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<h3 class="section"><code>.macro</code></h3>



   <p>The commands <code>.macro</code> and <code>.endm</code> allow you to define macros that

generate assembly output.  For example, this definition specifies a macro

<code>sum</code> that puts a sequence of numbers into memory:



<pre class="example">             .macro  sum from=0, to=5

             .long   \from

             .if     \to-\from

             sum     "(\from+1)",\to

             .endif

             .endm

     </pre>



<p>With that definition, <code>SUM 0,5</code> is equivalent to this assembly input:



<pre class="example">             .long   0

             .long   1

             .long   2

             .long   3

             .long   4

             .long   5

     </pre>



     <dl>

<dt><code>.macro </code><var>macname</var><code></code>

     <dd><dt><code>.macro </code><var>macname</var><code> </code><var>macargs</var><code> ...</code>

     <dd>Begin the definition of a macro called <var>macname</var>.  If your macro

definition requires arguments, specify their names after the macro name,

separated by commas or spaces.  You can supply a default value for any

macro argument by following the name with <code>=</code><var>deflt</var><code></code>.  For

example, these are all valid <code>.macro</code> statements:



          <dl>

<dt><code>.macro comm</code>

          <dd>Begin the definition of a macro called <code>comm</code>, which takes no

arguments.



          <br><dt><code>.macro plus1 p, p1</code>

          <dd><dt><code>.macro plus1 p p1</code>

          <dd>Either statement begins the definition of a macro called <code>plus1</code>,

which takes two arguments; within the macro definition, write

<code>\p</code> or <code>\p1</code> to evaluate the arguments.



          <br><dt><code>.macro reserve_str p1=0 p2</code>

          <dd>Begin the definition of a macro called <code>reserve_str</code>, with two

arguments.  The first argument has a default value, but not the second. 

After the definition is complete, you can call the macro either as

<code>reserve_str </code><var>a</var><code>,</code><var>b</var><code></code> (with <code>\p1</code> evaluating to

<var>a</var> and <code>\p2</code> evaluating to <var>b</var>), or as <code>reserve_str

,</code><var>b</var><code></code> (with <code>\p1</code> evaluating as the default, in this case

<code>0</code>, and <code>\p2</code> evaluating to <var>b</var>). 

</dl>



     <p>When you call a macro, you can specify the argument values either by

position, or by keyword.  For example, <code>sum 9,17</code> is equivalent to

<code>sum to=17, from=9</code>.



     <br><dt><code>.endm</code>

     <dd>Mark the end of a macro definition.



     <br><dt><code>.exitm</code>

     <dd>Exit early from the current macro definition.



     <br><dt><code>\@</code>

     <dd><code>as</code> maintains a counter of how many macros it has

executed in this pseudo-variable; you can copy that number to your

output with <code>\@</code>, but <em>only within a macro definition</em>.



   </dl>



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