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<h3 class="section">3.3 Comments</h3>

<p><a name="index-comments-123"></a>There are two ways of rendering comments to <samp><span class="command">as</span></samp>.  In both
cases the comment is equivalent to one space.

   <p>Anything from &lsquo;<samp><span class="samp">/*</span></samp>&rsquo; through the next &lsquo;<samp><span class="samp">*/</span></samp>&rsquo; is a comment. 
This means you may not nest these comments.

<pre class="smallexample">     /*
       The only way to include a newline ('\n') in a comment
       is to use this sort of comment.
     */
     
     /* This sort of comment does not nest. */
</pre>
   <p><a name="index-line-comment-character-124"></a>Anything from the <dfn>line comment</dfn> character to the next newline
is considered a comment and is ignored.  The line comment character is
&lsquo;<samp><span class="samp">;</span></samp>&rsquo; on the ARC;
&lsquo;<samp><span class="samp">@</span></samp>&rsquo; on the ARM;
&lsquo;<samp><span class="samp">;</span></samp>&rsquo; for the H8/300 family;
&lsquo;<samp><span class="samp">;</span></samp>&rsquo; for the HPPA;
&lsquo;<samp><span class="samp">#</span></samp>&rsquo; on the i386 and x86-64;
&lsquo;<samp><span class="samp">#</span></samp>&rsquo; on the i960;
&lsquo;<samp><span class="samp">;</span></samp>&rsquo; for the PDP-11;
&lsquo;<samp><span class="samp">;</span></samp>&rsquo; for picoJava;
&lsquo;<samp><span class="samp">#</span></samp>&rsquo; for Motorola PowerPC;
&lsquo;<samp><span class="samp">#</span></samp>&rsquo; for IBM S/390;
&lsquo;<samp><span class="samp">#</span></samp>&rsquo; for the Sunplus SCORE;
&lsquo;<samp><span class="samp">!</span></samp>&rsquo; for the Renesas / SuperH SH;
&lsquo;<samp><span class="samp">!</span></samp>&rsquo; on the SPARC;
&lsquo;<samp><span class="samp">#</span></samp>&rsquo; on the ip2k;
&lsquo;<samp><span class="samp">#</span></samp>&rsquo; on the m32c;
&lsquo;<samp><span class="samp">#</span></samp>&rsquo; on the m32r;
&lsquo;<samp><span class="samp">|</span></samp>&rsquo; on the 680x0;
&lsquo;<samp><span class="samp">#</span></samp>&rsquo; on the 68HC11 and 68HC12;
&lsquo;<samp><span class="samp">#</span></samp>&rsquo; on the RX;
&lsquo;<samp><span class="samp">;</span></samp>&rsquo; on the TMS320C6X;
&lsquo;<samp><span class="samp">#</span></samp>&rsquo; on the Vax;
&lsquo;<samp><span class="samp">;</span></samp>&rsquo; for the Z80;
&lsquo;<samp><span class="samp">!</span></samp>&rsquo; for the Z8000;
&lsquo;<samp><span class="samp">#</span></samp>&rsquo; on the V850;
&lsquo;<samp><span class="samp">#</span></samp>&rsquo; for Xtensa systems;
see <a href="Machine-Dependencies.html#Machine-Dependencies">Machine Dependencies</a>.  
<!-- FIXME What about i860? -->

   <p>On some machines there are two different line comment characters.  One
character only begins a comment if it is the first non-whitespace character on
a line, while the other always begins a comment.

   <p>The V850 assembler also supports a double dash as starting a comment that
extends to the end of the line.

   <p>&lsquo;<samp><span class="samp">--</span></samp>&rsquo;;

   <p><a name="index-g_t_0023-125"></a><a name="index-lines-starting-with-_0040code_007b_0023_007d-126"></a><a name="index-logical-line-numbers-127"></a>To be compatible with past assemblers, lines that begin with &lsquo;<samp><span class="samp">#</span></samp>&rsquo; have a
special interpretation.  Following the &lsquo;<samp><span class="samp">#</span></samp>&rsquo; should be an absolute
expression (see <a href="Expressions.html#Expressions">Expressions</a>): the logical line number of the <em>next</em>
line.  Then a string (see <a href="Strings.html#Strings">Strings</a>) is allowed: if present it is a
new logical file name.  The rest of the line, if any, should be whitespace.

   <p>If the first non-whitespace characters on the line are not numeric,
the line is ignored.  (Just like a comment.)

<pre class="smallexample">                               # This is an ordinary comment.
     # 42-6 "new_file_name"    # New logical file name
                               # This is logical line # 36.
</pre>
   <p>This feature is deprecated, and may disappear from future versions
of <samp><span class="command">as</span></samp>.

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