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<a name="MSP430-Built_002din-Functions-1"></a>
<h4 class="subsection">6.60.18 MSP430 Built-in Functions</h4>

<p>GCC provides a couple of special builtin functions to aid in the
writing of interrupt handlers in C.
</p>
<dl compact="compact">
<dt><code>__bic_SR_register_on_exit (int <var>mask</var>)</code></dt>
<dd><p>This clears the indicated bits in the saved copy of the status register
currently residing on the stack.  This only works inside interrupt
handlers and the changes to the status register will only take affect
once the handler returns.
</p>
</dd>
<dt><code>__bis_SR_register_on_exit (int <var>mask</var>)</code></dt>
<dd><p>This sets the indicated bits in the saved copy of the status register
currently residing on the stack.  This only works inside interrupt
handlers and the changes to the status register will only take affect
once the handler returns.
</p>
</dd>
<dt><code>__delay_cycles (long long <var>cycles</var>)</code></dt>
<dd><p>This inserts an instruction sequence that takes exactly <var>cycles</var>
cycles (between 0 and about 17E9) to complete.  The inserted sequence
may use jumps, loops, or no-ops, and does not interfere with any other
instructions.  Note that <var>cycles</var> must be a compile-time constant
integer - that is, you must pass a number, not a variable that may be
optimized to a constant later.  The number of cycles delayed by this
builtin is exact.
</p></dd>
</dl>


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