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<h5 class="subsubsection">9.10.2.2 Register Names</h5>

<p><a name="index-H8_002f300-registers-810"></a><a name="index-register-names_002c-H8_002f300-811"></a>You can use predefined symbols of the form &lsquo;<samp><span class="samp">r</span><var>n</var><span class="samp">h</span></samp>&rsquo; and
&lsquo;<samp><span class="samp">r</span><var>n</var><span class="samp">l</span></samp>&rsquo; to refer to the H8/300 registers as sixteen 8-bit
general-purpose registers.  <var>n</var> is a digit from &lsquo;<samp><span class="samp">0</span></samp>&rsquo; to
&lsquo;<samp><span class="samp">7</span></samp>&rsquo;); for instance, both &lsquo;<samp><span class="samp">r0h</span></samp>&rsquo; and &lsquo;<samp><span class="samp">r7l</span></samp>&rsquo; are valid
register names.

   <p>You can also use the eight predefined symbols &lsquo;<samp><span class="samp">r</span><var>n</var></samp>&rsquo; to refer
to the H8/300 registers as 16-bit registers (you must use this form for
addressing).

   <p>On the H8/300H, you can also use the eight predefined symbols
&lsquo;<samp><span class="samp">er</span><var>n</var></samp>&rsquo; (&lsquo;<samp><span class="samp">er0</span></samp>&rsquo; <small class="dots">...</small> &lsquo;<samp><span class="samp">er7</span></samp>&rsquo;) to refer to the 32-bit
general purpose registers.

   <p>The two control registers are called <code>pc</code> (program counter; a
16-bit register, except on the H8/300H where it is 24 bits) and
<code>ccr</code> (condition code register; an 8-bit register).  <code>r7</code> is
used as the stack pointer, and can also be called <code>sp</code>.

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