112 lines
4.6 KiB
HTML
112 lines
4.6 KiB
HTML
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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
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<html>
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<!-- Copyright (C) 1992-2017 Free Software Foundation, Inc.
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Contributed by Cygnus Support. Written by Julia Menapace, Jim Kingdon,
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and David MacKenzie.
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Permission is granted to copy, distribute and/or modify this document
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under the terms of the GNU Free Documentation License, Version 1.3 or
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any later version published by the Free Software Foundation; with no
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Invariant Sections, with no Front-Cover Texts, and with no Back-Cover
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Texts. A copy of the license is included in the section entitled "GNU
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Free Documentation License". -->
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<!-- Created by GNU Texinfo 5.2, http://www.gnu.org/software/texinfo/ -->
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<head>
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<title>STABS: Based Variables</title>
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<meta name="description" content="STABS: Based Variables">
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<meta name="keywords" content="STABS: Based Variables">
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<meta name="Generator" content="makeinfo">
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
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<link href="index.html#Top" rel="start" title="Top">
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<link href="Symbol-Types-Index.html#Symbol-Types-Index" rel="index" title="Symbol Types Index">
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<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
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<link href="Variables.html#Variables" rel="up" title="Variables">
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<link href="Parameters.html#Parameters" rel="next" title="Parameters">
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<link href="Statics.html#Statics" rel="prev" title="Statics">
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-->
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</style>
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</head>
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<body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000">
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<a name="Based-Variables"></a>
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<div class="header">
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<p>
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Next: <a href="Parameters.html#Parameters" accesskey="n" rel="next">Parameters</a>, Previous: <a href="Statics.html#Statics" accesskey="p" rel="prev">Statics</a>, Up: <a href="Variables.html#Variables" accesskey="u" rel="up">Variables</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>
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</div>
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<hr>
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<a name="Fortran-Based-Variables"></a>
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<h3 class="section">4.6 Fortran Based Variables</h3>
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<p>Fortran (at least, the Sun and SGI dialects of FORTRAN-77) has a feature
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which allows allocating arrays with <code>malloc</code>, but which avoids
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blurring the line between arrays and pointers the way that C does. In
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stabs such a variable uses the ‘<samp>b</samp>’ symbol descriptor.
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</p>
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<p>For example, the Fortran declarations
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</p>
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<div class="example">
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<pre class="example">real foo, foo10(10), foo10_5(10,5)
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pointer (foop, foo)
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pointer (foo10p, foo10)
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pointer (foo105p, foo10_5)
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</pre></div>
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<p>produce the stabs
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</p>
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<div class="example">
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<pre class="example">foo:b6
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foo10:bar3;1;10;6
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foo10_5:bar3;1;5;ar3;1;10;6
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</pre></div>
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<p>In this example, <code>real</code> is type 6 and type 3 is an integral type
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which is the type of the subscripts of the array (probably
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<code>integer</code>).
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</p>
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<p>The ‘<samp>b</samp>’ symbol descriptor is like ‘<samp>V</samp>’ in that it denotes a
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statically allocated symbol whose scope is local to a function; see
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See <a href="Statics.html#Statics">Statics</a>. The value of the symbol, instead of being the address
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of the variable itself, is the address of a pointer to that variable.
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So in the above example, the value of the <code>foo</code> stab is the address
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of a pointer to a real, the value of the <code>foo10</code> stab is the
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address of a pointer to a 10-element array of reals, and the value of
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the <code>foo10_5</code> stab is the address of a pointer to a 5-element array
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of 10-element arrays of reals.
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</p>
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</body>
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</html>
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