/*

 * Copyright 1997-2006 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 *

 */

// arrayOopDesc is the abstract baseclass for all arrays.

class arrayOopDesc : public oopDesc {

  friend class VMStructs;

 private:

  int _length; // number of elements in the array

 public:

  // Interpreter/Compiler offsets

  static int length_offset_in_bytes()             { return offset_of(arrayOopDesc, _length); }

  static int base_offset_in_bytes(BasicType type) { return header_size(type) * HeapWordSize; }

  // Returns the address of the first element.

  void* base(BasicType type) const              { return (void*) (((intptr_t) this) + base_offset_in_bytes(type)); }

  // Tells whether index is within bounds.

  bool is_within_bounds(int index) const        { return 0 <= index && index < length(); }

  // Accessores for instance variable

  int length() const                            { return _length;   }

  void set_length(int length)                   { _length = length; }

  // Header size computation.

  // Should only be called with constants as argument (will not constant fold otherwise)

  static int header_size(BasicType type) {

    return Universe::element_type_should_be_aligned(type)

      ? align_object_size(sizeof(arrayOopDesc)/HeapWordSize)

      : sizeof(arrayOopDesc)/HeapWordSize;

  }

  // This method returns the  maximum length that can passed into

  // typeArrayOop::object_size(scale, length, header_size) without causing an

  // overflow. We substract an extra 2*wordSize to guard against double word

  // alignments.  It gets the scale from the type2aelembytes array.

  static int32_t max_array_length(BasicType type) {

    assert(type >= 0 && type < T_CONFLICT, "wrong type");

    assert(type2aelembytes[type] != 0, "wrong type");

    // We use max_jint, since object_size is internally represented by an 'int'

    // This gives us an upper bound of max_jint words for the size of the oop.

    int32_t max_words = (max_jint - header_size(type) - 2);

    int elembytes = (type == T_OBJECT) ? T_OBJECT_aelem_bytes : type2aelembytes[type];

    jlong len = ((jlong)max_words * HeapWordSize) / elembytes;

    return (len > max_jint) ? max_jint : (int32_t)len;

  }

};