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/*
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* Copyright 1997-2006 Sun Microsystems, Inc. All Rights Reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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* CA 95054 USA or visit www.sun.com if you need additional information or
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* have any questions.
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*
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*/
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// arrayOopDesc is the abstract baseclass for all arrays.
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class arrayOopDesc : public oopDesc {
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friend class VMStructs;
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private:
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int _length; // number of elements in the array
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public:
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// Interpreter/Compiler offsets
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static int length_offset_in_bytes() { return offset_of(arrayOopDesc, _length); }
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static int base_offset_in_bytes(BasicType type) { return header_size(type) * HeapWordSize; }
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// Returns the address of the first element.
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void* base(BasicType type) const { return (void*) (((intptr_t) this) + base_offset_in_bytes(type)); }
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// Tells whether index is within bounds.
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bool is_within_bounds(int index) const { return 0 <= index && index < length(); }
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// Accessores for instance variable
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int length() const { return _length; }
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void set_length(int length) { _length = length; }
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// Header size computation.
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// Should only be called with constants as argument (will not constant fold otherwise)
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static int header_size(BasicType type) {
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return Universe::element_type_should_be_aligned(type)
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? align_object_size(sizeof(arrayOopDesc)/HeapWordSize)
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: sizeof(arrayOopDesc)/HeapWordSize;
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}
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// This method returns the maximum length that can passed into
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// typeArrayOop::object_size(scale, length, header_size) without causing an
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// overflow. We substract an extra 2*wordSize to guard against double word
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// alignments. It gets the scale from the type2aelembytes array.
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static int32_t max_array_length(BasicType type) {
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assert(type >= 0 && type < T_CONFLICT, "wrong type");
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assert(type2aelembytes[type] != 0, "wrong type");
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// We use max_jint, since object_size is internally represented by an 'int'
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// This gives us an upper bound of max_jint words for the size of the oop.
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int32_t max_words = (max_jint - header_size(type) - 2);
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int elembytes = (type == T_OBJECT) ? T_OBJECT_aelem_bytes : type2aelembytes[type];
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jlong len = ((jlong)max_words * HeapWordSize) / elembytes;
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return (len > max_jint) ? max_jint : (int32_t)len;
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}
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};
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