93 lines
4.7 KiB
HTML
93 lines
4.7 KiB
HTML
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<html lang="en">
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<head>
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<title>Statements - Using as</title>
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<meta http-equiv="Content-Type" content="text/html">
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<meta name="description" content="Using as">
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<meta name="generator" content="makeinfo 4.13">
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<link title="Top" rel="start" href="index.html#Top">
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<link rel="up" href="Syntax.html#Syntax" title="Syntax">
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<link rel="prev" href="Symbol-Intro.html#Symbol-Intro" title="Symbol Intro">
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<link rel="next" href="Constants.html#Constants" title="Constants">
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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) 1991-2019 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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<style type="text/css"><!--
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--></style>
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</head>
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<body>
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<div class="node">
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<a name="Statements"></a>
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<p>
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Next: <a rel="next" accesskey="n" href="Constants.html#Constants">Constants</a>,
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Previous: <a rel="previous" accesskey="p" href="Symbol-Intro.html#Symbol-Intro">Symbol Intro</a>,
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Up: <a rel="up" accesskey="u" href="Syntax.html#Syntax">Syntax</a>
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<hr>
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</div>
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<h3 class="section">3.5 Statements</h3>
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<p><a name="index-statements_002c-structure-of-132"></a><a name="index-line-separator-character-133"></a><a name="index-statement-separator-character-134"></a>
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A <dfn>statement</dfn> ends at a newline character (‘<samp><span class="samp">\n</span></samp>’) or a
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<dfn>line separator character</dfn>. The line separator character is target
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specific and described in the <em>Syntax</em> section of each
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target's documentation. Not all targets support a line separator character.
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The newline or line separator character is considered to be part of the
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preceding statement. Newlines and separators within character constants are an
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exception: they do not end statements.
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<p><a name="index-newline_002c-required-at-file-end-135"></a><a name="index-EOF_002c-newline-must-precede-136"></a>It is an error to end any statement with end-of-file: the last
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character of any input file should be a newline.
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<p>An empty statement is allowed, and may include whitespace. It is ignored.
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<p><a name="index-instructions-and-directives-137"></a><a name="index-directives-and-instructions-138"></a><!-- "key symbol" is not used elsewhere in the document; seems pedantic to -->
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<!-- @defn{} it in that case, as was done previously... doc@cygnus.com, -->
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<!-- 13feb91. -->
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A statement begins with zero or more labels, optionally followed by a
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key symbol which determines what kind of statement it is. The key
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symbol determines the syntax of the rest of the statement. If the
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symbol begins with a dot ‘<samp><span class="samp">.</span></samp>’ then the statement is an assembler
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directive: typically valid for any computer. If the symbol begins with
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a letter the statement is an assembly language <dfn>instruction</dfn>: it
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assembles into a machine language instruction.
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Different versions of <samp><span class="command">as</span></samp> for different computers
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recognize different instructions. In fact, the same symbol may
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represent a different instruction in a different computer's assembly
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language.
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<p><a name="index-g_t_0040code_007b_003a_007d-_0028label_0029-139"></a><a name="index-label-_0028_0040code_007b_003a_007d_0029-140"></a>A label is a symbol immediately followed by a colon (<code>:</code>).
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Whitespace before a label or after a colon is permitted, but you may not
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have whitespace between a label's symbol and its colon. See <a href="Labels.html#Labels">Labels</a>.
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<p>For HPPA targets, labels need not be immediately followed by a colon, but
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the definition of a label must begin in column zero. This also implies that
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only one label may be defined on each line.
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<pre class="smallexample"> label: .directive followed by something
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another_label: # This is an empty statement.
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instruction operand_1, operand_2, ...
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</pre>
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</body></html>
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