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   4 <title>fcontext_t and related functions</title>
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  26 <div class="titlepage"><div><div><h3 class="title">
  27 <a name="context.context.boost_fcontext"></a><a class="link" href="boost_fcontext.html" title="fcontext_t and related functions"><code class="computeroutput"><span class="identifier">fcontext_t</span></code>
  28       and related functions</a>
  29 </h3></div></div></div>
  30 <pre class="programlisting"><span class="keyword">struct</span> <span class="identifier">stack_t</span>
  31 <span class="special">{</span>
  32     <span class="keyword">void</span><span class="special">*</span> <span class="identifier">sp</span><span class="special">;</span>
  33     <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">size</span><span class="special">;</span>
  34 <span class="special">};</span>
  35
  36 <span class="keyword">typedef</span> <span class="special">&lt;</span><span class="identifier">opaque</span> <span class="identifier">pointer</span> <span class="special">&gt;</span> <span class="identifier">fcontext_t</span><span class="special">;</span>
  37
  38 <span class="identifier">intptr_t</span> <span class="identifier">jump_fcontext</span><span class="special">(</span><span class="identifier">fcontext_t</span><span class="special">*</span> <span class="identifier">ofc</span><span class="special">,</span><span class="identifier">fcontext_t</span> <span class="identifier">nfc</span><span class="special">,</span><span class="identifier">intptr_t</span> <span class="identifier">vp</span><span class="special">,</span><span class="keyword">bool</span> <span class="identifier">preserve_fpu</span><span class="special">=</span><span class="keyword">true</span><span class="special">);</span>
  39 <span class="identifier">fcontext_t</span> <span class="identifier">make_fcontext</span><span class="special">(</span><span class="keyword">void</span><span class="special">*</span> <span class="identifier">sp</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="keyword">void</span><span class="special">(*</span><span class="identifier">fn</span><span class="special">)(</span><span class="identifier">intptr_t</span><span class="special">));</span>
  40 </pre>
  41 <h5>
  42 <a name="context.context.boost_fcontext.h0"></a>
  43         <span><a name="context.context.boost_fcontext._code__phrase_role__identifier__sp__phrase___code_"></a></span><a class="link" href="boost_fcontext.html#context.context.boost_fcontext._code__phrase_role__identifier__sp__phrase___code_"><code class="computeroutput"><span class="identifier">sp</span></code></a>
  44       </h5>
  45 <div class="variablelist">
  46 <p class="title"><b></b></p>
  47 <dl>
  48 <dt><span class="term">Member:</span></dt>
  49 <dd><p>
  50               Pointer to the beginning of the stack (depending of the architecture
  51               the stack grows downwards or upwards).
  52             </p></dd>
  53 </dl>
  54 </div>
  55 <h5>
  56 <a name="context.context.boost_fcontext.h1"></a>
  57         <span><a name="context.context.boost_fcontext._code__phrase_role__identifier__size__phrase___code_"></a></span><a class="link" href="boost_fcontext.html#context.context.boost_fcontext._code__phrase_role__identifier__size__phrase___code_"><code class="computeroutput"><span class="identifier">size</span></code></a>
  58       </h5>
  59 <div class="variablelist">
  60 <p class="title"><b></b></p>
  61 <dl>
  62 <dt><span class="term">Member:</span></dt>
  63 <dd><p>
  64               Size of the stack in bytes.
  65             </p></dd>
  66 </dl>
  67 </div>
  68 <h5>
  69 <a name="context.context.boost_fcontext.h2"></a>
  70         <span><a name="context.context.boost_fcontext._code__phrase_role__identifier__fc_stack__phrase___code_"></a></span><a class="link" href="boost_fcontext.html#context.context.boost_fcontext._code__phrase_role__identifier__fc_stack__phrase___code_"><code class="computeroutput"><span class="identifier">fc_stack</span></code></a>
  71       </h5>
  72 <div class="variablelist">
  73 <p class="title"><b></b></p>
  74 <dl>
  75 <dt><span class="term">Member:</span></dt>
  76 <dd><p>
  77               Tracks the memory for the context's stack.
  78             </p></dd>
  79 </dl>
  80 </div>
  81 <h5>
  82 <a name="context.context.boost_fcontext.h3"></a>
  83         <span><a name="context.context.boost_fcontext._code__phrase_role__identifier__intptr_t__phrase___phrase_role__identifier__jump_fcontext__phrase__phrase_role__special_____phrase__phrase_role__identifier__fcontext_t__phrase__phrase_role__special_____phrase___phrase_role__identifier__ofc__phrase__phrase_role__special_____phrase__phrase_role__identifier__fcontext_t__phrase___phrase_role__identifier__nfc__phrase__phrase_role__special_____phrase__phrase_role__identifier__intptr_t__phrase___phrase_role__identifier__p__phrase__phrase_role__special_____phrase__phrase_role__keyword__bool__phrase___phrase_role__identifier__preserve_fpu__phrase__phrase_role__special_____phrase__phrase_role__keyword__true__phrase__phrase_role__special_____phrase___code_"></a></span><a class="link" href="boost_fcontext.html#context.context.boost_fcontext._code__phrase_role__identifier__intptr_t__phrase___phrase_role__identifier__jump_fcontext__phrase__phrase_role__special_____phrase__phrase_role__identifier__fcontext_t__phrase__phrase_role__special_____phrase___phrase_role__identifier__ofc__phrase__phrase_role__special_____phrase__phrase_role__identifier__fcontext_t__phrase___phrase_role__identifier__nfc__phrase__phrase_role__special_____phrase__phrase_role__identifier__intptr_t__phrase___phrase_role__identifier__p__phrase__phrase_role__special_____phrase__phrase_role__keyword__bool__phrase___phrase_role__identifier__preserve_fpu__phrase__phrase_role__special_____phrase__phrase_role__keyword__true__phrase__phrase_role__special_____phrase___code_"><code class="computeroutput"><span class="identifier">intptr_t</span> <span class="identifier">jump_fcontext</span><span class="special">(</span><span class="identifier">fcontext_t</span><span class="special">*</span> <span class="identifier">ofc</span><span class="special">,</span><span class="identifier">fcontext_t</span> <span class="identifier">nfc</span><span class="special">,</span><span class="identifier">intptr_t</span> <span class="identifier">p</span><span class="special">,</span><span class="keyword">bool</span>
  84         <span class="identifier">preserve_fpu</span><span class="special">=</span><span class="keyword">true</span><span class="special">)</span></code></a>
  85       </h5>
  86 <div class="variablelist">
  87 <p class="title"><b></b></p>
  88 <dl>
  89 <dt><span class="term">Effects:</span></dt>
  90 <dd><p>
  91               Stores the current context data (stack pointer, instruction pointer,
  92               and CPU registers) to <code class="computeroutput"><span class="special">*</span><span class="identifier">ofc</span></code> and restores the context data
  93               from <code class="computeroutput"><span class="identifier">nfc</span></code>, which implies
  94               jumping to <code class="computeroutput"><span class="identifier">nfc</span></code>'s execution
  95               context. The intptr_t argument, <code class="computeroutput"><span class="identifier">p</span></code>,
  96               is passed to the current context to be returned by the most recent
  97               call to <code class="computeroutput"><span class="identifier">jump_fcontext</span><span class="special">()</span></code> in the same thread. The last argument
  98               controls if fpu registers have to be preserved.
  99             </p></dd>
 100 <dt><span class="term">Returns:</span></dt>
 101 <dd><p>
 102               The third pointer argument passed to the most recent call to <code class="computeroutput"><span class="identifier">jump_fcontext</span><span class="special">()</span></code>,
 103               if any.
 104             </p></dd>
 105 </dl>
 106 </div>
 107 <h5>
 108 <a name="context.context.boost_fcontext.h4"></a>
 109         <span><a name="context.context.boost_fcontext._code__phrase_role__identifier__fcontext_t__phrase___phrase_role__identifier__make_fcontext__phrase__phrase_role__special_____phrase__phrase_role__keyword__void__phrase__phrase_role__special_____phrase___phrase_role__identifier__sp__phrase__phrase_role__special_____phrase__phrase_role__identifier__std__phrase__phrase_role__special______phrase__phrase_role__identifier__size_t__phrase___phrase_role__identifier__size__phrase__phrase_role__special_____phrase__phrase_role__keyword__void__phrase__phrase_role__special______phrase__phrase_role__identifier__fn__phrase__phrase_role__special______phrase__phrase_role__identifier__intptr_t__phrase__phrase_role__special______phrase___code_"></a></span><a class="link" href="boost_fcontext.html#context.context.boost_fcontext._code__phrase_role__identifier__fcontext_t__phrase___phrase_role__identifier__make_fcontext__phrase__phrase_role__special_____phrase__phrase_role__keyword__void__phrase__phrase_role__special_____phrase___phrase_role__identifier__sp__phrase__phrase_role__special_____phrase__phrase_role__identifier__std__phrase__phrase_role__special______phrase__phrase_role__identifier__size_t__phrase___phrase_role__identifier__size__phrase__phrase_role__special_____phrase__phrase_role__keyword__void__phrase__phrase_role__special______phrase__phrase_role__identifier__fn__phrase__phrase_role__special______phrase__phrase_role__identifier__intptr_t__phrase__phrase_role__special______phrase___code_"><code class="computeroutput"><span class="identifier">fcontext_t</span> <span class="identifier">make_fcontext</span><span class="special">(</span><span class="keyword">void</span><span class="special">*</span>
 110         <span class="identifier">sp</span><span class="special">,</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span>
 111         <span class="identifier">size</span><span class="special">,</span><span class="keyword">void</span><span class="special">(*</span><span class="identifier">fn</span><span class="special">)(</span><span class="identifier">intptr_t</span><span class="special">))</span></code></a>
 112       </h5>
 113 <div class="variablelist">
 114 <p class="title"><b></b></p>
 115 <dl>
 116 <dt><span class="term">Precondition:</span></dt>
 117 <dd><p>
 118               Stack <code class="computeroutput"><span class="identifier">sp</span></code> and function
 119               pointer <code class="computeroutput"><span class="identifier">fn</span></code> are valid
 120               (depending on the architecture <code class="computeroutput"><span class="identifier">sp</span></code>
 121               points to the top or bottom of the stack) and <code class="computeroutput"><span class="identifier">size</span></code>
 122               &gt; 0.
 123             </p></dd>
 124 <dt><span class="term">Effects:</span></dt>
 125 <dd><p>
 126               Creates an fcontext_t on top of the stack and prepares the stack to
 127               execute the <span class="emphasis"><em>context-function</em></span> <code class="computeroutput"><span class="identifier">fn</span></code>.
 128             </p></dd>
 129 <dt><span class="term">Returns:</span></dt>
 130 <dd><p>
 131               Returns a fcontext_t which is placed on the stack.
 132             </p></dd>
 133 </dl>
 134 </div>
 135 </div>
 136 <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
 137 <td align="left"></td>
 138 <td align="right"><div class="copyright-footer">Copyright &#169; 2014 Oliver Kowalke<p>
 139         Distributed under the Boost Software License, Version 1.0. (See accompanying
 140         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>)
 141       </p>
 142 </div></td>
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