Example usage for java.math BigInteger shiftRight

Introduction

In this page you can find the example usage for java.math BigInteger shiftRight.

Prototype

public BigInteger shiftRight(int n) 

Source Link

Document

Returns a BigInteger whose value is (this >> n) .

Usage

From source file:com.bigdata.dastor.utils.FBUtilities.java

/**
 * Given two bit arrays represented as BigIntegers, containing the given
 * number of significant bits, calculate a midpoint.
 *
 * @param left The left point./*  w  w w.  j a v a2  s  . com*/
 * @param right The right point.
 * @param sigbits The number of bits in the points that are significant.
 * @return A midpoint that will compare bitwise halfway between the params, and
 * a boolean representing whether a non-zero lsbit remainder was generated.
 */
public static Pair<BigInteger, Boolean> midpoint(BigInteger left, BigInteger right, int sigbits) {
    BigInteger midpoint;
    boolean remainder;
    if (left.compareTo(right) < 0) {
        BigInteger sum = left.add(right);
        remainder = sum.testBit(0);
        midpoint = sum.shiftRight(1);
    } else {
        BigInteger max = TWO.pow(sigbits);
        // wrapping case
        BigInteger distance = max.add(right).subtract(left);
        remainder = distance.testBit(0);
        midpoint = distance.shiftRight(1).add(left).mod(max);
    }
    return new Pair(midpoint, remainder);
}

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From source file:Util.java

public static BigInteger bitwiseGcd(BigInteger u, BigInteger v) {
    if (u.equals(BigInteger.ZERO))
        return v;
    if (v.equals(BigInteger.ZERO))
        return u;

    //      System.out.format("u=%s=%s\nu.getLowestSetBit()=%s\n%s>>%s=%s = %s\n", u, u.toString(2), u.getLowestSetBit(), u, u.getLowestSetBit(), u.shiftRight(u.getLowestSetBit()), u.shiftRight(u.getLowestSetBit()).toString(2));

    int uBit = u.getLowestSetBit();
    int vBit = v.getLowestSetBit();
    int k = (uBit <= vBit ? uBit : vBit);

    while (u.signum() > 0) {
        // first ensure that both are odd
        u = u.shiftRight(u.getLowestSetBit());
        v = v.shiftRight(v.getLowestSetBit());
        if (u.subtract(v).signum() >= 0) {
            u = (u.subtract(v)).shiftRight(1);
        } else {//from   ww w . java 2 s. co m
            v = (v.subtract(u)).shiftRight(1);
        }
    }

    return v.shiftLeft(k);
}

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From source file:Main.java

/**
 * Computes the Window NAF (non-adjacent Form) of an integer.
 * @param width The width <code>w</code> of the Window NAF. The width is
 * defined as the minimal number <code>w</code>, such that for any
 * <code>w</code> consecutive digits in the resulting representation, at
 * most one is non-zero.//from  w  w  w.  j  ava 2 s.c om
 * @param k The integer of which the Window NAF is computed.
 * @return The Window NAF of the given width, such that the following holds:
 * <code>k = &sum;<sub>i=0</sub><sup>l-1</sup> k<sub>i</sub>2<sup>i</sup>
 * </code>, where the <code>k<sub>i</sub></code> denote the elements of the
 * returned <code>byte[]</code>.
 */
public static byte[] generateWindowNaf(int width, BigInteger k) {
    if (width == 2) {
        return generateNaf(k);
    }

    if (width < 2 || width > 8) {
        throw new IllegalArgumentException("'width' must be in the range [2, 8]");
    }

    byte[] wnaf = new byte[k.bitLength() + 1];

    // 2^width and a mask and sign bit set accordingly
    int pow2 = 1 << width;
    int mask = pow2 - 1;
    int sign = pow2 >>> 1;

    boolean carry = false;
    int length = 0, pos = 0;

    while (pos <= k.bitLength()) {
        if (k.testBit(pos) == carry) {
            ++pos;
            continue;
        }

        k = k.shiftRight(pos);

        int digit = k.intValue() & mask;
        if (carry) {
            ++digit;
        }

        carry = (digit & sign) != 0;
        if (carry) {
            digit -= pow2;
        }

        length += (length > 0) ? pos - 1 : pos;
        wnaf[length++] = (byte) digit;
        pos = width;
    }

    // Reduce the WNAF array to its actual length
    if (wnaf.length > length) {
        wnaf = trim(wnaf, length);
    }

    return wnaf;
}

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From source file:Main.java

/**
 * Computes the Window NAF (non-adjacent Form) of an integer.
 * @param width The width <code>w</code> of the Window NAF. The width is
 * defined as the minimal number <code>w</code>, such that for any
 * <code>w</code> consecutive digits in the resulting representation, at
 * most one is non-zero.//from  ww  w  .  ja va2  s.c  o m
 * @param k The integer of which the Window NAF is computed.
 * @return The Window NAF of the given width, such that the following holds:
 * <code>k = &sum;<sub>i=0</sub><sup>l-1</sup> k<sub>i</sub>2<sup>i</sup>
 * </code>, where the <code>k<sub>i</sub></code> denote the elements of the
 * returned <code>byte[]</code>.
 */
public static byte[] generateWindowNaf(int width, BigInteger k) {
    if (width == 2) {
        return generateNaf(k);
    }

    if (width < 2 || width > 8) {
        throw new IllegalArgumentException("'width' must be in the range [2, 8]");
    }
    if (k.signum() == 0) {
        return EMPTY_BYTES;
    }

    byte[] wnaf = new byte[k.bitLength() + 1];

    // 2^width and a mask and sign bit set accordingly
    int pow2 = 1 << width;
    int mask = pow2 - 1;
    int sign = pow2 >>> 1;

    boolean carry = false;
    int length = 0, pos = 0;

    while (pos <= k.bitLength()) {
        if (k.testBit(pos) == carry) {
            ++pos;
            continue;
        }

        k = k.shiftRight(pos);

        int digit = k.intValue() & mask;
        if (carry) {
            ++digit;
        }

        carry = (digit & sign) != 0;
        if (carry) {
            digit -= pow2;
        }

        length += (length > 0) ? pos - 1 : pos;
        wnaf[length++] = (byte) digit;
        pos = width;
    }

    // Reduce the WNAF array to its actual length
    if (wnaf.length > length) {
        wnaf = trim(wnaf, length);
    }

    return wnaf;
}

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From source file:Main.java

public static byte[] generateJSF(BigInteger g, BigInteger h) {
    int digits = Math.max(g.bitLength(), h.bitLength()) + 1;
    byte[] jsf = new byte[digits];

    BigInteger k0 = g, k1 = h;
    int j = 0, d0 = 0, d1 = 0;

    while (k0.signum() > 0 || k1.signum() > 0 || d0 > 0 || d1 > 0) {
        int n0 = (k0.intValue() + d0) & 7, n1 = (k1.intValue() + d1) & 7;

        int u0 = n0 & 1;
        if (u0 != 0) {
            u0 -= (n0 & 2);//from ww w  .jav  a2 s.  c o m
            if ((n0 + u0) == 4 && (n1 & 3) == 2) {
                u0 = -u0;
            }
        }

        int u1 = n1 & 1;
        if (u1 != 0) {
            u1 -= (n1 & 2);
            if ((n1 + u1) == 4 && (n0 & 3) == 2) {
                u1 = -u1;
            }
        }

        if ((d0 << 1) == 1 + u0) {
            d0 = 1 - d0;
        }
        if ((d1 << 1) == 1 + u1) {
            d1 = 1 - d1;
        }

        k0 = k0.shiftRight(1);
        k1 = k1.shiftRight(1);

        jsf[j++] = (byte) ((u0 << 4) | (u1 & 0xF));
    }

    // Reduce the JSF array to its actual length
    if (jsf.length > j) {
        jsf = trim(jsf, j);
    }

    return jsf;
}

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From source file:Main.java

public static int[] generateCompactWindowNaf(int width, BigInteger k) {
    if (width == 2) {
        return generateCompactNaf(k);
    }//  w ww  .j a  v a 2  s . com

    if (width < 2 || width > 16) {
        throw new IllegalArgumentException("'width' must be in the range [2, 16]");
    }
    if ((k.bitLength() >>> 16) != 0) {
        throw new IllegalArgumentException("'k' must have bitlength < 2^16");
    }

    int[] wnaf = new int[k.bitLength() / width + 1];

    // 2^width and a mask and sign bit set accordingly
    int pow2 = 1 << width;
    int mask = pow2 - 1;
    int sign = pow2 >>> 1;

    boolean carry = false;
    int length = 0, pos = 0;

    while (pos <= k.bitLength()) {
        if (k.testBit(pos) == carry) {
            ++pos;
            continue;
        }

        k = k.shiftRight(pos);

        int digit = k.intValue() & mask;
        if (carry) {
            ++digit;
        }

        carry = (digit & sign) != 0;
        if (carry) {
            digit -= pow2;
        }

        int zeroes = length > 0 ? pos - 1 : pos;
        wnaf[length++] = (digit << 16) | zeroes;
        pos = width;
    }

    // Reduce the WNAF array to its actual length
    if (wnaf.length > length) {
        wnaf = trim(wnaf, length);
    }

    return wnaf;
}

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From source file:com.wms.utils.DataUtil.java

public static boolean checkValidateIPv4(String fromIPAddress, String toIPAddress, int mask) {

    BigInteger fromIP = ipv4ToNumber(fromIPAddress);
    BigInteger toIP = ipv4ToNumber(toIPAddress);
    BigInteger subnet = new BigInteger("FFFFFFFF", 16);

    fromIP = fromIP.shiftRight(32 - mask).shiftLeft(32 - mask);
    subnet = subnet.shiftRight(mask);//from w  ww  .  jav a 2s .  c  om

    BigInteger broadcastIP = fromIP.xor(subnet);

    if (toIP.compareTo(broadcastIP) == 1) {
        return false;
    }

    return true;
}

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From source file:com.wms.utils.DataUtil.java

public static String numberToIpv4(BigInteger ipNumber) {

    String ipString = "";
    BigInteger a = new BigInteger("FF", 16);

    for (int i = 0; i < 4; i++) {
        ipString = ipNumber.and(a).toString() + "." + ipString;

        ipNumber = ipNumber.shiftRight(8);
    }//from  w  w  w. j a  v  a  2s  .c o m

    return ipString.substring(0, ipString.length() - 1);
}

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From source file:com.wms.utils.DataUtil.java

public static String numberToIPv6(BigInteger ipNumber) {
    String ipString = "";
    BigInteger a = new BigInteger("FFFF", 16);

    for (int i = 0; i < 8; i++) {
        ipString = ipNumber.and(a).toString(16) + ":" + ipString;

        ipNumber = ipNumber.shiftRight(16);
    }/*from w  w w  .  j a  va2 s .  c  om*/

    return ipString.substring(0, ipString.length() - 1);

}

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From source file:Main.java

public static int[] generateCompactWindowNaf(int width, BigInteger k) {
    if (width == 2) {
        return generateCompactNaf(k);
    }/*from  w  ww.jav a2 s .com*/

    if (width < 2 || width > 16) {
        throw new IllegalArgumentException("'width' must be in the range [2, 16]");
    }
    if ((k.bitLength() >>> 16) != 0) {
        throw new IllegalArgumentException("'k' must have bitlength < 2^16");
    }
    if (k.signum() == 0) {
        return EMPTY_INTS;
    }

    int[] wnaf = new int[k.bitLength() / width + 1];

    // 2^width and a mask and sign bit set accordingly
    int pow2 = 1 << width;
    int mask = pow2 - 1;
    int sign = pow2 >>> 1;

    boolean carry = false;
    int length = 0, pos = 0;

    while (pos <= k.bitLength()) {
        if (k.testBit(pos) == carry) {
            ++pos;
            continue;
        }

        k = k.shiftRight(pos);

        int digit = k.intValue() & mask;
        if (carry) {
            ++digit;
        }

        carry = (digit & sign) != 0;
        if (carry) {
            digit -= pow2;
        }

        int zeroes = length > 0 ? pos - 1 : pos;
        wnaf[length++] = (digit << 16) | zeroes;
        pos = width;
    }

    // Reduce the WNAF array to its actual length
    if (wnaf.length > length) {
        wnaf = trim(wnaf, length);
    }

    return wnaf;
}

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