1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/os/kernelhwsrv/kernel/eka/compsupp/symaehabi/symbian_rtti.cpp Fri Jun 15 03:10:57 2012 +0200
1.3 @@ -0,0 +1,159 @@
1.4 +// Copyright (c) 2004-2009 Nokia Corporation and/or its subsidiary(-ies).
1.5 +// All rights reserved.
1.6 +// This component and the accompanying materials are made available
1.7 +// under the terms of the License "ARM EABI LICENCE.txt"
1.8 +// which accompanies this distribution, and is available
1.9 +// in kernel/eka/compsupp.
1.10 +//
1.11 +// Initial Contributors:
1.12 +// Nokia Corporation - initial contribution.
1.13 +//
1.14 +// Contributors:
1.15 +//
1.16 +// Description:
1.17 +// e32/compsupp/symaehabi/symbian_rtti.cpp
1.18 +//
1.19 +//
1.20 +
1.21 +#include "cxxabi.h"
1.22 +#include "unwind_env.h"
1.23 +#include "unwinder.h"
1.24 +#include "symbian_support.h"
1.25 +
1.26 +// For information about these classes, se
1.27 +// www.codesourcery.com/public/cxx-abi/abi.html#rtti.
1.28 +using abi::__class_type_info;
1.29 +using abi::__si_class_type_info;
1.30 +using abi::__vmi_class_type_info;
1.31 +using abi::__base_class_type_info;
1.32 +
1.33 +
1.34 +// Given base class info (aBaseInfo) and a derived object pointer (aDerivedObj),
1.35 +// this function implements "cast to base" and stores result in aBaseObj. This
1.36 +// essentially sets aBaseObj to point to a memory location that represents
1.37 +// aDerivedObj as the given base class. This function requires that aBaseInfo
1.38 +// describes a base class of the aDerivedObj's class.
1.39 +static void _CastUp(const __base_class_type_info& aBaseInfo, TAny** aDerivedObj, TAny** aBaseObj)
1.40 + {
1.41 + // Guard against a null pointer for aDerivedObj
1.42 + if ( ! (*aDerivedObj) )
1.43 + {
1.44 + *aBaseObj = NULL;
1.45 + return;
1.46 + }
1.47 +
1.48 + TInt offset = aBaseInfo.__offset_flags >> aBaseInfo.__offset_shift;
1.49 +
1.50 + if (aBaseInfo.__offset_flags & aBaseInfo.__virtual_mask)
1.51 + {
1.52 + // For virtual bases, look up offset in vtable + offset.
1.53 +
1.54 + // Get vtbl pointer as the first 4 bytes of **aDerivedObj
1.55 + TUint32* vptr = (TUint32*) ( *( (TUint32*) (*aDerivedObj) ) );
1.56 +
1.57 + offset = *( vptr + offset / sizeof(TUint32) );
1.58 + }
1.59 +
1.60 + // Apply the offset.
1.61 + *aBaseObj = (TAny*) ( ( (TUint8*) *aDerivedObj ) + offset );
1.62 + }
1.63 +
1.64 +
1.65 +// For a description of this function, see comments in unwind_env.h.
1.66 +extern "C" TBool _DoDerivedToBaseConversion(const std::type_info* aDerivedType,
1.67 + const std::type_info* aBaseType,
1.68 + TAny** aDerivedObj,
1.69 + TAny** aBaseObj)
1.70 + {
1.71 +
1.72 + const std::type_info& type_base_type = typeid(*aBaseType);
1.73 + const std::type_info& type_derived_type = typeid(*aDerivedType);
1.74 +
1.75 + // We must proceed depending on the type of the type_info objects for derived
1.76 + // class.
1.77 + if ( type_derived_type == typeid(__si_class_type_info) )
1.78 + {
1.79 + // The __si_class_type_info means that the derived type has a single,
1.80 + // public, non-virtual base, and that the base is at offset zero. We should
1.81 + // be able to simply compare the base type from __si_class_type_info with
1.82 + // aBaseType
1.83 +
1.84 + const __si_class_type_info* derived = (const __si_class_type_info*) aDerivedType;
1.85 +
1.86 + if ( *(derived->__base_type) == *aBaseType )
1.87 + {
1.88 + // The types match, work done.
1.89 + *aBaseObj = *aDerivedObj;
1.90 + return true;
1.91 + }
1.92 + else
1.93 + {
1.94 + // The types don't match. We should proceed to comparison with the any
1.95 + // classes. In this case there is a single base as follows:
1.96 + const __class_type_info* bType = derived->__base_type;
1.97 +
1.98 + // No pointer adjustment required for __si_class_type_info.
1.99 + return _DoDerivedToBaseConversion(bType, aBaseType, aDerivedObj, aBaseObj);
1.100 + }
1.101 + }
1.102 + else if ( type_derived_type == typeid(__vmi_class_type_info) )
1.103 + {
1.104 + // The __vmi_class_type_info is for all other scenarios. We get an array of
1.105 + // bases which we need to traverse and do comparison on.
1.106 +
1.107 + const __vmi_class_type_info* derived = (const __vmi_class_type_info*)aDerivedType;
1.108 +
1.109 + const unsigned count = derived->__base_count;
1.110 +
1.111 + for ( unsigned i = 0; i < count; i++ )
1.112 + {
1.113 + // Get the base info for this base class
1.114 + const __base_class_type_info bInfo = derived->__base_info[i];
1.115 +
1.116 + if ( ! ( bInfo.__offset_flags & bInfo.__public_mask) )
1.117 + {
1.118 + // The base is non-public base, so the remainder of the hierarchy
1.119 + // above this base is of no interest
1.120 + continue;
1.121 + }
1.122 +
1.123 + // Get the class type info for this base
1.124 + const __class_type_info* bType = bInfo.__base_type;
1.125 +
1.126 + // First check if the type from the list corresponds to requested base
1.127 + // type.
1.128 + if ( (*bType) == (*aBaseType) )
1.129 + {
1.130 + // Match! Convert the pointer to point to the base.
1.131 + _CastUp(bInfo, aDerivedObj, aBaseObj);
1.132 + return true;
1.133 + }
1.134 +
1.135 + // No match, we must now recursively delve into superclasses of bType.
1.136 + // To do that, we need to advance the derived class pointer to point to
1.137 + // the current base class as in bInfo.
1.138 + TAny* newDerivedPtr;
1.139 + _CastUp(bInfo, aDerivedObj, &newDerivedPtr);
1.140 +
1.141 + // Now go recursive, substituting aDerivedObj with adjusted pointer and bType instead of aDerivedType
1.142 + TBool result = _DoDerivedToBaseConversion(bType, aBaseType, (TAny**)(&newDerivedPtr), aBaseObj);
1.143 +
1.144 + // Return only if the match is found, otherwise continue with the loop
1.145 + if ( result )
1.146 + {
1.147 + // Match came back from recursion, pass up.
1.148 + return true;
1.149 + }
1.150 +
1.151 + // No match from recursion, advance to next base.
1.152 + }
1.153 + }
1.154 + else
1.155 + {
1.156 + // assert(0);
1.157 + }
1.158 +
1.159 + // No match was found for aBaseType in the aDerivedType's ancestry.
1.160 + return false;
1.161 + }
1.162 +