deallocate__phrase__phrase_role__special_____phrase___phrase_role__identifier__stack_context__phrase___phrase_role__special___amp___phrase___phrase_role__identifier__sctx__phrase__phrase_role__special_____phrase___code_"><code class="computeroutput"><span class="keyword">void</span> <span class="identifier">deallocate</span><span class="special">(</span> <span class="identifier">stack_context</span> |
| <span class="special">&</span> <span class="identifier">sctx</span><span class="special">)</span></code></a> |
| </h5> |
| <div class="variablelist"> |
| <p class="title"><b></b></p> |
| <dl class="variablelist"> |
| <dt><span class="term">Preconditions:</span></dt> |
| <dd><p> |
| <code class="computeroutput"><span class="identifier">sctx</span><span class="special">.</span><span class="identifier">sp</span></code> is valid, <code class="computeroutput"><span class="identifier">traits_type</span><span class="special">::</span><span class="identifier">minimum</span><span class="special">:</span><span class="identifier">size</span><span class="special">()</span> <span class="special"><=</span> <span class="identifier">sctx</span><span class="special">.</span><span class="identifier">size</span></code> and <code class="computeroutput"><span class="special">!</span> |
| <span class="identifier">traits_type</span><span class="special">::</span><span class="identifier">is_unbounded</span><span class="special">()</span> |
| <span class="special">&&</span> <span class="special">(</span> |
| <span class="identifier">traits_type</span><span class="special">::</span><span class="identifier">maximum</span><span class="special">:</span><span class="identifier">size</span><span class="special">()</span> |
| <span class="special">>=</span> <span class="identifier">sctx</span><span class="special">.</span><span class="identifier">size</span><span class="special">)</span></code>. |
| </p></dd> |
| <dt><span class="term">Effects:</span></dt> |
| <dd><p> |
| Deallocates the stack space. |
| </p></dd> |
| </dl> |
| </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 © 2014 Oliver Kowalke<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> |
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