| author | timkelly |
| Thu, 10 Dec 2009 13:45:47 -0600 | |
| branch | RCL_2_4 |
| changeset 671 | 80524b72f957 |
| parent 0 | fb279309251b |
| child 990 | 5d016a880824 |
| child 1024 | 48b401835d0a |
| permissions | -rw-r--r-- |
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" |
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"http://www.w3.org/TR/html4/loose.dtd"> |
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<html><head> |
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<title>Dumping the Contents of Classes</title> |
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<link href="sysdoc-eclipse.css" type="text/css" rel="stylesheet" media="screen"> |
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<link href="sysdoc-eclipse.css" type="text/css" rel="stylesheet" media="print"> |
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<link href="../../book.css" type="text/css" rel="stylesheet" > |
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<div class="Head1"> |
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<h2>Dumping the Contents of Classes</h2> |
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</div> |
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<div> |
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<p>You can use the |
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<a href="CrashDebugger_cmd_m.guide.html" title="The debug monitor and command syntax / m - do a memory dump">m</a> command to |
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inspect the contents of structures and class instances, but you need to be |
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aware of a few things about the memory layout:</p> |
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<ul> |
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<li> |
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<p>Symbian OS is little-endian, which means that all values are |
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stored so that the least significant bytes are stored at the lower addresses in |
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memory (or “backwards” as commonly perceived).</p> |
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<p>For example, the value 0x1234ABCD would be shown in the memory |
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dump as:</p> |
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<p class="listing">CD AB 34 12</p> |
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</li> |
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<li> |
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<p>The compiler may add padding between variables either to speed |
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up access or to avoid alignment restrictions; for example, words cannot be on |
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odd addresses. </p> |
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<p>As an example, the following struct:</p> |
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<p class="listing">struct SExample<br> |
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{<br>
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TUint8 iByte;<br> |
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TInt iInteger;<br> |
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};</p> |
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<p>would be laid out in memory as:</p> |
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<p class="listing">+0(1) iByte<br> |
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+1(3) padding<br> |
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+4(4) iInteger</p> |
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<p>The padding and alignment is compiler-dependent. Generally, |
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fields must be aligned on a boundary equal to their size; for example, a TUint32 is 4 bytes wide so it must lie on a 4-byte |
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boundary, i.e. the least significant two bits of the address must be |
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zero.</p> |
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<p>When using GCC, classes which derive from CBase will have a virtual table pointer as the first word |
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in the class data and classes which derive from DBase will |
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have a virtual table pointer as the second word in the class data.</p> |
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<p>When using an EABI-compliant compiler, the virtual table |
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pointer is always the first word of the class.</p> |
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</li> |
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</ul> |
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</div> |
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<div id="footer">Copyright © 2009 Nokia Corporation and/or its subsidiary(-ies). All rights reserved. <br>License: <a href="http://www.eclipse.org/legal/epl-v10.html">http://www.eclipse.org/legal/epl-v10.html</a></div> |
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</body> |
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</html> |
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