You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
93 lines
4.7 KiB
HTML
93 lines
4.7 KiB
HTML
4 years ago
|
<html lang="en">
|
||
|
|
<head>
|
||
|
|
<title>Statements - Using as</title>
|
||
|
|
<meta http-equiv="Content-Type" content="text/html">
|
||
|
|
<meta name="description" content="Using as">
|
||
|
|
<meta name="generator" content="makeinfo 4.13">
|
||
|
|
<link title="Top" rel="start" href="index.html#Top">
|
||
|
|
<link rel="up" href="Syntax.html#Syntax" title="Syntax">
|
||
|
|
<link rel="prev" href="Symbol-Intro.html#Symbol-Intro" title="Symbol Intro">
|
||
|
|
<link rel="next" href="Constants.html#Constants" title="Constants">
|
||
|
|
<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage">
|
||
|
|
<!--
|
||
|
|
This file documents the GNU Assembler "as".
|
||
|
|
|
||
|
|
Copyright (C) 1991-2015 Free Software Foundation, Inc.
|
||
|
|
|
||
|
|
Permission is granted to copy, distribute and/or modify this document
|
||
|
|
under the terms of the GNU Free Documentation License, Version 1.3
|
||
|
|
or any later version published by the Free Software Foundation;
|
||
|
|
with no Invariant Sections, with no Front-Cover Texts, and with no
|
||
|
|
Back-Cover Texts. A copy of the license is included in the
|
||
|
|
section entitled ``GNU Free Documentation License''.
|
||
|
|
|
||
|
|
-->
|
||
|
|
<meta http-equiv="Content-Style-Type" content="text/css">
|
||
|
|
<style type="text/css"><!--
|
||
|
|
pre.display { font-family:inherit }
|
||
|
|
pre.format { font-family:inherit }
|
||
|
|
pre.smalldisplay { font-family:inherit; font-size:smaller }
|
||
|
|
pre.smallformat { font-family:inherit; font-size:smaller }
|
||
|
|
pre.smallexample { font-size:smaller }
|
||
|
|
pre.smalllisp { font-size:smaller }
|
||
|
|
span.sc { font-variant:small-caps }
|
||
|
|
span.roman { font-family:serif; font-weight:normal; }
|
||
|
|
span.sansserif { font-family:sans-serif; font-weight:normal; }
|
||
|
|
--></style>
|
||
|
|
</head>
|
||
|
|
<body>
|
||
|
|
<div class="node">
|
||
|
|
<a name="Statements"></a>
|
||
|
|
<p>
|
||
|
|
Next: <a rel="next" accesskey="n" href="Constants.html#Constants">Constants</a>,
|
||
|
|
Previous: <a rel="previous" accesskey="p" href="Symbol-Intro.html#Symbol-Intro">Symbol Intro</a>,
|
||
|
|
Up: <a rel="up" accesskey="u" href="Syntax.html#Syntax">Syntax</a>
|
||
|
|
<hr>
|
||
|
|
</div>
|
||
|
|
|
||
|
|
<h3 class="section">3.5 Statements</h3>
|
||
|
|
|
||
|
|
<p><a name="index-statements_002c-structure-of-130"></a><a name="index-line-separator-character-131"></a><a name="index-statement-separator-character-132"></a>
|
||
|
|
A <dfn>statement</dfn> ends at a newline character (‘<samp><span class="samp">\n</span></samp>’) or a
|
||
|
|
<dfn>line separator character</dfn>. The line separator character is target
|
||
|
|
specific and described in the <em>Syntax</em> section of each
|
||
|
|
target's documentation. Not all targets support a line separator character.
|
||
|
|
The newline or line separator character is considered to be part of the
|
||
|
|
preceding statement. Newlines and separators within character constants are an
|
||
|
|
exception: they do not end statements.
|
||
|
|
|
||
|
|
<p><a name="index-newline_002c-required-at-file-end-133"></a><a name="index-EOF_002c-newline-must-precede-134"></a>It is an error to end any statement with end-of-file: the last
|
||
|
|
character of any input file should be a newline.
|
||
|
|
|
||
|
|
<p>An empty statement is allowed, and may include whitespace. It is ignored.
|
||
|
|
|
||
|
|
<p><a name="index-instructions-and-directives-135"></a><a name="index-directives-and-instructions-136"></a><!-- "key symbol" is not used elsewhere in the document; seems pedantic to -->
|
||
|
|
<!-- @defn{} it in that case, as was done previously... doc@cygnus.com, -->
|
||
|
|
<!-- 13feb91. -->
|
||
|
|
A statement begins with zero or more labels, optionally followed by a
|
||
|
|
key symbol which determines what kind of statement it is. The key
|
||
|
|
symbol determines the syntax of the rest of the statement. If the
|
||
|
|
symbol begins with a dot ‘<samp><span class="samp">.</span></samp>’ then the statement is an assembler
|
||
|
|
directive: typically valid for any computer. If the symbol begins with
|
||
|
|
a letter the statement is an assembly language <dfn>instruction</dfn>: it
|
||
|
|
assembles into a machine language instruction.
|
||
|
|
Different versions of <samp><span class="command">as</span></samp> for different computers
|
||
|
|
recognize different instructions. In fact, the same symbol may
|
||
|
|
represent a different instruction in a different computer's assembly
|
||
|
|
language.
|
||
|
|
|
||
|
|
<p><a name="index-g_t_0040code_007b_003a_007d-_0028label_0029-137"></a><a name="index-label-_0028_0040code_007b_003a_007d_0029-138"></a>A label is a symbol immediately followed by a colon (<code>:</code>).
|
||
|
|
Whitespace before a label or after a colon is permitted, but you may not
|
||
|
|
have whitespace between a label's symbol and its colon. See <a href="Labels.html#Labels">Labels</a>.
|
||
|
|
|
||
|
|
<p>For HPPA targets, labels need not be immediately followed by a colon, but
|
||
|
|
the definition of a label must begin in column zero. This also implies that
|
||
|
|
only one label may be defined on each line.
|
||
|
|
|
||
|
|
<pre class="smallexample"> label: .directive followed by something
|
||
|
|
another_label: # This is an empty statement.
|
||
|
|
instruction operand_1, operand_2, ...
|
||
|
|
</pre>
|
||
|
|
</body></html>
|
||
|
|
|