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<H2><A NAME="SECTION005616000000000000000">
4.6.16 Generic Pointers</A>
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<P>
Generic pointers are implemented in PIC16 port as 3-byte (24-bit)
types. There are 3 types of generic pointers currently implemented
data, code and eeprom pointers. They are differentiated by the value
of the 7th and 6th bits of the upper byte:

<P>
<DIV ALIGN="CENTER">
<TABLE CELLPADDING=3 BORDER="1">
<TR><TD ALIGN="CENTER">pointer type</TD>
<TD ALIGN="CENTER">7th bit</TD>
<TD ALIGN="CENTER">6th bit</TD>
<TD ALIGN="CENTER">rest of the pointer</TD>
<TD ALIGN="LEFT">description</TD>
</TR>
<TR><TD ALIGN="CENTER">data</TD>
<TD ALIGN="CENTER">1</TD>
<TD ALIGN="CENTER">0</TD>
<TD ALIGN="CENTER"><TT><I><I>uuuuuu uuuuxxxx xxxxxxxx</I></I></TT></TD>
<TD ALIGN="LEFT">a 12-bit data pointer in data RAM memory</TD>
</TR>
<TR><TD ALIGN="CENTER">code</TD>
<TD ALIGN="CENTER">0</TD>
<TD ALIGN="CENTER">0</TD>
<TD ALIGN="CENTER"><TT><I><I>uxxxxx xxxxxxxx xxxxxxxx</I></I></TT></TD>
<TD ALIGN="LEFT">a 21-bit code pointer in FLASH memory</TD>
</TR>
<TR><TD ALIGN="CENTER">eeprom</TD>
<TD ALIGN="CENTER">0</TD>
<TD ALIGN="CENTER">1</TD>
<TD ALIGN="CENTER"><TT><I><I>uuuuuu uuuuuuxx xxxxxxxx</I></I></TT></TD>
<TD ALIGN="LEFT">a 10-bit eeprom pointer in EEPROM memory</TD>
</TR>
<TR><TD ALIGN="CENTER">(unimplemented)</TD>
<TD ALIGN="CENTER">1</TD>
<TD ALIGN="CENTER">1</TD>
<TD ALIGN="CENTER"><TT><I><I>xxxxxx xxxxxxxx xxxxxxxx</I></I></TT></TD>
<TD ALIGN="LEFT">unimplemented pointer type</TD>
</TR>
</TABLE>
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<P>
Generic pointer are read and written with a set of library
functions which read/write 1, 2, 3, 4 bytes.

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2011-03-20
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