jdk/src/java.base/share/classes/sun/security/util/math/MutableIntegerModuloP.java

/*
 * Copyright (c) 2018, 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
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package sun.security.util.math;

import java.nio.ByteBuffer;

/**
 * An interface for mutable integers modulo a prime value. This interface
 * should be used to improve performance and avoid the allocation of a large
 * number of temporary objects.
 *
 * Methods in this interface that modify the value also return the modified
 * element. This structure enables fluent expressions like:
 * a.setSum(b).setProduct(c).setDifference(d).setSquare()
 *
 */

public interface MutableIntegerModuloP extends IntegerModuloP {

    /**
     * Set this value to the value of b when set has the value 1.
     * No change is made to this element when set has the value 0. The
     * result is undefined when set has a value other than 0 or 1. The set
     * parameter is an int (rather than boolean) to allow the implementation
     * to perform the assignment using branch-free integer arithmetic.
     *
     * @param b the element to conditionally swap with
     * @param set an int that determines whether to set
     */
    void conditionalSet(IntegerModuloP b, int set);

    /**
     * Swap the value of this with the value of b when swap has the value 1.
     * No change is made to either element when swap has the value 0. The
     * result is undefined when swap has a value other than 0 or 1. The swap
     * parameter is an int (rather than boolean) to allow the implementation
     * to perform the swap using branch-free integer arithmetic.
     *
     * @param b the element to conditionally swap with
     * @param swap an int that determines whether to swap
     */
    void conditionalSwapWith(MutableIntegerModuloP b, int swap);

    /**
     * Set the value of this element equal to the value of the supplied
     * element. The argument is not modified.
     *
     * @param v the element whose value should be copied to this
     * @return this
     */
    MutableIntegerModuloP setValue(IntegerModuloP v);

    /**
     * Set the value equal to the little-endian unsigned integer stored at the
     * specified position in an array. The range of accepted values is
     * implementation-specific. This method also takes a byte which is
     * interpreted as an additional high-order byte of the number.
     *
     * @param v an array containing a little-endian unsigned integer
     * @param offset the starting position of the integer
     * @param length the number of bytes to read
     * @param highByte the high-order byte of the number
     * @return this
     */
    MutableIntegerModuloP setValue(byte[] v, int offset, int length,
                                   byte highByte);

    /**
     * Set the value equal to the little-endian unsigned integer stored in a
     * buffer. The range of accepted values is implementation-specific.
     * This method also takes a byte which is interpreted as an additional
     * high-order byte of the number.
     *
     * @param buf a buffer containing a little-endian unsigned integer
     * @param length the number of bytes to read
     * @param highByte the high-order byte of the number
     * @return this
     */
    MutableIntegerModuloP setValue(ByteBuffer buf, int length, byte highByte);

    /**
     * Set the value of this element equal to this * this.
     *
     * @return this
     */
    MutableIntegerModuloP setSquare();

    /**
     * Set the value of this element equal to this + b. The argument is
     * not modified.
     *
     * @param b the sumand
     * @return this
     */
    MutableIntegerModuloP setSum(IntegerModuloP b);

    /**
     * Set the value of this element equal to this - b. The argument is
     * not modified.
     *
     * @param b the subtrahend
     * @return this
     */
    MutableIntegerModuloP setDifference(IntegerModuloP b);

    /**
     * Set the value of this element equal to this * b. The argument is
     * not modified.
     *
     * @param b the multiplicand
     * @return this
     */
    MutableIntegerModuloP setProduct(IntegerModuloP b);

    /**
     * Set the value of this element equal to this * v. The argument is
     * not modified.
     *
     * @param v the small multiplicand
     * @return this
     */
    MutableIntegerModuloP setProduct(SmallValue v);

    /**
     * Set the value of this element equal to 0 - this.
     *
     * @return this
     */
    MutableIntegerModuloP setAdditiveInverse();

    /**
     * Some implementations required reduction operations to be requested
     * by the client at certain times. This method reduces the representation.
     *
     * @return this
     */
    MutableIntegerModuloP setReduced();
}