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<H2><A NAME="SECTION009112000000000000000"></A><A NAME="4278"></A><A NAME="4279"></A>
<BR>
8.1.12 Higher Order Byte / Higher Order Word
</H2>
<P>
It is also frequently required to obtain a higher order byte or word
of a larger integral type (long, int or short types). SDCC recognizes
the following expressions to yield the higher order byte or word and
generates optimized code for it, e.g.:
<BLOCKQUOTE>
<TT>unsigned int gint; </TT>
<BR><TT>unsigned long int glong; </TT>
<BR>
<BR><TT>foo () { </TT>
<BR><TT> unsigned char hob1, hob2; </TT>
<BR><TT> unsigned int how1, how2; </TT>
<BR><TT> ... </TT>
<BR><TT> hob1 = (gint >> 8) & 0xFF; </TT>
<BR><TT> hob2 = glong >> 24; </TT>
<BR><TT> how1 = (glong >> 16) & 0xFFFF;
</TT>
<BR><TT> how2 = glong >> 8; </TT>
<BR><TT> .. </TT>
<BR><TT>}</TT>
</BLOCKQUOTE>
will generate the following code:
<BLOCKQUOTE>
<TT> 91 ;
hob.c 15 </TT>
<BR><TT>0037 85*01*06 92
mov _foo_hob1_1_1,(_gint + 1) </TT>
<BR><TT> 93 ;
hob.c 16 </TT>
<BR><TT>003A 85*05*07 94
mov _foo_hob2_1_1,(_glong + 3) </TT>
<BR><TT> 95 ;
hob.c 17 </TT>
<BR><TT>003D 85*04*08 96
mov _foo_how1_1_1,(_glong + 2) </TT>
<BR><TT>0040 85*05*09 97
mov (_foo_how1_1_1 + 1),(_glong + 3) </TT>
<BR><TT>0043 85*03*0A 98
mov _foo_how2_1_1,(_glong + 1) </TT>
<BR><TT>0046 85*04*0B 99
mov (_foo_how2_1_1 + 1),(_glong + 2) </TT>
</BLOCKQUOTE>
Again, variations of these cases may <I>not</I> be recognized. They
are standard C expressions, so I heartily recommend these be the only
way to get the higher order byte/word, (it is portable). Of course
it will be recognized even if it is embedded in other expressions,
e.g.:
<BLOCKQUOTE>
<TT>xyz = gint + ((gint >> 8) & 0xFF);</TT>
</BLOCKQUOTE>
will still be recognized.
<P>
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