82 lines
3.5 KiB
HTML
82 lines
3.5 KiB
HTML
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<html lang="en">
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<head>
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<title>Based Variables - STABS</title>
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<meta name="description" content="STABS">
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<link title="Top" rel="start" href="index.html#Top">
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<link rel="up" href="Variables.html#Variables" title="Variables">
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<link rel="prev" href="Statics.html#Statics" title="Statics">
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<link rel="next" href="Parameters.html#Parameters" title="Parameters">
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Copyright (C) 1992-2019 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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<body>
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<div class="node">
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<a name="Based-Variables"></a>
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<p>
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Next: <a rel="next" accesskey="n" href="Parameters.html#Parameters">Parameters</a>,
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Previous: <a rel="previous" accesskey="p" href="Statics.html#Statics">Statics</a>,
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Up: <a rel="up" accesskey="u" href="Variables.html#Variables">Variables</a>
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<hr>
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</div>
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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><span class="samp">b</span></samp>’ symbol descriptor.
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<p>For example, the Fortran declarations
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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>
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<p>produce the stabs
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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>
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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>The ‘<samp><span class="samp">b</span></samp>’ symbol descriptor is like ‘<samp><span class="samp">V</span></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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</body></html>
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