82 lines
4.1 KiB
HTML
82 lines
4.1 KiB
HTML
<html lang="en">
|
|
<head>
|
|
<title>P2align - 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="Pseudo-Ops.html#Pseudo-Ops" title="Pseudo Ops">
|
|
<link rel="prev" href="Org.html#Org" title="Org">
|
|
<link rel="next" href="PopSection.html#PopSection" title="PopSection">
|
|
<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage">
|
|
<!--
|
|
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''.
|
|
|
|
-->
|
|
<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="P2align"></a>
|
|
<p>
|
|
Next: <a rel="next" accesskey="n" href="PopSection.html#PopSection">PopSection</a>,
|
|
Previous: <a rel="previous" accesskey="p" href="Org.html#Org">Org</a>,
|
|
Up: <a rel="up" accesskey="u" href="Pseudo-Ops.html#Pseudo-Ops">Pseudo Ops</a>
|
|
<hr>
|
|
</div>
|
|
|
|
<h3 class="section">7.69 <code>.p2align[wl] </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-given-a-power-of-two-431"></a><a name="index-g_t_0040code_007bp2align_007d-directive-432"></a>Pad the location counter (in the current subsection) to a particular
|
|
storage boundary. The first expression (which must be absolute) is the
|
|
number of low-order zero bits the location counter must have after
|
|
advancement. For example ‘<samp><span class="samp">.p2align 3</span></samp>’ 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.
|
|
|
|
<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 most 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><a name="index-g_t_0040code_007bp2alignw_007d-directive-433"></a><a name="index-g_t_0040code_007bp2alignl_007d-directive-434"></a>The <code>.p2alignw</code> and <code>.p2alignl</code> directives are variants of the
|
|
<code>.p2align</code> directive. The <code>.p2alignw</code> directive treats the fill
|
|
pattern as a two byte word value. The <code>.p2alignl</code> directives treats the
|
|
fill pattern as a four byte longword value. For example, <code>.p2alignw
|
|
2,0x368d</code> will align to a multiple of 4. If it skips two bytes, they will be
|
|
filled in with the value 0x368d (the exact placement of the bytes depends upon
|
|
the endianness of the processor). If it skips 1 or 3 bytes, the fill value is
|
|
undefined.
|
|
|
|
</body></html>
|
|
|