arduino-0018-windows
This commit is contained in:
parent
157fd6f1a1
commit
f39fc49523
5182 changed files with 950586 additions and 0 deletions
|
@ -0,0 +1,90 @@
|
|||
<html lang="en">
|
||||
<head>
|
||||
<title>Word - 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="Weakref.html#Weakref" title="Weakref">
|
||||
<link rel="next" href="Deprecated.html#Deprecated" title="Deprecated">
|
||||
<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="Word"></a>Next: <a rel="next" accesskey="n" href="Deprecated.html#Deprecated">Deprecated</a>,
|
||||
Previous: <a rel="previous" accesskey="p" href="Weakref.html#Weakref">Weakref</a>,
|
||||
Up: <a rel="up" accesskey="u" href="Pseudo-Ops.html#Pseudo-Ops">Pseudo Ops</a>
|
||||
<hr><br>
|
||||
</div>
|
||||
|
||||
<h3 class="section">7.120 <code>.word </code><var>expressions</var></h3>
|
||||
|
||||
<p><a name="index-_0040code_007bword_007d-directive-499"></a>This directive expects zero or more <var>expressions</var>, of any section,
|
||||
separated by commas.
|
||||
|
||||
<p>The size of the number emitted, and its byte order,
|
||||
depend on what target computer the assembly is for.
|
||||
|
||||
<!-- on amd29k, i960, sparc the "special treatment to support compilers" doesn't -->
|
||||
<!-- happen-32-bit addressability, period; no long/short jumps. -->
|
||||
<p><a name="index-difference-tables-altered-500"></a><a name="index-altered-difference-tables-501"></a><blockquote>
|
||||
<em>Warning: Special Treatment to support Compilers</em>
|
||||
</blockquote>
|
||||
|
||||
<p>Machines with a 32-bit address space, but that do less than 32-bit
|
||||
addressing, require the following special treatment. If the machine of
|
||||
interest to you does 32-bit addressing (or doesn't require it;
|
||||
see <a href="Machine-Dependencies.html#Machine-Dependencies">Machine Dependencies</a>), you can ignore this issue.
|
||||
|
||||
<p>In order to assemble compiler output into something that works,
|
||||
<span class="command">as</span> occasionally does strange things to <span class="samp">.word</span> directives.
|
||||
Directives of the form <span class="samp">.word sym1-sym2</span> are often emitted by
|
||||
compilers as part of jump tables. Therefore, when <span class="command">as</span> assembles a
|
||||
directive of the form <span class="samp">.word sym1-sym2</span>, and the difference between
|
||||
<code>sym1</code> and <code>sym2</code> does not fit in 16 bits, <span class="command">as</span>
|
||||
creates a <dfn>secondary jump table</dfn>, immediately before the next label.
|
||||
This secondary jump table is preceded by a short-jump to the
|
||||
first byte after the secondary table. This short-jump prevents the flow
|
||||
of control from accidentally falling into the new table. Inside the
|
||||
table is a long-jump to <code>sym2</code>. The original <span class="samp">.word</span>
|
||||
contains <code>sym1</code> minus the address of the long-jump to
|
||||
<code>sym2</code>.
|
||||
|
||||
<p>If there were several occurrences of <span class="samp">.word sym1-sym2</span> before the
|
||||
secondary jump table, all of them are adjusted. If there was a
|
||||
<span class="samp">.word sym3-sym4</span>, that also did not fit in sixteen bits, a
|
||||
long-jump to <code>sym4</code> is included in the secondary jump table,
|
||||
and the <code>.word</code> directives are adjusted to contain <code>sym3</code>
|
||||
minus the address of the long-jump to <code>sym4</code>; and so on, for as many
|
||||
entries in the original jump table as necessary.
|
||||
|
||||
<!-- end DIFF-TBL-KLUGE -->
|
||||
</body></html>
|
||||
|
Reference in a new issue