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26 | <div class="titlepage"><div><div><h2 class="title" style="clear: both"> | |
27 | <a name="context.context"></a><a class="link" href="context.html" title="Struct fcontext_t">Struct fcontext_t</a> | |
28 | </h2></div></div></div> | |
29 | <p> | |
30 | Each instance of <span class="emphasis"><em>fcontext_t</em></span> represents a context (CPU | |
31 | registers and stack space). Together with its related functions <span class="emphasis"><em>jump_fcontext()</em></span> | |
32 | and <span class="emphasis"><em>make_fcontext()</em></span> it provides a execution control transfer | |
33 | mechanism similar interface like <a href="http://www.kernel.org/doc/man-pages/online/pages/man2/getcontext.2.html" target="_top">ucontext_t</a>. | |
34 | <span class="emphasis"><em>fcontext_t</em></span> and its functions are located in <span class="emphasis"><em>boost::context</em></span> | |
35 | and the functions are declared as extern "C". | |
36 | </p> | |
37 | <div class="warning"><table border="0" summary="Warning"> | |
38 | <tr> | |
39 | <td rowspan="2" align="center" valign="top" width="25"><img alt="[Warning]" src="../../../../../doc/src/images/warning.png"></td> | |
40 | <th align="left">Warning</th> | |
41 | </tr> | |
42 | <tr><td align="left" valign="top"><p> | |
43 | If <span class="emphasis"><em>fcontext_t</em></span> is used in a multi threaded application, | |
44 | it can migrated between threads, but must not reference <span class="emphasis"><em>thread-local | |
45 | storage</em></span>. | |
46 | </p></td></tr> | |
47 | </table></div> | |
48 | <div class="important"><table border="0" summary="Important"> | |
49 | <tr> | |
50 | <td rowspan="2" align="center" valign="top" width="25"><img alt="[Important]" src="../../../../../doc/src/images/important.png"></td> | |
51 | <th align="left">Important</th> | |
52 | </tr> | |
53 | <tr><td align="left" valign="top"><p> | |
54 | The low level API is the part to port to new platforms. | |
55 | </p></td></tr> | |
56 | </table></div> | |
57 | <div class="note"><table border="0" summary="Note"> | |
58 | <tr> | |
59 | <td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../../../doc/src/images/note.png"></td> | |
60 | <th align="left">Note</th> | |
61 | </tr> | |
62 | <tr><td align="left" valign="top"><p> | |
63 | If <span class="emphasis"><em>fiber-local storage</em></span> is used on Windows, the user | |
64 | is responsible for calling <span class="emphasis"><em>::FlsAlloc()</em></span>, <span class="emphasis"><em>::FlsFree()</em></span>. | |
65 | </p></td></tr> | |
66 | </table></div> | |
67 | <h4> | |
68 | <a name="context.context.h0"></a> | |
69 | <span><a name="context.context.executing_a_context"></a></span><a class="link" href="context.html#context.context.executing_a_context">Executing | |
70 | a context</a> | |
71 | </h4> | |
72 | <p> | |
73 | A new context supposed to execute a <span class="emphasis"><em>context-function</em></span> (returning | |
74 | void and accepting void * as argument) will be created on top of the stack | |
75 | (at 16 byte boundary) by function <span class="emphasis"><em>make_fcontext()</em></span>. | |
76 | </p> | |
77 | <pre class="programlisting"><span class="comment">// context-function</span> | |
78 | <span class="keyword">void</span> <span class="identifier">f</span><span class="special">(</span><span class="identifier">intptr</span><span class="special">);</span> | |
79 | ||
80 | <span class="comment">// creates a new stack</span> | |
81 | <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="number">8192</span><span class="special">;</span> | |
82 | <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">malloc</span><span class="special">(</span><span class="identifier">size</span><span class="special">));</span> | |
83 | ||
84 | <span class="comment">// context fc uses f() as context function</span> | |
85 | <span class="comment">// fcontext_t is placed on top of context stack</span> | |
86 | <span class="comment">// a pointer to fcontext_t is returned</span> | |
87 | <span class="identifier">fcontext_t</span> <span class="identifier">fc</span><span class="special">(</span><span class="identifier">make_fcontext</span><span class="special">(</span><span class="identifier">sp</span><span class="special">,</span><span class="identifier">size</span><span class="special">,</span><span class="identifier">f</span><span class="special">));</span> | |
88 | </pre> | |
89 | <p> | |
90 | Calling <span class="emphasis"><em>jump_fcontext()</em></span> invokes the <span class="emphasis"><em>context-function</em></span> | |
91 | in a newly created context complete with registers, flags, stack and instruction | |
92 | pointers. When control should be returned to the original calling context, | |
93 | call <span class="emphasis"><em>jump_fcontext()</em></span>. The current context information | |
94 | (registers, flags, and stack and instruction pointers) is saved and the original | |
95 | context information is restored. Calling <span class="emphasis"><em>jump_fcontext()</em></span> | |
96 | again resumes execution in the second context after saving the new state of | |
97 | the original context. | |
98 | </p> | |
99 | <pre class="programlisting"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">context</span><span class="special">::</span><span class="identifier">fcontext_t</span> <span class="identifier">fcm</span><span class="special">,</span><span class="identifier">fc1</span><span class="special">,</span><span class="identifier">fc2</span><span class="special">;</span> | |
100 | ||
101 | <span class="keyword">void</span> <span class="identifier">f1</span><span class="special">(</span><span class="keyword">void</span> <span class="special">*)</span> | |
102 | <span class="special">{</span> | |
103 | <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span><span class="special"><<</span><span class="string">"f1: entered"</span><span class="special"><<</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span> | |
104 | <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span><span class="special"><<</span><span class="string">"f1: call jump_fcontext( & fc1, fc2, 0)"</span><span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span> | |
105 | <span class="identifier">boost</span><span class="special">::</span><span class="identifier">context</span><span class="special">::</span><span class="identifier">jump_fcontext</span><span class="special">(&</span><span class="identifier">fc1</span><span class="special">,</span><span class="identifier">fc2</span><span class="special">,</span><span class="number">0</span><span class="special">);</span> | |
106 | <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span><span class="special"><<</span><span class="string">"f1: return"</span><span class="special"><<</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span> | |
107 | <span class="identifier">boost</span><span class="special">::</span><span class="identifier">context</span><span class="special">::</span><span class="identifier">jump_fcontext</span><span class="special">(&</span><span class="identifier">fc1</span><span class="special">,</span><span class="identifier">fcm</span><span class="special">,</span><span class="number">0</span><span class="special">);</span> | |
108 | <span class="special">}</span> | |
109 | ||
110 | <span class="keyword">void</span> <span class="identifier">f2</span><span class="special">(</span><span class="keyword">void</span> <span class="special">*)</span> | |
111 | <span class="special">{</span> | |
112 | <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span><span class="special"><<</span><span class="string">"f2: entered"</span><span class="special"><<</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span> | |
113 | <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span><span class="special"><<</span><span class="string">"f2: call jump_fcontext( & fc2, fc1, 0)"</span><span class="special"><<</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span> | |
114 | <span class="identifier">boost</span><span class="special">::</span><span class="identifier">context</span><span class="special">::</span><span class="identifier">jump_fcontext</span><span class="special">(&</span><span class="identifier">fc2</span><span class="special">,</span><span class="identifier">fc1</span><span class="special">,</span><span class="number">0</span><span class="special">);</span> | |
115 | <span class="identifier">BOOST_ASSERT</span><span class="special">(</span><span class="keyword">false</span><span class="special">&&!</span><span class="string">"f2: never returns"</span><span class="special">);</span> | |
116 | <span class="special">}</span> | |
117 | ||
118 | <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="number">8192</span><span class="special">);</span> | |
119 | <span class="keyword">void</span><span class="special">*</span> <span class="identifier">sp1</span><span class="special">(</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">malloc</span><span class="special">(</span><span class="identifier">size</span><span class="special">));</span> | |
120 | <span class="keyword">void</span><span class="special">*</span> <span class="identifier">sp2</span><span class="special">(</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">malloc</span><span class="special">(</span><span class="identifier">size</span><span class="special">));</span> | |
121 | ||
122 | <span class="identifier">fc1</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">make_fcontext</span><span class="special">(</span><span class="identifier">sp1</span><span class="special">,</span><span class="identifier">size</span><span class="special">,</span><span class="identifier">f1</span><span class="special">);</span> | |
123 | <span class="identifier">fc2</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">make_fcontext</span><span class="special">(</span><span class="identifier">sp2</span><span class="special">,</span><span class="identifier">size</span><span class="special">,</span><span class="identifier">f2</span><span class="special">);</span> | |
124 | ||
125 | <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span><span class="special"><<</span><span class="string">"main: call jump_fcontext( & fcm, fc1, 0)"</span><span class="special"><<</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span> | |
126 | <span class="identifier">boost</span><span class="special">::</span><span class="identifier">context</span><span class="special">::</span><span class="identifier">jump_fcontext</span><span class="special">(&</span><span class="identifier">fcm</span><span class="special">,</span><span class="identifier">fc1</span><span class="special">,</span><span class="number">0</span><span class="special">);</span> | |
127 | ||
128 | <span class="identifier">output</span><span class="special">:</span> | |
129 | <span class="identifier">main</span><span class="special">:</span> <span class="identifier">call</span> <span class="identifier">jump_fcontext</span><span class="special">(</span> <span class="special">&</span> <span class="identifier">fcm</span><span class="special">,</span> <span class="identifier">fc1</span><span class="special">,</span> <span class="number">0</span><span class="special">)</span> | |
130 | <span class="identifier">f1</span><span class="special">:</span> <span class="identifier">entered</span> | |
131 | <span class="identifier">f1</span><span class="special">:</span> <span class="identifier">call</span> <span class="identifier">jump_fcontext</span><span class="special">(</span> <span class="special">&</span> <span class="identifier">fc1</span><span class="special">,</span> <span class="identifier">fc2</span><span class="special">,</span> <span class="number">0</span><span class="special">)</span> | |
132 | <span class="identifier">f2</span><span class="special">:</span> <span class="identifier">entered</span> | |
133 | <span class="identifier">f2</span><span class="special">:</span> <span class="identifier">call</span> <span class="identifier">jump_fcontext</span><span class="special">(</span> <span class="special">&</span> <span class="identifier">fc2</span><span class="special">,</span> <span class="identifier">fc1</span><span class="special">,</span> <span class="number">0</span><span class="special">)</span> | |
134 | <span class="identifier">f1</span><span class="special">:</span> <span class="keyword">return</span> | |
135 | </pre> | |
136 | <p> | |
137 | First call of <span class="emphasis"><em>jump_fcontext()</em></span> enters the <span class="emphasis"><em>context-function</em></span> | |
138 | <code class="computeroutput"><span class="identifier">f1</span><span class="special">()</span></code> | |
139 | by starting context fc1 (context fcm saves the registers of <code class="computeroutput"><span class="identifier">main</span><span class="special">()</span></code>). For jumping between context's fc1 and fc2 | |
140 | <code class="computeroutput"><span class="identifier">jump_fcontext</span><span class="special">()</span></code> | |
141 | is called. Because context fcm is chained to fc1, <code class="computeroutput"><span class="identifier">main</span><span class="special">()</span></code> is entered (returning from <span class="emphasis"><em>jump_fcontext()</em></span>) | |
142 | after context fc1 becomes complete (return from <code class="computeroutput"><span class="identifier">f1</span><span class="special">()</span></code>). | |
143 | </p> | |
144 | <div class="warning"><table border="0" summary="Warning"> | |
145 | <tr> | |
146 | <td rowspan="2" align="center" valign="top" width="25"><img alt="[Warning]" src="../../../../../doc/src/images/warning.png"></td> | |
147 | <th align="left">Warning</th> | |
148 | </tr> | |
149 | <tr><td align="left" valign="top"><p> | |
150 | Calling <span class="emphasis"><em>jump_fcontext()</em></span> to the same context from inside | |
151 | the same context results in undefined behaviour. | |
152 | </p></td></tr> | |
153 | </table></div> | |
154 | <div class="important"><table border="0" summary="Important"> | |
155 | <tr> | |
156 | <td rowspan="2" align="center" valign="top" width="25"><img alt="[Important]" src="../../../../../doc/src/images/important.png"></td> | |
157 | <th align="left">Important</th> | |
158 | </tr> | |
159 | <tr><td align="left" valign="top"><p> | |
160 | The size of the stack is required to be larger than the size of fcontext_t. | |
161 | </p></td></tr> | |
162 | </table></div> | |
163 | <div class="note"><table border="0" summary="Note"> | |
164 | <tr> | |
165 | <td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../../../doc/src/images/note.png"></td> | |
166 | <th align="left">Note</th> | |
167 | </tr> | |
168 | <tr><td align="left" valign="top"><p> | |
169 | In contrast to threads, which are preemtive, <span class="emphasis"><em>fcontext_t</em></span> | |
170 | switches are cooperative (programmer controls when switch will happen). The | |
171 | kernel is not involved in the context switches. | |
172 | </p></td></tr> | |
173 | </table></div> | |
174 | <h4> | |
175 | <a name="context.context.h1"></a> | |
176 | <span><a name="context.context.transfer_of_data"></a></span><a class="link" href="context.html#context.context.transfer_of_data">Transfer | |
177 | of data</a> | |
178 | </h4> | |
179 | <p> | |
180 | The third argument passed to <span class="emphasis"><em>jump_fcontext()</em></span>, in one context, | |
181 | is passed as the first argument of the <span class="emphasis"><em>context-function</em></span> | |
182 | if the context is started for the first time. In all following invocations | |
183 | of <span class="emphasis"><em>jump_fcontext()</em></span> the void * passed to <span class="emphasis"><em>jump_fcontext()</em></span>, | |
184 | in one context, is returned by <span class="emphasis"><em>jump_fcontext()</em></span> in the | |
185 | other context. | |
186 | </p> | |
187 | <pre class="programlisting"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">context</span><span class="special">::</span><span class="identifier">fcontext_t</span> <span class="identifier">fcm</span><span class="special">,</span><span class="identifier">fc</span><span class="special">;</span> | |
188 | ||
189 | <span class="keyword">typedef</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span><span class="special"><</span><span class="keyword">int</span><span class="special">,</span><span class="keyword">int</span><span class="special">></span> <span class="identifier">pair_t</span><span class="special">;</span> | |
190 | ||
191 | <span class="keyword">void</span> <span class="identifier">f</span><span class="special">(</span><span class="keyword">void</span> <span class="special">*</span> <span class="identifier">param</span><span class="special">)</span> | |
192 | <span class="special">{</span> | |
193 | <span class="identifier">pair_t</span><span class="special">*</span> <span class="identifier">p</span><span class="special">=(</span><span class="identifier">pair_t</span><span class="special">*)</span><span class="identifier">param</span><span class="special">;</span> | |
194 | <span class="identifier">p</span><span class="special">=(</span><span class="identifier">pair_t</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">jump_fcontext</span><span class="special">(&</span><span class="identifier">fc</span><span class="special">,</span><span class="identifier">fcm</span><span class="special">,(</span><span class="keyword">void</span> <span class="special">*)(</span><span class="identifier">p</span><span class="special">-></span><span class="identifier">first</span><span class="special">+</span><span class="identifier">p</span><span class="special">-></span><span class="identifier">second</span><span class="special">));</span> | |
195 | <span class="identifier">boost</span><span class="special">::</span><span class="identifier">context</span><span class="special">::</span><span class="identifier">jump_fcontext</span><span class="special">(&</span><span class="identifier">fc</span><span class="special">,</span><span class="identifier">fcm</span><span class="special">,(</span><span class="keyword">void</span> <span class="special">*)(</span><span class="identifier">p</span><span class="special">-></span><span class="identifier">first</span><span class="special">+</span><span class="identifier">p</span><span class="special">-></span><span class="identifier">second</span><span class="special">));</span> | |
196 | <span class="special">}</span> | |
197 | ||
198 | <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="number">8192</span><span class="special">);</span> | |
199 | <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">malloc</span><span class="special">(</span><span class="identifier">size</span><span class="special">));</span> | |
200 | ||
201 | <span class="identifier">pair_t</span> <span class="identifier">p</span><span class="special">(</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">make_pair</span><span class="special">(</span><span class="number">2</span><span class="special">,</span><span class="number">7</span><span class="special">));</span> | |
202 | <span class="identifier">fc</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">make_fcontext</span><span class="special">(</span><span class="identifier">sp</span><span class="special">,</span><span class="identifier">size</span><span class="special">,</span><span class="identifier">f</span><span class="special">);</span> | |
203 | ||
204 | <span class="keyword">int</span> <span class="identifier">res</span><span class="special">=(</span><span class="keyword">int</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">jump_fcontext</span><span class="special">(&</span><span class="identifier">fcm</span><span class="special">,</span><span class="identifier">fc</span><span class="special">,(</span><span class="keyword">void</span> <span class="special">*)&</span><span class="identifier">p</span><span class="special">);</span> | |
205 | <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span><span class="special"><<</span><span class="identifier">p</span><span class="special">.</span><span class="identifier">first</span><span class="special"><<</span><span class="string">" + "</span><span class="special"><<</span><span class="identifier">p</span><span class="special">.</span><span class="identifier">second</span><span class="special"><<</span><span class="string">" == "</span><span class="special"><<</span><span class="identifier">res</span><span class="special"><<</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span> | |
206 | ||
207 | <span class="identifier">p</span><span class="special">=</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">make_pair</span><span class="special">(</span><span class="number">5</span><span class="special">,</span><span class="number">6</span><span class="special">);</span> | |
208 | <span class="identifier">res</span><span class="special">=(</span><span class="keyword">int</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">jump_fcontext</span><span class="special">(&</span><span class="identifier">fcm</span><span class="special">,</span><span class="identifier">fc</span><span class="special">,(</span><span class="keyword">void</span> <span class="special">*)&</span><span class="identifier">p</span><span class="special">);</span> | |
209 | <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span><span class="special"><<</span><span class="identifier">p</span><span class="special">.</span><span class="identifier">first</span><span class="special"><<</span><span class="string">" + "</span><span class="special"><<</span><span class="identifier">p</span><span class="special">.</span><span class="identifier">second</span><span class="special"><<</span><span class="string">" == "</span><span class="special"><<</span><span class="identifier">res</span><span class="special"><<</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span> | |
210 | ||
211 | <span class="identifier">output</span><span class="special">:</span> | |
212 | <span class="number">2</span> <span class="special">+</span> <span class="number">7</span> <span class="special">==</span> <span class="number">9</span> | |
213 | <span class="number">5</span> <span class="special">+</span> <span class="number">6</span> <span class="special">==</span> <span class="number">11</span> | |
214 | </pre> | |
215 | <h4> | |
216 | <a name="context.context.h2"></a> | |
217 | <span><a name="context.context.exceptions_in__emphasis_context_function__emphasis_"></a></span><a class="link" href="context.html#context.context.exceptions_in__emphasis_context_function__emphasis_">Exceptions | |
218 | in <span class="emphasis"><em>context-function</em></span></a> | |
219 | </h4> | |
220 | <p> | |
221 | If the <span class="emphasis"><em>context-function</em></span> emits an exception, the behaviour | |
222 | is undefined. | |
223 | </p> | |
224 | <div class="important"><table border="0" summary="Important"> | |
225 | <tr> | |
226 | <td rowspan="2" align="center" valign="top" width="25"><img alt="[Important]" src="../../../../../doc/src/images/important.png"></td> | |
227 | <th align="left">Important</th> | |
228 | </tr> | |
229 | <tr><td align="left" valign="top"><p> | |
230 | <span class="emphasis"><em>context-function</em></span> should wrap the code in a try/catch | |
231 | block. | |
232 | </p></td></tr> | |
233 | </table></div> | |
234 | <div class="important"><table border="0" summary="Important"> | |
235 | <tr> | |
236 | <td rowspan="2" align="center" valign="top" width="25"><img alt="[Important]" src="../../../../../doc/src/images/important.png"></td> | |
237 | <th align="left">Important</th> | |
238 | </tr> | |
239 | <tr><td align="left" valign="top"><p> | |
240 | Do not jump from inside a catch block and then re-throw the exception in | |
241 | another execution context. | |
242 | </p></td></tr> | |
243 | </table></div> | |
244 | <h4> | |
245 | <a name="context.context.h3"></a> | |
246 | <span><a name="context.context.stack_unwinding"></a></span><a class="link" href="context.html#context.context.stack_unwinding">Stack | |
247 | unwinding</a> | |
248 | </h4> | |
249 | <p> | |
250 | Sometimes it is necessary to unwind the stack of an unfinished context to destroy | |
251 | local stack variables so they can release allocated resources (RAII pattern). | |
252 | The user is responsible for this task. | |
253 | </p> | |
254 | <h4> | |
255 | <a name="context.context.h4"></a> | |
256 | <span><a name="context.context._code__phrase_role__identifier__fcontext_t__phrase___code__and_related_functions"></a></span><a class="link" href="context.html#context.context._code__phrase_role__identifier__fcontext_t__phrase___code__and_related_functions"><code class="computeroutput"><span class="identifier">fcontext_t</span></code> and related functions</a> | |
257 | </h4> | |
258 | <pre class="programlisting"><span class="keyword">struct</span> <span class="identifier">stack_t</span> | |
259 | <span class="special">{</span> | |
260 | <span class="keyword">void</span><span class="special">*</span> <span class="identifier">sp</span><span class="special">;</span> | |
261 | <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">size</span><span class="special">;</span> | |
262 | <span class="special">};</span> | |
263 | ||
264 | <span class="keyword">typedef</span> <span class="special"><</span><span class="identifier">opaque</span> <span class="identifier">pointer</span> <span class="special">></span> <span class="identifier">fcontext_t</span><span class="special">;</span> | |
265 | ||
266 | <span class="keyword">void</span> <span class="special">*</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="keyword">void</span> <span class="special">*</span> <span class="identifier">vp</span><span class="special">);</span> | |
267 | <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="keyword">void</span> <span class="special">*));</span> | |
268 | </pre> | |
269 | <h4> | |
270 | <a name="context.context.h5"></a> | |
271 | <span><a name="context.context._code__phrase_role__identifier__sp__phrase___code_"></a></span><a class="link" href="context.html#context.context._code__phrase_role__identifier__sp__phrase___code_"><code class="computeroutput"><span class="identifier">sp</span></code></a> | |
272 | </h4> | |
273 | <div class="variablelist"> | |
274 | <p class="title"><b></b></p> | |
275 | <dl> | |
276 | <dt><span class="term">Member:</span></dt> | |
277 | <dd><p> | |
278 | Pointer to the beginning of the stack (depending of the architecture | |
279 | the stack grows downwards or upwards). | |
280 | </p></dd> | |
281 | </dl> | |
282 | </div> | |
283 | <h4> | |
284 | <a name="context.context.h6"></a> | |
285 | <span><a name="context.context._code__phrase_role__identifier__size__phrase___code_"></a></span><a class="link" href="context.html#context.context._code__phrase_role__identifier__size__phrase___code_"><code class="computeroutput"><span class="identifier">size</span></code></a> | |
286 | </h4> | |
287 | <div class="variablelist"> | |
288 | <p class="title"><b></b></p> | |
289 | <dl> | |
290 | <dt><span class="term">Member:</span></dt> | |
291 | <dd><p> | |
292 | Size of the stack in bytes. | |
293 | </p></dd> | |
294 | </dl> | |
295 | </div> | |
296 | <h4> | |
297 | <a name="context.context.h7"></a> | |
298 | <span><a name="context.context._code__phrase_role__identifier__fc_stack__phrase___code_"></a></span><a class="link" href="context.html#context.context._code__phrase_role__identifier__fc_stack__phrase___code_"><code class="computeroutput"><span class="identifier">fc_stack</span></code></a> | |
299 | </h4> | |
300 | <div class="variablelist"> | |
301 | <p class="title"><b></b></p> | |
302 | <dl> | |
303 | <dt><span class="term">Member:</span></dt> | |
304 | <dd><p> | |
305 | Tracks the memory for the context's stack. | |
306 | </p></dd> | |
307 | </dl> | |
308 | </div> | |
309 | <h4> | |
310 | <a name="context.context.h8"></a> | |
311 | <span><a name="context.context._code__phrase_role__keyword__void__phrase___phrase_role__special_____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__keyword__void__phrase___phrase_role__special_____phrase___phrase_role__identifier__p__phrase__phrase_role__special_____phrase___code_"></a></span><a class="link" href="context.html#context.context._code__phrase_role__keyword__void__phrase___phrase_role__special_____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__keyword__void__phrase___phrase_role__special_____phrase___phrase_role__identifier__p__phrase__phrase_role__special_____phrase___code_"><code class="computeroutput"><span class="keyword">void</span> <span class="special">*</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="keyword">void</span> <span class="special">*</span> | |
312 | <span class="identifier">p</span><span class="special">)</span></code></a> | |
313 | </h4> | |
314 | <div class="variablelist"> | |
315 | <p class="title"><b></b></p> | |
316 | <dl> | |
317 | <dt><span class="term">Effects:</span></dt> | |
318 | <dd><p> | |
319 | Stores the current context data (stack pointer, instruction pointer, | |
320 | and CPU registers) to <code class="computeroutput"><span class="special">*</span><span class="identifier">ofc</span></code> and restores the context data from | |
321 | <code class="computeroutput"><span class="identifier">nfc</span></code>, which implies jumping | |
322 | to execution context <code class="computeroutput"><span class="identifier">nfc</span></code>. | |
323 | The void * argument, <code class="computeroutput"><span class="identifier">p</span></code>, | |
324 | is passed to the current context to be returned by the most recent call | |
325 | to <code class="computeroutput"><span class="identifier">jump_fcontext</span><span class="special">()</span></code> | |
326 | in the same thread. | |
327 | </p></dd> | |
328 | <dt><span class="term">Returns:</span></dt> | |
329 | <dd><p> | |
330 | 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>, | |
331 | if any. | |
332 | </p></dd> | |
333 | </dl> | |
334 | </div> | |
335 | <h4> | |
336 | <a name="context.context.h9"></a> | |
337 | <span><a name="context.context._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__keyword__void__phrase___phrase_role__special_______phrase___code_"></a></span><a class="link" href="context.html#context.context._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__keyword__void__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> | |
338 | <span class="identifier">sp</span><span class="special">,</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> | |
339 | <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="keyword">void</span> <span class="special">*))</span></code></a> | |
340 | </h4> | |
341 | <div class="variablelist"> | |
342 | <p class="title"><b></b></p> | |
343 | <dl> | |
344 | <dt><span class="term">Precondition:</span></dt> | |
345 | <dd><p> | |
346 | Stack <code class="computeroutput"><span class="identifier">sp</span></code> and function | |
347 | pointer <code class="computeroutput"><span class="identifier">fn</span></code> are valid | |
348 | (depending on the architecture <code class="computeroutput"><span class="identifier">sp</span></code> | |
349 | points to the top or bottom of the stack) and <code class="computeroutput"><span class="identifier">size</span></code> | |
350 | > 0. | |
351 | </p></dd> | |
352 | <dt><span class="term">Effects:</span></dt> | |
353 | <dd><p> | |
354 | Creates an fcontext_t on top of the stack and prepares the stack to execute | |
355 | the <span class="emphasis"><em>context-function</em></span> <code class="computeroutput"><span class="identifier">fn</span></code>. | |
356 | </p></dd> | |
357 | <dt><span class="term">Returns:</span></dt> | |
358 | <dd><p> | |
359 | Returns a fcontext_t which is placed on the stack. | |
360 | </p></dd> | |
361 | </dl> | |
362 | </div> | |
363 | </div> | |
364 | <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> | |
365 | <td align="left"></td> | |
366 | <td align="right"><div class="copyright-footer">Copyright © 2014 Oliver Kowalke<p> | |
367 | Distributed under the Boost Software License, Version 1.0. (See accompanying | |
368 | 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>) | |
369 | </p> | |
370 | </div></td> | |
371 | </tr></table> | |
372 | <hr> | |
373 | <div class="spirit-nav"> | |
374 | <a accesskey="p" href="requirements.html"><img src="../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../index.html"><img src="../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../index.html"><img src="../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="abstract_context.html"><img src="../../../../../doc/src/images/next.png" alt="Next"></a> | |
375 | </div> | |
376 | </body> | |
377 | </html> |