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.
95 lines
4.0 KiB
HTML
95 lines
4.0 KiB
HTML
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
|
|
<html>
|
|
<!-- This file documents the GNU Assembler "as".
|
|
|
|
Copyright (C) 1991-2019 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".
|
|
-->
|
|
<!-- Created by GNU Texinfo 6.4, http://www.gnu.org/software/texinfo/ -->
|
|
<head>
|
|
<title>Symbol Value (Using as)</title>
|
|
|
|
<meta name="description" content="Symbol Value (Using as)">
|
|
<meta name="keywords" content="Symbol Value (Using as)">
|
|
<meta name="resource-type" content="document">
|
|
<meta name="distribution" content="global">
|
|
<meta name="Generator" content="makeinfo">
|
|
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
|
|
<link href="index.html#Top" rel="start" title="Top">
|
|
<link href="AS-Index.html#AS-Index" rel="index" title="AS Index">
|
|
<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
|
|
<link href="Symbol-Attributes.html#Symbol-Attributes" rel="up" title="Symbol Attributes">
|
|
<link href="Symbol-Type.html#Symbol-Type" rel="next" title="Symbol Type">
|
|
<link href="Symbol-Attributes.html#Symbol-Attributes" rel="prev" title="Symbol Attributes">
|
|
<style type="text/css">
|
|
<!--
|
|
a.summary-letter {text-decoration: none}
|
|
blockquote.indentedblock {margin-right: 0em}
|
|
blockquote.smallindentedblock {margin-right: 0em; font-size: smaller}
|
|
blockquote.smallquotation {font-size: smaller}
|
|
div.display {margin-left: 3.2em}
|
|
div.example {margin-left: 3.2em}
|
|
div.lisp {margin-left: 3.2em}
|
|
div.smalldisplay {margin-left: 3.2em}
|
|
div.smallexample {margin-left: 3.2em}
|
|
div.smalllisp {margin-left: 3.2em}
|
|
kbd {font-style: oblique}
|
|
pre.display {font-family: inherit}
|
|
pre.format {font-family: inherit}
|
|
pre.menu-comment {font-family: serif}
|
|
pre.menu-preformatted {font-family: serif}
|
|
pre.smalldisplay {font-family: inherit; font-size: smaller}
|
|
pre.smallexample {font-size: smaller}
|
|
pre.smallformat {font-family: inherit; font-size: smaller}
|
|
pre.smalllisp {font-size: smaller}
|
|
span.nolinebreak {white-space: nowrap}
|
|
span.roman {font-family: initial; font-weight: normal}
|
|
span.sansserif {font-family: sans-serif; font-weight: normal}
|
|
ul.no-bullet {list-style: none}
|
|
-->
|
|
</style>
|
|
|
|
|
|
</head>
|
|
|
|
<body lang="en">
|
|
<a name="Symbol-Value"></a>
|
|
<div class="header">
|
|
<p>
|
|
Next: <a href="Symbol-Type.html#Symbol-Type" accesskey="n" rel="next">Symbol Type</a>, Up: <a href="Symbol-Attributes.html#Symbol-Attributes" accesskey="u" rel="up">Symbol Attributes</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>
|
|
</div>
|
|
<hr>
|
|
<a name="Value"></a>
|
|
<h4 class="subsection">5.5.1 Value</h4>
|
|
|
|
<a name="index-value-of-a-symbol"></a>
|
|
<a name="index-symbol-value"></a>
|
|
<p>The value of a symbol is (usually) 32 bits. For a symbol which labels a
|
|
location in the text, data, bss or absolute sections the value is the
|
|
number of addresses from the start of that section to the label.
|
|
Naturally for text, data and bss sections the value of a symbol changes
|
|
as <code>ld</code> changes section base addresses during linking. Absolute
|
|
symbols’ values do not change during linking: that is why they are
|
|
called absolute.
|
|
</p>
|
|
<p>The value of an undefined symbol is treated in a special way. If it is
|
|
0 then the symbol is not defined in this assembler source file, and
|
|
<code>ld</code> tries to determine its value from other files linked into the
|
|
same program. You make this kind of symbol simply by mentioning a symbol
|
|
name without defining it. A non-zero value represents a <code>.comm</code>
|
|
common declaration. The value is how much common storage to reserve, in
|
|
bytes (addresses). The symbol refers to the first address of the
|
|
allocated storage.
|
|
</p>
|
|
|
|
|
|
|
|
</body>
|
|
</html>
|