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<H2><A NAME="SECTION004101000000000000000">
3.10.1 Critical Functions and Critical Statements</A>
</H2>
<P>
A special keyword may be associated with a block or a function declaring
it as <I>critical</I>. SDCC will generate code to disable all interrupts<A NAME="1765"></A>
upon entry to a critical function and restore the interrupt enable
to the previous state before returning. Nesting critical functions
will need one additional byte on the stack<A NAME="1766"></A> for each
call.
<BLOCKQUOTE>
<TT>int foo () __critical<A NAME="1768"></A><A NAME="1769"></A>
</TT>
<BR><TT>{ </TT>
<BR><TT> ... </TT>
<BR><TT> ... </TT>
<BR><TT>}</TT>
</BLOCKQUOTE>
The critical attribute maybe used with other attributes like <I>reentrant.</I>
<BR>
The keyword <I>critical</I> may also be used to disable interrupts
more locally:
<BLOCKQUOTE>
<TT>__critical{ i++; }</TT>
</BLOCKQUOTE>
More than one statement could have been included in the block.
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2011-03-20
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