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/*
 * Copyright (c) 2020, 2021, 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.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * 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
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 */

package java.nio;

import jdk.internal.misc.Unsafe;

import java.io.FileDescriptor;
import java.io.IOException;
import java.io.UncheckedIOException;

/* package */ class MappedMemoryUtils {

    static boolean isLoaded(long address, boolean isSync, long size) {
        // a sync mapped buffer is always loaded
        if (isSync) {
            return true;
        }
        if ((address == 0) || (size == 0))
            return true;
        long offset = mappingOffset(address);
        long length = mappingLength(offset, size);
        return isLoaded0(mappingAddress(address, offset), length, Bits.pageCount(length));
    }

    static void load(long address, boolean isSync, long size) {
        // no need to load a sync mapped buffer
        if (isSync) {
            return;
        }
        if ((address == 0) || (size == 0))
            return;
        long offset = mappingOffset(address);
        long length = mappingLength(offset, size);
        load0(mappingAddress(address, offset), length);

        // Read a byte from each page to bring it into memory. A checksum
        // is computed as we go along to prevent the compiler from otherwise
        // considering the loop as dead code.
        Unsafe unsafe = Unsafe.getUnsafe();
        int ps = Bits.pageSize();
        long count = Bits.pageCount(length);
        long a = mappingAddress(address, offset);
        byte x = 0;
        for (long i=0; i