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124 lines
4.5 KiB
HTML
124 lines
4.5 KiB
HTML
4 years ago
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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
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<html>
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<!-- This file documents the GNU Assembler "as".
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Copyright (C) 1991-2019 Free Software Foundation, Inc.
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Permission is granted to copy, distribute and/or modify this document
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under the terms of the GNU Free Documentation License, Version 1.3
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or any later version published by the Free Software Foundation;
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with no Invariant Sections, with no Front-Cover Texts, and with no
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Back-Cover Texts. A copy of the license is included in the
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section entitled "GNU Free Documentation License".
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-->
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<!-- Created by GNU Texinfo 6.4, http://www.gnu.org/software/texinfo/ -->
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<head>
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<title>Previous (Using as)</title>
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<meta name="description" content="Previous (Using as)">
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<meta name="keywords" content="Previous (Using as)">
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<meta name="resource-type" content="document">
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<meta name="distribution" content="global">
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<meta name="Generator" content="makeinfo">
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
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<link href="index.html#Top" rel="start" title="Top">
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<link href="AS-Index.html#AS-Index" rel="index" title="AS Index">
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<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
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<link href="Pseudo-Ops.html#Pseudo-Ops" rel="up" title="Pseudo Ops">
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<link href="Print.html#Print" rel="next" title="Print">
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<link href="PopSection.html#PopSection" rel="prev" title="PopSection">
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<style type="text/css">
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<!--
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a.summary-letter {text-decoration: none}
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blockquote.indentedblock {margin-right: 0em}
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blockquote.smallindentedblock {margin-right: 0em; font-size: smaller}
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blockquote.smallquotation {font-size: smaller}
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div.display {margin-left: 3.2em}
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div.example {margin-left: 3.2em}
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div.lisp {margin-left: 3.2em}
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div.smalldisplay {margin-left: 3.2em}
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div.smallexample {margin-left: 3.2em}
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div.smalllisp {margin-left: 3.2em}
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kbd {font-style: oblique}
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pre.display {font-family: inherit}
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pre.format {font-family: inherit}
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pre.menu-comment {font-family: serif}
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pre.menu-preformatted {font-family: serif}
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pre.smalldisplay {font-family: inherit; font-size: smaller}
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pre.smallexample {font-size: smaller}
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pre.smallformat {font-family: inherit; font-size: smaller}
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pre.smalllisp {font-size: smaller}
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span.nolinebreak {white-space: nowrap}
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span.roman {font-family: initial; font-weight: normal}
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span.sansserif {font-family: sans-serif; font-weight: normal}
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ul.no-bullet {list-style: none}
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-->
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</style>
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</head>
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<body lang="en">
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<a name="Previous"></a>
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<div class="header">
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<p>
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Next: <a href="Print.html#Print" accesskey="n" rel="next">Print</a>, Previous: <a href="PopSection.html#PopSection" accesskey="p" rel="prev">PopSection</a>, Up: <a href="Pseudo-Ops.html#Pseudo-Ops" accesskey="u" rel="up">Pseudo Ops</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="AS-Index.html#AS-Index" title="Index" rel="index">Index</a>]</p>
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</div>
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<hr>
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<a name="g_t_002eprevious"></a>
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<h3 class="section">7.71 <code>.previous</code></h3>
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<a name="index-previous-directive"></a>
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<a name="index-Section-Stack-1"></a>
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<p>This is one of the ELF section stack manipulation directives. The others are
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<code>.section</code> (see <a href="Section.html#Section">Section</a>), <code>.subsection</code> (see <a href="SubSection.html#SubSection">SubSection</a>),
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<code>.pushsection</code> (see <a href="PushSection.html#PushSection">PushSection</a>), and <code>.popsection</code>
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(see <a href="PopSection.html#PopSection">PopSection</a>).
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</p>
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<p>This directive swaps the current section (and subsection) with most recently
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referenced section/subsection pair prior to this one. Multiple
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<code>.previous</code> directives in a row will flip between two sections (and their
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subsections). For example:
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</p>
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<div class="smallexample">
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<pre class="smallexample">.section A
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.subsection 1
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.word 0x1234
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.subsection 2
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.word 0x5678
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.previous
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.word 0x9abc
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</pre></div>
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<p>Will place 0x1234 and 0x9abc into subsection 1 and 0x5678 into subsection 2 of
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section A. Whilst:
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</p>
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<div class="smallexample">
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<pre class="smallexample">.section A
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.subsection 1
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# Now in section A subsection 1
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.word 0x1234
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.section B
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.subsection 0
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# Now in section B subsection 0
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.word 0x5678
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.subsection 1
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# Now in section B subsection 1
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.word 0x9abc
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.previous
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# Now in section B subsection 0
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.word 0xdef0
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</pre></div>
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<p>Will place 0x1234 into section A, 0x5678 and 0xdef0 into subsection 0 of
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section B and 0x9abc into subsection 1 of section B.
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</p>
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<p>In terms of the section stack, this directive swaps the current section with
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the top section on the section stack.
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</p>
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</body>
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</html>
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