| <html lang="en"> |
| <head> |
| <title>Common Blocks - STABS</title> |
| <meta http-equiv="Content-Type" content="text/html"> |
| <meta name="description" content="STABS"> |
| <meta name="generator" content="makeinfo 4.13"> |
| <link title="Top" rel="start" href="index.html#Top"> |
| <link rel="up" href="Variables.html#Variables" title="Variables"> |
| <link rel="prev" href="Register-Variables.html#Register-Variables" title="Register Variables"> |
| <link rel="next" href="Statics.html#Statics" title="Statics"> |
| <link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage"> |
| <!-- |
| Copyright (C) 1992-2019 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''.--> |
| <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="Common-Blocks"></a> |
| <p> |
| Next: <a rel="next" accesskey="n" href="Statics.html#Statics">Statics</a>, |
| Previous: <a rel="previous" accesskey="p" href="Register-Variables.html#Register-Variables">Register Variables</a>, |
| Up: <a rel="up" accesskey="u" href="Variables.html#Variables">Variables</a> |
| <hr> |
| </div> |
| |
| <h3 class="section">4.4 Common Blocks</h3> |
| |
| <p>A common block is a statically allocated section of memory which can be |
| referred to by several source files. It may contain several variables. |
| I believe Fortran is the only language with this feature. |
| |
| <p><a name="index-N_005fBCOMM-31"></a><a name="index-N_005fECOMM-32"></a><a name="index-C_005fBCOMM-33"></a><a name="index-C_005fECOMM-34"></a>A <code>N_BCOMM</code> stab begins a common block and an <code>N_ECOMM</code> stab |
| ends it. The only field that is significant in these two stabs is the |
| string, which names a normal (non-debugging) symbol that gives the |
| address of the common block. According to IBM documentation, only the |
| <code>N_BCOMM</code> has the name of the common block (even though their |
| compiler actually puts it both places). |
| |
| <p><a name="index-N_005fECOML-35"></a><a name="index-C_005fECOML-36"></a>The stabs for the members of the common block are between the |
| <code>N_BCOMM</code> and the <code>N_ECOMM</code>; the value of each stab is the |
| offset within the common block of that variable. IBM uses the |
| <code>C_ECOML</code> stab type, and there is a corresponding <code>N_ECOML</code> |
| stab type, but Sun's Fortran compiler uses <code>N_GSYM</code> instead. The |
| variables within a common block use the ‘<samp><span class="samp">V</span></samp>’ symbol descriptor (I |
| believe this is true of all Fortran variables). Other stabs (at least |
| type declarations using <code>C_DECL</code>) can also be between the |
| <code>N_BCOMM</code> and the <code>N_ECOMM</code>. |
| |
| </body></html> |
| |
