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| <h3 class="section">2.2 Paths and Names of the Source Files</h3> |
| |
| <p><a name="index-N_005fSO-2"></a>Before any other stabs occur, there must be a stab specifying the source |
| file. This information is contained in a symbol of stab type |
| <code>N_SO</code>; the string field contains the name of the file. The |
| value of the symbol is the start address of the portion of the |
| text section corresponding to that file. |
| |
| <p>Some compilers use the desc field to indicate the language of the |
| source file. Sun's compilers started this usage, and the first |
| constants are derived from their documentation. Languages added |
| by gcc/gdb start at 0x32 to avoid conflict with languages Sun may |
| add in the future. A desc field with a value 0 indicates that no |
| language has been specified via this mechanism. |
| |
| <dl> |
| <dt><code>N_SO_AS</code> (0x1)<dd>Assembly language |
| <br><dt><code>N_SO_C</code> (0x2)<dd>K&R traditional C |
| <br><dt><code>N_SO_ANSI_C</code> (0x3)<dd>ANSI C |
| <br><dt><code>N_SO_CC</code> (0x4)<dd>C++ |
| <br><dt><code>N_SO_FORTRAN</code> (0x5)<dd>Fortran |
| <br><dt><code>N_SO_PASCAL</code> (0x6)<dd>Pascal |
| <br><dt><code>N_SO_FORTRAN90</code> (0x7)<dd>Fortran90 |
| <br><dt><code>N_SO_OBJC</code> (0x32)<dd>Objective-C |
| <br><dt><code>N_SO_OBJCPLUS</code> (0x33)<dd>Objective-C++ |
| </dl> |
| |
| <p>Some compilers (for example, GCC2 and SunOS4 <samp><span class="file">/bin/cc</span></samp>) also |
| include the directory in which the source was compiled, in a second |
| <code>N_SO</code> symbol preceding the one containing the file name. This |
| symbol can be distinguished by the fact that it ends in a slash. Code |
| from the <code>cfront</code> C<tt>++</tt> compiler can have additional <code>N_SO</code> symbols for |
| nonexistent source files after the <code>N_SO</code> for the real source file; |
| these are believed to contain no useful information. |
| |
| <p>For example: |
| |
| <pre class="example"> .stabs "/cygint/s1/users/jcm/play/",100,0,0,Ltext0 # <span class="roman">100 is N_SO</span> |
| .stabs "hello.c",100,0,0,Ltext0 |
| .text |
| Ltext0: |
| </pre> |
| <p><a name="index-C_005fFILE-3"></a>Instead of <code>N_SO</code> symbols, XCOFF uses a <code>.file</code> assembler |
| directive which assembles to a <code>C_FILE</code> symbol; explaining this in |
| detail is outside the scope of this document. |
| |
| <!-- FIXME: Exactly when should the empty N_SO be used? Why? --> |
| <p>If it is useful to indicate the end of a source file, this is done with |
| an <code>N_SO</code> symbol with an empty string for the name. The value is |
| the address of the end of the text section for the file. For some |
| systems, there is no indication of the end of a source file, and you |
| just need to figure it ended when you see an <code>N_SO</code> for a different |
| source file, or a symbol ending in <code>.o</code> (which at least some |
| linkers insert to mark the start of a new <code>.o</code> file). |
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