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 /*

  * Copyright (c) 2011, Oracle and/or its affiliates. All rights reserved.

  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

  *

  * This code is free software; you can redistribute it and/or modify it

  * under the terms of the GNU General Public License version 2 only, as

  * published by the Free Software Foundation.

  *

  * This code is distributed in the hope that it will be useful, but WITHOUT

  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

  * version 2 for more details (a copy is included in the LICENSE file that

  * accompanied this code).

  *

  * You should have received a copy of the GNU General Public License version

  * 2 along with this work; if not, write to the Free Software Foundation,

  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

  *

  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

  * or visit www.oracle.com if you need additional information or have any

  * questions.

  *

  */

 #ifndef SHARE_VM_OOPS_FIELDINFO_HPP

 #define SHARE_VM_OOPS_FIELDINFO_HPP

 #include "oops/typeArrayOop.hpp"

 #include "classfile/vmSymbols.hpp"

 // This class represents the field information contained in the fields

 // array of an instanceKlass.  Currently it's laid on top an array of

 // Java shorts but in the future it could simply be used as a real

 // array type.  FieldInfo generally shouldn't be used directly.

 // Fields should be queried either through instanceKlass or through

 // the various FieldStreams.

 class FieldInfo VALUE_OBJ_CLASS_SPEC {

   friend class fieldDescriptor;

   friend class JavaFieldStream;

   friend class ClassFileParser;

  public:

   // fields

   // Field info extracted from the class file and stored

   // as an array of 7 shorts

   enum FieldOffset {

     access_flags_offset      = 0,

     name_index_offset        = 1,

     signature_index_offset   = 2,

     initval_index_offset     = 3,

     low_offset               = 4,

     high_offset              = 5,

     generic_signature_offset = 6,

     field_slots              = 7

   };

  private:

   u2 _shorts[field_slots];

   void set_name_index(u2 val)                    { _shorts[name_index_offset] = val;         }

   void set_signature_index(u2 val)               { _shorts[signature_index_offset] = val;    }

   void set_initval_index(u2 val)                 { _shorts[initval_index_offset] = val;      }

   void set_generic_signature_index(u2 val)       { _shorts[generic_signature_offset] = val;  }

   u2 name_index() const                          { return _shorts[name_index_offset];        }

   u2 signature_index() const                     { return _shorts[signature_index_offset];   }

   u2 initval_index() const                       { return _shorts[initval_index_offset];     }

   u2 generic_signature_index() const             { return _shorts[generic_signature_offset]; }

  public:

   static FieldInfo* from_field_array(typeArrayOop fields, int index) {

     return ((FieldInfo*)fields->short_at_addr(index * field_slots));

   }

   void initialize(u2 access_flags,

                   u2 name_index,

                   u2 signature_index,

                   u2 initval_index,

                   u2 generic_signature_index,

                   u4 offset) {

     _shorts[access_flags_offset] = access_flags;

     _shorts[name_index_offset] = name_index;

     _shorts[signature_index_offset] = signature_index;

     _shorts[initval_index_offset] = initval_index;

     _shorts[generic_signature_offset] = generic_signature_index;

     set_offset(offset);

   }

   u2 access_flags() const                        { return _shorts[access_flags_offset];            }

   u4 offset() const                              { return build_int_from_shorts(_shorts[low_offset], _shorts[high_offset]); }

   Symbol* name(constantPoolHandle cp) const {

     int index = name_index();

     if (is_internal()) {

       return lookup_symbol(index);

     }

     return cp->symbol_at(index);

   }

   Symbol* signature(constantPoolHandle cp) const {

     int index = signature_index();

     if (is_internal()) {

       return lookup_symbol(index);

     }

     return cp->symbol_at(index);

   }

   Symbol* generic_signature(constantPoolHandle cp) const {

     int index = generic_signature_index();

     if (index == 0) {

       return NULL;

     }

     return cp->symbol_at(index);

   }

   void set_access_flags(u2 val)                  { _shorts[access_flags_offset] = val;             }

   void set_offset(u4 val)                        {

     _shorts[low_offset] = extract_low_short_from_int(val);

     _shorts[high_offset] = extract_high_short_from_int(val);

   }

   bool is_internal() const {

     return (access_flags() & JVM_ACC_FIELD_INTERNAL) != 0;

   }

   Symbol* lookup_symbol(int symbol_index) const {

     assert(is_internal(), "only internal fields");

     return vmSymbols::symbol_at((vmSymbols::SID)symbol_index);

   }

 };

 #endif // SHARE_VM_OOPS_FIELDINFO_HPP