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<title>Using as: S12Z Syntax Overview</title>

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<a name="S12Z-Syntax-Overview"></a>
<div class="header">
<p>
Next: <a href="S12Z-Addressing-Modes.html#S12Z-Addressing-Modes" accesskey="n" rel="next">S12Z Addressing Modes</a>, Up: <a href="S12Z-Syntax.html#S12Z-Syntax" accesskey="u" rel="up">S12Z Syntax</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="AS-Index.html#AS-Index" title="Index" rel="index">Index</a>]</p>
</div>
<hr>
<a name="Overview-2"></a>
<h4 class="subsubsection">9.24.2.1 Overview</h4>

<p>In the S12Z syntax, the instruction name comes first and it may
be followed by one, or by several operands.
In most cases the maximum number of operands is three.
Operands are separated by a comma (&lsquo;<samp>,</samp>&rsquo;).
A comma however does not act as a separator if it appears within parentheses
(&lsquo;<samp>()</samp>&rsquo;) or within square brackets (&lsquo;<samp>[]</samp>&rsquo;).
<code>as</code> will complain if too many, too few or inappropriate operands
are specified for a given instruction.
</p>
<p>Some instructions accept and (in certain situations require) a suffix
indicating the size of the operand.
The suffix is separated from the instruction name by a period (&lsquo;<samp>.</samp>&rsquo;)
and may be one of &lsquo;<samp>b</samp>&rsquo;, &lsquo;<samp>w</samp>&rsquo;, &lsquo;<samp>p</samp>&rsquo; or &lsquo;<samp>l</samp>&rsquo; indicating
&lsquo;byte&rsquo; (a single byte), &lsquo;word&rsquo; (2 bytes), &lsquo;pointer&rsquo; (3 bytes) or &lsquo;long&rsquo; (4 bytes)
respectively.
</p>
<p>Example:
</p>
<div class="smallexample">
<pre class="smallexample">	bset.b  0xA98, #5
	mov.b   #6, 0x2409
	ld      d0, #4
	mov.l   (d0, x), 0x2409
	inc     d0
	cmp     d0, #12
	blt     *-4
	lea     x, 0x2409
	st      y,  (1, x)
</pre></div>

<a name="index-line-comment-character_002c-S12Z"></a>
<p>The presence of a &lsquo;<samp>;</samp>&rsquo; character anywhere
on a line indicates the start of a comment that extends to the end of
that line.
</p>
<p>A &lsquo;<samp>*</samp>&rsquo; or a &lsquo;<samp>#</samp>&rsquo; character at the start of a line also
introduces a line comment, but these characters do not work elsewhere
on the line.  If the first character of the line is a &lsquo;<samp>#</samp>&rsquo; then as
well as starting a comment, the line could also be logical line number
directive (see <a href="Comments.html#Comments">Comments</a>) or a preprocessor control command
(see <a href="Preprocessing.html#Preprocessing">Preprocessing</a>).
</p>
<a name="index-line-separator_002c-S12Z"></a>
<a name="index-statement-separator_002c-S12Z"></a>
<a name="index-S12Z-line-separator"></a>
<p>The S12Z assembler does not currently support a line separator
character.
</p>

<hr>
<div class="header">
<p>
Next: <a href="S12Z-Addressing-Modes.html#S12Z-Addressing-Modes" accesskey="n" rel="next">S12Z Addressing Modes</a>, Up: <a href="S12Z-Syntax.html#S12Z-Syntax" accesskey="u" rel="up">S12Z Syntax</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="AS-Index.html#AS-Index" title="Index" rel="index">Index</a>]</p>
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