160 lines
7.3 KiB
HTML
160 lines
7.3 KiB
HTML
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
|
|
<html>
|
|
<!-- Copyright (C) 1992-2017 Free Software Foundation, Inc.
|
|
Contributed by Cygnus Support. Written by Julia Menapace, Jim Kingdon,
|
|
and David MacKenzie.
|
|
|
|
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 5.2, http://www.gnu.org/software/texinfo/ -->
|
|
<head>
|
|
<title>STABS: Arrays</title>
|
|
|
|
<meta name="description" content="STABS: Arrays">
|
|
<meta name="keywords" content="STABS: Arrays">
|
|
<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="Symbol-Types-Index.html#Symbol-Types-Index" rel="index" title="Symbol Types Index">
|
|
<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
|
|
<link href="Types.html#Types" rel="up" title="Types">
|
|
<link href="Strings.html#Strings" rel="next" title="Strings">
|
|
<link href="Subranges.html#Subranges" rel="prev" title="Subranges">
|
|
<style type="text/css">
|
|
<!--
|
|
a.summary-letter {text-decoration: none}
|
|
blockquote.smallquotation {font-size: smaller}
|
|
div.display {margin-left: 3.2em}
|
|
div.example {margin-left: 3.2em}
|
|
div.indentedblock {margin-left: 3.2em}
|
|
div.lisp {margin-left: 3.2em}
|
|
div.smalldisplay {margin-left: 3.2em}
|
|
div.smallexample {margin-left: 3.2em}
|
|
div.smallindentedblock {margin-left: 3.2em; font-size: smaller}
|
|
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.nocodebreak {white-space:nowrap}
|
|
span.nolinebreak {white-space:nowrap}
|
|
span.roman {font-family:serif; font-weight:normal}
|
|
span.sansserif {font-family:sans-serif; font-weight:normal}
|
|
ul.no-bullet {list-style: none}
|
|
-->
|
|
</style>
|
|
|
|
|
|
</head>
|
|
|
|
<body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000">
|
|
<a name="Arrays"></a>
|
|
<div class="header">
|
|
<p>
|
|
Next: <a href="Strings.html#Strings" accesskey="n" rel="next">Strings</a>, Previous: <a href="Subranges.html#Subranges" accesskey="p" rel="prev">Subranges</a>, Up: <a href="Types.html#Types" accesskey="u" rel="up">Types</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Symbol-Types-Index.html#Symbol-Types-Index" title="Index" rel="index">Index</a>]</p>
|
|
</div>
|
|
<hr>
|
|
<a name="Array-Types"></a>
|
|
<h3 class="section">5.5 Array Types</h3>
|
|
|
|
<p>Arrays use the ‘<samp>a</samp>’ type descriptor. Following the type descriptor
|
|
is the type of the index and the type of the array elements. If the
|
|
index type is a range type, it ends in a semicolon; otherwise
|
|
(for example, if it is a type reference), there does not
|
|
appear to be any way to tell where the types are separated. In an
|
|
effort to clean up this mess, IBM documents the two types as being
|
|
separated by a semicolon, and a range type as not ending in a semicolon
|
|
(but this is not right for range types which are not array indexes,
|
|
see <a href="Subranges.html#Subranges">Subranges</a>). I think probably the best solution is to specify
|
|
that a semicolon ends a range type, and that the index type and element
|
|
type of an array are separated by a semicolon, but that if the index
|
|
type is a range type, the extra semicolon can be omitted. GDB (at least
|
|
through version 4.9) doesn’t support any kind of index type other than a
|
|
range anyway; I’m not sure about dbx.
|
|
</p>
|
|
<p>It is well established, and widely used, that the type of the index,
|
|
unlike most types found in the stabs, is merely a type definition, not
|
|
type information (see <a href="String-Field.html#String-Field">String Field</a>) (that is, it need not start with
|
|
‘<samp><var>type-number</var>=</samp>’ if it is defining a new type). According to a
|
|
comment in GDB, this is also true of the type of the array elements; it
|
|
gives ‘<samp>ar1;1;10;ar1;1;10;4</samp>’ as a legitimate way to express a two
|
|
dimensional array. According to AIX documentation, the element type
|
|
must be type information. GDB accepts either.
|
|
</p>
|
|
<p>The type of the index is often a range type, expressed as the type
|
|
descriptor ‘<samp>r</samp>’ and some parameters. It defines the size of the
|
|
array. In the example below, the range ‘<samp>r1;0;2;</samp>’ defines an index
|
|
type which is a subrange of type 1 (integer), with a lower bound of 0
|
|
and an upper bound of 2. This defines the valid range of subscripts of
|
|
a three-element C array.
|
|
</p>
|
|
<p>For example, the definition:
|
|
</p>
|
|
<div class="example">
|
|
<pre class="example">char char_vec[3] = {'a','b','c'};
|
|
</pre></div>
|
|
|
|
<p>produces the output:
|
|
</p>
|
|
<div class="example">
|
|
<pre class="example">.stabs "char_vec:G19=ar1;0;2;2",32,0,0,0
|
|
.global _char_vec
|
|
.align 4
|
|
_char_vec:
|
|
.byte 97
|
|
.byte 98
|
|
.byte 99
|
|
</pre></div>
|
|
|
|
<p>If an array is <em>packed</em>, the elements are spaced more
|
|
closely than normal, saving memory at the expense of speed. For
|
|
example, an array of 3-byte objects might, if unpacked, have each
|
|
element aligned on a 4-byte boundary, but if packed, have no padding.
|
|
One way to specify that something is packed is with type attributes
|
|
(see <a href="String-Field.html#String-Field">String Field</a>). In the case of arrays, another is to use the
|
|
‘<samp>P</samp>’ type descriptor instead of ‘<samp>a</samp>’. Other than specifying a
|
|
packed array, ‘<samp>P</samp>’ is identical to ‘<samp>a</samp>’.
|
|
</p>
|
|
<p>An open array is represented by the ‘<samp>A</samp>’ type descriptor followed by
|
|
type information specifying the type of the array elements.
|
|
</p>
|
|
<p>An N-dimensional dynamic array is represented by
|
|
</p>
|
|
<div class="example">
|
|
<pre class="example">D <var>dimensions</var> ; <var>type-information</var>
|
|
</pre></div>
|
|
|
|
<p><var>dimensions</var> is the number of dimensions; <var>type-information</var>
|
|
specifies the type of the array elements.
|
|
</p>
|
|
<p>A subarray of an N-dimensional array is represented by
|
|
</p>
|
|
<div class="example">
|
|
<pre class="example">E <var>dimensions</var> ; <var>type-information</var>
|
|
</pre></div>
|
|
|
|
<p><var>dimensions</var> is the number of dimensions; <var>type-information</var>
|
|
specifies the type of the array elements.
|
|
</p>
|
|
<hr>
|
|
<div class="header">
|
|
<p>
|
|
Next: <a href="Strings.html#Strings" accesskey="n" rel="next">Strings</a>, Previous: <a href="Subranges.html#Subranges" accesskey="p" rel="prev">Subranges</a>, Up: <a href="Types.html#Types" accesskey="u" rel="up">Types</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Symbol-Types-Index.html#Symbol-Types-Index" title="Index" rel="index">Index</a>]</p>
|
|
</div>
|
|
|
|
|
|
|
|
</body>
|
|
</html>
|