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| <title>STABS: Common Blocks</title> |
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| <a name="Common-Blocks-1"></a> |
| <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"></a> |
| <a name="index-N_005fECOMM"></a> |
| <a name="index-C_005fBCOMM"></a> |
| <a name="index-C_005fECOMM"></a> |
| <p>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"></a> |
| <a name="index-C_005fECOML"></a> |
| <p>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>V</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>. |
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