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<html><head><title>XLISP poke</title>
<link rel="stylesheet" type="text/css" href="reference.css">
</head>
<body>
<a href="../start.htm">Nyquist / XLISP 2.0</a> -
<a href="../manual/contents.htm">Contents</a> |
<a href="../tutorials/tutorials.htm">Tutorials</a> |
<a href="../examples/examples.htm">Examples</a> |
<a href="reference-index.htm">Reference</a>
<hr>
<h1>poke</h1>
<hr>
<p><table cellpadding="0" cellspacing="0" style="margin-left:10px"><tbody>
<tr valign="top">
<td><nobr>Type:</nobr></td>
<td><nobr> - </nobr></td>
<td width="100%"><nobr>function (subr)</nobr></td>
</tr>
<tr valign="top">
<td><nobr>Source:</nobr></td>
<td><nobr> - </nobr></td>
<td width="100%"><nobr>xlsys.c</nobr></td>
</tr>
</tbody></table></p>
<h2>Syntax</h2>
<dl>
<dt>(poke <i>address expr</i>)</dt>
<dd><i>address</i> - an integer expression<br>
<i>expr</i> - an integer expression<br>
returns - the value</dd>
</dl>
<h2>Description</h2>
<p>The 'poke' function writes the 'expr' at the internal memory value at the
specified 'address'. The returned value is 'expr'. Be very careful with this
function.</p>
<h2>Examples</h2>
<pre class="example">
(setq var 0) <font color="#008844">; set up VAR with 0</font>
(address-of var) <font color="#008844">; returns 123224</font>
(address-of 'var) <font color="#008844">; returns 161922</font>
(peek (address-of var)) <font color="#008844">; returns 83951616</font>
(peek (1+ (address-of var))) <font color="#008844">; returns 16777216</font>
(peek (+ 2 (address-of var))) <font color="#008844">; returns 0 <-- value of VAR</font>
(setq var 14) <font color="#008844">; change the value to 14</font>
(peek (+ 2 (address-of var))) <font color="#008844">; returns 14</font>
(poke (+ 2 (address-of var)) 1023) <font color="#008844">; POKE the value to 1023</font>
(print var) <font color="#008844">; prints 1023</font>
</pre>
<p><b>Caution:</b> Be careful when modifying the internal state of XLISP. If
you have modified it, it would be a good idea to exit XLISP and re-enter
before doing any work you really want to retain.</p>
<p><b>Caution:</b> It is possible to <a href="peek.htm">peek</a>
and 'poke' not just XLISP's memory put other parts of your computer's
memory. Be very careful when doing this. Also, in some computers, just
looking at a memory location can cause things to happen, I/O locations fall
in this category.</p>
<p>See the
<a href="../manual/xlisp-man-031.htm#poke">poke</a>
function in the <nobr>XLISP 2.0</nobr> manual.</p>
<p><nobr> <a href="#top">Back to Top</nobr></a></p>
<hr>
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<a href="../manual/contents.htm">Contents</a> |
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