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package com.oracle.svm.core.util;

import org.graalvm.word.UnsignedWord;
import org.graalvm.word.WordFactory;

import com.oracle.svm.core.annotate.Uninterruptible;

Utility methods on Unsigned values.
/**
 * Utility methods on Unsigned values.
 */
public final class UnsignedUtils {

    
The UnsignedWord of the greatest magnitude. /** The UnsignedWord of the greatest magnitude. */
    public static final UnsignedWord MAX_VALUE = WordFactory.unsigned(0xffffffffffffffffL);

    private UnsignedUtils() {
        // This is a class of static methods, so no need for any instances.
    }

    
Round an Unsigned down to the nearest smaller multiple.
Params:
that – The Unsigned to be rounded down.
multiple – The multiple to which that Unsigned should be decreased.
Returns:
That Unsigned, but rounded down./**
     * Round an Unsigned down to the nearest smaller multiple.
     *
     * @param that The Unsigned to be rounded down.
     * @param multiple The multiple to which that Unsigned should be decreased.
     * @return That Unsigned, but rounded down.
     */
    @Uninterruptible(reason = "Used in uninterruptible code.", mayBeInlined = true)
    public static UnsignedWord roundDown(UnsignedWord that, UnsignedWord multiple) {
        return that.unsignedDivide(multiple).multiply(multiple);
    }

    
Round an Unsigned up to the nearest larger multiple.
Params:
that – The Unsigned to be rounded up.
multiple – The multiple to which that Unsigned should be increased.
Returns:
That Unsigned, but rounded up./**
     * Round an Unsigned up to the nearest larger multiple.
     *
     * @param that The Unsigned to be rounded up.
     * @param multiple The multiple to which that Unsigned should be increased.
     * @return That Unsigned, but rounded up.
     */
    @Uninterruptible(reason = "Used in uninterruptible code.", mayBeInlined = true)
    public static UnsignedWord roundUp(UnsignedWord that, UnsignedWord multiple) {
        return UnsignedUtils.roundDown(that.add(multiple.subtract(1)), multiple);
    }

    
Check that an Unsigned is an even multiple.
Params:
that – The Unsigned to be verified as a multiple.
multiple – The multiple against which the Unsigned should be verified.
Returns:
true if that Unsigned is a multiple, false otherwise./**
     * Check that an Unsigned is an even multiple.
     *
     * @param that The Unsigned to be verified as a multiple.
     * @param multiple The multiple against which the Unsigned should be verified.
     * @return true if that Unsigned is a multiple, false otherwise.
     */
    @Uninterruptible(reason = "Used in uninterruptible code.", mayBeInlined = true)
    public static boolean isAMultiple(UnsignedWord that, UnsignedWord multiple) {
        return that.unsignedRemainder(multiple).equal(0);
    }

    
The minimum of two Unsigneds.
Params:
x – An Unsigned.
y – Another Unsigned.
Returns:
The whichever Unsigned is smaller./**
     * The minimum of two Unsigneds.
     *
     * @param x An Unsigned.
     * @param y Another Unsigned.
     * @return The whichever Unsigned is smaller.
     */
    @Uninterruptible(reason = "Used in uninterruptible code.", mayBeInlined = true)
    public static UnsignedWord min(UnsignedWord x, UnsignedWord y) {
        return (x.belowOrEqual(y)) ? x : y;
    }

    
The maximum of two Unsigneds.
Params:
x – An Unsigned.
y – Another Unsigned.
Returns:
The whichever Unsigned is larger./**
     * The maximum of two Unsigneds.
     *
     * @param x An Unsigned.
     * @param y Another Unsigned.
     * @return The whichever Unsigned is larger.
     */
    public static UnsignedWord max(UnsignedWord x, UnsignedWord y) {
        return (x.aboveOrEqual(y)) ? x : y;
    }

    
Converts an UnsignedWord to a positive signed int, asserting that it can be correctly represented. /**
     * Converts an {@link UnsignedWord} to a positive signed {@code int}, asserting that it can be
     * correctly represented.
     */
    public static int safeToInt(UnsignedWord w) {
        long l = w.rawValue();
        assert l >= 0 && l == (int) l;
        return (int) l;
    }
}