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:Main.java

public static void main(String[] argv) throws Exception {
    byte[] bytes = new byte[] { 0x1, 0x00, 0x00 };
    BigInteger bi = new BigInteger(bytes);
    bi = bi.shiftRight(1);

}

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From source file:Main.java

public static void main(String[] args) {

    BigInteger bi1 = new BigInteger("4");

    // perform right shift operation on bi1 using 2 and -2
    BigInteger bi2 = bi1.shiftRight(2);
    BigInteger bi3 = bi1.shiftRight(-2);

    System.out.println(bi2);//from  ww w  .  java  2s . co m
    System.out.println(bi3);
}

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From source file:Main.java

public static BigInteger modNear(BigInteger a, BigInteger b) {
    BigInteger res = a.mod(b);/*from w w  w .  j av  a  2  s  .com*/

    if (res.compareTo(b.shiftRight(1)) == 1)
        res = res.subtract(b);

    return res;
}

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From source file:Main.java

private static boolean passesMillerRabin(BigInteger us, int iterations, Random rnd) {
    final BigInteger ONE = BigInteger.ONE;
    final BigInteger TWO = BigInteger.valueOf(2);
    // Find a and m such that m is odd and this == 1 + 2**a * m
    BigInteger thisMinusOne = us.subtract(ONE);
    BigInteger m = thisMinusOne;
    int a = m.getLowestSetBit();
    m = m.shiftRight(a);

    // Do the tests
    if (rnd == null) {
        rnd = new SecureRandom();
    }/*ww  w .j  a  v  a 2s.  com*/
    for (int i = 0; i < iterations; i++) {
        // Generate a uniform random on (1, this)
        BigInteger b;
        do {
            b = new BigInteger(us.bitLength(), rnd);
        } while (b.compareTo(ONE) <= 0 || b.compareTo(us) >= 0);

        int j = 0;
        BigInteger z = b.modPow(m, us);
        while (!((j == 0 && z.equals(ONE)) || z.equals(thisMinusOne))) {
            if (j > 0 && z.equals(ONE) || ++j == a)
                return false;
            z = z.modPow(TWO, us);
        }
    }
    return true;
}

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From source file:Main.java

private static BigInteger findSquareRoot(BigInteger alpha, BigInteger p) {
    BigInteger beta = null;//from   ww  w .  j a  v a2 s.c  o  m
    if (p.mod(BigInteger.valueOf(4)).compareTo(BigInteger.valueOf(3)) == 0) {
        BigInteger k = p.shiftRight(2).add(ONE);
        beta = alpha.modPow(k, p);
    } else if (p.mod(BigInteger.valueOf(8)).compareTo(BigInteger.valueOf(5)) == 0) {
        System.out.println("p = 8 mod 5");
        BigInteger k = p.subtract(BigInteger.valueOf(5)).divide(BigInteger.valueOf(8));
        BigInteger gamma = alpha.multiply(BigInteger.valueOf(2)).modPow(k, p);
        BigInteger i = alpha.multiply(BigInteger.valueOf(2)).multiply(gamma.pow(2)).mod(p);
        beta = alpha.multiply(gamma).multiply(i.subtract(ONE)).mod(p);
    } else if (p.mod(BigInteger.valueOf(8)).compareTo(BigInteger.valueOf(1)) == 0) {
        beta = null;
        //TODO
        System.out.println("finding square root not fully implemented yet");
    }
    return beta;
}

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From source file:Main.java

/**
 * Convert to base 128 (bigendian), using shifts.
 * @param val//from  ww  w  . jav  a  2s  .c  om
 * @return
 */
public static ArrayList<Integer> base128(BigInteger val) {
    ArrayList<Integer> result = new ArrayList<Integer>();
    int part = val.and(BN127).intValue();
    val = val.shiftRight(7);
    result.add(0, new Integer(part));
    while (!val.equals(BigInteger.ZERO)) {
        part = val.and(BN127).intValue();
        val = val.shiftRight(7);
        part += 128;
        result.add(0, new Integer(part));
    }
    ;
    return result;
}

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From source file:Main.java

/**
 * Compute the square root of x to a given scale, x >= 0. Use Newton's
 * algorithm./* w  ww .  j  a  v a2s.co  m*/
 * 
 * @param x
 *            the value of x
 * @return the result value
 */
public static BigDecimal sqrt(BigDecimal x) {
    // Check that x >= 0.
    if (x.signum() < 0) {
        throw new ArithmeticException("x < 0");
    }

    // n = x*(10^(2*SCALE))
    BigInteger n = x.movePointRight(SCALE << 1).toBigInteger();

    // The first approximation is the upper half of n.
    int bits = (n.bitLength() + 1) >> 1;
    BigInteger ix = n.shiftRight(bits);
    BigInteger ixPrev;

    // Loop until the approximations converge
    // (two successive approximations are equal after rounding).
    do {
        ixPrev = ix;

        // x = (x + n/x)/2
        ix = ix.add(n.divide(ix)).shiftRight(1);

        Thread.yield();
    } while (ix.compareTo(ixPrev) != 0);

    return new BigDecimal(ix, SCALE);
}

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From source file:Main.java

public static BigInteger pow(BigInteger base, BigInteger exponent) {
    BigInteger result = BigInteger.ONE;
    while (exponent.signum() > 0) {
        if (exponent.testBit(0))
            result = result.multiply(base);
        base = base.multiply(base);/*from  w  w  w.  j  a v  a2  s  . c o  m*/
        exponent = exponent.shiftRight(1);
    }
    return result;
}

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From source file:Main.java

static BigInteger mulmod(BigInteger a, BigInteger b, BigInteger p) {
    BigInteger r = BigInteger.ZERO;
    while (b.compareTo(BigInteger.ZERO) > 0) {
        if (!b.and(BigInteger.ONE).equals(BigInteger.ZERO)) {
            r = addmod(r, a, p);/*from w ww.  j  a v  a 2  s  . c  om*/
        }
        b = b.shiftRight(1);
        a = addmod(a, a, p);
    }
    return r;
}

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From source file:com.clustercontrol.repository.util.RepositoryUtil.java

/**
 * BigIntegerIP(IPv6)?????/*from w ww . j av a2s .com*/
 * @param argInt IPv6?
 * @return String
 */
public static String bigIntToIpV6(BigInteger argInt) {

    StringBuilder str = new StringBuilder();
    for (int i = 15; i >= 0; i--) {
        int shift = 8 * i;
        Integer n = 0xff;
        BigInteger num = argInt.shiftRight(shift).and(new BigInteger(n.toString()));
        int intNum = num.intValue();
        String s = Integer.toHexString(intNum);
        if (s.length() < 2) {
            s = "0" + s;
        }
        str.append(s);
        if (i > 0 && i < 15) {
            int f = i % 2;
            str.append(f == 0 ? ":" : "");
        }
    }
    return str.toString();
}

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