66 lines
2.9 KiB
HTML
66 lines
2.9 KiB
HTML
<html lang="en">
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<head>
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<title>bss - Using as</title>
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<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage">
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<!--
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This file documents the GNU Assembler "as".
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Copyright (C) 1991, 92, 93, 94, 95, 96, 97, 98, 99, 2000, 2001, 2002,
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2006, 2007 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 1.1
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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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</head>
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<body>
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<div class="node">
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<p>
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<a name="bss"></a>Previous: <a rel="previous" accesskey="p" href="Sub_002dSections.html#Sub_002dSections">Sub-Sections</a>,
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Up: <a rel="up" accesskey="u" href="Sections.html#Sections">Sections</a>
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<hr><br>
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</div>
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<h3 class="section">4.5 bss Section</h3>
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<p><a name="index-bss-section-206"></a><a name="index-common-variable-storage-207"></a>The bss section is used for local common variable storage.
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You may allocate address space in the bss section, but you may
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not dictate data to load into it before your program executes. When
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your program starts running, all the contents of the bss
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section are zeroed bytes.
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<p>The <code>.lcomm</code> pseudo-op defines a symbol in the bss section; see
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<a href="Lcomm.html#Lcomm"><code>.lcomm</code></a>.
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<p>The <code>.comm</code> pseudo-op may be used to declare a common symbol, which is
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another form of uninitialized symbol; see <a href="Comm.html#Comm"><code>.comm</code></a>.
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<p>When assembling for a target which supports multiple sections, such as ELF or
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COFF, you may switch into the <code>.bss</code> section and define symbols as usual;
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see <a href="Section.html#Section"><code>.section</code></a>. You may only assemble zero values into the
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section. Typically the section will only contain symbol definitions and
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<code>.skip</code> directives (see <a href="Skip.html#Skip"><code>.skip</code></a>).
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</body></html>
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