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26 <div class="titlepage"><div><div><h3 class="title">
27 <a name="context.rationale.x86_and_floating_point_env"></a><a class="link" href="x86_and_floating_point_env.html" title="x86 and floating-point env">x86 and
28 floating-point env</a>
29 </h3></div></div></div>
31 <a name="context.rationale.x86_and_floating_point_env.h0"></a>
32 <span class="phrase"><a name="context.rationale.x86_and_floating_point_env.i386"></a></span><a class="link" href="x86_and_floating_point_env.html#context.rationale.x86_and_floating_point_env.i386">i386</a>
35 "The FpCsr and the MxCsr register must be saved and restored before
36 any call or return by any procedure that needs to modify them ..."
37 <a href="#ftn.context.rationale.x86_and_floating_point_env.f0" class="footnote" name="context.rationale.x86_and_floating_point_env.f0"><sup class="footnote">[4]</sup></a>.
40 <a name="context.rationale.x86_and_floating_point_env.h1"></a>
41 <span class="phrase"><a name="context.rationale.x86_and_floating_point_env.x86_64"></a></span><a class="link" href="x86_and_floating_point_env.html#context.rationale.x86_and_floating_point_env.x86_64">x86_64</a>
44 <a name="context.rationale.x86_and_floating_point_env.h2"></a>
45 <span class="phrase"><a name="context.rationale.x86_and_floating_point_env.windows"></a></span><a class="link" href="x86_and_floating_point_env.html#context.rationale.x86_and_floating_point_env.windows">Windows</a>
48 MxCsr - "A callee that modifies any of the non-volatile fields within
49 MxCsr must restore them before returning to its caller. Furthermore, a caller
50 that has modified any of these fields must restore them to their standard
51 values before invoking a callee ..." <a href="#ftn.context.rationale.x86_and_floating_point_env.f1" class="footnote" name="context.rationale.x86_and_floating_point_env.f1"><sup class="footnote">[5]</sup></a>.
54 FpCsr - "A callee that modifies any of the fields within FpCsr must
55 restore them before returning to its caller. Furthermore, a caller that has
56 modified any of these fields must restore them to their standard values before
57 invoking a callee ..." <a href="#ftn.context.rationale.x86_and_floating_point_env.f2" class="footnote" name="context.rationale.x86_and_floating_point_env.f2"><sup class="footnote">[6]</sup></a>.
60 "The MMX and floating-point stack registers (MM0-MM7/ST0-ST7) are preserved
61 across context switches. There is no explicit calling convention for these
62 registers." <a href="#ftn.context.rationale.x86_and_floating_point_env.f3" class="footnote" name="context.rationale.x86_and_floating_point_env.f3"><sup class="footnote">[7]</sup></a>.
65 "The 64-bit Microsoft compiler does not use ST(0)-ST(7)/MM0-MM7".
66 <a href="#ftn.context.rationale.x86_and_floating_point_env.f4" class="footnote" name="context.rationale.x86_and_floating_point_env.f4"><sup class="footnote">[8]</sup></a>.
69 "XMM6-XMM15 must be preserved" <a href="#ftn.context.rationale.x86_and_floating_point_env.f5" class="footnote" name="context.rationale.x86_and_floating_point_env.f5"><sup class="footnote">[9]</sup></a>
72 <a name="context.rationale.x86_and_floating_point_env.h3"></a>
73 <span class="phrase"><a name="context.rationale.x86_and_floating_point_env.sysv"></a></span><a class="link" href="x86_and_floating_point_env.html#context.rationale.x86_and_floating_point_env.sysv">SysV</a>
76 "The control bits of the MxCsr register are callee-saved (preserved
77 across calls), while the status bits are caller-saved (not preserved). The
78 x87 status word register is caller-saved, whereas the x87 control word (FpCsr)
79 is callee-saved." <a href="#ftn.context.rationale.x86_and_floating_point_env.f6" class="footnote" name="context.rationale.x86_and_floating_point_env.f6"><sup class="footnote">[10]</sup></a>.
81 <div class="footnotes">
82 <br><hr style="width:100; text-align:left;margin-left: 0">
83 <div id="ftn.context.rationale.x86_and_floating_point_env.f0" class="footnote"><p><a href="#context.rationale.x86_and_floating_point_env.f0" class="para"><sup class="para">[4] </sup></a>
84 'Calling Conventions', Agner Fog
86 <div id="ftn.context.rationale.x86_and_floating_point_env.f1" class="footnote"><p><a href="#context.rationale.x86_and_floating_point_env.f1" class="para"><sup class="para">[5] </sup></a>
87 <a href="http://http://msdn.microsoft.com/en-us/library/yxty7t75.aspx" target="_top">MSDN
90 <div id="ftn.context.rationale.x86_and_floating_point_env.f2" class="footnote"><p><a href="#context.rationale.x86_and_floating_point_env.f2" class="para"><sup class="para">[6] </sup></a>
91 <a href="http://http://msdn.microsoft.com/en-us/library/ms235300.aspx" target="_top">MSDN
94 <div id="ftn.context.rationale.x86_and_floating_point_env.f3" class="footnote"><p><a href="#context.rationale.x86_and_floating_point_env.f3" class="para"><sup class="para">[7] </sup></a>
95 <a href="http://msdn.microsoft.com/en-us/library/a32tsf7t%28VS.80%29.aspx" target="_top">MSDN
96 article 'Legacy Floating-Point Support'</a>
98 <div id="ftn.context.rationale.x86_and_floating_point_env.f4" class="footnote"><p><a href="#context.rationale.x86_and_floating_point_env.f4" class="para"><sup class="para">[8] </sup></a>
99 'Calling Conventions', Agner Fog
101 <div id="ftn.context.rationale.x86_and_floating_point_env.f5" class="footnote"><p><a href="#context.rationale.x86_and_floating_point_env.f5" class="para"><sup class="para">[9] </sup></a>
102 <a href="http://msdn.microsoft.com/en-us/library/9z1stfyw%28v=vs.100%29.aspx" target="_top">MSDN
103 article 'Register Usage'</a>
105 <div id="ftn.context.rationale.x86_and_floating_point_env.f6" class="footnote"><p><a href="#context.rationale.x86_and_floating_point_env.f6" class="para"><sup class="para">[10] </sup></a>
106 SysV ABI AMD64 Architecture Processor Supplement Draft Version 0.99.4,
111 <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
112 <td align="left"></td>
113 <td align="right"><div class="copyright-footer">Copyright © 2009 Oliver Kowalke<p>
114 Distributed under the Boost Software License, Version 1.0. (See accompanying
115 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>)
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