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<a name="1204581"> </a><font color="#003366" face="Verdana, Arial, Helvetica, sans-serif">6.3 Restrictions on placement</font>
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<p> <font size=2 face="Verdana, Arial, Helvetica, sans-serif"><li ><a name="1204582"> </a>When placing data in ROM, ensure that only sections containing <font size=2 face=Courier><strong>const</strong></font> data are placed. The linker issues a warning if it detects read/write data being placed in ROM.</font></p>
<p> <font size=2 face="Verdana, Arial, Helvetica, sans-serif"><li ><a name="1204583"> </a>Data items cannot be placed in a C file if they are declared using the <font size=2 face=Courier><strong>extern</strong></font> storage class specifier. The only exception to this is the case where the declaration includes an initializer, in which case the <font size=2 face=Courier><strong>extern</strong></font> specifier is ignored. In other words - only data items which reserve storage in a C file can be placed. Some examples:</font></p>
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<p> <font size=2 face="Verdana, Arial, Helvetica, sans-serif"><li ><a name="1204584"> </a><font size=2 face=Courier><strong>int x;</strong></font></font></p>
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<dt> <a name="1204585"> </a><font size=2 face="Verdana, Arial, Helvetica, sans-serif">This can be placed as it reserves storage for <font size=2 face=Courier><strong>x</strong></font>. It is a definition of <font size=2 face=Courier><strong>x</strong></font>.</font>
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<p> <font size=2 face="Verdana, Arial, Helvetica, sans-serif"><li ><a name="1204586"> </a><font size=2 face=Courier><strong>int x = 1;</strong></font></font></p>
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<dt> <a name="1204587"> </a><font size=2 face="Verdana, Arial, Helvetica, sans-serif">This can be placed as it reserves storage for <font size=2 face=Courier><strong>x</strong></font>. It is a definition of <font size=2 face=Courier><strong>x</strong></font>.</font>
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<p> <font size=2 face="Verdana, Arial, Helvetica, sans-serif"><li ><a name="1204588"> </a><font size=2 face=Courier><strong>extern int x;</strong></font></font></p>
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<dt> <a name="1206078"> </a><font size=2 face="Verdana, Arial, Helvetica, sans-serif">This can not be placed as it does not reserve storage for <font size=2 face=Courier><strong>x</strong></font>. The definition of <font size=2 face=Courier><strong>x</strong></font> may be in another file.</font>
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<p> <font size=2 face="Verdana, Arial, Helvetica, sans-serif"><li ><a name="1206079"> </a><font size=2 face=Courier><strong>extern int x = 1;</strong></font></font></p>
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<dt> <a name="1204591"> </a><font size=2 face="Verdana, Arial, Helvetica, sans-serif">This can be placed as the initializer causes the <font size=2 face=Courier><strong>extern</strong></font> keyword to be ignored and it becomes a definition of <font size=2 face=Courier><strong>x</strong></font>.</font>
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<p> <font size=2 face="Verdana, Arial, Helvetica, sans-serif"><li ><a name="1204592"> </a>Code or data items may not be explicitly placed into any of the default sections created at compile time, that is: <font size=2 face=Courier><strong><em><Filename_text></em></strong></font>, <font size=2 face=Courier><strong><em><Filename_const></em></strong></font>, <font size=2 face=Courier><strong><em><Filename_data></em></strong></font> or <font size=2 face=Courier><strong><em><Filename_bss></em></strong></font>.</font></p>
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