Example usage for java.math BigInteger testBit

Introduction

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

Prototype

public boolean testBit(int n) 

Source Link

Document

Returns true if and only if the designated bit is set.

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);
    boolean b = bi.testBit(3);
    b = bi.testBit(16);//from  ww  w. j ava  2  s .  c  o m
}

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From source file:Main.java

public static void main(String[] args) {

    BigInteger bi = new BigInteger("10");

    Boolean b1 = bi.testBit(2);
    Boolean b2 = bi.testBit(3);/*from   w w w  .ja va 2s  .c  om*/
    // print b1, b2 values
    System.out.println(b1);
    System.out.println(b2);
}

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From source file:Main.java

public static byte[] generateNaf(BigInteger k) {
    if (k.signum() == 0) {
        return EMPTY_BYTES;
    }// w  w w.j  a  v  a2s. c o m

    BigInteger _3k = k.shiftLeft(1).add(k);

    int digits = _3k.bitLength() - 1;
    byte[] naf = new byte[digits];

    BigInteger diff = _3k.xor(k);

    for (int i = 1; i < digits; ++i) {
        if (diff.testBit(i)) {
            naf[i - 1] = (byte) (k.testBit(i) ? -1 : 1);
            ++i;
        }
    }

    naf[digits - 1] = 1;

    return naf;
}

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From source file:Main.java

public static int hammingWeight(BigInteger value) {
    int weight = 0;
    for (int i = 0; i <= value.bitLength(); i++) {
        if (value.testBit(i))
            weight++;/*from  ww w .  ja  v a2 s . c o m*/
    }
    return weight;
}

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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  ava2s  .  co  m
        exponent = exponent.shiftRight(1);
    }
    return result;
}

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From source file:Main.java

public static byte[] generateNaf(BigInteger k) {
    BigInteger _3k = k.shiftLeft(1).add(k);

    int digits = _3k.bitLength() - 1;
    byte[] naf = new byte[digits];

    for (int i = 1; i <= digits; ++i) {
        boolean _3kBit = _3k.testBit(i);
        boolean kBit = k.testBit(i);

        naf[i - 1] = (byte) (_3kBit == kBit ? 0 : kBit ? -1 : 1);
    }/* ww  w .ja  va  2  s .c o m*/

    return naf;
}

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From source file:Main.java

public static int[] generateCompactNaf(BigInteger k) {
    if ((k.bitLength() >>> 16) != 0) {
        throw new IllegalArgumentException("'k' must have bitlength < 2^16");
    }//  ww w  .  j  a v a 2  s.  c o m
    if (k.signum() == 0) {
        return EMPTY_INTS;
    }

    BigInteger _3k = k.shiftLeft(1).add(k);

    int bits = _3k.bitLength();
    int[] naf = new int[bits >> 1];

    BigInteger diff = _3k.xor(k);

    int highBit = bits - 1, length = 0, zeroes = 0;
    for (int i = 1; i < highBit; ++i) {
        if (!diff.testBit(i)) {
            ++zeroes;
            continue;
        }

        int digit = k.testBit(i) ? -1 : 1;
        naf[length++] = (digit << 16) | zeroes;
        zeroes = 1;
        ++i;
    }

    naf[length++] = (1 << 16) | zeroes;

    if (naf.length > length) {
        naf = trim(naf, length);
    }

    return naf;
}

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From source file:Main.java

public static int[] generateCompactNaf(BigInteger k) {
    if ((k.bitLength() >>> 16) != 0) {
        throw new IllegalArgumentException("'k' must have bitlength < 2^16");
    }/*ww w. j  a va  2s  .  c o  m*/

    BigInteger _3k = k.shiftLeft(1).add(k);

    int digits = _3k.bitLength() - 1;
    int[] naf = new int[(digits + 1) >> 1];

    int length = 0, zeroes = 0;
    for (int i = 1; i <= digits; ++i) {
        boolean _3kBit = _3k.testBit(i);
        boolean kBit = k.testBit(i);

        if (_3kBit == kBit) {
            ++zeroes;
        } else {
            int digit = kBit ? -1 : 1;
            naf[length++] = (digit << 16) | zeroes;
            zeroes = 0;
        }
    }

    if (naf.length > length) {
        naf = trim(naf, length);
    }

    return naf;
}

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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.//  www .j a v  a  2s  .c  o m
 * @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:org.apache.cassandra.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.//from   w ww .  j a v  a  2 s  . co m
 * @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<BigInteger, Boolean>(midpoint, remainder);
}

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