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66Next: <a href="Symbol-Type.html#Symbol-Type" accesskey="n" rel="next">Symbol Type</a>, Up: <a href="Symbol-Attributes.html#Symbol-Attributes" accesskey="u" rel="up">Symbol Attributes</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="AS-Index.html#AS-Index" title="Index" rel="index">Index</a>]</p>
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69<a name="Value"></a>
70<h4 class="subsection">5.5.1 Value</h4>
71
72<a name="index-value-of-a-symbol"></a>
73<a name="index-symbol-value"></a>
74<p>The value of a symbol is (usually) 32 bits.  For a symbol which labels a
75location in the text, data, bss or absolute sections the value is the
76number of addresses from the start of that section to the label.
77Naturally for text, data and bss sections the value of a symbol changes
78as <code>ld</code> changes section base addresses during linking.  Absolute
79symbols&rsquo; values do not change during linking: that is why they are
80called absolute.
81</p>
82<p>The value of an undefined symbol is treated in a special way.  If it is
830 then the symbol is not defined in this assembler source file, and
84<code>ld</code> tries to determine its value from other files linked into the
85same program.  You make this kind of symbol simply by mentioning a symbol
86name without defining it.  A non-zero value represents a <code>.comm</code>
87common declaration.  The value is how much common storage to reserve, in
88bytes (addresses).  The symbol refers to the first address of the
89allocated storage.
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