Example usage for java.math BigInteger shiftLeft

Introduction

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

Prototype

public BigInteger shiftLeft(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.shiftLeft(3);

}

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From source file:Main.java

public static void main(String[] args) {

    BigInteger bi1 = new BigInteger("10");

    // perform leftshift operation on bi1 using 2 and -2
    BigInteger bi2 = bi1.shiftLeft(2);
    BigInteger bi3 = bi1.shiftLeft(-2);

    System.out.println(bi2);/*from www.  j ava  2  s.  c o m*/
    System.out.println(bi3);
}

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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);
    }//from   www  .  ja v  a  2  s.  c  o m

    return naf;
}

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From source file:Main.java

public static int getNafWeight(BigInteger k) {
    if (k.signum() == 0) {
        return 0;
    }/*ww w  .j  a  v  a  2  s . com*/
    return k.shiftLeft(1).add(k).xor(k).bitCount();
}

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From source file:Main.java

public static int getNafWeight(BigInteger k) {
    if (k.signum() == 0) {
        return 0;
    }// w  w w. j  av a  2 s .  com

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

    return diff.bitCount();
}

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From source file:Main.java

public static BigInteger byteArrayToBigInteger(byte[] b, int offset, int length) {
    if (b.length < offset + length) {
        throw new IllegalArgumentException("offset + length must be less than or equal to b.length");
    }//from   w w  w.  ja  va2s  . co  m

    BigInteger value = BigInteger.valueOf(0);
    for (int i = 0; i < length; i++) {
        value = value.shiftLeft(8);
        value = value.add(BigInteger.valueOf(b[i + offset] & 0x000000ff));
    }
    return value;
}

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From source file:Main.java

public static byte[] generateNaf(BigInteger k) {
    if (k.signum() == 0) {
        return EMPTY_BYTES;
    }/*from  ww w.ja  va 2 s . 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:ID.java

public static String getHexString(byte[] bytes) {
    // This method cannot change even if it's wrong.
    BigInteger bigInteger = BigInteger.ZERO;
    int shift = 0;
    for (int i = bytes.length; --i >= 0;) {
        BigInteger contrib = BigInteger.valueOf(bytes[i] & 0xFF);
        contrib = contrib.shiftLeft(shift);
        bigInteger = bigInteger.add(contrib);
        shift += 8;/*from  ww  w  .  ja v  a2s. c o m*/
    }
    return bigInteger.toString(16).toUpperCase();
}

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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");
    }/*from w ww  .  j av  a2s  .  com*/

    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:Main.java

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