--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Symbian3/PDK/Source/GUID-5E358AB4-03A7-5859-ABF2-A8B64B74AF56.dita	Fri Jan 22 18:26:19 2010 +0000
@@ -0,0 +1,41 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Copyright (c) 2007-2010 Nokia Corporation and/or its subsidiary(-ies) All rights reserved. -->
+<!-- This component and the accompanying materials are made available under the terms of the License 
+"Eclipse Public License v1.0" which accompanies this distribution, 
+and is available at the URL "http://www.eclipse.org/legal/epl-v10.html". -->
+<!-- Initial Contributors:
+    Nokia Corporation - initial contribution.
+Contributors: 
+-->
+<!DOCTYPE concept
+  PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">
+<concept id="GUID-5E358AB4-03A7-5859-ABF2-A8B64B74AF56" xml:lang="en"><title>Vector
+Floating Point Architecture (VFP)</title><shortdesc>Describes the implementation of the ARM Vector Floating Point Architecture
+(VFPv2) on Symbian platform. </shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>
+<p>ARM provide a hardware floating point coprocessor that provides floating
+point computation that is fully compliant with IEEE Std 754-1985.We refer
+to the coprocessor as the <i>VFP unit</i>. </p>
+<p>Symbian platform supports the use of VFPv2 on platforms where the required
+hardware is present in both <i>RunFast</i> mode and in <i>IEEE-without-exceptions</i> mode.
+See ARM's Vector Floating-point Coprocessor Technical reference Manual for
+more details on the coprocessor, its architecture, and its execution modes. </p>
+<p>You should read the information in <xref href="GUID-D525B9A9-6B32-535B-A282-60C85A48D3FB.dita">Floating
+point support</xref> about applications and user side code as this is also
+applicable to code running on the kernel side. However there are a number
+of restrictions that must be observed: </p>
+<ul>
+<li id="GUID-2205026D-0E6F-54AE-B74F-5478D6047B70"><p>You <i>cannot</i> use
+VFP instructions in any interrupt service routine. </p> </li>
+<li id="GUID-C8D896E1-CF36-52CD-A984-61D7A8189268"><p>You <i>cannot</i> use
+VFP instructions when the kernel is locked, for example, in an IDFC or after
+calling <xref href="GUID-3A3C08F3-3D33-3D9E-80E7-7855C7B21E02.dita#GUID-3A3C08F3-3D33-3D9E-80E7-7855C7B21E02/GUID-7CBBF72B-4519-38DD-92CA-38AF636AFD8A"><apiname>NKern::Lock()</apiname></xref>  </p> </li>
+<li id="GUID-A7466A83-A8F2-58CE-AB8B-E05607BB6D95"><p>You <i>cannot</i> use
+VFP instructions in any section of code which runs with a fast mutex held. </p> </li>
+</ul>
+<p>Using VFP instructions in these situations can lead to data being corrupted,
+or the kernel panicking. If you rely on the compiler to generate VFP instructions,
+rather than using inline assembler, it is extremely important that you do
+not use any floating point values in these situations. The compiler may generate
+VFP instructions for the most trivial floating point operations and even for
+simple assignments. </p>
+</conbody></concept>
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