89 lines
4.3 KiB
HTML
89 lines
4.3 KiB
HTML
<html lang="en">
|
|
<head>
|
|
<title>Align - Using as</title>
|
|
<meta http-equiv="Content-Type" content="text/html">
|
|
<meta name="description" content="Using as">
|
|
<meta name="generator" content="makeinfo 4.7">
|
|
<link title="Top" rel="start" href="index.html#Top">
|
|
<link rel="up" href="Pseudo-Ops.html#Pseudo-Ops" title="Pseudo Ops">
|
|
<link rel="prev" href="ABORT-_0028COFF_0029.html#ABORT-_0028COFF_0029" title="ABORT (COFF)">
|
|
<link rel="next" href="Altmacro.html#Altmacro" title="Altmacro">
|
|
<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage">
|
|
<!--
|
|
This file documents the GNU Assembler "as".
|
|
|
|
Copyright (C) 1991, 92, 93, 94, 95, 96, 97, 98, 99, 2000, 2001, 2002,
|
|
2006, 2007 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 1.1
|
|
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''.
|
|
|
|
man end-->
|
|
<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; }
|
|
--></style>
|
|
</head>
|
|
<body>
|
|
<div class="node">
|
|
<p>
|
|
<a name="Align"></a>Next: <a rel="next" accesskey="n" href="Altmacro.html#Altmacro">Altmacro</a>,
|
|
Previous: <a rel="previous" accesskey="p" href="ABORT-_0028COFF_0029.html#ABORT-_0028COFF_0029">ABORT (COFF)</a>,
|
|
Up: <a rel="up" accesskey="u" href="Pseudo-Ops.html#Pseudo-Ops">Pseudo Ops</a>
|
|
<hr><br>
|
|
</div>
|
|
|
|
<h3 class="section">7.3 <code>.align </code><var>abs-expr</var><code>, </code><var>abs-expr</var><code>, </code><var>abs-expr</var></h3>
|
|
|
|
<p><a name="index-padding-the-location-counter-275"></a><a name="index-_0040code_007balign_007d-directive-276"></a>Pad the location counter (in the current subsection) to a particular storage
|
|
boundary. The first expression (which must be absolute) is the alignment
|
|
required, as described below.
|
|
|
|
<p>The second expression (also absolute) gives the fill value to be stored in the
|
|
padding bytes. It (and the comma) may be omitted. If it is omitted, the
|
|
padding bytes are normally zero. However, on some systems, if the section is
|
|
marked as containing code and the fill value is omitted, the space is filled
|
|
with no-op instructions.
|
|
|
|
<p>The third expression is also absolute, and is also optional. If it is present,
|
|
it is the maximum number of bytes that should be skipped by this alignment
|
|
directive. If doing the alignment would require skipping more bytes than the
|
|
specified maximum, then the alignment is not done at all. You can omit the
|
|
fill value (the second argument) entirely by simply using two commas after the
|
|
required alignment; this can be useful if you want the alignment to be filled
|
|
with no-op instructions when appropriate.
|
|
|
|
<p>The way the required alignment is specified varies from system to system.
|
|
For the arc, hppa, i386 using ELF, i860, iq2000, m68k, or32,
|
|
s390, sparc, tic4x, tic80 and xtensa, the first expression is the
|
|
alignment request in bytes. For example <span class="samp">.align 8</span> advances
|
|
the location counter until it is a multiple of 8. If the location counter
|
|
is already a multiple of 8, no change is needed. For the tic54x, the
|
|
first expression is the alignment request in words.
|
|
|
|
<p>For other systems, including ppc, i386 using a.out format, arm and
|
|
strongarm, it is the
|
|
number of low-order zero bits the location counter must have after
|
|
advancement. For example <span class="samp">.align 3</span> advances the location
|
|
counter until it a multiple of 8. If the location counter is already a
|
|
multiple of 8, no change is needed.
|
|
|
|
<p>This inconsistency is due to the different behaviors of the various
|
|
native assemblers for these systems which GAS must emulate.
|
|
GAS also provides <code>.balign</code> and <code>.p2align</code> directives,
|
|
described later, which have a consistent behavior across all
|
|
architectures (but are specific to GAS).
|
|
|
|
</body></html>
|
|
|