toolchain/gcc-linaro-6.3.1-2017.02-x8.../share/doc/as.html/Previous.html

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<a name="g_t_002eprevious"></a>
<h3 class="section">7.67 <code>.previous</code></h3>
<a name="index-previous-directive"></a>
<a name="index-Section-Stack-1"></a>
<p>This is one of the ELF section stack manipulation directives. The others are
<code>.section</code> (see <a href="Section.html#Section">Section</a>), <code>.subsection</code> (see <a href="SubSection.html#SubSection">SubSection</a>),
<code>.pushsection</code> (see <a href="PushSection.html#PushSection">PushSection</a>), and <code>.popsection</code>
(see <a href="PopSection.html#PopSection">PopSection</a>).
</p>
<p>This directive swaps the current section (and subsection) with most recently
referenced section/subsection pair prior to this one. Multiple
<code>.previous</code> directives in a row will flip between two sections (and their
subsections). For example:
</p>
<div class="smallexample">
<pre class="smallexample">.section A
.subsection 1
.word 0x1234
.subsection 2
.word 0x5678
.previous
.word 0x9abc
</pre></div>
<p>Will place 0x1234 and 0x9abc into subsection 1 and 0x5678 into subsection 2 of
section A. Whilst:
</p>
<div class="smallexample">
<pre class="smallexample">.section A
.subsection 1
# Now in section A subsection 1
.word 0x1234
.section B
.subsection 0
# Now in section B subsection 0
.word 0x5678
.subsection 1
# Now in section B subsection 1
.word 0x9abc
.previous
# Now in section B subsection 0
.word 0xdef0
</pre></div>
<p>Will place 0x1234 into section A, 0x5678 and 0xdef0 into subsection 0 of
section B and 0x9abc into subsection 1 of section B.
</p>
<p>In terms of the section stack, this directive swaps the current section with
the top section on the section stack.
</p>
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