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<p>
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<a name="Pseudo-Instructions"></a>
<h4 class="subsection">9.5.4 Pseudo Instructions</h4>
<p>The only available pseudo-instruction <code>__gcc_isr</code> can be activated by
option <samp>-mgcc-isr</samp>.
</p>
<dl compact="compact">
<dt><code>__gcc_isr 1</code></dt>
<dd><p>Emit code chunk to be used in avr-gcc ISR prologue.
It will expand to at most six 1-word instructions, all optional:
push of <code>tmp_reg</code>, push of <code>SREG</code>,
push and clear of <code>zero_reg</code>, push of <var>Reg</var>.
</p>
</dd>
<dt><code>__gcc_isr 2</code></dt>
<dd><p>Emit code chunk to be used in an avr-gcc ISR epilogue.
It will expand to at most five 1-word instructions, all optional:
pop of <var>Reg</var>, pop of <code>zero_reg</code>,
pop of <code>SREG</code>, pop of <code>tmp_reg</code>.
</p>
</dd>
<dt><code>__gcc_isr 0, <var>Reg</var></code></dt>
<dd><p>Finish avr-gcc ISR function. Scan code since the last prologue
for usage of: <code>SREG</code>, <code>tmp_reg</code>, <code>zero_reg</code>.
Prologue chunk and epilogue chunks will be replaced by appropriate code
to save / restore <code>SREG</code>, <code>tmp_reg</code>, <code>zero_reg</code> and <var>Reg</var>.
</p>
</dd>
</dl>
<p>Example input:
</p>
<div class="example">
<pre class="example">__vector1:
__gcc_isr 1
lds r24, var
inc r24
sts var, r24
__gcc_isr 2
reti
__gcc_isr 0, r24
</pre></div>
<p>Example output:
</p>
<div class="example">
<pre class="example">00000000 <__vector1>:
0: 8f 93 push r24
2: 8f b7 in r24, 0x3f
4: 8f 93 push r24
6: 80 91 60 00 lds r24, 0x0060 ; 0x800060 <var>
a: 83 95 inc r24
c: 80 93 60 00 sts 0x0060, r24 ; 0x800060 <var>
10: 8f 91 pop r24
12: 8f bf out 0x3f, r24
14: 8f 91 pop r24
16: 18 95 reti
</pre></div>
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