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| author | Chanho Park <chanho61.park@samsung.com> | 2014-12-11 18:55:56 +0900 |
|---|---|---|
| committer | Chanho Park <chanho61.park@samsung.com> | 2014-12-11 18:55:56 +0900 |
| commit | 08c1e93fa36a49f49325a07fe91ff92c964c2b6c (patch) | |
| tree | 7a7053ceb8874b28ec4b868d4c49b500008a102e /doc/html/align/rationale.html | |
| parent | bb4dd8289b351fae6b55e303f189127a394a1edd (diff) | |
| download | boost-08c1e93fa36a49f49325a07fe91ff92c964c2b6c.tar.gz boost-08c1e93fa36a49f49325a07fe91ff92c964c2b6c.tar.bz2 boost-08c1e93fa36a49f49325a07fe91ff92c964c2b6c.zip | |
Imported Upstream version 1.57.0upstream/1.57.0
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| -rw-r--r-- | doc/html/align/rationale.html | 179 |
1 files changed, 179 insertions, 0 deletions
diff --git a/doc/html/align/rationale.html b/doc/html/align/rationale.html new file mode 100644 index 0000000000..0c4df9ab73 --- /dev/null +++ b/doc/html/align/rationale.html @@ -0,0 +1,179 @@ +<html> +<head> +<meta http-equiv="Content-Type" content="text/html; charset=US-ASCII"> +<title>Rationale</title> +<link rel="stylesheet" href="../../../doc/src/boostbook.css" type="text/css"> +<meta name="generator" content="DocBook XSL Stylesheets V1.78.1"> +<link rel="home" href="../index.html" title="The Boost C++ Libraries BoostBook Documentation Subset"> +<link rel="up" href="../align.html" title="Chapter 2. Boost.Align"> +<link rel="prev" href="../align.html" title="Chapter 2. Boost.Align"> +<link rel="next" href="tutorial.html" title="Tutorial"> +</head> +<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> +<table cellpadding="2" width="100%"><tr> +<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../boost.png"></td> +<td align="center"><a href="../../../index.html">Home</a></td> +<td align="center"><a href="../../../libs/libraries.htm">Libraries</a></td> +<td align="center"><a href="http://www.boost.org/users/people.html">People</a></td> +<td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td> +<td align="center"><a href="../../../more/index.htm">More</a></td> +</tr></table> +<hr> +<div class="spirit-nav"> +<a accesskey="p" href="../align.html"><img src="../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../align.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="tutorial.html"><img src="../../../doc/src/images/next.png" alt="Next"></a> +</div> +<div class="section"> +<div class="titlepage"><div><div><h2 class="title" style="clear: both"> +<a name="align.rationale"></a><a class="link" href="rationale.html" title="Rationale">Rationale</a> +</h2></div></div></div> +<h4> +<a name="align.rationale.h0"></a> + <span class="phrase"><a name="align.rationale.dynamic_allocation"></a></span><a class="link" href="rationale.html#align.rationale.dynamic_allocation">Dynamic + allocation</a> + </h4> +<p> + C++11 added the ability to specify increased alignment (over-alignment) for + class types. Unfortunately, <code class="computeroutput"><span class="special">::</span><span class="keyword">operator</span> <span class="keyword">new</span></code> + allocation functions, <code class="computeroutput"><span class="keyword">new</span></code> expressions, + and the default allocator, <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">allocator</span></code>, + do not support dynamic memory allocation of over-aligned data. This library + provides allocation functions, allocators, allocator adaptors, and deleters, + that are alignment aware. + </p> +<div class="table"> +<a name="align.rationale.boost_align_solutions"></a><p class="title"><b>Table 2.2. Boost.Align solutions</b></p> +<div class="table-contents"><table class="table" summary="Boost.Align solutions"> +<colgroup> +<col> +<col> +</colgroup> +<thead><tr> +<th> + <p> + Problem + </p> + </th> +<th> + <p> + Solution + </p> + </th> +</tr></thead> +<tbody> +<tr> +<td> + <p> + <code class="computeroutput"><span class="special">::</span><span class="keyword">operator</span> + <span class="keyword">new</span><span class="special">(</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span><span class="special">,</span> + <span class="keyword">const</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">no_throw_t</span><span class="special">&)</span></code> + </p> + </td> +<td> + <p> + <code class="computeroutput"><span class="identifier">aligned_alloc</span><span class="special">(</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span><span class="special">,</span> + <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span><span class="special">)</span></code> + </p> + </td> +</tr> +<tr> +<td> + <p> + <code class="computeroutput"><span class="special">::</span><span class="keyword">operator</span> + <span class="keyword">delete</span><span class="special">(</span><span class="keyword">void</span><span class="special">*)</span></code> + </p> + </td> +<td> + <p> + <code class="computeroutput"><span class="identifier">aligned_free</span><span class="special">(</span><span class="keyword">void</span><span class="special">*)</span></code> + </p> + </td> +</tr> +<tr> +<td> + <p> + <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">allocator</span><span class="special"><</span><span class="identifier">T</span><span class="special">></span></code> + </p> + </td> +<td> + <p> + <code class="computeroutput"><span class="identifier">aligned_allocator</span><span class="special"><</span><span class="identifier">T</span><span class="special">></span></code> + </p> + </td> +</tr> +<tr> +<td> + <p> + <code class="computeroutput"><span class="identifier">Allocator</span></code> + </p> + </td> +<td> + <p> + <code class="computeroutput"><span class="identifier">aligned_allocator_adaptor</span><span class="special"><</span><span class="identifier">Allocator</span><span class="special">></span></code> + </p> + </td> +</tr> +<tr> +<td> + <p> + <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">default_delete</span><span class="special"><</span><span class="identifier">T</span><span class="special">></span></code> + </p> + </td> +<td> + <p> + <code class="computeroutput"><span class="identifier">aligned_delete</span></code> + </p> + </td> +</tr> +</tbody> +</table></div> +</div> +<br class="table-break"><h4> +<a name="align.rationale.h1"></a> + <span class="phrase"><a name="align.rationale.alignment_functions"></a></span><a class="link" href="rationale.html#align.rationale.alignment_functions">Alignment + functions</a> + </h4> +<p> + C++11 provided <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">align</span></code> in the standard library to align a + pointer value. Unfortunately some C++ standard library implementations do not + support it yet (libstdc++ as far as gcc 4.8.0) and other standard library implementations + implement it incorrectly (dinkumware in msvc 11.0). This library provides it + for those implementations and also for C++03 compilers where it is equally + useful. + </p> +<h4> +<a name="align.rationale.h2"></a> + <span class="phrase"><a name="align.rationale.alignment_traits"></a></span><a class="link" href="rationale.html#align.rationale.alignment_traits">Alignment + traits</a> + </h4> +<p> + C++11 provided the <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">alignment_of</span></code> trait in the standard library + to query the alignment requirement of a type. Unfortunately some C++ standard + library vendors do not implement it in an entirely standard conforming manner, + such as for array types (libc++ as far as clang 3.4). This library provides + it for those implementations and also for C++03 compilers where it is equally + useful. + </p> +<h4> +<a name="align.rationale.h3"></a> + <span class="phrase"><a name="align.rationale.alignment_testing"></a></span><a class="link" href="rationale.html#align.rationale.alignment_testing">Alignment + testing</a> + </h4> +<p> + This library provides a function to test the alignment of a pointer value. + It is generally useful in assertions to validate that memory is correctly aligned. + </p> +</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 Glen Fernandes<p> + Distributed under the <a href="http://boost.org/LICENSE_1_0.txt" target="_top">Boost + Software License, Version 1.0</a>. + </p> +</div></td> +</tr></table> +<hr> +<div class="spirit-nav"> +<a accesskey="p" href="../align.html"><img src="../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../align.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="tutorial.html"><img src="../../../doc/src/images/next.png" alt="Next"></a> +</div> +</body> +</html> |