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+<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
+
+<html>
+
+<head>
+<title>instance-of</title>
+<link rel=stylesheet href="opcode.css">
+</head>
+
+<body>
+
+<h1>instance-of</h1>
+
+<h2>Purpose</h2>
+
+<p>
+Store in the given destination register 1 if the indicated reference is an
+instance of the given type, or 0 if not. The type must be a reference type (not
+a primitive type).
+</p>
+
+<h2>Details</h2>
+
+<table class="instruc">
+<thead>
+<tr>
+  <th>Op &amp; Format</th>
+  <th>Mnemonic / Syntax</th>
+  <th>Arguments</th>
+</tr>
+</thead>
+<tbody>
+<tr>
+  <td>20 22c</td>
+  <td>instance-of vA, vB, type@CCCC</td>
+  <td><code>A:</code> destination register (4 bits)<br/>
+    <code>B:</code> reference-bearing register (4 bits)<br/>
+    <code>C:</code> type index (16 bits)</td>
+</tr>
+</tbody>
+</table>
+
+<h2>Constraints</h2>
+
+<ul>
+  <li>
+    Both A and B must be a valid register indices for the current stack frame.
+  </li>
+  <li>
+    Register vB must contain a reference value.
+  </li>
+  <li>
+    C must be a valid index into the type constant pool.
+  </li>
+  <li>
+    Type constant pool entry C must contain a valid type descriptor for a
+    reference type.
+  </li> 
+</ul>
+
+<h2>Behavior</h2>
+
+<ul>
+  <li>
+    An attempt is made to get a reference to the class K the name of which is
+    contained in type pool entry C.
+  </li>
+  <li>
+    If K has not been loaded and resolved before, it is being loaded and
+    resolved. All exceptions that are possible during class loading can occur at
+    this point.
+  </li>
+  <li>
+    The run-time type of the object reference vB is compared against K. The
+    register vA reflects the result:
+    <ul>
+      <li>
+        vA' = 1 if (and only if) vB is not null and vB is assignment compatible
+        with K according to the usual rules of the Java programming language.
+      </li>
+      <li>
+        vA' = 0 otherwise
+      </li>
+    </ul>
+  </li>
+  <li>
+    If v(A-1) is the lower half of a register pair, v(A-1)' becomes undefined.
+  </li>
+  <li>
+    If v(A+1) is the upper half of a register pair, v(A+1)' becomes undefined.
+  </li> 
+
+<h2>Exceptions</h2>
+
+<p>
+None.
+</p>
+
+</body>
+</html>