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100 lines
4.3 KiB
HTML
100 lines
4.3 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>GNU Assembler (Using as)</title>
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<meta name="description" content="GNU Assembler (Using as)">
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<meta name="keywords" content="GNU Assembler (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="Overview.html#Overview" rel="up" title="Overview">
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<link href="Object-Formats.html#Object-Formats" rel="next" title="Object Formats">
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<link href="Manual.html#Manual" rel="prev" title="Manual">
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<style type="text/css">
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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="GNU-Assembler"></a>
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<div class="header">
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<p>
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Next: <a href="Object-Formats.html#Object-Formats" accesskey="n" rel="next">Object Formats</a>, Previous: <a href="Manual.html#Manual" accesskey="p" rel="prev">Manual</a>, Up: <a href="Overview.html#Overview" accesskey="u" rel="up">Overview</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="The-GNU-Assembler"></a>
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<h3 class="section">1.2 The GNU Assembler</h3>
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<p><small>GNU</small> <code>as</code> is really a family of assemblers.
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If you use (or have used) the <small>GNU</small> assembler on one architecture, you
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should find a fairly similar environment when you use it on another
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architecture. Each version has much in common with the others,
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including object file formats, most assembler directives (often called
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<em>pseudo-ops</em>) and assembler syntax.
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</p>
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<a name="index-purpose-of-GNU-assembler"></a>
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<p><code>as</code> is primarily intended to assemble the output of the
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<small>GNU</small> C compiler <code>gcc</code> for use by the linker
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<code>ld</code>. Nevertheless, we’ve tried to make <code>as</code>
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assemble correctly everything that other assemblers for the same
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machine would assemble.
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Any exceptions are documented explicitly (see <a href="Machine-Dependencies.html#Machine-Dependencies">Machine Dependencies</a>).
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This doesn’t mean <code>as</code> always uses the same syntax as another
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assembler for the same architecture; for example, we know of several
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incompatible versions of 680x0 assembly language syntax.
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</p>
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<p>Unlike older assemblers, <code>as</code> is designed to assemble a source
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program in one pass of the source file. This has a subtle impact on the
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<kbd>.org</kbd> directive (see <a href="Org.html#Org"><code>.org</code></a>).
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</p>
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</body>
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</html>
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